Weak Penalty Constraint (WPEC) option
For Version 3.8, a new "weak penalty constraint" (WPEC) option has been added to WRFDA which aims to enforce quasi-gradient balance on a WRFDA analysis. It was designed with the specific aim of improving assimilation of radar data within tropical cyclones, but may be useful for other weather phenomena of similar scales. It can be used with 3DVAR or hybrid 3DVAR (4DVAR is not compatible with this new capability). Further details about this method can be found in the relevant section of the User's Guide and in the following publication by the developers of this capability:
Li, Xin, Jie Ming, Ming Xue, Yuan Wang, and Kun Zhao, 2015: Implementation of a dynamic equation constraint based on the steady state momentum equations within the WRF hybrid ensemble–3DVar data assimilation system and test with radar T-TREC wind assimilation for tropical Cyclone Chanthu (2010). J. Geophys. Res. Atmos., 120, 4017–4039, doi:10.1002/2014JD022706.
AMSR2 radiance assimilation
The GCOM-W1 satellite carries the Advanced Microwave Scanning Radiometer 2 (AMSR2) instrument. WRFDA can now assimilate radiance observations from this instrument, which are available in HDF5 format from the Japanese Aerospace Exploration Agency (JAXA). The relevent namelist options are as follows:
&wrfvar4
use_amsr2obs (logical) Switch for reading AMSR2 observations.
true: WRFDA will read AMSR2 data
false: no AMSR2 data will be read (default)
&wrfvar14
rtminit_platform = 29, (GCOM-W)
rtminit_satid = 1 (for GCOM-W1)
rtminit_sensor = 63, (AMSR2)
More information on this capability (including file naming conventions) can be found in the relevant section of the User's Guide. The AMSR2 data is made available in HDF5 format, which requires compilation of WRFDA with HDF5 libraries. This procedure is described in the User's Guide as well.
