Motivation:

• The analysis of significant wave height (HOWV) and 10-m wind gust (GUST) are listed as standard product in the operational (2D)RTMA/URMA product suites. To keep providing these two products in next generation RTMA/URMA (ie, 3DRTMA) system, the capability to directly analyze wave height and wind gust must be added into GSI 3DVar analysis.

Method:

• The kernel part of the analysis code (such as stphowv.f90, setuphowv.f90, inthowv.f90, gsi_howvOper.f90 and m_howvNode.f90 for HOWV, and similar code for GUST) for wave height and wind gust had already been introduced into GSI through the implementation of 2DRTMA. So most of the code work for analysis of HOWV and GUST in 3DVar, are mainly focused on the I/O interfaces for the firstguess provided by various models (i.e. reading background of HOWV/GUST from firstguess file and writing the updated HOWV/GUST back to the final analysis file).
• The I/O interfaces for FV3-LAM model based firstguess had been done in previous work (see issue Adding I/O for Analysis of Significant Wave Height for 3DRTMA #601 and issue Adding I/O for direct analysis of near-surface wind gust for RRFS-based 3DRTMA #726). Since RRFS-3DRTMAv1 has been switched to be based on HRRR model, so in this work, some efforts are made to add the I/O interfaces in GSI for WRF-ARW model based firstguess.
• This issue is linked to the working branch "feature/rtma3d_wavhgtwndgst_wrfarw" in my fork of EMC-GSI repository on github.