diff --git a/source/simulate.f90 b/source/simulate.f90
index be349b70e19038d4053dc0beb37ce830a7ba8068..6f7759cf538cc23d252a35db8fbe7228b5648aec 100644
--- a/source/simulate.f90
+++ b/source/simulate.f90
@@ -151,7 +151,7 @@ subroutine simulate(iter, files, config, fluxes, obs, states, grad_o, cost_o)
     else
       lsatellite = .false.
     endif
-    print*, 'simulate: lsatellite = ',lsatellite
+!    print*, 'simulate: lsatellite = ',lsatellite
 
     ! read correction factor for dry dir (ratio rho_wet/rho_dry)
     if ( month.ne.prevmonth ) then
@@ -238,7 +238,13 @@ subroutine simulate(iter, files, config, fluxes, obs, states, grad_o, cost_o)
     ! convert s.m3/kg to s.m2/kg
     grid = grid/outheight(1)
     ! convert from equivalent ppt to observation units (e.g. ppmv)
-    grid = grid*config%coeff*mmair/config%molarmass
+    ! sec not do it for bca
+    if ( config%spec.eq.'bca' ) then
+       grid = grid*config%coeff
+    else
+       grid = grid*config%coeff*mmair/config%molarmass
+    endif
+
     ! apply numerical scaling
     grid = grid/numscale
 !    if ( lsatellite ) then
@@ -306,7 +312,13 @@ subroutine simulate(iter, files, config, fluxes, obs, states, grad_o, cost_o)
       ! convert s.m3/kg to s.m2/kg
       gridnest = gridnest/outheight(1)
       ! convert from equivalent ppt to observation units (e.g. ppmv) 
-      gridnest = gridnest*config%coeff*mmair/config%molarmass
+      ! sec not do it for bca
+      if ( config%spec.eq.'bca' ) then
+        gridnest = gridnest*config%coeff
+      else
+        gridnest = gridnest*config%coeff*mmair/config%molarmass
+      endif
+
       ! apply numerical scaling
       gridnest = gridnest/numscale
 !      if ( lsatellite ) then