Correction to calc_cost in mod_analytic for optimization of offsets

source/mod_analytic.f90

@@ -552,16 +552,17 @@ module mod_analytic
     ! Jo = (y - Hx)^TR^(-1)(y - Hx)
     cost_o = 0.
     do i = 1, nobs
-      ! only calculate delta if state variables contribute to mixing ratio
-      if ( obs%model(i).ne.0. ) then
-        if ( config%spec.eq.'co2' ) then
-          obs%delta(i) = obs%model(i) + obs%nee(i) + obs%fff(i) + obs%ocn(i) + obs%bbg(i) - &
-                        obs%conc(i) + obs%bkg(i) + obs%cini(i)
+      if ( config%spec.eq.'co2' ) then
+        obs%delta(i) = obs%model(i) + obs%nee(i) + obs%fff(i) + obs%ocn(i) + obs%bbg(i) - &
+                      obs%conc(i) + obs%bkg(i) + obs%cini(i)
+      else
+        if ( .not.config%offsets ) then
+          ! optimize fluxes themselves
+          obs%delta(i) = obs%model(i) + obs%ocn(i) - obs%conc(i) + obs%bkg(i) + obs%cini(i)
         else
-          obs%delta(i) = obs%model(i) - obs%conc(i) + obs%bkg(i) + obs%cini(i)
+          ! optimize offsets so account for contribution from best guess fluxes (ghg)
+          obs%delta(i) = obs%model(i) + obs%ghg(i) - obs%conc(i) + obs%bkg(i) + obs%cini(i)
         endif
-      else
-        obs%delta(i) = 0.
       endif
       cost_o = cost_o + obs%delta(i)**2/obs%err(i)**2
     end do