#!/usr/bin/perl
#    use strict;
#    use warnings;
#   changed to calculate the monthly averages first.
use Time::Local
    my @CC=();
    my @mvap=();
    my @nhit=();
    @mdays=(31,28,31,30,31,30,31,31,30,31,30,31);
# date set at half of december 1987 for the mid month normalization
    $time = timegm(1,1,12,15,0,1988)-978307200;
    $command = 'ncdump -v MnCldAmt MnCldAmt.nc';
    $istart = 0;
    my @docs = qx($command);
        	$icount=0
        	foreach my $line (@docs) {
               chomp $line;
               if ($istart eq 0) {
                   if ($line =~ /water_vapor =/)
                   {
                      $istart =1;
                      $lon=0;
                      $lat=0;
                      $imonth=0;                    
                    }
                } else {
                  $icount++;
                  my @values = split(',', $line);
  			      foreach my $val (@values) 
  			      {
  					  if ($val < 10.0) {
  					    	$mvap[$lon][$lat][$imonth] = $val;

#  					    	print $lon.'  '.$lat.'  '.$mvap[$lon][$lat][$imonth] ,"   \n";
  					    }
  					    $lon++;
                      }
                      if ($lon > 144) {
                        $lon=0;
                        $lat++;
                      } 
                      if ($lat > 72) {
# make mnthly average
#
           			for ($i=0; $i<360; $i++)
           			{
             		for ($j=0; $j<180; $j++)
             		{
#          			 print $mdays[$imonth].'   '.$lon.'  '.$lat.'  '.$mvap[$lon][$lat][$imonth] ,"   \n";
             		if ($mvap[$i][$j][$imonth] > 0.0) {
               			$wvap[$i][$j] = $mvap[$i][$j][$imonth]/$nhit[$i][$j];
               			$nhit[$i][$j] = 0;
               			$mvap[$i][$j][$imonth]=0.0;
#               	print $lon.'  '.$lat.'  '.$wvap[$lon][$lat],"   \n";
           	    	} else {
               		$wvap[$i][$j] = -9999;
                	}
        		 }
         	 }
 
#
#  - calculate global average
#
    		my $W_tot_NH = 0;
    		my $A_tot_NH = 0;
    		my $W_tot_SH = 0;
   			my $A_tot_SH = 0;
   		
    		for ( my $j = 0 ; $j < 180 ; $j++ ) {

        #Grid-box area is proportional to cosine of latitude
       	 		my $Lat = 90 - ( $j + 0.5 );
        		if ( $Lat > 90 || $Lat < -90 ) { next; }
        		my $Weight = cos( $Lat * 3.141592 / 180 );
        		for ( my $i = 0 ; $i < 360 ; $i++ ) {
            		if ( $wvap[$i][$j] < -9000 ) { next; }
            		if ( $Lat > 0 ) {
                		$W_tot_NH += $Weight;
                		$A_tot_NH += $wvap[$i][$j] * $Weight;
 #               print $Weight,"   \n";
            		}
            		else {
               	 		$W_tot_SH += $Weight;
                		$A_tot_SH += $wvap[$i][$j] * $Weight;
            		}

        		}
    		}
    		if ( $W_tot_NH > 0 && $W_tot_SH > 0 ) {
    			$glavg = ( $A_tot_NH / $W_tot_NH + $A_tot_SH / $W_tot_SH ) / 2;
    			$navg = $A_tot_NH / $W_tot_NH;
    			$savg = $A_tot_SH / $W_tot_SH; 
#            print $iyear.'   '.$iday.'   '.$glavg.'   '.$navg.'   '.$savg,"   \n";
				print $time.'   '.$glavg.'   '.$navg.'   '.$savg,"   \n";
				$time = $time+$mdays[$imonth]*86400;
        	}
           $imonth = $imonth + 1;
           $dmonth= 0;
        } else {
           $dmonth++;
        }
           
      }
    }