program read_SWHtpx
c
c	Peter M. Woiceshyn	June 30, 2000
c       818-354-1450
c	wd21pw@pacific.jpl.nasa.gov
c
c   Sample program provides read statements to read in the
c          TOPEX/POSEIDON Significant Wave Height data (SWH) in meters.
c
c   The SWH  data are on a 360 X 180 element grid with the origin at
c      -89.5 South latitude and 0.125 degrees East longitude (i.e.,
C      a 0.25 by 0.25 degree lat/lon grid resolution ranging from
C      -89.5 (S) to 89.5 (N) in latitude & from 0.5 to 359.5
C      in East longitude).
c    
c   One array exist in the file.  The array, 'swh', contains the
c     the TOPEX/POSEIDON Significant Wave Height values.  
c
c     A 'swh' value equal to 32767.0 indicates that there were NO swh values
c     for that grid point (over the ocean -- and obviously not over land).
c
c   There are 12 months of data for 1998.
c
c  Declarations:

	REAL lon(360), lat(180)
C	
	REAL del_deg, swh(360,180)
C
	INTEGER*2    lon2, lat2
C	
	CHARACTER*3  c_mon(12)
	CHARACTER*2  yc, mc(12)
	CHARACTER*18 f_in
	CHARACTER*5  f_label
	CHARACTER*4  f_ycmc
	CHARACTER*7  suff

C----------------------------------------------------------------------C

	DATA   c_mon/'Jan','Feb','Mar','Apr','May','Jun',
     &	              'Jul','Aug','Sep','Oct','Nov','Dec'/

	DATA  mc/'01','02','03','04','05','06',
     &	         '07','08','09','10','11','12'/


C----------------------------------------------------------------------C

	     yc = '98'
	
	   suff = 'TPX.dat'

        f_label = c_mon(1)//yc	! Jan98
         f_ycmc = yc//mc(1)
  
           f_in = 'SWHakh'//f_label//suff
	   PRINT *,' ' 
	   PRINT *,'    '//f_in

C----------------------------------------------------------------------C

	     lon2 = 360
	     lat2 = 180
  
	  del_deg = 1.0
  
	   PRINT *,' ' 
	   PRINT *,'    longitude array dimension =  ',lon2
	   PRINT *,'     latitude array dimension =  ',lat2
	   PRINT *,'            delta lat/lon deg = ',del_deg
	   PRINT *,' ' 

C  Construct lat & lon arrays

	DO jj = 0, lat2 - 1
	
                   lat(jj+1) = jj*del_deg - 90.0 + del_deg/2.0
	ENDdo

	DO ii = 0, lon2 - 1
	
                   lon(ii+1) = ii*del_deg + del_deg/2.0
	ENDdo
  
c
c
c	Lat range:	-89.5(S) to  89.5(N) degrees 
c
c	Lon range:	0.5(E) to 359.5(E) degrees 
c
c
	   PRINT *,' ' 
	   PRINT *,'    Reading file: ',f_in
	   PRINT *,' ' 

	       OPEN(22,file=f_in,form='unformatted')

                           print *, '    Read array swh'
	                   PRINT *,' ' 

		      read(22) swh
	
	       CLOSE(22)

	DO j = 90, 91
	     DO i = 1, 5

	  WRITE (6,'(2x,A4,I3,2x,A4,I4,2x,A6,F7.3,2X,A6,F7.3,2X,
     &               A6,F10.2)') 
     &       'i = ', i,'j = ', j,
     &       ' lat = ', lat(j),' lon = ', lon(i),
     &          ' swh = ',swh(i,j)
	       
	     ENDDO
	        WRITE (6,'(A2)') ' ' 
	ENDDO
	        WRITE (6,'(A2)') ' ' 
C----------------------------------------------------------------------C
	       
	STOP

	END

C----------------------------------------------------------------------C
C
C  Output from executing this FORTRAN 77 program:
C
C host{wd21pw}432> read_SWHtpx.x
C  
C     SWHakhJan98TPX.dat
C  
C     longitude array dimension =    360
C      latitude array dimension =    180
C             delta lat/lon deg =     1.00000
C  
C  
C     Reading file: SWHakhJan98TPX.dat
C  
C     Read array swh
C  
C  i =   1  j =   90   lat = -0.500   lon =  0.500   swh =      1.37
C  i =   2  j =   90   lat = -0.500   lon =  1.500   swh =  32767.00
C  i =   3  j =   90   lat = -0.500   lon =  2.500   swh =      1.34
C  i =   4  j =   90   lat = -0.500   lon =  3.500   swh =      1.17
C  i =   5  j =   90   lat = -0.500   lon =  4.500   swh =      1.45
C  
C  i =   1  j =   91   lat =  0.500   lon =  0.500   swh =      1.29
C  i =   2  j =   91   lat =  0.500   lon =  1.500   swh =      1.31
C  i =   3  j =   91   lat =  0.500   lon =  2.500   swh =      1.26
C  i =   4  j =   91   lat =  0.500   lon =  3.500   swh =      1.09
C  i =   5  j =   91   lat =  0.500   lon =  4.500   swh =      1.28
C  
C  
C host{wd21pw}433> 
C
C----------------------------------------------------------------------C