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WRF Model Version 3: UPDATES

WRF Model Update

WRF model tar file has been updated to Version 3 on April 4, 2008.

For WRF 3.0.1 updates, please click here.

WRF Pre-Processing System (WPS) replaces funcstions of SI in Version 3.

Note: The V3 WRF is NOT backward compatible with old input files. One must rerun WPS to generate data for real/wrf. New options have not been tested extensively. Please use with caution.

Also see 'Known Problems' in this release. If you are interested in seeing how V3 has been tested, click here.

In this new release, the following new features and updates are provided:


New in this release:

- Morrison 2-moment microphysics (contributed by H. Morrison, NCAR)
- Goddard microphysics (contributed by Shi and Tao, NASA)
- New Grell cumulus ensemble scheme (work better at ~ 5km grid sizes)
- Unified Noah LSM. Improved emissivity treatment over snow.
- ACM2 (Asymmetric convection model 2) PBL scheme (contributed by Pleim and Gilliam, EPA)
- Pleim-Xiu LSM (2 level) (contributed by Pleim, Xiu and Gilliam, EPA)
- Zaengl radiation/topography (slope/shadowing) effects for Dudhia shortwave scheme (contributed by Zaengl, Germany)
- Sea ice and albedo updating capability for long simulations
- 3D TKE coupled with surface fluxes (LES PBL)
- Simple ocean mixed model (based on Pollard, Rhines and Thompson (1973), coupled with 5-layer soil model)
- Modified surface drag for tropical storm application

Improvements and Bug fixes:


- YSU: improvement for stable PBL.

Surface layer physics:

- MM5 surface layer scheme (sf_sfclay_physics = 1) now uses convective velocity following Wyngaard (old MM5 method) to help in zero wind case

Land surface physics:

- RUC LSM: minor update. Improved initialization from NAM data.
- LANDUSE.TBL: some changes to emissivity values.
- UCM has anthropogenic heat source added


- WSM6 schemes: use snow/graupel combined fall speed to represent gradual snow-to-graupel transition
- WSM5: performance improvement. Will change result within roundoff
- Lin: minor correction to graupel ventilation factor
- Ferrier: 1. During melting precipitation ice particles are assumed to have the same mean diameter (1 mm) as at the freezing level. 2. Two changes intended to increase the presence of supercooled liquid water and improve forecast products for use in aircraft icing algorithms: 3a. The temperature at which small amounts of supercooled liquid water, if present, are assumed to be glaciated to ice was lowered from -30C to -40C. 3b. The temperature at which ice nucleation is allowed to occur was lowered from -5C to -15C based on aircraft icing observations

Cumulus schemes:

- BMJ:
1. Triggering of deep and shallow convection is considered only for grid points with positive cape throughout a parcel's ascent; the search for parcel instability is extended to include not only whether the most unstable (highest theta-e) parcel can support convection, but also whether parcels originating at higher levels become positively buoyant when lifted to their LCL. Convective adjustments are made with respect to the parcel associated with the greatest instability (largest CAPE)
2. The search for the most unstable parcel is extended from the lowest twenty percent of the atmosphere to the lowest 40 percent of the atmosphere.
3. Water loading effects are now included in assessing the buoyant instability of parcels from which a revised (lower) cloud top is determined to be at the highest level of positive buoyancy.
4. The latent heat of vaporization used to calculate equivalent potential temperatures during model integration is made to be consistent with the value used in generating the initial lookup tables.
5. When a grid point fails the entropy check for deep convection but still has positive CAPE, changes in temperature and moisture by shallow convection are then considered at these so-called "swap" points. The first-guess estimate for the top of shallow convection is based on the highest level where the parcel remains positively buoyant (this is more restrictive than positive CAPE), and the vertical extent of shallow convection is not to exceed 0.2 times the atmospheric pressure depth (e.g., 200 hPa for a surface pressure of 1000 hPa). A final adjustment is made to the top of shallow convection in which it can extend to higher altitudes if the mean ambient relative humidity (RH) in the cloud layer exceeds a threshold RH while remaining positively buoyant (i.e. CAPE greater than 0). The threshold RH is based on the RH at cloud base that is consistent with a deficit saturation pressure of 25 mb (usually near 90%). (The maximum cloud top height for shallow convection remains limited to 450 hPa.)
6. The first-guess reference temperatures in the upper-half of shallow convective clouds are limited to be no more than 1 deg C colder than the ambient temperature..

