.. role:: underline :class: underline =========== WRF Physics =========== | | .. figure:: ../images/users_guide/phys_processes.png :width: 700px :align: center :height: 400px | Earth's atmosphere houses a variety of interacting physical processes, as are illustrated in the above image. * Shortwave radiation from the sun is absorbed, reflected, and/or scattered by Earth's surface, clouds, aerosols, gases, etc. * Longwave radiation emitted from Earth's surface either exits the atmosphere or is deflected back by gas particles and clouds. * Heating from diurnal radiation creates a boundary-layer, which increases turbulence and potentially convection. * Clouds are created by radiative or lifting processes, and produce precipitation in various forms (e.g., rain, snow, and graupel). * Chemical components (e.g., aerosols, ozone, and pollutants) can modify clouds and radiation. * At the surface, the roughness and other properties of land types (e.g., mountains, trees, buildings) modify surface fluxes. | All of these processes work together to create our weather and climate. The WRF model code offers various physics that employ different calulation methods to best represent Earth's atmospheric. The below image illustrates the ways in which the schemes interact. | .. figure:: ../images/users_guide/phys_scheme_interaction.png :width: 700px :align: center :height: 400px | | | | | Cumulus Parameterization ======================== .. figure:: ../images/users_guide/cu.png :width: 600px :align: center :height: 350px | | .. container:: row m-0 p-0 .. container:: col-md-12 pl-0 pr-3 py-3 m-0 .. container:: card px-0 h-100 .. rst-class:: card-header-def .. rubric:: WRF Cumulus Parameterization Schemes .. container:: card-body-def Physics schemes that parameterize sub-grid-scale effects of convective and shallow clouds. | Cumulus schemes activate column-by-column, depending on the presence of convective instability, and are responsible for the following: * Providing column tendencies of heat and moisture to the model * Providing the convective component of surface rainfall to the model * Redistributing air in gridded columns to account for vertical convective fluxes * Updrafts lift boundary layer air, while downdrafts bring mid-level air downward. Schemes determine when and how quickly to trigger a convective column. | WRF cumulus schemes (except BMJ) are mass flux schemes, determining updraft/downdraft mass (and other) fluxes - this can include momentum transport. Updrafts, driven by buoyancy, send moist surface air up to the upper troposphere, and condensation becomes convective rainfall. Downdrafts occur when convective rain evaporates, which cools air to the boundary layer. Subsidence, the primary warming contributor in the column, warms and dries the troposphere. The BMJ scheme is an adjustment type, and relaxes toward a post-convective (mixed) sounding. | **It is not always necessary to use cumulus parameterization**. It is designed for grid sizes unable to parameterize the convective processes (i.e., when updrafts and downdrafts are sub-grid). | | .. figure:: ../images/users_guide/cu_recommendations.png :width: 550px :align: center :height: 350px | | The following are general rules for WRF cumulus parameterization, which are illustrated in the above image: .. csv-table:: :header: Domain Grid Spacing, Guidelines :escape: \ :width: 80% :widths: 20,60 **>=10km** , a cumulus scheme is necessary **<=3km** , a cumulus scheme is likely unnecessary\, though it may help if convection exists just prior to the simulation start time **>=3km** to **<=10km** , This is a "gray zone" where cumulus parameterization may or may not be necessary; try to avoid domains this size; if unavoidable\, use the Multi-scale Kain Fritsch or Grell-Freitas scheme\, which account for these scales. | | .. seealso:: `See the WRF Tutorial presentation on cumulus parameterization `_ for additional details. | | | | Cumulus Options --------------- Moisture tendencies below represent mixing ratios of: * **c** : cloud water * **r** : rain water * **i** : cloud ice * **s** : snow | .. csv-table:: :widths: 70, 30, 50, 50, 60, 50 :align: left :header: "Scheme", "Option", "Moisture Tendencies", "Momentum Tendencies", "Shallow Convection", "Radiation Interaction" "Kain-Fritsch (KF)", 1, "Qc Qr Qi Qs", no, yes, yes "BMJ", 2, "N/A", no, yes, GFDL "Grell-Freitas", 3, "Qc Qi", no, yes, yes "Old SAS", 4, "Qc Qi", no, yes, GFDL "Grell-3", 5, "Qc Qi", no, yes, yes "Tiedtke", 6, "Qc Qi", yes, yes, no "Zhang-McFarlane", 7, "Qc Qi", yes, yes, RRTMG "KF-CuP", 10, "Qc Qi", no, yes, yes "Multi-scale KF", 11, "Qc Qr Qi Qs", no, yes, ? "KIAPS SAS", 14, "Qc Qi", yes, use shcu_physics=4, GFDL "New Tiedtke", 16, "Qc Qi", yes, yes, no "Grell-Devenyi", 93, "Qc Qi", no, no, yes "NSAS", 96, "Qc Qi", yes, no/yes, GFDL "Old KF", 99, "Qc Qr Qi Qs", no, no, GFDL | | | | Cumulus Details and References ------------------------------ | Kain-Fritsch (KF) +++++++++++++++++ *cu_physics=1* |br| Deep and shallow convection sub-grid scheme using a mass flux approach with downdrafts and CAPE removal time scale |br| `Kain, 2004 `_ | The following additional options may be used with this scheme: * **kfeta_trigger** : * *=1* : default trigger * *=2* : moisture-advection modulated trigger function (`Ma and Tan, 2009 `_), which can improve results in subtropical regions with weak large-scale forcing * *=3* : RH-dependent perturbation - additional to option 1 | * **cu_rad_feedback=.true.** : allows sub-grid cloud fraction interaction with radiation (`Alapaty et al., 2012 `_) | | | Betts-Miller-Janjic (BMJ) +++++++++++++++++++++++++ *cu_physics=2* |br| Operational Eta scheme. Column moist adjustment scheme relaxing towards a well-mixed profile. |br| `Janjic, 1994 `_ | | | Grell-Freitas (GF) ++++++++++++++++++ *cu_physics=3* |br| An improved :ref:`GD scheme` that attempts smoothing the transition to cloud-resolving scales, as proposed by `Arakawa et al., 2004 `_ |br| `Grell and Freitas, 2014 `_ | | | Simplified Arakawa-Schubert (SAS) +++++++++++++++++++++++++++++++++ *cu_physics=4* |br| Simple mass-flux scheme with quasi-equilibrium closure, that includes a shallow mixing scheme. |br| `Pan et al., 1995 `_ | | | Grell 3D (G3) +++++++++++++ *cu_physics=5* |br| An improved :ref:`GD scheme` that can be used with high (and coarse) resolution when subsidence spreading (*cugd_avedx*) is turned on. |br| `Grell, 1993 `_ |br| `Grell and Devenyi, 2002 `_ | | | Tiedtke scheme ++++++++++++++ *cu_physics=6* |br| (U. of Hawaii version); Mass-flux scheme with a CAPE-removal time scale, shallow component, and momentum transport. |br| `Tiedtke, 1989 `_ |br| `Zhang et al., 2011 `_ | | | Zhang-McFarlane +++++++++++++++ *cu_physics=7* |br| Mass-flux CAPE-removal deep convection scheme with momentum transport - from the CESM climate model. |br| `Zhang and McFarlane, 1995 `_ | | | Kain-Fritsch (KF) +++++++++++++++++ *cu_physics=10* |br| Cumulus Potential scheme, which modifies the KF ad-hoc trigger function. This scheme links to boundary layer turbulence via probability density functions (PDFs) and computes cumulus cloud fraction based on a time scale relevant for shallow cumuli. |br| `Berg et al., 2013 `_ | | | .. _Multi-scale Kain-Fritsch: Multi-scale Kain-Fritsch ++++++++++++++++++++++++ *cu_physics=11* |br| LCC-based entrainment, using a scale-dependent dynamic adjustment timescale and a trigger function based on `Bechtold et al., 2001 `_; includes an option to use CESM aerosol. Since wrfv4.2 convective momentum transport is added and turned on, by default - turn off by setting *cmt_opt_flag = .false.* in *wrf/phys/module_cu_mskf.F* - then recompile WRF (no need to use 'clean -a' or reconfigure). |br| `Zheng et al., 2016 `_ |br| `Glotfelty et al., 2019 `_ | | | KIAPS SAS (KSAS) ++++++++++++++++ *cu_physics=14* |br| Based on :ref:`NSAS`, but scale-aware |br| `Han and Pan, 2011 `_ |br| `Kwon and Hong, 2017 `_ | | | New Tiedtke +++++++++++ *cu_physics=16* |br| Similar to the Tiedtke scheme used in REGCM4 and ECMWF cy40r1. |br| `Zhang and Wang, 2017 `_ | | | .. _GD scheme: Grell-Devenyi (GD) ++++++++++++++++++ *cu_physics=93* |br| A multi-closure, multi-parameter, ensemble method with (typically) 144 sub-grid members. |br| `Grell and Devenyi, 2002 `_ | | | .. _NSAS: New Simplified Arakawa-Schubert (NSAS) ++++++++++++++++++++++++++++++++++++++ *cu_physics=96* |br| A mass-flux scheme with deep/shallow components, and momentum transport. |br| `Han and Pan, 2011 `_ | | | Old Kain-Fritsch ++++++++++++++++ *cu_physics=99* |br| Deep convection scheme that uses a mass flux approach, including downdrafts and a CAPE removal time scale. |br| `Kain and Fritsch, 1990 `_ | | | | | Shallow Convection ------------------ In addition to cumulus parameterization, shallow convection schemes can be used for grid sizes in which shallow cumulus clouds (>1 km) are not resolved. These scheme allow non-precipitating shallow mixing to dry the planetary boundary layer, and then moisten and cool above by enhanced mixing, or with a mass-flux approach. The following cumulus schemes already include shallow convection: * Kain-Fritsch * Old SAS * KIAPS SAS * Grell-3 * Grell-Freitas * BMJ * Tiedtke | | The following standalone shallow schemes are available: .. csv-table:: :escape: \ :width: 80% :widths: 15, 65 **ishallow=1** , Shallow convection that works with the Grell 3D scheme (*cu_physics=5*) **shcu_physics=2** , UW (Bretherton and Park) shallow cumulus option from the CESM climate model - includes momentum transport |br| `Park et al.\, 2009 `_ **shcu_physics=3** , GRIMS (Global/Regional Integrated Modeling System) scheme; represents the shallow convection process with eddy-diffusion and the pal algorithm\, and couples directly to the YSU PBL scheme |br| `Hong and Jang\, 2018 `_ **shcu_physics=4** , NSAS shallow scheme; extracted from NSAS\, and should be used with the KSAS deep cumulus scheme **shcu_physics=5** , Deng shallow scheme; only works with the MYNN and MYJ PBL schemes; *(available since wrfv4.1)* |br| `Deng et al.\, 2003 `_ | | | | | Microphysics ============ .. figure:: ../images/users_guide/mp.png :width: 600px :align: center :height: 350px | | .. container:: row m-0 p-0 .. container:: col-md-12 pl-0 pr-3 py-3 m-0 .. container:: card px-0 h-100 .. rst-class:: card-header-def .. rubric:: WRF Microphysics Schemes .. container:: card-body-def Physics schemes that resolve cloud and precipitation processes, with some accounting for ice and/or mixed-phases processes. | | WRF microphysics schemes provide atmospheric heat and moisture tendencies, and the resolved-scale (non-convective) rainfall at the surface. They consider various microphysical processes and different particle formation, depending on their type: * Cloud droplets (10s of microns) condense from vapor at water saturation * Rain (~mm diameter) forms from cloud droplet growth * Ice crystals (10s of microns) form from droplet freezing or deposition on nuclei, which are assumed or explicit (e.g., dust particles) * Snow (100s of microns) forms from growth of ice crystals at ice supersaturation and aggregation * Graupel/hail (mm to cm) form and grow from mixed-phase interactions between water and ice particles * Precipitating particles are typically assigned to an observationally-based size distribution | | WRF includes the following types of microphysics schemes: .. note:: More advanced scheme types are more computationally expensive. | .. csv-table:: :escape: \ :width: 80% :widths: 15, 65 **Single-moment**, Use a single prediction mass equation per species\, where particle size distribution is derived from fixed parameters (Qr\, Qs\, etc.) **Double-moment**, Add a number concentration prediction equation per double-moment species (Nr\, Ns\, etc.)