program nvap_resize
c***********************************************************************
c
c  this program takes the nvap-ng 1/2 degree data and averages up the
c  4 grid boxes to create a 1 degree data set - for comparison with the
c  nvap dataset.   Averaging is done since this is the process which
c  would create a 1 degree data set.
c
c  written by dave randel stc/metsat
c          in august 2003
c
c**********************************************************************

        real sa(360,180), rna(360,180), data2(360,180)
        character*80 flname,flout
        character*1 decc,dec
        logical ex  
c                     
c--------common block which holds the data and header information---------
c
       real nvdata(720,360), headr(4), zindef
cmy fix
       integer*2 headi(11), igrd
cend fix
       character label*40
       common /nvapdata/ nvdata, headr, zindef, headi, label
c		   
  1     format(a,$)
  2     format(a)
  3     format(i3)

c**read input filename**********

        write(6,*)' NVAP-NG  1/2 degree to 1 degree routine'
	  write(6,*)
  5     write(6,*)
        write(6,1)' Input 1/2 degree NVAP-NG filename? : '
        read(5,2) flname
        if(flname .eq. ' ') then
                pause
                stop
        endif
c
c**get output filename

        write(6,1)'         Output 1 degree filename? : '
        read(5,2) flout

c**get field averaging information
c
        write(6,*)
        write(6,1)' Resize all fields in file? (y/n) [y] : '
        read(5,2) dec
        if(dec .eq. ' ') dec = 'y'
        if(dec.eq.'n' .or. dec.eq.'N') then
             write(6,1)'      start with field number? : '
             read(5,3) nstart
             write(6,1)'   number of fields to resize? : '
             read(5,3) nflds
        else
             nstart = 1
cmy fix
             nflds = 1000
cend fix
        endif

c**start averaging/resizing process

        ioutfld = 0
        do igrd = nstart,nstart+nflds-1
          do j = 1,180
            do i = 1,360
              rna(i,j) = 0.0
              sa(i,j) = 0.0
            enddo
          enddo
	    istat = 0
          call nvap_read(flname, igrd, istat)    !read  1/2 degree data
          if(istat .ne. 0) then 
              write(6,*)'error reading grid ',igrd
              stop 10
          else
              write(6,*)(headi(j),j=4,5)
          endif
c
          do j = 1,360
	      do i = 1, 180
	        do k = 1,2
                do m = 1,2
	            nk = (j-1)*2 + k
	            nm = (i-1)*2 + m
	            if(nvdata(nk,nm) .ne. zindef) then
	                sa(j,i) = sa(j,i) + nvdata(nk,nm)
                      rna(j,i) = rna(j,i) + 1.
			    endif
			  enddo
			enddo
		  enddo
		enddo 
c	            
          do j = 1,360                            !calc average
            do i = 1, 180
              if(rna(j,i) .eq. 0) then
                     nvdata(j,i) = zindef
              else
                     nvdata(j,i) = sa(j,i) / rna(j,i)
              endif
            enddo
          enddo
c
          ioutgrd = ioutgrd + 1                                    !write out
          headi(3)=3
	    headi(10) = 360
	    headi(11) = 180
	    headr(1) = 1.0
	    headr(2) = -1.0
	    headr(3) = 89.5
	    headr(4) = 0.5

          call nvap_write(flout, ioutgrd,istat)
          if(istat .ne. 0) then
             write(6,*)' error writing data grid '
          else
             write(6,*)' resized field written to: ',flout(1:40)
          endif
       enddo
c
       write(6,1)' continue with another file? (y/n) [y] : '
       read(5,2) decc
       if(decc .eq. ' ') decc = 'y'
       if(decc.eq.'y' .or. decc.eq.'Y') then
            go to 5
       endif
       stop
       end