id summary reporter owner description type status priority milestone component version resolution keywords cc 916 VERY IMPORTANT: Update WRF ESMF/NUOPC cap module arango "We have carefully examined the **DATA-WRF-ROMS** coupling system with the **ESMF/NUOPC** library. We fixed [[span(style=color: #0000FF, **esmf_atm_wrf.h**)]] **NUOPC** ''cap'' module after a detailed analysis of the heat flux balance equation. The documentation of WRF fluxes in the code is confusing about the direction (downward/upward) and the sign (positive/negative) of the **latent** and **sensible** heat fluxes. The [[span(style=color: #FF0000,net heat flux)]] previously exported from WRF to ROMS was incorrect due to the confusing information. * There are several variables in WRF for the heat component fluxes: -- There is downwelling shortwave flux (**swdnb**, downward) and upwelling shortwave flux (**swupb**, upward) at the atmosphere bottom. Both are positive and with W/m^2^ units. Therefore, the net shortwave radiation flux is **swdnb** minus **swupb**, stored in variable **gsw**, is positive and downward since **swupb** is around 8 percent of the magnitude of **swdnb**. Notice that the variable **swdown** is equivalent to **swdnb**. Both are positive and with W/m^2^ units. -- Since the ocean needs [[span(style=color: #FF0000,net shortwave radiation flux)]], we decided to use the downward (**swdnb**) and upward (**swupb**) fluxes for clarity. Also, the time-averaged values **swdnb_mean** and **swupb_mean** are available when the RAMS diagnostics are activated for semi-implicit coupling. -- Similarly, there is downwelling longwave flux (**lwdnb**, downward) and upwelling longwave flux (**lwupb**, upward) at the atmosphere bottom. The variable **lwupb** is basically [[span(style=color: #0000FF,''!StefBo * emiss * Tsur^4^'')]]. **Tsur** is the land and ocean temperature at the atmosphere bottom (Kelvin). Likewise, notice that the variable **glw** is equivalent to **lwdnb**. We will use **glw** because its equivalent time-averaged variable is **glw_mean** when the RAMS diagnostics are activated for semi-implicit coupling. The [[span(style=color: #FF0000,net longwave radiation flux)]], **glw** minus **lwupb**, can be positive or negative. -- The variable **hfx** is the sensible heat flux (W/m^2^), and **lh** is the latent heat flux (W/m^2^). Both fluxes are **positive** and **upward** from the bottom of the atmosphere. [[span(style=color: #0000FF,Please ignore the conflicting documentation in the WRF source code for these fluxes)]]. The time-averaged values are **hfx_mean** and **lh_mean**, respectively. Therefore, we need to flip the sign and use **minus** when computing the ocean [[span(style=color: #FF0000,surface net heat flux)]]. -- Therefore, if **BULK_FLUXES** is off, the [[span(style=color: #FF0000, surface net heat flux)]] (W/m^2^) exported to the ocean in subroutine [[span(style=color: #FF0000, **WRF_Export**)]] of ''cap'' module [[span(style=color: #0000FF, **esmf_atm_wrf.h**)]] needs to be: {{{ CASE ('nflx', 'shflux') MyFmin(1)= MISSING_dp MyFmax(1)=-MISSING_dp DO j=Jstr,Jend DO i=Istr,Iend # ifdef WRF_TIMEAVG Fval=(grid%swdnb_mean(i,j)-grid%swupb_mean(i,j))+ & & (grid%glw_mean(i,j)-grid%lwupb_mean(i,j))- & & grid%lh_mean (i,j)- & & grid%hfx_mean(i,j) # else Fval=(grid%swdnb(i,j)-grid%swupb(i,j))+ & & (grid%glw(i,j)-grid%lwupb(i,j))- & & grid%lh (i,j)- & & grid%hfx(i,j) # endif MyFmin(1)=MIN(MyFmin(1),Fval) MyFmax(1)=MAX(MyFmax(1),Fval) ptr2d(i,j)=Fval END DO END DO }}} Here, the CPP option **WRF_TIMEAVG** is used to compute the flux with the RAMS time-averaged diagnostics for semi-implicit coupling (see [https://www.myroms.org/wiki/Model_Coupling RunSequence in wikiROMS]). * Several routines in ROMS were updated to allow importing the components of the heat flux balance for debugging and output purposes when **BULK_FLUXES** is off. * The test case for Hurricane Irene has been revised accordingly in the **test** repository. Please check this application when configuring your coupling system. ---- Snapshots of WRF land and ocean surface temperature and heat flux components are shown below for the hurricane Irene application: [[Image(https://www.myroms.org/trac/wrf_irene_tsur.png, center, 600)]] [[Image(https://www.myroms.org/trac/wrf_irene_swflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/wrf_irene_lwflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/wrf_irene_lhflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/wrf_irene_shflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/wrf_irene_nhflx.png, center, 600)]] ---- Then, the atmospheric field imported by ROMS are: [[Image(https://www.myroms.org/trac/roms_irene_swflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/roms_irene_lwflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/roms_irene_lhflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/roms_irene_shflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/roms_irene_nhflx.png, center, 600)]] [[Image(https://www.myroms.org/trac/roms_irene_EminusP.png, center, 600)]] [[Image(https://www.myroms.org/trac/roms_irene_wstress.png, center, 600)]] [[Image(https://www.myroms.org/trac/roms_irene_pair.png, center, 600)]] ---- Many thanks to my colleagues at Rutgers, John Wilkin, Julia Levin, and Travis Miles, for the discussions about WRF-ROMS coupling. ---- The zero values in the latent heat flux in the Mid-Atlantic Bight (MAB) were corrected by commenting a limiter kluge in WRF modules **module_sf_sfclay.F** and **module_sf_sfclayrev.F**. But unfortunately, it has been there for years, and the WRF developers refuse to correct it. Specifically, we need to comment on these two lines: {{{ ! line 898 QFX(I)=AMAX1(QFX(I),0.) ! And line 916 HFX(I)=AMAX1(HFX(I),-250.) }}} Furthermore, unlimited and limited latent heat flux and its difference (unlimited minus limited) values are shown below. Notice the effects of the removing the limiters along the US East Coast, MAB, and the Gulf of Maine. [[Image(https://www.myroms.org/trac/wrf_irene_lhfU.png, center, 600)]] [[Image(https://www.myroms.org/trac/wrf_irene_lhfL.png, center, 600)]] [[Image(https://www.myroms.org/trac/wrf_irene_lhf_diff.png, center, 600)]] The resulting [[span(style=color: #FF0000,net heat flux)]] difference between using unlimited and limited latent heat fluxes yields: [[Image(https://www.myroms.org/trac/wrf_irene_nhflx_diff.png, center, 600)]] Therefore, users need to be aware of the latent heat flux **limiters** in the WRF modules mentioned above and experiment in their particular applications." upgrade closed major Release ROMS/TOMS 4.1 Nonlinear 4.0 Done