\, allowing for additional processes (e.g.\, size-sorting during fall-out\, aerosol effects\, etc.) **Spectral bin**, resolve size distribution by doubling mass bins | .. seealso:: `See the WRF Tutorial presentation on microphysics `_ for additional details. | | | | Microphysics Options -------------------- In the table below, abbreviations are defined as follows: .. figure:: ../images/users_guide/mp_abbreviations.png :width: 670px :height: 350px | | .. csv-table:: :widths: 50, 20, 50, 50 :align: left :header: "Scheme", "Option", "Mass Variables", "Number Variables" "Kessler", 1, "Qc Qr", N/A "Purdue Lin", 2, "Qc Qr Qi Qs Qg", N/A "WSM3", 3, "Qc Qr", N/A "WSM5", 4, "Qc Qr Qi Qs", N/A "Eta (Ferrier)", 5, "Qc Qr Qs Qt*", N/A "WSM6", 6, "Qc Qr Qi Qs Qg", N/A "Goddard 4-ice", 7, "Qc Qr Qi Qs Qg Qh", N/A "Thompson", 8, "Qc Qr Qi Qs Qg", "Ni Nr" "Milbrandt 2-mom", 9, "Qc Qr Qi Qs Qg Qh", "Nc Nr Ni Ns Ng Nh" "Morrison 2-mom", 10, "Qc Qr Qi Qs Qg", "Nr Ni Ns Ng" "CAM 5.1", 11, "Qc Qr Qi Qs", "Nc Nr Ni Ns" "SBU-YLin", 13, "Qc Qr Qi Qs", N/A "WDM5", 14, "Qc Qr Qi Qs", "Nn Nc Nr" "WDM6", 16, "Qc Qr Qi Qs Qg", "Nn Nc Nr" "NSSL", 18, "Qc Qr Qi Qs Qg Qh", "Nc Nr Ni Ns Ng Nh Nn" "WSM7", 24, "Qc Qr Qi Qs Qg Qh", N/A "WDM7", 26, "Qc Qr Qi Qs Qg Qh", "Nc Nr" "Thompson Aerosol", 28, "Qc Qr Qi Qs Qg", "Nc Ni Nr Nn Nni" "HUJI Fast", 30, "Qc Qr Qi Qs Qg", "Nn Nc Nr Ni Ns Ng" "Thompson Hail/Graupel/Aerosol", 38, "Qc Qr Qi Qs Qg", "Nc Ni Nr Nn Nni Ng Vg" Morrison 2-mom Aerosol, 40, Qc Qr Qi Qs Qg, "" "P3", 50, "Qc Qr Qi", "Nr Ni Ri Bi" "P3-nc", 51, "Qc Qr Qi", "Nc Nr Ni Ri Bi" "P3-2nd", 52, "Qc Qr Qi2", "Nc Nr Ni Ni2 Ri Ri2 Bi Bi2" "P3-3mc", 53, "Qc Qr Qi", "Nc Nr Ni Ri Bi Zi" "ISHMAEL", 55, "Qc Qr Qi Qi2 Qi3", "Nr Ni Ni2 Ni3 Vi Vi2 Vi3 Ai Ai2 Ai3" "NTU", 56, "Qc Qr Qi Qs Qg Qh Qden Qten Qccn Qrcn", "Nc Nr Ni Ns Ng Nh Nin Ai As Ag Ah Vi Vs Vg Fi Fs" .. "HUJI Full", 32, "Qc Qr Qic Qip Qid Qs Qg Qh", "Nn Nc Nr Nic Nip Nid Ns Ng Nh" | | | | Microphysics Option Details and References ------------------------------------------ | Kessler +++++++ *mp_physics=1* |br| A warm-rain (no ice) scheme used commonly in idealized cloud modeling studies |br| `Kessler, 1969 `_ | | | Purdue Lin ++++++++++ *mp_physics=2* |br| A sophisticated scheme that includes ice, snow, and graupel processes suitable for real-data high-resolution simulations |br| `Chen and Sun, 2002 `_ | | | .. _WSM3: WRF Single-moment 3-class (WSM3) ++++++++++++++++++++++++++++++++ *mp_physics=3* |br| A simple, efficient scheme with ice and snow processes, suitable for mesoscale grid sizes |br| `Hong et al., 2004 `_ | | | .. _WSM5: WRF Single-moment 5-class (WSM5) ++++++++++++++++++++++++++++++++ *mp_physics=4* |br| A slightly more sophisticated version of :ref:`WSM3` that allows for mixed-phase processes and super-cooled water |br| `Hong et al., 2004 `_ | | | Ferrier Eta +++++++++++ *mp_physics=5* |br| The operational microphysics used in NCEP models; simple and efficient, with diagnostic mixed-phase processes; for fine resolutions (<5km) |br| `NOAA, 2001 `_ | | | .. _WSM6: WRF Single-moment 6-class (WSM6) ++++++++++++++++++++++++++++++++ *mp_physics=6* |br| Includes ice, snow and graupel processes, suitable for high-resolution simulations |br| `Hong and Lim, 2006 `_ | | | Goddard 4-ice +++++++++++++ *mp_physics=7* |br| Predicts hail and graupel separately; provides effective radii for radiation. *Replaced older Goddard scheme since wrfv4.1.* |br| `Tao et al., 1989 `_ |br| `Tao et al., 2016 `_ | | | Thompson et al. +++++++++++++++ *mp_physics=8* |br| Includes ice, snow and graupel processes suitable for high-resolution simulations |br| `Thompson et al., 2008 `_ | | | Milbrandt-Yau Double-moment 7-class +++++++++++++++++++++++++++++++++++ *mp_physics=9* |br| Includes separate categories for hail and graupel with double-moment cloud, rain, ice, snow, graupel and hail |br| `Milbrandt and Yau, 2005 (Part I) `_ |br| `Milbrandt and Yau, 2005 (Part II) `_ | | | .. _Morrison Double-moment: Morrison Double-moment ++++++++++++++++++++++ *mp_physics=10* |br| Double-moment ice, snow, rain and graupel for cloud-resolving simulations |br| `Morrison et al., 2009 `_ | | | CAM V5.1 2-moment 5-class +++++++++++++++++++++++++ *mp_physics=11* |br| `User's Guide to the CAM-5.1 `_ | | | Stony Brook University (Y. Lin) +++++++++++++++++++++++++++++++ *mp_physics=13* |br| A 5-class scheme with riming intensity predicted to account for mixed-phase processes |br| `Lin and Colle, 2011 `_ | | | WRF Double-moment 5-class (WDM5) ++++++++++++++++++++++++++++++++ *mp_physics=14* |br| Similar to :ref:`WSM5`, but includes double-moment rain, and cloud and CCN for warm processes |br| `Lim and Hong, 2010 `_ | | | .. _WDM6: WRF Double-moment 6-class (WDM6) ++++++++++++++++++++++++++++++++ *mp_physics=16* |br| Similar to :ref:`WSM6`, but includes double-moment rain, and cloud and CCN for warm processes |br| `Lim and Hong, 2010 `_ .. seealso:: * See *WRF/doc/README.NSSLmp* for details about NSSL microphysics schemes. * If using WRF prior to v4.6.0, and an NSSL microphysics scheme, `see NSSL Options Prior to v4.6.0 `_. | | | NSSL 3-moment scheme with hail and CCN prediction +++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=18* |br| and either of the following: * **nssl_3moment=1** : predict radar reflectivity from rain * **nssl_3moment=2** : predict radar reflectivity of rain and hail | `Mansell et al., 2010 `_ .. note:: This option is available for WRF v4.6.0+. | | | NSSL 2-moment scheme with hail and CCN prediction +++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=18* |br| `Mansell et al., 2010 `_ | | | NSSL 2-moment scheme without hail +++++++++++++++++++++++++++++++++ *mp_physics=18* |br| and either of the following: * **nssl_hail_on=0** * **nssl_ccn_on=0** | `Mansell et al., 2010 `_ .. note:: This option is equivalent to *mp_physics=22* from versions prior to v4.6.0. | | | NSSL 2-moment scheme with hail and constant background CCN ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=18*, and |br| *nssl_ccn_on=0* |br| `Mansell et al., 2010 `_ .. note:: This option is equivalent to *mp_physics=17* from versions prior to v4.6.0. | | | NSSL single-moment scheme, 7-class with predicted graupel density +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=18*, and |br| *nssl_2moment_on=0* |br| *nssl_ccn_on=0* |br| `Mansell et al., 2010 `_ .. note:: This option is equivalent to *mp_physics=19* from versions prior to v4.6.0. | | | NSSL single-moment scheme, 6-class with predicted graupel density +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=18*, and |br| *nssl_2moment_on=0* |br| `Mansell et al., 2010 `_ .. note:: This option is equivalent to *mp_physics=19* from versions prior to v4.6.0. | | | NSSL single-moment scheme, 6-class ++++++++++++++++++++++++++++++++++ *mp_physics=18*, and |br| *nssl_2moment_on=0* |br| *nssl_hail_on=0* |br| *nssl_ccn_on=0* |br| *nssl_density_on=0* |br| `Mansell et al., 2010 `_ .. note:: This option is equivalent to *mp_physics=21* from versions prior to v4.6.0. | | | WRF Single-moment 7-class (WSM7) ++++++++++++++++++++++++++++++++ *mp_physics=24* |br| Similar to :ref:`WSM6`, but with an added hail category *(effective beginning with v4.1)* |br| `Bae et al., 2018 `_ | | | WRF Double-moment 7-class (WDM7) ++++++++++++++++++++++++++++++++ *mp_physics=26* |br| Similar to :ref:`WDM6`, but with an added hail category *(effective beginning with v4.1)* |br| `Bae et al., 2018 `_ | | | .. _`Thompson Aerosol-aware`: Thompson Aerosol-aware ++++++++++++++++++++++ *mp_physics=28* |br| Considers water- and ice-friendly aerosols |br| `Thompson and Eidhammer, 2014 `_ * A climatology data set may be used to specify initial and boundary conditions for the aerosol variables; includes a surface dust scheme. * Since wrfv4.4 a `black carbon aerosol category `_ is added; biomass burning is an options. | | | Hebrew University of Jerusalem Fast (HUJI) ++++++++++++++++++++++++++++++++++++++++++ *mp_physics=30* |br| Spectral bin microphysics, fast version |br| `Shpund et al., 2019 `_ | .. **Hebrew University of Jerusalem Full (HUJI)** |br| .. *mp_physics=32* |br| .. Spectral bin microphysics, full version |br| .. `Khain et al., 2004`_ | | | Thompson Hail/Graupel/Aerosol +++++++++++++++++++++++++++++ *mp_physics=38* |br| Similar to :ref:`Thompson Aerosol-aware`, but computes two-moment prognostics for graupel and hail and includes a predicted density graupel category. Datafile `qr_acr_qg_mp38V1.dat `_ must be in the directory where wrf.exe is run, or it can alternatively be computed using namelist option *write_thompson_mp38table=.true.* (note this may take ~20 mins using 12 CPUs, ~5 mins with 128 CPUs, and several hours with a single CPU). | | | Morrison double-moment scheme with CESM aerosol +++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=40* |br| Similar to :ref:`Morrison Double-moment`, but with CESM aerosol added. This option is only valid with the :ref:`Multi-scale Kain-Fritsch` cumulus scheme (*cu_physics=11*) and requires `CESM RCP4.5 data `_ - after downloading, unpack the file and link one of the available files to the directory where wrf.exe is run. |br| *No publication available for this specific scheme* | | | .. _Morrison and Milbrandt Predicted Particle Property (P3): Morrison and Milbrandt Predicted Particle Property (P3) +++++++++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=50* |br| A single ice category representing a combination of ice, snow and graupel that carries prognostic arrays for rimed ice mass and volume; single-moment rain and ice. |br| `Morrison and Milbrandt, 2015 `_ | | | Morrison and Milbrandt Predicted Particle Property (P3-nc) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=51* |br| As in :ref:`Morrison and Milbrandt Predicted Particle Property (P3)`, but adds supersaturation-dependent activation and double-moment cloud water |br| `Morrison and Milbrandt, 2015 `_ | | | Morrison and Milbrandt Predicted Particle Property (P3-2ice) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=52* |br| As in :ref:`Morrison and Milbrandt Predicted Particle Property (P3)`, but with two ice arrays and double-moment cloud water |br| `Morrison and Milbrandt, 2015 `_ | | | Morrison and Milbrandt Predicted Particle Property (P3-3moment) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ *mp_physics=53* |br| As in :ref:`Morrison and Milbrandt Predicted Particle Property (P3)`, but with 3-moment ice and double-moment cloud water |br| *No publication available for this scheme* | | | Jensen ISHMAEL ++++++++++++++ *mp_physics=55* |br| Predicts particle shapes and habits in ice crystal growth; *(available since wrfv4.1)* |br| `Jensen et al., 2017 `_ | | | National Taiwan University (NTU) ++++++++++++++++++++++++++++++++ *mp_physics=56* |br| Double-moment liquid phase and triple-moment ice phase, considers ice crystal shape and density variations; supersaturation is resolved so that condensation nuclei (CN) activation is explicitly calculated; CN’s droplet mass accounts for aerosol recycling. |br| `Tsai and Chen, 2020 `_ | | | | | Radiation ========= | .. figure:: ../images/users_guide/rad.png :width: 600px :align: center :height: 350px | | .. container:: row m-0 p-0 .. container:: col-md-12 pl-0 pr-3 py-3 m-0 .. container:: card px-0 h-100 .. rst-class:: card-header-def .. rubric:: WRF Radiation Schemes .. container:: card-body-def WRF physics schemes that obtain cloud properties from the microphysics scheme to compute atmospheric temperature tendency profiles and longwave/shortwave surface radiative fluxes. | | **Longwave Radiation Schemes** Compute longwave radiation emitted and absorbed by the