Fully Integrated WRF and TLM/ADJ code

Prior to version 4.0, WRFPlus code had been developed and maintained in a separated branch from WRF. From V4.0, it is now fully integrated into the same WRF branch. TLM/ADJ code is located in the 'wrftladj' directory.

Compilation procedure of WRFPlus is also changed:

./configure wrfplus

./compile wrfplus

Executable created is now named wrfplus.exe under 'main' directory

GOES-Imager radiance data assimilation

New capability to assimilate GOES-13/14/15-Imager 4 IR channels (channel 2,3,4,6) radiance data in NETCDF GVAR format. Each channel's data are in separate file with names like goes-13-imager-01/02/03/04.nc for channel 2,3,4,6 respectively.

Triplet (platform, satid, sensorid) of GOES-Imager: (4, 13-15, 22)

For more details, the users are refered to Yang et al. (2017).

Yang, C., Z. Liu, F. Gao, P. P. Childs, and J. Min, 2017: Impact of assimilating GOES imager clear-sky radiance with a rapid refresh assimilation system for convection-permitting forecast over Mexico. J. Geophys. Res. Atmos., 122, 5472–5490.

GPSRO Excess PHase (GPSEPH) observation operator

The GPS Excess Phase nonlocal operator is described in Chen et al. (2009).The parallelization strategies are described in Zhang et al. (2014).

Chen, S. Y., C. Y. Huang, Y. H. Kuo, Y. R. Guo, and S. Sokolovskiy, 2009: Assimilation of GPS refractivity from FORMOSAT-3/COSMIC using a nonlocal operator with WRF 3DVAR and its impact on the prediction of a typhoon event. Terr. Atmos. Ocean. Sci., 20, 133-154, doi: 10.3319/TAO.2007.11.29.01(F3C)

Zhang, X.,Y.-H. Kuo, S.-Y. Chen, X.-Y. Huang, and L.F. Hsiao, 2014: Parallelization Strategies for the GPS Radio Occultation Data Assimilation with a Nonlocal Operator in the Weather Research and Forecasting Model. JTECH, https://doi.org/10.1175/JTECH-D-13-00195.1

Large-scale analysis constraint (LSAC)

The purpose of LSAC is to ensure that the convective-scale analysis does not distort the underlining large-scale balance and to eliminate possible large-scale bias in WRF back-ground. The global analysis or forecast, such as that from GFS or FNL, is treated as bogus observations and assimilated via WRFDA. The user can choose the scale of the large-scale to be enforced by skipping grid points both in the horizontal and vertical directions (see V4.0 users guide). For more detailed description of the LSAC, the user is referred to Vendrasco et al. (2016). The input data for LSAC is prepared using WPS, the same as preparing WRF input data by dowscaling.

Vendrasco, Eder Paulo, Juanzhen Sun, Dirceu Luis Herdies, Carlos Frederico de Angelis, 2016: Constraining a 3DVAR Radar Data Assimilation System with Large-Scale Analysis to Improve Short-Range Precipitation Forecasts. J. Appl. Meteor. Climatol., 55, 673–690.

Divergence constraint (DIVC)

A constraint term DIVC was added to model the correlation between u and v. The DIVC was implemented by adding a term in the cost function that constrains the horizontal divergence. For the detailed formulation of the new term, the user is referred to Tong et al. (2016) . The DIVC is evoked by setting use_divc = .true.. The effect of the DIVC is controlled by the value of the parameter divc_facter. The greater this value is, the smaller effect the DIVC has. Our recent experience showed that a value between 5000 and 10000 produced appropriate results, which did not significantly alter the pattern of precipitation while noise was eliminated.

Tong, W., G. Li, J. Sun, X. Tang and Y. Zhang, 2016: Design Strategies of an Hourly Update 3DVAR Data Assimilation System for Improved Convective Forecasting. Weather and Forecasting, 31, 1673–1695.