id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
964	VERY IMPORTANT: Wind Minus Current revisited during ESMF coupling	arango		"The **ROMS** and **WRF** **NUOPC** cap modules were updated to exchange surface current (**Usur**, **Vsur**) between ocean and atmosphere couple components.

We are currently using the **WRF** code from https://github.com/myroms, which we applied a couple of corrections to the code submitted to its developers and will appear in future releases. As before, there will be no need to patch **WRF** for each release version.

== Test Case ==

The Hurricane **IRENE** application has a new test case in the **IRENE/Coupling/data_wrf_roms_wmc** subdirectory. For more details, please check the link to the **roms_test** repository in!GitHub for detailed information and instructions:

https://github.com/myroms/roms_test/blob/main/IRENE/Coupling/data_wrf_roms_wmc/Readme.md

The **ROMS** and **WRF** grids are incongruent in this test case. Since ROMS doesn't cover all the ocean points in the WRF grid (red domain below), a **DATA** component is used to supply such values from the 3-hour **HyCOM** dataset. **ROMS** and **DATA** components export surface ocean current at the cell center (**RHO**-points). Then, the ocean currents from **DATA** and **ROMS** are melded smoothly using the appropriate weights.

||= Surface Ocean U-velocity =||= Surface Ocean V-velocity ||
|| [[Image(https://www.myroms.org/trac/wrf_import_Usur.png, center, 400)]] || [[Image(https://www.myroms.org/trac/wrf_import_Vsur.png, center, 400)]] ||
|| [[Image(https://www.myroms.org/trac/wrf_import_dUsur.png, center, 400)]] || [[Image(https://www.myroms.org/trac/wrf_import_dVsur.png, center, 400)]] ||
|| [[Image(https://www.myroms.org/trac/wrf_merged_Usur-dUsur.png, center, 400)]] || [[Image(https://www.myroms.org/trac/wrf_merged_Vsur-dVsur.png, center, 400)]] ||

The meldes surface currents are imported by **WRF** into variables **grid%uoce** and **grid%voce**. We will continue exploring WRF internal parameters to study the effects of the surface currents on the winds and wind stress. As shown by Renault ''et al.'' (2016), the feedback from surface ocean currents to the atmosphere is an eddy-killing effect stabilizing the Gulf Stream separation at Cape Hatteras in **WRF-ROMS** fully coupled applications. The result is around 0.3 N/m^2^ weaker surface wind stress in the core of the Gulf Stream."	upgrade	closed	major	Release ROMS/TOMS 4.2	Nonlinear	4.1	Done