earth's surface/clouds, and gases (e.g., water vapor, CO2). Wavelengths are thermal IR - longer than ~ 3 microns. **Shortwave schemes** Compute incoming solar fluxes reflected by Earth's surface/clouds or absorbed by gases (e.g., water vapor, ozone, aerosols). These schemes account for annual and diurnal cycles and include ultraviolet, visible, and near-IR solar spectrum wavelengths. | | .. figure:: ../images/users_guide/rad_visual.png :width: 600px :align: center :height: 350px | | .. seealso:: `See the WRF Tutorial presentation on radiation `_ for additional details. | | | | .. _Longwave Radiation Schemes: Longwave Radiation Schemes -------------------------- WRF longwave radiation schemes: * Compute clear-sky and cloud upward and downward raditation fluxes * Consider infrared emissions from layers * Calculate surface emissivity based on the land type at each grid point * Cools each layer, due to flux divergence of layer emissions * Considers downward flux at the surface, which is crucial to the land-energy budget * Infrared radiation generally leads to cooling in clear air (~2K/day), with stronger cooling at cloud tops and warming at cloud bases | | In the table below, microphysics interactions represent mixing ratios of: * **c** : cloud water * **r** : rain water * **i** : cloud ice * **s** : snow * **g** : graupel | .. csv-table:: :widths: 45, 25, 50, 55, 70 :align: left :header: "Scheme", "Option", "Microphysics Interaction", "Cloud Fraction", "GHG" "RRTM", 1, "Qc Qr Qi Qs Qg", 1/0, "constant or yearly GHG" "CAM", 3, "Qc Qi Qs", "Max-rand overlap", "yearly CO2 or GHG" "RRTMG", 4, "Qc Qr Qi Qs", "Max-rand overlap", "constant or yearly GHG" "New Goddard", 5, "Qc Qr Qi Qs Qg", "Max-rand", "constant" "FLG", 7, "Qc Qr Qi Qs Qg", "1/0", "constant" "RRTMG-K", 14, "Qc Qr Qi Qs", "Max-rand overlap", "constant" "Held-Suarez", 31, "none", "none", "none" "GFDL", 99, "Qc Qr Qi Qs", "Max-rand overlap", "constant" | | **The following are WRF's available longwave radiation schemes:** | | .. _RRTM: RRTM ++++ *ra_lw_physics=1* |br| Rapid Radiative Transfer Model. An accurate scheme using look-up tables for efficiency. Accounts for multiple bands, and microphysics species. For trace gases, the volume-mixing ratio values are *CO2=379e-6, N2O=319e-9* and *CH4=1774e-9*. See the time-varying option in :ref:`Options for Radiation Input`. |br| `Mlawer et al., 1997 `_ | | | CAM +++ *ra_lw_physics=3* |br| An option from CESM's CAM 3 climate model that allows for aerosols and trace gases. It uses yearly CO2, and constant N2O (311e-9) and CH4 (1714e-9). See the time-varying option in :ref:`Options for Radiation Input`. |br| `Collins et al., 2004 `_ | | | .. _RRTMG: RRTMG +++++ *ra_lw_physics=4* |br| A newer version of :ref:`RRTM` that includes the MCICA random cloud overlap method. For major trace gases, CO2=379e-6 (valid for 2005), N2O=319e-9, CH4=1774e-9. See the time-varying option in :ref:`Options for Radiation Input`. |br| Since wrfv4.2, the CO2 value is determined by the function: CO2(ppm) = 280 + 90 exp (0.02*(year-2000)). This function exhibits approximately 4% error when compared to observed values from the 1920s and 1960s, and about 1% error for years after 2000. A cloud overlap option is available beginning in wrfv4.4. |br| `Iacono et al., 2008 `_ | | | New Goddard +++++++++++ *ra_lw_physics=5* |br| An efficient scheme with multiple bands that uses ozone from simple climatology. It is designed to run with Goddard microphysics particle radius information. The scheme had an update in wrfv4.1. |br| `Chou and Suarez, 1999 `_ |br| `Chou et al., 2001 `_ | | | Fu-Liou-Gu (FLG) ++++++++++++++++ *ra_lw_physics=7* |br| A scheme with multiple bands that includes cloud and cloud fraction effects and profiles ozone based on climatology and tracer gases CO2=345e-6. |br| `Gu et al., 2011 `_ |br| `Fu and Liou, 1992 `_ | | | RRTMG-K +++++++ *ra_lw_physics=14* |br| An improved version of the :ref:`RRTMG` scheme. |br| `Baek, 2017 `_ .. note:: To use this option, WRF must be built with the configuration setting *-DBUILD_RRTMK = 1* (this can be set by modifying *configure.wrf* prior to building WRF). | | | RRTMG-fast ++++++++++ *ra_lw_physics=24* |br| A fast version of the :ref:`RRTMG` scheme for GPUs and MIC. Beginning in wrv4.2, the following are the default GHG values: * co2vmr=(280. + 90.*exp(0.02*(yr-2000)))*1.e-6 * n2ovmr=319.e-9 * ch4vmr=1774.e-9 * cfc11=0.251e-9 * cfc12=0.538e-9 | `Iacono et al., 2008 `_ | | | GFDL ++++ *ra_lw_physics=99* |br| This is the Eta operational radiation scheme - an older multi-band scheme with carbon dioxide, ozone and microphysics effects |br| `Fels and Schwarzkopf, 1981 `_ | | | | | Shortwave Radiation Schemes --------------------------- WRF shortwave radiation schemes: * Compute clear-sky and cloudy solar fluxes * Include annual and diurnal solar cycles * Consider downward and upward (reflected) fluxes *(with the exception of the Dudhia (option 1) scheme, which only considers downward flux)* * Have a primarily warming effect in clear sky * Are an important component of surface energy balance | | In the table below, microphysics interactions represent mixing ratios of: * **c** : cloud water * **r** : rain water * **i** : cloud ice * **s** : snow * **g** : graupel | .. csv-table:: :widths: 70, 30, 50, 50, 50 :align: left :header: "Scheme", "Option", "Microphysics Interaction", "Cloud Fraction", "GHG" "Dudhia", 1, "Qc Qr Qi Qs Qg", 1/0, "none" "Goddard", 2, "Qc Qi", 1/0, "5 profiles" "CAM", 3, "Qc Qi Qs", "Max-rand overlap", "lat/month" "RRTMG", 4, "Qc Qr Qi Qs", "Max-rand overlap", "1 profile or lat/month" "New Goddard", 5, "Qc Qr Qi Qs Qg", "Max-rand", "5 profiles" "FLG", 7, "Qc Qr Qi Qs Qg", "1/0", "5 profiles" "RRTMG-K", 14, "Qc Qr Qi Qs", "Max-rand overlap", "1 profile or lat/month" "GFDL", 99, "Qc Qr Qi Qs", "Max-rand overlap", "lat/month" | | **The following are WRF's available shortwave radiation schemes:** | | Dudhia ++++++ *ra_sw_physics=1* |br| A scheme that uses simple downward integration, allowing for efficient clear-sky absorption and scattering for clouds. |br| `Dudhia, 1989 `_ | | | Goddard +++++++ *ra_sw_physics=2* |br| A two-stream, multi-band scheme that uses cloud effects and climatological ozone |br| `Chou and Suarez, 1994 `_ |br| `Matsui et al., 2018 `_ | | | CAM +++ *ra_sw_physics=3* |br| A scheme that originates from CESM's CAM 3 climate model - allows for aerosols and trace gases |br| `Collins et al., 2004 `_ | | | .. _shortwave_RRTMG: RRTMG +++++ *ra_sw_physics=4* |br| A scheme that uses the MCICA random cloud overlap method; for major trace gases, use CO2=379e-6 (valid for 2005), N2O=319e-9, CH4=1774e-9. See the time-varying option in :ref:`Options for Radiation Input`. Since wrfv4.2, the CO2 value is determined by the function: CO2(ppm) = 280 + 90 exp (0.02*(year-2000)). This function exhibits approximately 4% error when compared to observed values from the 1920s and 1960s, and about 1% error for years after 2000. To use the cloud overlap option (available beginning in wrfv4.4), add *cldovrlp = 1,2,3,4*,or *5*. For *cldovrlp=4 or 5*, use the decorrelation length option *idcor=0 or 1*. `See Namelist Variables `_ for details. | | | New Goddard +++++++++++ *ra_sw_physics=5* |br| An efficient scheme with multiple bands that uses climatological ozone. It is designed to run with Goddard microphysics particle radius information. The scheme was updated in WRFv4.1. |br| `Chou and Suarez, 1999 `_ |br| `Chou et al., 2001 `_ | | | Fu-Liou-Gu (FLG) ++++++++++++++++ *ra_sw_physics=7* |br| A scheme with multiple bands, cloud and cloud fraction effects, and uses a climatological ozone profile. This scheme has the ability to allow for aerosols |br| `Gu et al., 2011 `_ |br| `Fu and Liou, 1992 `_ | | | RRTMG-K +++++++ *ra_sw_physics=14* |br| An improved version of the :ref:`shortwave_RRTMG` scheme |br| `Baek, 2017 `_ .. note:: To use this option, WRF must be built with the configuration setting *-DBUILD_RRTMK = 1* (this can be modified in *configure.wrf* prior to compiling). | | | RRTMG-fast ++++++++++ *ra_sw_physics=24* |br| A fast version of :ref:`shortwave_RRTMG` |br| `Iacono et al., 2008 `_ | | | Held-Suarez +++++++++++ *ra_sw_physics=31* |br| A temperature relaxation scheme designed **for idealized tests only** |br| *No publication available* | | | GFDL ++++ *ra_sw_physics=99* |br| The Eta operational two-stream, multi-band scheme that includes cloud effects and climatological ozone |br| `Fels and Schwarzkopf, 1981 `_ | | | | Namelist Options Related to Shortwave Radiation ----------------------------------------------- .. csv-table:: :width: 100% :widths: 20, 70 :escape: \ **slope_rad=1** , include slope and shading effects; modifies surface solar radiation flux according to terrain slope **topo_shading=1** , allows for shadowing of neighboring grid cells; *use only with with a grid size less than a few kilometers* **swrad_scat** , scattering turning parameter for use with *ra_sw_physics=1*; default value is 1\, which is equivalent to 1.e-5 m2/kg; when greater than 1\, scattering is increased **ra_sw_eclipse=1** , eclipse effect on shortwave radiation; only works with *ra_sw_physics* options *1* (Dudhia)\, *2* (Goddard)\, *4* (RRTMG)\, and *5* (New Goddard). Eclipse data from 1950 – 2050 is provided in *WRF/run/eclipse_besselian_elements.dat*. **swint_opt=1** , interpolation of shortwave radiation based on the solar zenith angle code between shortwave calls **swint_opt=2** , activates the Fast All-sky Radiation Model for Solar applications (FARMS)\, which is a fast radiative transfer model that allows simulations of broadband solar radiation every model time step. The model uses lookup tables of cloud transmittances and reflectances by varying cloud optical thicknesses\, cloud particle sizes\, and solar zenith angles. See `Xie et al.\, 2016 `_ for details. | | | | .. _Options for Radiation Input: Options for Radiation Input --------------------------- | CAM Green House Gases +++++++++++++++++++++ This option incorporates yearly green house gases from 1765 to 2500. Radiation schemes (*ra_lw_physics)*) CAM (option 3), RRTM (option 1), and RRTMG (option 4) work with this option. Set the following in *namelist.input* to turn it on: .. code-block:: &physics ghg_input = 1 ra_lw_physics = 1, 3, or 4 | The following files contain different scenarios and are available in the *WRF/test/em_real* and *WRF/run* directories: * from IPCC AR5: *CAMtr_volume_mixing_ratio.RCP4.5/RCP6/RCP8.5* * from IPCC AR4: *CAMtr_volume_mixing_ratio.A1B/A2* * from IPCC AR6: *CAMtr_volume_mixing_ratio.SSP119/SSP126/SSP245/SSP370/SSP585* * the default points to the *CAMtr_volume_mixing_ratio.SSP245* file | .. note:: The *ghg_input* namelist option is not available in versions prior to WRFv4.4. If using an older version, to activate this option, the code must be configured with the *-DCLWRFGHG* macro (or set in *configure.wrf*) prior to compiling. | | | RRTMG Climatological Ozone ++++++++++++++++++++++++++ When using RRTMG radiation (*ra_sw(lw)_physics=4*), ozone data, adapted from CAM radiation (*ra_lw(sw)_physics=3*), incorporates latitudinal (2.82 degrees), height, and monthly variations - unlike the default height-only option. Set the following in *namelist.input* to use this option: .. code-block:: &physics o3input = 2 ra_sw_physics = 4 (for each domain) ra_lw_physics = 4 (for each domain) | | | RRTMG Aerosol Options +++++++++++++++++++++ | **aer_opt = 1** Aerosol data based on `Tegen et al., 1997 `_ are available for use with RRTMG radiation (*ra_sw(lw)_physics=4*). The data have spatial (5 degrees in longitude and 4 degrees in latitudes) and monthly variations, and include: * organic carbon * black carbon * sulfate * sea salt * dust * stratospheric aerosol (volcanic ash, which is zero) | Set the following in *namelist.input* to use this option: .. code-block:: &physics aer_opt = 1 ra_sw_physics = 4 (for each domain) ra_lw_physics = 4 (for each domain) | | | **aer_opt = 2** When using RRTMG radiation (*ra_sw(lw)_physics=4*), Aerosol Optical Depth (AOD) - either alone or with the Angstrom exponent, single scattering albedo, and cloud asymmetry can be provided as constant namelist values or as 2D input fields (via auxiliary input stream 15), with an option to specify aerosol type. To activate this option, set the following in *namelist.input*: .. code-block:: &physics aer_opt = 2 ra_sw_physics = 4 or 5 (for each domain) ra_lw_physics = 4 or 5 (for each domain) | | | **aer_opt = 3** When using RRTMG radiation (*ra_sw(lw)_physics=4*) and Thompson aerosol-aware microphysics (*mp_physics=28*), climatological water- and ice-friendly aerosols can be used. To activate this option, use the following *namelist.input* settings: .. code-block:: &physics aer_opt = 2 ra_sw_physics = 4 or 5 (for each domain) ra_lw_physics = 4 or 5 (for each domain) mp_physic = 28 (for each domain) | | | RRTMG Effective Cloud water, Ice and Snow Radii +++++++++++++++++++++++++++++++++++++++++++++++ When using RRTMG radiation (*ra_sw(lw)_physics=4*), effective cloud water, ice, and snow radii data are available with the following *namelist.input* setting: .. code-block:: &physics use_mp_re = 1 ra_sw_physics = 4 or 5 (for each domain) ra_lw_physics = 4 or 5 (for each domain) | These data originate from the following microphysics schemes: * Thompson (*mp_physics=8*) * WSM (*mp_physics=3,4,6,24*) * WDM (*mp_physics=14,16,26*) * Goddard 4-ice (*mp_physics=7*) * NSSL (*mp_physics=17,18,19,21,22*) * P3 (*mp_physics=50-53*) | | | | | Clouds and Cloud Fraction Options --------------------------------- | Longwave Radiation and Clouds +++++++++++++++++++++++++++++ Every radiation scheme interacts with model-resolved cloud fields, which allows ice and water clouds and precipitating species, with the following nuances: * Some microphysics options pass their own particle sizes (cloud droplets, ice and snow) to RRTMG radiation. * Other combinations only use mass information from microphysics schemes, and assume effective sizes in the radiation scheme. * Rain and graupel effects are smaller than cloud and snow, and are not often explicitly considered. | Clouds have a significant effect on infrared radiation (IR) across all wavelengths. Considered “grey bodies,” they are nearly opaque to it. | | | Shortwave Radiation and Clouds ++++++++++++++++++++++++++++++ Considerations for shortwave radiation schemes are similar to those of longwave schemes (above). There are interactions with model-resolved clouds, and, in some cases, cumulus schemes. There are fraction and overlap assumptions, as well as cloud albedo reflection. Surface albedo reflection is based on the land-surface type and snow cover. | | | Cloud Fraction for Microphysics Clouds ++++++++++++++++++++++++++++++++++++++ * **icloud=1** : Xu and Randall method; fraction is only < 1 for small cloud amounts, 0 for no resolved cloud * **icloud=2** : Simple 0 or 1 method with small resolved cloud threshold * **icloud=3** : Thompson option (RH dependent); 1 > Fraction > 0 for high RH and no resolved clouds | | | Cloud Fraction for Unresolved Convective Clouds +++++++++++++++++++++++++++++++++++++++++++++++ * **cu_rad_feedback=.true.** : only works for Kain Fritsch (*cu_physics=1*), Grell Freitas (*cu_physics=3*), Grell 3 (*cu_physics=5*), Grell-Devenyi (*cu_physics=93*) cumulus options. * ZM separately provides cloud fraction to radiation | | | | | Radiation Time Step ------------------- The namelist parameter *radt* (in the *&physics* record) controls the radiation time step. Consider the following when setting *radt*. * Radiation is too expensive to call every step * Frequency should resolve cloud-cover changes with time * *radt* should be set to about one minute per km grid size (of the innermost domain) (e.g., *radt=10* for :math:`dx=10000` - *or 10 km*). * When using *feedback=1*, it is recommended to set *radt* to the same value for each domain. | | | | | Planetary Boundary Layer Physics ================================ | .. figure:: ../images/users_guide/pbl.png :width: 600px :align: center :height: 350px | | .. container:: row m-0 p-0 .. container:: col-md-12 pl-0 pr-3 py-3 m-0 .. container:: card px-0 h-100 .. rst-class:: card-header-def .. rubric:: WRF Planetary Boundary Layer (PBL) Schemes .. container:: card-body-def WRF physics schemes that distribute surface fluxes with boundary layer eddy fluxes, allow for PBL growth by entrainment, and vertical mixing above the boundary layer. | | There are two classes of PBL schemes: #. **Turbulent kinetic energy prediction schemes** The following WRF PBL schemes fall under this class: * MYJ (*bl_pbl_physics=2*) * MYNN (*bl_pbl_physics=5,6*) * QNSE-EDMF (*bl_pbl_physics=4*) * BouLac (*bl_pbl_physics=8*) * CAM UW (*bl_pbl_physics=9*) * TEMF (*bl_pbl_physics=10*) | QNSE-EDMF, MYNN, and TEMF schemes also include non-local mass-flux terms. | #. **Diagnostic non-local schemes** The following WRF PBL schemes fall under this class: * YSU (*bl_pbl_physics=1*) * GFS (*bl_pbl_physics=3*) * ACM2 (*bl_pbl_physics=7*) * MRF (*bl_pbl_physics=99*) | | Note the following regarding WRF PBL schemes: * Due to turbulence, all PBL schemes perform vertical diffusion above the PBL. * PBL schemes can be used for most grid sizes when surface fluxes are present; however, this assumption breaks down at grid size :math:`dx << 1 km`, when 3-D diffusion should be used instead of a PBL scheme (coupled to surface physics). This works best when :math:`dx` and :math:`dz` are comparable. * The lowest level should be located in the surface layer (0.1h) for correct surface (2m, 10m) diagnostic interpolation. * With ACM2, GFS, and MRF PBL schemes, the lowest full level should be .99 or .995 (not too close to 1). * TKE schemes and YSU can use thinner surface layers. * PBL schemes assume PBL eddies are not resolved. | | .. figure:: ../images/users_guide/pbl_processes.png :width: 500px :align: center :height: 350px | | .. seealso:: `See the WRF Tutorial presentation on PBLi `_ for additional details. | | | PBL Scheme Options ------------------ | .. csv-table:: :widths: 60, 40, 70, 55, 70, 50 :align: left :header: "Scheme", "Option", "Works With |br| sfclay Option", "Prognostic Variables", "Diagnostic Variables", "Cloud Mixing" "YSU", 1, "1 91", none, exch_h, "QC QI" "MYJ", 2, 2, 4, "EL_PBL exch_h", "QC QI" "QNSE-EDMF", 4, 4, TKE_PBL, "EL_PBL exch_h exch_m", "QC QI" "MYNN2", 5, "1 2 5 91", QKE, "Tsq Qsq Cov exch_h exch_m", QC "MYNN3", 6, 1 2 5 91, QKE Tsq Qsq Cov, exch_h exch_m, QC "ACM2", 7, "1 7 91", " ", " ", "QC QI" "BouLac", 8, "1 2 91", TKE_PBL, "EL_PBL exch_h exch_m", QC "UW", 9, "1 2 91", TKE_PBL, "exch_h exch_m", QC "TEMF", 10, 10, TE_TEMF, "\*_temf", "QC QI" "Shin-Hong", 11, "1 91", " ", exch_h, "QC QI" "GBM", 12, "1 91", TKE_PBL, "EL_PBL exch_h exch_m", "QC QI" "EEPS", 16, "1 5 91 ", "PEK_PBL PEP_PBL", "exch_h exch_m", "QC QI" "KEPS", 17, "1 2", "TPE_PBL DISS_PBL TKE_PBL", "exch_h exch_m", "QC" "MRF", 99, "1 91", " ", " ", "QC QI" | | | PBL Scheme Details and References --------------------------------- | .. _YSU: Yonsei University (YSU) +++++++++++++++++++++++ *bl_pbl_physics=1* |br| A non-local-K scheme with an explicit entrainment layer and parabolic K profile in the unstable mixed layer. This option includes top-down mixing for turbulence, driven by cloud-top radiative cooling (this is separate from bottom-up surface-flux-driven mixing). |br| `Hong et al., 2006 `_ Additional options specific for use with YSU: * **topo_wind** : *=1* - applies a topographic correction to surface winds. The correction accounts for increased drag due to sub-grid topography and enhanced flow at hill tops (`Jimenez and Dudhia, 2012 `_); *=2* - a simpler terrain variance-related correction * **ysu_topdown_pblmix=1** : applies top-down mixing driven by radiative cooling (`Wilson and Fovell, 2018 `_) | | | Mellor-Yamada-Janjic (MYJ) ++++++++++++++++++++++++++ *bl_pbl_physics=2* |br| Eta operational scheme - a one-dimensional prognostic turbulent kinetic energy scheme with local vertical mixing |br| `Janjic, 1994 `_ |br| `Mesinger, 1993 `_ | | | Quasi-Normal Scale Elimination (QNSE-EDMF) ++++++++++++++++++++++++++++++++++++++++++ *bl_pbl_physics=4* |br| A TKE-prediction option that incorporates a theory for stably-stratified regions. For the daytime, an eddy diffusivity mass-flux method with shallow convection (*mfshconv=1*) is used. It includes shallow convection using a mass-flux approach through the entire cloud-topped boundary layer |br| `Sukoriansky et al., 2005 `_ | | | Mellor-Yamada Nakanishi and Niino Level 2.5 (MYNN2) +++++++++++++++++++++++++++++++++++++++++++++++++++ *bl_pbl_physics=5* |br| Predicts sub-grid TKE terms; includes shallow convection using a mass-flux approach through the entire cloud-topped boundary layer; includes top-down mixing for turbulence driven by cloud-top radiative cooling, which is separate from bottom-up surface-flux-driven mixing |br| `Nakanishi and Niino, 2006 `_ |br| `Nakanishi and Niino, 2009 `_ |br| `Olson et al., 2019 `_ Additional options specific for use with MYNN: * **icloud_bl=1** : option to couple MYNN subgrid-scale clouds with radiation * **bl_mynn_cloudpdf** : *=1* - `Kuwano et al., 2010 `_ ; *=2* - `Chaboureau and Bechtold, 2002 `_ (with modifications; this is the default setting) * **bl_mynn_cloudmix=1** : mixing cloud water and ice (*qnc* and *qni* are mixed when *scalar_pblmix=1*) * **bl_mynn_edmf=1** : activate mass-flux in MYNN * **bl_mynn_mixlength** : *=1* is from RAP/HRRR; *=2* is from blending | | | Mellor-Yamada Nakanishi and Niino Level 3 (MYNN3) +++++++++++++++++++++++++++++++++++++++++++++++++ *bl_pbl_physics=6* |br| Predicts TKE and other second-moment terms |br| `Nakanishi and Niino, 2006 `_ |br| `Nakanishi and Niino, 2009 `_ |br| `Olson et al., 2019 `_ .. note:: This option is only available in versions, up through WRFv4.4.2. See the :ref:`MYNN Closure` option if using WRFv4.5+. | | | .. _MYNN Closure: MYNN Closure ++++++++++++ *bl_mynn_closure* * **= 2.5** : level 2.5 * **= 2.6** : level 2.6 * **= 3.0** : level 3.0 | | | ACM2 ++++ *bl_pbl_physics=7* |br| Asymmetric Convective Model with non-local upward mixing and local downward mixing |br| `Pleim, 2007 `_ | | | BouLac ++++++ *bl_pbl_physics=8* |br| Bougeault-Lacarrère PBL; a TKE-prediction option; for use with the BEP urban model (*sf_urban_physics=2*) |br| `Bougeault, 1989 `_ | | | UW ++ *bl_pbl_physics=9* |br| A TKE scheme from the CESM climate model; includes shallow convection using a mass-flux approach from the cloud base; includes topdown mixing for turbulence driven by cloud-top radiative cooling, which is separate from bottom-up surface-flux-driven mixing |br| `Bretherton and Park, 2009 `_ | | | Total Energy - Mass Flux (TEMF) +++++++++++++++++++++++++++++++ *bl_pbl_physics=10* |br| Sub-grid total energy prognostic variable, plus a mass-flux approach for shallow convection throughout the entire cloud-topped boundary layer |br| `Angevine et al., 2010 `_ | | | Shin-Hong +++++++++ *bl_pbl_physics=11* |br| Includes scale dependency for vertical transport in the convective PBL; vertical mixing in the stable PBL and free atmosphere follows :ref:`YSU`; this scheme includes diagnosed TKE and mixing length output |br| `Shin and Hong, 2015 `_ | | | Grenier-Bretherton-McCaa (GBM) ++++++++++++++++++++++++++++++ *bl_pbl_physics=12* |br| A TKE scheme that has been tested in cloud-topped PBL