From d3b022867c8405c7188c978bc5213b08c90cd012 Mon Sep 17 00:00:00 2001
From: zarzycki <czarzycki@psu.edu>
Date: Mon, 6 Mar 2023 11:35:23 -0500
Subject: [PATCH] add some comments to docn gen code from ALCC runs

---
 slab-ocn/external-to-docn.ncl | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/slab-ocn/external-to-docn.ncl b/slab-ocn/external-to-docn.ncl
index 7fa32e4..320a1cb 100644
--- a/slab-ocn/external-to-docn.ncl
+++ b/slab-ocn/external-to-docn.ncl
@@ -1,5 +1,8 @@
 begin
 
+; this script takes in some sort of external file (infile) with different vars
+; for SST and ice (ex: sst and icec) and converts it to monthly means at the midpoint
+; of each month in proper format to be used for CIME DOCN streams.
 
 f=addfile(infile,"r")
 
@@ -14,9 +17,10 @@ lon_out = r->lon
 var_in = f->sst(:,::-1,:)
 ice_in = f->icec(:,::-1,:)
 
+; get rid of missing data (usually over land areas)
+; first go east/west, then north/south for SST and set to 0 for ICEFRAC
 var_in = linmsg(var_in,-1)
 var_in = linmsg_n(var_in,-1,1)
-
 ice_in = linmsg(ice_in,-1)
 ice_in = where(ismissing(ice_in),0.0,ice_in)
 
@@ -27,36 +31,41 @@ dd = toint(alldates(:,2))
 sssss = toint(alldates(:,5))
 
 do ii = 0,dimsizes(time_in)-1
+  ; all months of 30 + 31 have midpoint on 16th day, but feb is on 15th
   if (mm(ii) .eq. 2) then
     dd(ii) = 15
   else
     dd(ii) = 16
   end if
-  
+
+  ; if month has even number of day, midpoint is at 0, if not at 43200
   if (mm(ii) .eq. 2 .or. mm(ii) .eq. 4  .or. mm(ii) .eq. 6  .or. mm(ii) .eq. 9  .or. mm(ii) .eq. 11) then
     sssss(ii) = 0
   else
     sssss(ii) = 43200
   end if
-
 end do
 
+; get YYYYMMDD
 date = yyyy*10000 + mm*100 + dd
 date!0 = "time"
 
+; get SSSSS
 datesec = sssss
 datesec!0 = "time"
 
 print(date+" "+datesec)
 
+;----- write ouput file with correct format
+
 SST_write_file=infile+"_CIMEified.nc"
 system("/bin/rm -f -v "+SST_write_file)
 out = addfile(SST_write_file,"c")
-     
+
 fAtt               = True
 fAtt@creation_date = systemfunc ("date")
 fileattdef(out, fAtt)
-filedimdef(out,"time",-1,True) 
+filedimdef(out,"time",-1,True)
 
 ; copy over some vars. Not sure top 2 are needed.
 ;out->date = in->date
@@ -69,7 +78,6 @@ out->time = time_in
 out->date = (/date/)
 out->datesec = (/datesec/)
 
-
 ; output SST and ice fields
 out->SST = var_in
 out->ICEFRAC = ice_in