Atmospheric radiation:

- CAM radiation can now be combined with other radiation schemes

Nudging Options:

- Bug fixes for three-dimensional grid analysis nudging (details)
- Bug fixes for observation nudging (details)

Dynamics/Diffusion/Filter Options:

- Global modeling capability on latitude and longitude grid. Works also on a rotated lat and long grid. (Contributed by Richardson, Cal Tech)
- Regional lat-long grid
- Implicit upper boundary gravity-wave absorbing layer (damp_opt=3)
- Diffusion modifications for isotropic and anisotropic mixing (mix_isotropic)
- Rigid lid upper boundary condition (namelist control, top_lid)

Initialization/Nesting/Restart/Lateral boundary/IO

- More options in program real to control near-surface interpolation. Option for not using surface data is added.
- Improved T and RH at nest boundaries
- Exponential lateral boundary function namelist option (spec_exp)
- Doubly periodic boundary support from RSL_LITE
- Automatic-vortex tracking level becomes runtime option (track_level).
- Digital filter initialization (thanks to the contributions from GSD/NOAA, and Min Chen of BMB, China)
- Variable time stepping: allows time step to increase and decrease according to model stability criterion during a model integration (contributed by Hutchinson of WSI)
- Time series outputting capability (checks for the presence of time series station file: tslist. See run/README.tslist for details)
- sst_update option now includes seaice and albedo update
- wrflowinp input stream is changed from auxiliary stream 5 to 4
- Three new idealized test cases:

* em_heldsuarez: idealized global case
* em_les: large eddy simulation case (contributed by Moeng, NCAR)
* em_seabreeze2d_x: an example to illustrate how to set up idealized case to utilize full physics, especially land surface physics (contribued by Joe Galewsky of University of NM)


- No need to add all new namelist record in the namelist file. The code will not abort because of missing namelist records. A warning will be printed for information.
- One namelist variable is removed:



New Features:

- Large netcdf file support (for netcdf file size larger than 2 Gb)

If the expected netcdf file size will be greater than 2 Gb, set environment variable WRFIO_NCD_LARGE_FILE_SUPPORT to 1 prior to compilation. This feature requires netcdf version of 3.6 or later.

- Streamlined infrastructure and memory utilization

* Dynamic core selection now done at compile time
* Reduced compile-time expansion of complex routines allowing more of WRF to be compiled with full optimization
* Memory for physics packages conditionally allocated at run time
* New, scalable data structures for lateral boundary conditions
* Simplified build unified over WRF models, Chemistry, and Var

- New or enhanced support for computer systems (compilers)

* IBM Blue Gene and Power series (Xlf)
* Linux x86, x86_64, and ia64 (PGI, Intel, Pathscale, g95, gfortran)
* WinCCS (PGI)
* Intel Mac (PGI, Intel, g95, and gfortran compilers)
* Cray XT3/4 (PGI, Pathscale)
* SGI Altix and Origin (Intel)
* HP
* NEC SX series
* MPI support: MPICH (various), vendor versions, and Open MPI, Intel MPI

- Misc:

* Single executable ensemble support
* Parallel NetCDF and enhanced Quilting
* ESMF component capability
* Full RSL_LITE support for nesting, transposes, periodic BC’s, etc. RSL communication package has been retired in V3
* GPU accelerated WSM5 microphysics (experimental)


Previous Update

WRF V2.1.2.
WRF V2.1.1.
WRF V2.1.
WRF V2.0.


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