cases, and includes shallow convection using a mass-flux approach from the cloud base |br| `Grenier and Bretherton, 2001 `_ | | | TKE (E)-TKE dissipation rate (epsilon) (EEPS) +++++++++++++++++++++++++++++++++++++++++++++ *bl_pbl_physics=16* |br| This scheme predicts and advects both TKE and the TKE dissipation rate |br| *No publication available* | .. note:: This option only works with *sf_sfclay_physics=1,5*, or *91*. | | | K-epsilon-theta\ :sup:`2` (KEPS) ++++++++++++++++++++++++++++++++ *bl_pbl_physics=17* |br| This scheme includes two additional prognostic equations for dissipation rate and temperature variance. |br| `Zonato et al., 2022 `_ | | | MRF +++ *bl_pbl_physics=99* |br| This is an older version of :ref:`YSU` (*bl_pbl_physics=1*) with implicit treatment of the entrainment layer as part of a non-local-K mixed layer |br| `Hong and Pan, 1996 `_ | | | Additional PBL Options ---------------------- | LES PBL +++++++ Settings for a large-eddy-simulation (LES) boundary layer: .. code-block:: &physics bl_pbl_physic = 0 (for each domain) isfflx = 1 sf_sfclay_physics = any option, except 0 (for each domain) sf_surface_physics = any option, except 0 (for each domain) diff_opt = 2 (for each domain) km_opt = 2 or 3 (for each domain) | * Diffusion is optional for vertical mixing. * *isfflx=0* or *2* can be used alternatively for idealized LES cases. * Use :math:`dx \approx dz`, especially in the boundary layer, and avoid stretching to very large :math:`dz/dx` aspect ratios at upper levels. This works better with continuous stretching to the top, instead of a fixed upper-level :math:`dz` when :math:`dz >> dx`. | | | SMS-3DTKE +++++++++ 3D TKE subgrid mixing scheme that self-adapts to the grid size between the large-eddy simulation (LES) and mesoscale limits. This option is available with WRFv4.2+ and is activated with the following settings: .. code-block:: &physics bl_pbl_physic = 0 (for each domain) km_opt = 5 (for each domain) diff_opt = 2 (for each domain) sf_sfclay_physics = 1, 5, or 91 (for each domain) | `See Zhang et al., 2018 `_ for details. | | | Orographic Gravity Wave Drag ++++++++++++++++++++++++++++ *gwd_opt* |br| An option to represent sub-grid orographic gravity-wave vertical momentum transport; can be used with appropriate geogrid input fields (details below) * **=1** : (default); subgrid topography effects gravity wave drag and low-level flow blocking; recommended for grid sizes > 5km; input wind is rotated to the Earth coordinate, and output is adjusted back to the projection domain, enabling use with all WRF-supported map projections; to apply this option, appropriate input fields from geogrid must be used; `See Gravity Wave Drag Scheme Static Data `_ for details. | * **=3** : gravity wave drag, blocking, small-scale gravity drag and turbulent orographic form drag; similar to option 1, with the following additional subgrid-scale sources of orographic drag: #. Small-scale GWD (`Tsiringakis et al., 2017 `_), which represents gravity wave propagation and breaking in and above the stable boundary layer #. Turbulent orographic form drag (`Beljaars et al., 2004 `_) | Both are applicable down to a grid size of 1 km. Large-scale GWD and low-level flow blocking from *gwd_opt=1* are adjusted for horizontal grid resolution. More diagnostic fields from the scheme can be output by setting namelist option *gwd_diags=1* in the *&dynamics* record. New GWD input fields are required from WPS. | | | Fog +++ *grav_settling=2* |br| Gravitational settling of fog/cloud droplets | | | | | .. _PBL and Land Surface Time Step: PBL and Land Surface Time Step ------------------------------ The namelist parameter *bldt* (in the *&physics* record) controls the PBL time step in minutes between boundary layer and land-surface model calls. The default value of 0 (every step) is reasonable for all schemes, except the CLM land-surface scheme (*sf_surface_physics = 5*), which is expensive and *bldt* may need to be increased. | | | | | Model Grid Spacing ------------------ | .. figure:: ../images/users_guide/pbl_grid_spacing.png :width: 700px :align: center :height: 350px | | In the above image: * WRF PBL schemes are designed for :math:`grid resolution >> I` * LES schemes are designed for :math:`grid resolution << I` | With coarse grid spacing, eddies are sub-grid, and 1-D column schemes handle sub-grid vertical fluxes. For fine grid spacing, major eddies are resolved, and 3-D turbulence schemes handle sub-grid mixing. The remaining sub-kilometer grid-spacing is a "grey-zone" with imperfect PBL and LES assumptions. The following scale-aware schemes are available for this zone: * **Shin-Hong PBL** based on :ref:`YSU`, designed for sub-kilometer transition scales (200 m – 1 km); nonlocal mass-flux; the :math:`Kv` term is reduced in strength as grid size decreases and resolved mixing increases * **3d TKE option (km_opt=5)** *(available in v4.2+)*; becomes 3-D LES at fine scales; adds scale-dependent Shin-Hong nonlocal mass flux and implicit vertical diffusion at coarse grid sizes * Other schemes may work in this range but resolved/sub-grid energy fractions are not correctly partitioned. | LES is preferable for grid sizes up to about 100 m. | | | | | Turbulence and Diffusion ------------------------ The *diff_opt* namelist option (in *&dynamics*) specifies the method used for turbulence and mixing. When diffusion is used with a PBL scheme, vertical diffusion is deactivated, therefore *diff_opt* only affects horizontal diffusion. * **diff_opt=0** : no turbulence or explicit spatial numerical filters * **diff_opt=1** : (default); evaluates the 2nd-order diffusion term on coordinate surfaces; uses the constant vertical diffusion coefficient (*kvdif*) unless a PBL option is used; do not use with calculated diffusion coefficient options (*km_opt=2,3*); can be used with PBL schemes that include internal vertical diffusion; horizontal diffusion acts along model levels - a simple numerical method with only neighboring points on the same model level * **diff_opt=2** : evaluates mixing terms in physical space (stress form - :math:`x,y,z`); strictly horizontal and better for complex terrain - avoids diffusion up and down slopes included in *diff_opt=1*; horizontal diffusion acts strictly on horizontal gradients; the numerical method includes a vertical correction term, using more grid points; for stability, diffusion strength is reduced in steep coordinate slopes (:math:`dz \approx dx`) | | Recommended Diffusion Options +++++++++++++++++++++++++++++ #. **Real-data case with PBL option on** * *diff_opt=2* * *km_opt=4* * Less diffusive in complex terrain (while *diff_opt=1* diffuses along slopes) * These options compliment the PBL scheme vertical diffusion #. **High-resolution real-data cases (~100m grid)** * No PBL scheme * *diff_opt=2* * TKE (*km_opt=2*) or Smagorinsky scheme (*km_opt=3*) #. **Idealized cloud-resolving modeling** (:math:`dx` = 1-3 km ; smooth or no topography, no surface heat fluxes) * *diff_opt=2* * *km_opt=2* or *3* | | | | | Surface Physics =============== .. figure:: ../images/users_guide/sfc.png :width: 600px :align: center :height: 450px | .. figure:: ../images/users_guide/sfc_extension.png :width: 350px :align: center :height: 275px | | | WRF surface physics consist of **surface layer (sfclay)** schemes and **land surface model (LSM)** schemes. .. container:: row m-0 p-0 .. container:: col-md-12 pl-0 pr-3 py-3 m-0 .. container:: card px-0 h-100 .. rst-class:: card-header-def .. rubric:: WRF Surface Layer (sfclay) Schemes .. container:: card-body-def WRF physics schemes that determine surface layer diagnostics, including exchange and transfer coefficients, and determine soil temperature, moisture, snow prediction and sea-ice temperature. They provide heat and moisture exchange coefficients to the land surface model (LSM). .. container:: col-md-12 pl-0 pr-3 py-3 m-0 .. container:: card px-0 h-100 .. rst-class:: card-header-def .. rubric:: WRF Land Surface Model (LSM) Schemes .. container:: card-body-def WRF physics schemes that provide land-surface fluxes of heat and moisture to the planetary boundary layer (PBL). | .. seealso:: `See the WRF Tutorial presentation on surface physics `_ for additional details. | | | | | Surface Layer Schemes ===================== | .. figure:: ../images/users_guide/sfc_processes.png :width: 500px :align: center :height: 350px | | The surface layer has a constant flux layer of about 0.1 x PBL height (~100 m). The lowest WRF model level is found within this layer (typically 10-50 m). The WRF surface layer scheme is determined by the namelist setting *sf_sfclay_physics* (in the *&physics* namelist record). Some key notes about WRF sfclay schemes are: * They use similarity theory to determine exchange coefficients and diagnostics of 2m temperature, 2m qvapor, and 10m winds. * They provide exchange coefficients to land-surface models (LSMs). * They provide friction velocity to the PBL scheme. * They provide surface fluxes over water points. * Schemes have variations in stability functions and roughness lengths. | | | Surface Layer Scheme Details and References ------------------------------------------- | Revised MM5 +++++++++++ *sf_sfclay_physics=1* |br| Removes limits and uses updated stability functions; over the ocean, the COARE 3 forumula (`Fairall et al., 2003 `_) is used for thermal and moisture roughness lengths (or heat and moisture exchange coefficients) |br| `Jimenez et al., 2012 `_ | | | Eta Similarity ++++++++++++++ *sf_sfclay_physics=2* |br| A scheme used in Eta model, based on Monin-Obukhov with Zilitinkevich thermal roughness length and standard similarity functions from look-up tables |br| `Monin and Obukhov, 1954 `_ |br| `Janjic, 1994 `_ |br| `Janjic, 1996 `_ |br| `Janjic, 2001 `_ | | | QNSE ++++ *sf_sfclay_physics=4* |br| Quasi-Normal Scale Elimination PBL scheme’s surface layer option |br| *No publication available* | | | MYNN ++++ *sf_sfclay_physics=5* |br| Nakanishi and Niino PBL’s surface layer scheme |br| `Olson et al, 2021 `_ | | | Pleim-Xiu +++++++++ *sf_sfclay_physics=7* |br| `Pleim, 2006 `_ | | | Total Energy - Mass Flux (TEMF) +++++++++++++++++++++++++++++++ *sf_sfclay_physics=10* |br| `Angevine et al., 2010 `_ | | | MM5 Similarity ++++++++++++++ *sf_sfclay_physics=91* |br| A scheme based on Monin-Obukhov, with Carslon-Boland viscous sub-layer and standard similarity functions from look-up tables; over the ocean, the COARE 3 forumula (`Fairall et al., 2003 `_) is used for thermal and moisture roughness lengths (or heat and moisture exchange coefficients) |br| `Paulson, 1970 `_ |br| `Dyer and Hicks, 1970 `_ |br| `Webb, 1970 `_ |br| `Belijaars, 1994 `_ |br| `Zhang and Anthes, 1982 `_ | | | | | Additional Options Related to the Surface Layer ----------------------------------------------- iz0tlnd +++++++ * **=1** : Chen-Zhang thermal roughness length over land, which depends on vegetation height (works with *sf_sfclay_physics = 1, 91*, and *5*) * **=0** : Original thermal roughness length in each sfclay option |br| `Chen and Zhang, 2009 `_ | | | shalwater_z0=1 ++++++++++++++ Shallow-water roughness with an offshore roughness adjustment in water depths less tha 100 m. This option works with a specified depth or real bathymetry input, and only with *sf_sfclay_physics=1*. The bathymetry data is available from the `WPS v4 Geographical Static Data Downloads Page `_. If no bathymetry data is available, set constant depth (in meters; must be positive) using namelist option *shalwater_depth*. Any depths outside the range of 10-100 m are rounded to the nearest limit value. |br| `GEBCO Compilation Group, 2021 `_ |br| `Jimenez and Dudhia, 2018 `_ | | | | | Land Surface