Fix outgoing lw for history and coupling. (CICE-Consortium#999)

This is a two-line change in ice_flux.F90 (scale_fluxes) to check for the condition where aice > 0, but flwout > -puny (effectively zero). This means the cell was ice free at the beginning of the step, but non-zero at the end. It sets the outgoing longwave to the open ocean value based on the freezing temperature. This is bfb, but will change the history output of flwup and flwup_ai. Test results are coming.

cicecore/cicedyn/general/ice_flux.F90

@@ -1209,15 +1209,15 @@ subroutine scale_fluxes (nx_block, ny_block, &
       real (kind=dbl_kind) :: &
           ar, &   ! 1/aice
           stefan_boltzmann, &
-          Tffresh
+          Tffresh, puny
 
       integer (kind=int_kind) :: &
           i, j    ! horizontal indices
 
       character(len=*), parameter :: subname = '(scale_fluxes)'
 
       call icepack_query_parameters(stefan_boltzmann_out=stefan_boltzmann, &
-         Tffresh_out=Tffresh)
+         Tffresh_out=Tffresh, puny_out=puny)
       call icepack_warnings_flush(nu_diag)
       if (icepack_warnings_aborted()) call abort_ice(error_message=subname, &
          file=__FILE__, line=__LINE__)
@@ -1231,6 +1231,9 @@ subroutine scale_fluxes (nx_block, ny_block, &
             fsens   (i,j) = fsens   (i,j) * ar
             flat    (i,j) = flat    (i,j) * ar
             fswabs  (i,j) = fswabs  (i,j) * ar
+            ! Special case where aice_init was zero and aice > 0.
+            if (flwout(i,j) > -puny) & 
+               flwout  (i,j) = -stefan_boltzmann *(Tf(i,j) + Tffresh)**4
             flwout  (i,j) = flwout  (i,j) * ar
             evap    (i,j) = evap    (i,j) * ar
             Tref    (i,j) = Tref    (i,j) * ar