Added model-based QC for (MODIS) snow cover area fraction observations #96

Author: gmao-rreichle

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Added functionality for model-based QC of MODIS SCF observations using soil layer 1 temperature.
 - Added functionality to simulate landice tiles.
 - Added functionality to read nc4-formatted tile file.
 

GEOSlandassim_GridComp/clsm_ensupd_upd_routines.F90

@@ -1213,8 +1213,9 @@ subroutine get_obs_pred(                                       &
 
        case('asnow')
 
-         get_asnow_l   = .true.
-         get_asnow_lH  = .true.
+          get_asnow_l   = .true.
+          get_asnow_lH  = .true.
+          get_tp_l      = .true.   ! needed for model-based QC
 
        case default
 
@@ -1365,7 +1366,7 @@ subroutine get_obs_pred(                                       &
 
           ! updated to new interface - reichle, 3 Apr 2012
 
-          call catch_calc_tp( N_catl, cat_param%poros,                  &
+          call catch_calc_tp( N_catl, cat_param%poros,                           &
                catprogn2ghtcnt(N_catl,cat_progn(:,n_e)), tp_l )
 
        end if
@@ -1461,9 +1462,12 @@ subroutine get_obs_pred(                                       &
                 call qc_model_based_for_Tb( N_catl, precip, Tb_v_l(:,j,n_e) )
 
              end do
-             
+
           end if
 
+          if (get_asnow_lH) &
+               call qc_model_based_for_asnow( N_catl, tp_l(1,:), asnow_l(:,n_e) )   
+
        end if
 
     end do  ! loop through ens members
@@ -2254,7 +2258,7 @@ subroutine qc_model_based_for_sat_sfmc( N_cat, precip, SWE, tsurf, &
 
     do i=1,N_cat
 
-       ! delete obs 
+       ! delete Obs_pred 
        ! - if there is snow on the ground 
        ! - if it is raining/snowing
        ! - if surface temperature is around or below freezing
@@ -2337,7 +2341,7 @@ subroutine qc_model_based_for_sat_tsurf( N_cat, precip, SWE, tp1,    &
 
     do i=1,N_cat
 
-       ! delete obs 
+       ! delete Obs_pred 
        ! - if there is snow on the ground 
        ! - if it is raining/snowing
        ! - if "avoid_frozen" and frozen
@@ -2391,7 +2395,7 @@ subroutine qc_model_based_for_Tb( N_cat, precip, Tb )
 
     do i=1,N_cat
 
-       ! delete obs 
+       ! delete Obs_pred 
        ! - if there is heavy rain or snow
 
        ! NOTE: subroutine mwRTM_get_Tb already returns no-data-values
@@ -2412,6 +2416,44 @@ subroutine qc_model_based_for_Tb( N_cat, precip, Tb )
     end do
 
   end subroutine qc_model_based_for_Tb
+
+    ! *****************************************************************
+  
+  subroutine qc_model_based_for_asnow( N_cat, tp1, asnow )
+    
+   ! Model-based quality control for MODIS SCF observations.
+   ! Sets "asnow" to no-data when layer-1 soil temperature exceeds a threshold.
+   !
+   ! amfox, 7 May 2025
+   !
+   ! --------------------------------------------------------------
+   
+   implicit none
+   
+   integer,                   intent(in)    :: N_cat
+   
+   real,    dimension(N_cat), intent(in)    :: tp1              ! layer-1 soil temperature [C]
+   
+   real,    dimension(N_cat), intent(inout) :: asnow            ! snow cover fraction [0-1]    
+   
+   ! local variables
+   
+   real, parameter :: temperature_threshold = 10.               ! [C]
+   
+   integer :: i
+   
+   ! ---------------------------------------    
+
+   do i=1,N_cat
+      
+      ! delete Obs_pred 
+      ! - if the layer-1 soil temperature exceeds threshold
+      
+      if (tp1(i) > temperature_threshold)  asnow(i) = nodata_generic
+
+   end do
+   
+ end subroutine qc_model_based_for_asnow
 
   ! *********************************************************************