Model ================== | .. figure:: ../images/users_guide/lsm_processes.png :width: 700px :align: center :height: 500px | | WRF LSM schemes are driven by surface energy and water fluxes. They predict soil temperature and soil moisture in 3 or 4 layers, depending on the scheme, as well as snow water equivalent on the ground. | | Vegetation and Soil ------------------- LSMs consider the effects of vegetation and soil components, such as vegetation fraction, vegetation categories (e.g., cropland, forest types, etc.), and soil categories (e.g., sandy, clay, etc.). Below are some key notes: * Processes include evapotranspiration, root zone, and leaf effects. * Vegetation fraction varies seasonally. * Soil categories are considered for drainage and thermal conductivity. | | | | Snow Cover ---------- LSMs include fractional snow cover and predict snow water equivalent development based on precipitation, sublimation, melting, and run-off. The number of layers is dependent on the scheme: * Single-layer snow (Noah - *sf_surface_physics=2*, PX - *sf_surface_physics=7*) * Multi-layer snow (RUC - *sf_surface_physics=3*, NoahMP - *sf_surface_physics=4*, CLM4 - *sf_surface_physics=5*, SSiB - *sf_surface_physics=8*) * The 5-layer option - *sf_surface_physics=2* - has no snow prediction .. note:: Frozen soil water is also predicted by the Noah, NoahMP, RUC, and CLM4 schemes. | | | | Urban Effects ------------- For larger-scale studies, the LSM urban category is usually sufficient. Alternatively, urban models are available for use with either the Noah (*sf_surface_physics=2*) or NoahMP (*sf_surface_physics=4*) LSM scheme by setting *sf_urban_physics* in the *&physics* namelist record to one of the following options: * **=1** : Urban Canopy Model (UCM); single layer; The following options are available when *sf_urban_physics=1* * **slucm_distributed_drag** : An option to use spatially-varying 2-D urban zero-plane displacement, momentum roughness length, and frontal area index. This option requires `SLUCM static input `_ for the WPS/geogrid process * **distributed_ahe_opt** : The method used for anthropogenic surface heat flux. An additional input to the *wrfinput* file is required. * *=0* : do not use anthropogenic surface heat flux from the input data * *=1* : add to the first level temperature tendency * *=2* : add to the surface sensible heat flux | * **=2** : Building Environment Parameterization (BEP); multi-layer; *only works with YSU, MYJ and BouLac PBL schemes (bl_pbl_physics= 1, 2, and 8)* * **=3** : Building Energy Model (BEM); adds heating and air-conditioning to BEP; *only works with YSU, MYJ and BouLac PBL schemes (bl_pbl_physics= 1, 2, and 8)* | .. note:: * `NUDAPT detailed map data `_ is available for use in WPS, and includes data for 40+ U.S. cities. * WRFv4.3+ code includes a capability to use local climate zones for all three urban applications (`see the README file `_ for details) | | | | LSM Tables ---------- LSM tables, found in *WRF/test/em_real* and *WRF/run*, are customizable text files with predefined categories. .. csv-table:: :header: Table, LSM scheme that uses the table :escape: \ **VEGPARM.TBL** , Noah and RUC\, for vegetation categories (albedo\, roughness length\, emissivity\, vegetation properties) **MPTABLE.TBL** , NoahMP **SOILPARM.TBL** , Noah and RUC\, for soil properties **LANDUSE.TBL** , 5-layer model (SLAB) **URBPARM.TBL** , urban models | | | | Initializing LSMs ----------------- All LSMs (except the SLAB option) require the following additional fields for initialization: * Soil temperature * Soil moisture * Snow liquid equivalent | These fields are available in the first-guess input files processed in WPS. They originate from "offline" operational analysis or reanalysis modeling systems driven by observations for rainfall, radiation, surface temperature, humidity, and wind. The following are model-derived data sets for Noah and RUC LSMs that correspond to WRF levels: * Eta/GFS/AGRMET/NNRP for Noah (older data have limited soil levels) * RUC for RUC (just North America; limited availability) | .. note:: When using ECMWF/ERA soil analyses, during real.exe mesoscale landuse resolution can cause inconsistency in elevation, soil type, and vegetation. Soil temperature adjustments occur during real.exe, and addresses elevation differences between the dataset and model elevations (using *SOILHGT*). Inconsistency leads to spin-up, as temperature and moisture adjustments occur at the beginning of simulation. This can be avoided by running an offline model on the same grid (e.g. HRLDAS for Noah), but soil moisture spin up may take months. Cycling the land state between forecasts also helps, but may propagate errors (e.g in rainfall effect on soil moisture). | | | | LSM Scheme Details and References --------------------------------- | 5-layer thermal diffusion (SLAB) ++++++++++++++++++++++++++++++++ *sf_surface_physics = 1* |br| A five-layer scheme that only considers soil temperature |br| `Dudhia, 1996 `_ | | | Noah ++++ *sf_surface_physics = 2* |br| The Unified NCEP/NCAR/AFWA four-layer scheme for soil temperature and moisture; includes fractional snow cover and frozen soil physics |br| `Tewari et al., 2004 `_ * Activate sub-tiling with *sf_surface_mosaic=1* in the *&physics* namelist record. The *mosaic_cat* namelist option defines the number of tiles per grid box (default : 3). | | | RUC +++ *sf_surface_physics = 3* |br| This model calculates energy and moisture budgets using a layer approach. Atmospheric and soil fluxes, computed at the middle of the first atmospheric layer and the top soil layer respectively, modify heat and moisture storage in the ground surface layer. The RUC LSM utilizes 9 soil levels, with higher resolution near the atmosphere interface. .. note:: Initializing from a low-resolution surface model, such as Noah LSM, can lead to overly moist top levels, causing moist/cold biases. The solution is to cycle soil moisture for several days, allowing it to spin up and align with the RUC LSM's vertical structure. | The RUC LSM models soil moisture as a prognostic variable - volumetric soil moisture content, minus residual soil moisture, which does not contribute to transport. It incorporates soil freezing and thawing processes and can utilize explicit mixed-phase precipitation from cloud microphysics schemes. For sea ice, the model solves for heat diffusion, allowing for evolving snow cover. During the warm season, the RUC LSM adjusts soil moisture in cropland areas to account for irrigation. On soil, snow accumulates in up to two layers, depending on its depth (ref S16). Thin layers combine with the topsoil layer to prevent excessive night time radiative cooling. If the snow water equivalent is below 3 cm, grid cells can be partially snow-covered, with surface parameters like roughness length and albedo calculated as a weighted average of snow-covered and snow-free areas. The energy budget employs an iterative snow melting algorithm. Melted water may partially refreeze within the snow layer; the rest percolates through the snowpack, infiltrates the soil, forming surface runoff. Snow density evolves based on snow temperature, depth, and compaction. Snow albedo, initialized from the given vegetation type’s maximum albedo, can be adjusted according to snow temperature and snow fraction. To better represent accumulated snow on the ground, the RUC LSM includes an estimation of frozen precipitation density. The RUC LSM includes refined interception of liquid or frozen precipitation by the canopy, and a "mosaic" approach for patchy snow, which separately treats energy and moisture budgets for snow-covered and snow-free portions of each grid cell, aggregating the solutions at the end of each time step. | The following data sets are required to initialize the RUC LSM: * High-resolution soil and land-use types * Climatological albedo for snow-free areas * Spatial distribution of maximum surface albedo in the presence of snow cover * Grid cell vegetation-type fraction - for sub-grid-scale heterogeneity in surface parameter computation * Grid cell soil-type fraction * Climatological greenness fraction * Climatological leaf area index * Climatological mean temperature at the bottom of soil domain * Real-time sea-ice concentration * Real-time snow cover to correct cycled-in RAP and HRRR snow fields | Recommended namelist options: * **sf_surface_physics=3** * **num_soil_layers=9** * **usemonalb=.true.** ; uses monthly albedo fields from geogrid instead of table values * **rdlai2d=.true.** ; uses monthly LAI data from geogrid, which is included in the *wrflowinp* file if *sst_update=1* * **mosaic_lu=1** * **mosaic_soil=1** | .. note:: See `RAP `_ and `HRRR `_, which use RUC LSM as their land component. `Benjamin et al., 2004 `_ |br| `Smirnova et al., 2016 `_ | | | Noah-MP +++++++ *sf_surface_physics = 4* |br| Uses multiple options for key land-atmosphere interaction processes, as well as the following: * Contains a separate vegetation canopy, defined by its top and bottom, with leaf physical and radiometric properties utilized in a two-stream canopy radiation transfer scheme that accounts for shading effects * Contains a multi-layer snow pack with liquid water storage, melt/refreeze capability, and a snow-interception model describing loading/unloading, melt/refreeze, and sublimation of the canopy-intercepted snow * Multiple options are available for surface water infiltration and runoff, and groundwater transfer and storage, including water table depth to an unconfined aquifer * Horizontal and vertical vegetation density can be prescribed or predicted using prognostic photosynthesis and dynamic vegetation models that allocate carbon to vegetation (leaf, stem, wood and root) and soil carbon pools (fast and slow) `Niu et al., 2011 `_ |br| `Yang et al., 2011 `_ |br| `Noah-MP Technical Note (He et al., 2023) `_ | | | Community Land Model Version 4 (CLM4) +++++++++++++++++++++++++++++++++++++ *sf_surface_physics = 5* |br| Contains sophisticated treatment of biogeophysics, hydrology, biogeochemistry, and dynamic vegetation. Each grid cell's land surface is defined by five sub-grid land cover types: glacier, lake, wetland, urban, and vegetated. The vegetated sub-grid consists of up to 4 plant functional types (PFTs) that differ in physiology and structure. WRF input land cover types are translated into the CLM4 PFTs through a look-up table. The CLM4 vertical structure includes a single-layer vegetation canopy, a five-layer snowpack, and a ten-layer soil column. `Oleson et al., 2010 `_ |br| `Lawrence et al., 2011 `_ |br| .. note:: An earlier version of CLM has been quantitatively evaluated within WRF; referenced in the following: |br| `Jin and Wen, 2012 `_ |br| `Lu and Kueppers, 2012 `_ |br| `Subin et al., 2011 `_ | | | Pleim-Xiu +++++++++ *sf_surface_physics = 7* |br| A two-layer scheme based on the ISBA model (`Noilhan and Planton, 1989 `_) that includes vegetation and sub-grid tiling, and provides realistic ground temperature, soil moisture, and surface sensible and latent heat fluxes in mesoscale models. It includes a 2-layer force-restore soil temperature and moisture model (1 cm thick top layer, 99 cm bottom layer). It derives grid aggregate vegetation and soil parameters from fractional coverage of land use categories and soil texture types. Two indirect nudging schemes correct 2-m air temperature and moisture biases by adjusting soil moisture (`Pleim and Xiu, 2003 `_) and deep soil temperature (`Pleim and Gilliam, 2009 `_). The PX LSM is primarily designed for retrospective simulations that utilize surface-based observations to guide indirect soil nudging. While soil nudging can be