Correct scattering index and enable error inflation in ATMS data, (#812)

src/gsi/clw_mod.f90

@@ -1961,6 +1961,7 @@ subroutine ret_amsua(tb_obs,nchanl,tsavg5,zasat,clwp_amsua,ierrret,scat)
 ! Declare local variables 
   real(r_kind) :: d0, d1, d2, coszat
 ! real(r_kind) :: c0, c1, c2
+  real(r_kind) :: tb890 = zero
 
 
   coszat=cos(zasat)
@@ -1979,9 +1980,18 @@ subroutine ret_amsua(tb_obs,nchanl,tsavg5,zasat,clwp_amsua,ierrret,scat)
   endif
 
   if (present(scat)) then
-      scat=-113.2_r_kind+(2.41_r_kind-0.0049_r_kind*tb_obs(1))*tb_obs(1)  &
-           +0.454_r_kind*tb_obs(2)-tb_obs(15)
-      scat=max(zero,scat)
+     if (nchanl == 15) then
+!       AMSU-A
+        tb890 = tb_obs(15)
+     else if (nchanl == 22) then
+!       ATMS
+        tb890 = tb_obs(16)
+     endif
+     if (tb890 > zero) then
+        scat=-113.2_r_kind+(2.41_r_kind-0.0049_r_kind*tb_obs(1))*tb_obs(1)  &
+             +0.454_r_kind*tb_obs(2)-tb890
+     endif
+     scat=max(zero,scat)
   end if
 
 end subroutine ret_amsua

src/gsi/qcmod.f90

@@ -3670,7 +3670,7 @@ subroutine qc_amsua(nchanl,is,ndat,nsig,npred,sea,land,ice,snow,mixed,luse,   &
            ework = ework+min(0.002_r_kind*sfc_speed**2*error0(i), 0.5_r_kind*error0(i))
            clwtmp=min(abs(clwp_amsua-clw_guess_retrieval), one)
            ework = ework+min(13.0_r_kind*clwtmp*error0(i), 3.5_r_kind*error0(i))
-           if (scatp>9.0_r_kind .and. nchanl==15) then
+           if (scatp>9.0_r_kind) then
               ework = ework+min(1.5_r_kind*(scatp-9.0_r_kind)*error0(i), 2.5_r_kind*error0(i))
            end if
            ework=ework**2