disabled (*pxlsm_soil_nudge* namelist ption in *&fdda*), this mode is not well-tested. `Gilliam and Pleim, 2010 `_ detail its WRF implementation and typical configurations. To activate soil nudging use the `OBSGRID `_ utility to produce a *wrfsfdda_d0\** surface nudging file, which the PX LSM uses for its 2-m temperature and mixing ratio re-analyses to nudge deep soil moisture and temperature. For forecast mode with soil nudging, OBSGRID can generate *wrfsfdda_d01\** files using forecasted 2-m temperature and mixing ratio with empty observation files, but results depend on the forecast model. .. note:: See a `detailed description of the PX LSM `_, including pros/cons, best practices, and recent improvements. **Additional References:** |br| `Pleim and Xiu, 1995 `_ |br| `Xiu et al., 2001 `_ | | | Simplified Simple Biosphere (SSiB) ++++++++++++++++++++++++++++++++++ *sf_surface_physics=8* |br| This is the third generation of the Simplified Simple Biosphere Model, and is developed for land/atmosphere interaction studies within climate models. It calculates aerodynamic resistance values in terms of vegetation properties, ground conditions and the bulk Richardson number per the modified Monin-bukhov similarity theory. SSiB-3 includes three snow layers to realistically simulate snow processes such as destructive metamorphism, densification due to snow load, and snow melting, which makes it a strong candidate for cold season studies. To use this option, *ra_lw_physics* and *ra_sw_physics* should be set to either *1, 3,* or *4*. The second full model level should be set to no larger than *0.982* so that its height is higher than vegetation height. `Xue et al., 1991 `_ |br| `Sun and Xue, 2001 `_ | | | | Other Options Related to LSMs ----------------------------- | ua_phys=.true. ++++++++++++++ University of Arizona snow physics for use with Noah LSM |br| `Wang et al., 2010 `_ | | | sf_surface_mosaic=1 +++++++++++++++++++ Sub-tiling option for use with Noah LSM |br| `Li et al., 2013 `_ | | | | PBL and Land Surface Time Step (bldt) ------------------------------------- See :ref:`PBL and Land Surface Time Step` in the PBL physics section. | | | | Tropical Cyclone Options ------------------------ The following namelist parameters are specific to tropical cyclone simulations and should be added to the *&physics* namelist record. | Ocean Mixed Layer Model +++++++++++++++++++++++ *sf_ocean_physics=1* |br| Ocean Mixed Layer Model; 1-d slab ocean mixed layer (specified initial depth); includes wind-driven ocean mixing for SST cooling feedback |br| `Pollard et al., 1973 `_ | | | 3d PWP Ocean ++++++++++++ *sf_ocean_physics=2* |br| 3-d multi-layer (~100) ocean, salinity effects; fixed depth |br| `Price, 1981 `_ |br| `Price et al., 1994 `_ |br| `Lee and Chen, 2012 `_ | | | Alternative surface-layer option for high-wind ocean ++++++++++++++++++++++++++++++++++++++++++++++++++++ *surface (isftcflx=1,2)* |br| Modifies the Charnock relation to decrease surface friction for high winds (lower :math:`Cd`); modifies surface enthalpy (:math:`Ck`, heat/moisture) either with constant :math:`z0q` (*isftcflx=1*) or Garratt formulation (*isftcflx=2*); must be used with *sf_sfclay_physics=1* | | | | Fractional Sea Ice ------------------ The fractional sea ice option (*fractional_seaice=1*) includes input sea-ice fraction data that partitions land and water fluxes within a grid box, treating sea-ice as a fractional field. This option requires fractional sea-ice input using GFS or the `National Snow and Ice Data Center `_ data; use *XICE* for the Vtable entry instead of *SEAICE*; this option works with *sf_sfclay_physics = 1, 2, 5,* and *7*, and *sf_surface_physics = 2, 3*, and *7*. | | | | Sub-grid Mosaic Option ---------------------- Without an additional sub-grid mosaic option, WRF defaults to using a single dominant vegetation and soil type per grid cell. However, additional mosaic options are available to use with the following schemes: .. csv-table:: :escape: \ :width: 80% Noah , use *sf_surface_mosaic=1* to allow for multiple categories within a grid cell RUC , use *mosaic_lu=1* and *mosaic_soil=1* to allow for multiple categories within a grid cell Pleim-Xu , additionally averages properties of sub-grid categories | | | | SST Update ---------- To use the Sea Surface Temperature (SST) update option, set *sst_update=1* in the *&physics* namelist record. This option reads a lower boundary file periodically to update SST (as opposed to a fixed-time SST). Notes about this option: * It is recommended to use for simulations lasting ~5 or more days * A *wrflowinp_d0\** file is created by real.exe * Sea-ice can be updated, as well * Vegetation fraction update is included, allowing seasonal change in albedo, emissivity, and roughness length if using the Noah LSM * Set *usemonalb=.true.* to include monthly albedo input | | | | Regional Climate Options ------------------------ **tmn_update=1** Updates deep-soil temperature for multi-year future-climate runs **sst_skin=1** Adds a diurnal cycle to sea-surface temperature **output_diagnostics=1** Ability to output max/min/mean/std of surface fields in a specified period (e.g. daily) **bucket_mm* and *bucket_J** Provides a more accurate way to accumulate water and energy for long-run budgets (see :ref:`Accumulation Budgets`) | | | | .. _Accumulation Budgets: Accumulation Budgets -------------------- Output fields, such as rain totals (RAINC, RAINNC) and radiation totals (ACLWUPT, ACSWDNB) accumulate throughout a simulation. Averages are determined by subtracting the initial value from the final value and dividing by the time interval. For longer (months+) regional climate simulations, 32-bit accuracy can lead to increasing inaccuracies in these accumulated variables over time because only ~7 significant figures are stored in model output. To overcome this issue, use *bucket_mm* and *bucket_J* to carry the total in integer and remainder parts, e.g. :math:`Total\ rain = RAINC + I\_RAINC * bucket\_mm` | The default bucket value is a typical monthly accumulation. * *bucket_mm* = 100 mm * *bucket_J* = 109 Joules | | | | Lake Model ---------- The CLM 4.5 lake model (*sf_lake_physics=1*), a modified version of the Community Land Model version 4.5 (CLM4) is a one-dimensional scheme that calculates mass and energy balance, incorporating 20-25 model layers. These layers consist of up to 5 snow layers on lake ice, 10 water layers, and 10 soil layers on the lake bottom. Lake points and lake depth can either be WPS-derived, or user-defined using namelist options *lake_min_elev* and *lakedepth_default* during WRF. The lake scheme is independent of a land surface scheme and therefore can be used with any land surface scheme available in WRF. |br| `Gu et al., 2013 `_ |br| `Subin et al., 2012 `_ | Bathymetry ++++++++++ Global bathymetry data, obtainable from `WPS Geographical Static Data Downloads `_ to be used during WPS/geogrid, are available for most lakes. | | | | WRF-Hydro --------- This capability couples the WRF model with hydrology processes (such as routing and channeling). It requires a separate compile using the *WRF_HYDRO* environment variable. Before configuring, issue the following: For a c-shell environment: .. code-block:: setenv WRF_HYDRO 1 | or for a bash environment: .. code-block:: export WRF_HYDRO=1 | Once WRF is compiled, copy files from the *WRF/hydro/Run* directory to the working directory (e.g. *WRF/test/em_real*). This option requires special initialization for hydrological data sets. `See RAL WRF-Hydro Modeling System `_ for details. | | | | | Physics Suites ============== A WRF physics suite is a set of physics options that performs well for a given application and is supported by a sponsoring group. Suites may provide guidance to users in applying WRF, improving understanding of model performance, and facilitating model advancement. The *physics_suite* setting in the *&physics* namelist record determines the suite. When this is set, the following parameters are included in the suite, meaning settings for specific schemes (e.g., mp_physics, cu_physics, etc.) do not need to be included: * mp_physics * cu_physics * bl_pbl_physics * sf_sfclay_physics * sf_surface_physics * ra_sw_physics * ra_lw_physics | Available physics suites are: #. NSF NCAR Convection-permitting Suite (CONUS) #. NSF NCAR Tropical Suite (tropical) | These suites consist of a thoroughly-tested combination of physics options that have shown reasonable results. | .. note:: The physics schemes used in the simulation are printed to the WRF output log (e.g., rsl.out.0000). | | | | NSF NCAR Convection-permitting Suite ------------------------------------ .. container:: row m-0 p-0 .. container:: col-md-12 pl-0 pr-3 py-3 m-0 .. container:: card px-0 h-100 .. rst-class:: card-header-def .. rubric:: NCAR Convection-permitting Suite (CONUS) .. container:: card-body-def A WRF physics suite for real-time forecasting focused on convective weather over the contiguous U.S. | Set the following in *namelist.input* to use this suite: .. code-block:: &physics physics_suite='CONUS' | | The following physics options are included with this suite: .. csv-table:: :align: left :widths: 25, 15, 25 :width: 65% :header: "Physics Type", "Scheme Name", "Namelist Option" Microphysics, Thompson, mp_physics=8 Cumulus, Tiedtke, cu_physics=6 Longwave Radiation, RRTMG, ra_lw_physics=4 Shortwave Radiation, RRTMG, ra_sw_physics=4 PBL, MYJ, bl_pbl_physics=2 Surface Layer, MYJ, sf_sfclay_physics=2 LSM, Noah, sf_surface_physics=2 | .. seealso:: See `NCAR Convection-permitting Suite `_ for details. | | | | NSF NCAR Tropical Suite ----------------------- .. container:: row m-0 p-0 .. container:: col-md-12 pl-0 pr-3 py-3 m-0 .. container:: card px-0 h-100 .. rst-class:: card-header-def .. rubric:: NCAR Tropical Suite (tropical) .. container:: card-body-def A WRF physics suite for real-Time forecasting focused on tropical storms and tropical convection | .. note:: This suite is identical to the "mesoscale_reference" suite in the MPAS model. | Set the following in *namelist.input* to use this suite: .. code-block:: &physics physics_suite = 'tropical' | The following physics options are included with this suite: .. csv-table:: :widths: 25, 15, 25 :width: 65% :align: left :header: "Physics Type", "Scheme Name", "Namelist Option" Microphysics, WSM6, mp_physics=6 Cumulus, New Tiedtke, cu_physics=16 Longwave Radiation, RRTMG, ra_lw_physics=4 Shortwave Radiation, RRTMG, ra_sw_physics=4 PBL, YSU, bl_pbl_physics=1 Surface Layer, MM5, sf_sfclay_physics=91 LSM, Noah, sf_surface_physics=2 | .. seealso:: See `NCAR Tropical Suite `_ for details. | | | | Overriding Physics Suite Options -------------------------------- To override a suite-included physics option, add that option and desired setting to the namelist. | Example 1 +++++++++ Turn off *cu_physics* for domain 3, when using the *CONUS* suite: .. note:: A setting of "-1" means the default setting is used. | .. code-block:: &physics physics_suite = 'CONUS' cu_physics = -1, -1, 0 | | | Example 2 +++++++++ When using the *CONUS* suite, choose a *cu_physics* option different than the default (*cu_physics=6*), and turn off *cu_physics* for domain 3: .. code-block:: &physics physics_suite = 'CONUS' cu_physics = 2, 2, 0 | | | | | Other Physics Applications ========================== | .. _Tropical Storms and Cyclones: Tropical Storms and Cyclones ---------------------------- The below options are available for use with tropical cyclone applications, and are set in the *&physics* record in *namelist.input*: | | 1-D Ocean Model +++++++++++++++ *sf_ocean_physics=1* A simple 1-D ocean mixed layer model following `Pollard et al., 1972 `_. The following are additional namelist options available with *sf_ocean_physics=1*: * **oml_hml0** : Specifies the initial ocean mixed layer depth * :math:`< 0` : initializes with real-time ocean mixed depth * :math:`=0` : initializes with climatological ocean mixed depth. | .. note:: User-supplied real mixed layer depth data may also be used. | * **oml_gamma** : Specifies a deep water temperature lapse rate (:math:`K/m`); this option works with all *sf_surface_physics* options. | | | 3D Ocean Model ++++++++++++++ *sf_ocean_physics=2* A 3D Price-Weller-Pinkel (PWP) ocean model based on `Price et al., 1994 `_. It predicts horizontal advection, pressure gradient force, and mixed layer processes. Only simple initialization via the following namelist variables is available. * **ocean_z** : vertical profile of layer depths for ocean (in meters) * **ocean_t** : vertical profile of ocean temps (K) * **ocean_s** : vertical profile of salinity | For e.g., .. code-block:: &physics sf_ocean_physics = 2 &domains ocean_z = 5., 15., 25., 35., 45., 55., 65., 75., 85., 95., 105., 115., 125., 135., 145., 155., 165., 175., 185., 195., 210., 230., 250., 270., 290., 310., 330., 350., 370., 390. ocean_t = 302.3493, 302.3493, 302.3493, 302.1055, 301.9763, 301.6818, 301.2220, 300.7531, 300.1200, 299.4778, 298.7443, 297.9194, 297.0883, 296.1443, 295.1941, 294.1979, 293.1558, 292.1136, 291.0714, 290.0293, 288.7377, 287.1967, 285.6557, 284.8503, 284.0450, 283.4316, 283.0102, 282.5888, 282.1674, 281.7461 ocean_s = 34.0127, 34.0127, 34.0127, 34.3217, 34.2624, 34.2632, 34.3240, 34.3824, 34.3980, 34.4113, 34.4220, 34.4303, 34.6173, 34.6409, 34.6535, 34.6550, 34.6565, 34.6527, 34.6490, 34.6446, 34.6396, 34.6347, 34.6297, 34.6247, 34.6490, 34.6446, 34.6396, 34.6347, 34.6297, 34.6247 | | | isftcflx ++++++++ This option, for use with *sf_sfclay_physics=1*, modifies surface bulk drag (Donelan) and enthalpy coefficients to reflect modern research on tropical storms/hurricanes. It also includes a dissipative heating term in heat flux. The following namelist options are available for computing enthalpy coefficients: * **isftcflx=1** : constant :math:`Z0q` for heat and moisture * **isftcflx=2** : Garratt formulation, slightly different forms for heat and moisture | | | | .. _Long Simulations: Long Simulations ---------------- Consider using the following options for simulations lasting 5 or more days: * **tmn_update=1** : update deep soil temperature * **sst_skin=1** : calculate skin SST based on `Zeng and Beljaars, 2005 `_ * **bucket_mm=1** : bucket reset value for water equivalent precipitation accumulations (value in mm, *-1* =inactive); see :ref:`Accumulation Budgets` for details * **bucket_J**: bucket reset value for energy accumulations (value in Joules, *-1* =inactive); only works with CAM and RRTMG radiation options (*ra_lw_physics = 3, 4, 14, 24* and *ra_sw_physics = 3, 4, 14, 24*); see :ref:`Accumulation Budgets` for details * If climate input does not include a leap year, prior to compiling WRF, edit the *configure.wrf* file by adding *-DNO_LEAP_CALENDAR* to the *ARCH_LOCAL* macro. | | | | .. _Windfarm: Windfarm -------- windfarm_opt=1 ++++++++++++++ This wind turbine drag parameterization scheme represents sub-grid effects of specified turbines on wind and TKE fields. Wind farm physical characteristics are read-in from a file; use of the manufacturer's specification is recommeded (e.g., *WRF/run/wind-turbine-1.tbl*). Turbine locations are read from the file *windturbines.txt*. See *README.windturbine* in the *WRF/doc* directory for additional details. |br| This option only works with 2.5 level MYNN PBL option (*bl_pbl_physics=5*). | | | windfarm_opt=2 ++++++++++++++ *Available for WRFv4.6.0+* This wind farm parameterization scheme (mav scheme), based on `Ma et al., 2022 `_, is similar to option 1 (above), but can also account for individual and overlapping sub-grid wakes of wind turbines. The following additional namelist options are available to use with this option: * **windfarm_wake_model** : Subgrid-scale wind turbine wake model *(default =2)* |br| |br| 1 = Jensen model |br| 2 = XA model |br| 3 = GM model *(windfarm_method is not used)* |br| 4 = Jensen and XA ensemble |br| 5 = Jensen, XA and GM ensemble | * **windfarm_overlap_method** : Wake superposition method for the Jensen and XA wind turbine wake model *(default = 4)* |br| |br| 1 = linear superposition |br| 2 = squared superposition |br| 3 = modified squared superposition |br| 4 = superposition of the hub-height wind speed (`Ma et al., 2022 `_) | * **windfarm_deg** : The rotation degree of the wind farm layout; only valid when *windfarm_opt=2* and *windfarm_ij=1*; `See Namelist Variables <./namelist_variables.html>`_ for details. | .. note:: When using *windfarm_opt=2*, the file *winturbines-ll.txt* must be present in the WRF running directory. The file is formatted with the wind turbine coordinates in the first two columns, followed by the *windfarm_id* and *windturbine_type*. For e.g., 33.0563 |nbsp| |nbsp| -78.6556 |nbsp| |nbsp| |nbsp| |nbsp| 2 |nbsp| |nbsp| |nbsp| |nbsp| 1 |br| 33.0534 |nbsp| |nbsp| -78.6407 |nbsp| |nbsp| |nbsp| |nbsp| 2 |nbsp| |nbsp| |nbsp| |nbsp| 1 |br| 33.0505 |nbsp| |nbsp| -78.6257 |nbsp| |nbsp| |nbsp| |nbsp| 2 |nbsp| |nbsp| |nbsp| |nbsp| 1 |br| 33.0446 |nbsp| |nbsp| -78.6594 |nbsp| |nbsp| |nbsp| |nbsp| 2 |nbsp| |nbsp| |nbsp| |nbsp| 1 |br| 33.0388 |nbsp| |nbsp| -78.6931 |nbsp| |nbsp| |nbsp| |nbsp| 2 |nbsp| |nbsp| |nbsp| |nbsp| 1 |br| 33.0359 |nbsp| |nbsp| -78.6781 |nbsp| |nbsp| |nbsp| |nbsp| 2 |nbsp| |nbsp| |nbsp| |nbsp| 1 |br| 33.0329 |nbsp| |nbsp| -78.6631 |nbsp| |nbsp| |nbsp| |nbsp| 2 |nbsp| |nbsp| |nbsp| |nbsp| 1 |br| 33.0271 |nbsp| |nbsp| -78.6332 |nbsp| |nbsp| |nbsp| |nbsp| 2 |nbsp| |nbsp| |nbsp| |nbsp| 1 | | | | .. _Surface Irrigation Parameterization: Surface Irrigation Parameterization ----------------------------------- *Available with WRFv4.2+* WRF includes the following surface irrigation options (set in the *&physics* namelist record), with explicit control over water amount and timing, each representing different water evaporative loss techniques, as follows (see `Vira et al., 2019 `_ for details): * **sf_surf_irr_scheme=1** : surface evapotranspiration; only works with Noah-LSM (*sf_surface_physics=2*) * **sf_surf_irr_scheme=2** : leaves/canopy interception and surface evapotranspiration * **sf_surf_irr_scheme=3** : microphysics process, leaves/canopy interception and surface evapotranspiration | The following additional options are available for use with surface irrigation schemes: * **irr_daily_amount** : The daily irrigation water amount applied (:math:`mm/day`) * **irr_start_hour** : UTC start hour for irrigation * **irr_num_hours** : The number of consecutive hours for irrigation * **irr_start_julianday** : The Julian start day of irrigation (e.g., 135) * **irr_end_julianday** : The Julian end day of irrigation (e.g., 255) * **irr_freq** : Irrigation frequency in days; can be set to values >1 to account for irrigation intervals greater than daily, thus water applied in the active day within the *irr_freq* period is: (:math:`irr\_daily\_amount * irr\_freq`) * **irr_ph** : Regulates spatial activation of irrigation (with *irr_freq >1*), especially determining whether it is activated for all domains on the same day (*irr_ph=0*); non-zero options are: * **irr_ph=1** : Psedo-random activation field as a function of (:math:`i,j,IRRIGATION`); ensures repeatability across compilers * **irr_ph=2** : Random activation field is created with the fortran RANDOM function; results may depend on the fortran RANDOM_SEED function | .. important:: When using nested domains, set irrigation schemes to run on only one domain to ensure the water application is not repeated and is consistent with the *irr_daily_amount*. See the `Irrigation Scheme GitHub Code Commit `_ for additional details. | | The following is an example of irrigation namelist parameters for a two-domain case: .. code-block:: sf_surf_irr_scheme = 0, 1 irr_daily_amount = 0, 8 irr_start_hour = 0, 14 irr_num_hours = 0, 2 irr_start_julianday = 0, 121 irr_end_julianday = 0, 170 irr_ph = 0, 0 irr_freq = 0, 3 | With the above settings, the channel method is used to irrigate the inner domain with *8* :math:`mm/day`, for *2* hours, starting at *14 UTC* on Julian day *121* and ending on Julian day *170*. Every *3* days (*irr_freq=3*) water is applied simultaneously to all irrigated grid-points in domain 02. This results in hourly irrigation of *12* :math:`mm/h` (daily application of *24* :math:`mm`), which is then multiplied by the irrigation percentage within the grid-cell (given by the IRRIGATION field processed in WPS). | | | | .. _WRF-Solar: WRF-Solar --------- WRF-Solar is a specific configuration and augmentation of the basic WRF model specifically designed for specialized numerical forecast products for solar energy applications. For additional information and instructions for use, visit the NSF NCAR Research Applications Laboratory's `WRF-Solar site `_. .. note:: WRF-Solar is managed and supported by the NSF NCAR/RAL group. All support inquiries should be posted to the `WRF-Solar forum `_ within the `WRF & MPAS-A Support Forum `_. | | | | .. _MAD-WRF: MAD-WRF ------- The MAD-WRF model is designed to improve cloud analysis and solar irradiance short-range forecasts. The following options are available: * **madwrf_opt = 1** : Initial hydrometeors are advected and diffused with the model dynamics, without microphysical processes; this option works with *mp_physics=96* and *use_mp_re=0* in the *&physics* namelist record * **madwrf_opt = 2** : Hydrometeor tracers are advected and diffused within the model dynamics. Initially, tracers equal the standard hydrometeors, which are nudged toward the tracers during simulation; namelist variable *madwrf_dt_nudge* sets the temporal period (in mins) for hydrometeor nudging, and *madwrf_dt_relax* sets the relaxation time (in seconds) for hydrometeor nudging. | Cloud initialization is available with MAD-WRF with the namelist setting *madwrf_cldinit=1* in the *&physics* record. By default the model enhances cloud analysis based on the analyzed relative humidity. Cloud initialization can be enhanced by providing additional variables to metgrid via the WPS intermediate format: * Cloud mask (CLDMASK variable): Remove clouds if clear (*cldmask=0*) * Cloud mask (CLDMASK variable) + brightness temperature (BRTEMP variable) sensitive to hydrometeor content (e.g. GOES-R channel 13): * Remove clouds if clear (*cldmask=0*) * Reduce/extend cloud top heights to match observations * Add clouds over clear sky regions (*cldmask=1*) | * Cloud top height (CLDTOPZ variable) with 0 values over clear sky regions: * Remove clouds if clear (*cldmask=0*) * Reduce/extend cloud top heights to match observations * Add clouds over clear sky regions (*cldmask=1*) | * Either 2 or 3 + the cloud base height (CLDBASEZ variable): * Remove clouds if clear (*cldmask=0*) * Reduce/extend cloud top/base heights to match observations | .. note:: Any missing values in these variables should be set to *-999.9*. | | | | .. _Physics Sensitivity Options: Physics Sensitivity Options --------------------------- * **no_mp_heating=1** : turns off latent heating from microphysics; only works with *cu_physics=0* * **icloud=0** : turns off cloud effect on optical depth in shortwave/longwave radiation options *1* and *4*; also controls the cloud fraction method used for radiation * **isfflx=0** : turns off both sensible and latent heat fluxes from the surface. This option works for *sf_sfclay_physics = 1, 5, 7, 11* * **ifsnow=0** : turns off snow effect in *sf_surface_physics=1* | | | | |