program read_SeaWiFS
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 SeaWiFS
c          Chlorophyll-a concentration data in mg/m**3.
c
c   The SeaWiFS Chlorophyll-a concentration data are on a 720 X 360 
c      element grid with the origin at -89.75 South latitude and 
c      0.25 degrees East longitude (i.e., a 0.50 by 0.50 degree 
C      lat/lon grid resolution ranging from -89.75 (S) to 89.75 (N) 
C      in latitude & from 0.125 to 359.875in East longitude).      
c    
c   Two arrays exist in the file.  The first array, 'ChlorA', contains the
c     the Chlorophyll-a concentration values. The second array, 'num', 
c     contains the value of 0 or 1.  A 'num' value equal to 0 (zero)
C     indicates that there were NO data values for that grid 
C     point (over the ocean -- and obviously not over land).
C     The 'num' array values of 1 (one) can therefore be used to
C     identify legitimate values of Chlorophyll-a concentration  
c     for each grid point.
c
c   There are 12 months of data for 1998.
c
c  Declarations:

	REAL lon(720), lat(360)
C	
	REAL del_deg, ChlorA(720,360)
C
	INTEGER*2    lon2, lat2, num(720,360)
C	
	CHARACTER*3  c_mon(12)
	CHARACTER*2  yc, mc(12)
	CHARACTER*16 f_in
	CHARACTER*5  f_label
	CHARACTER*4  suff, f_ycmc

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 = '.dat'

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

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

	     lon2 = 720
	     lat2 = 360
  
	  del_deg = 0.50
  
	   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:	-89.75(S) to  89.75(N) degrees 
c
c	Lon range:	0.25(E) to 359.75(E) degrees 
c
c
	   PRINT *,' ' 
	   PRINT *,'    Reading file: ',f_in
	   PRINT *,' ' 

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

                           print *, '    Read array ChlorA'
		      read(22) ChlorA

                           print *, '    Read array num'
                           print *, ' '
		      read(22) num
	
	       CLOSE(22)

	DO j = 180, 181
	     DO i = 1, 5

	  WRITE (6,'(2x,A4,I3,2x,A4,I4,2x,A6,F7.2,2X,A6,F7.2,2X,
     &               A10,F8.4,2x,A6,i3)') 
     &       'i = ', i,'j = ', j,
     &       ' lat = ', lat(j),' lon = ', lon(i),
     &          ' ChlorA = ',ChlorA(i,j), ' num = ',num(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_SeaWiFS.x
C  
C     SeaWiFS9801.dat     Jan98
C  
C     longitude array dimension =    720
C      latitude array dimension =    360
C             delta lat/lon deg =    0.500000
C  
C  
C     Reading file: SeaWiFS9801.dat 
C  
C     Read array ChlorA
C     Read array num
C  
C i =   1  j =  180   lat =  -0.25   lon =   0.25   ChlorA =   0.5071   num =  1
C i =   2  j =  180   lat =  -0.25   lon =   0.75   ChlorA =   0.4418   num =  1
C i =   3  j =  180   lat =  -0.25   lon =   1.25   ChlorA =   0.5629   num =  1
C i =   4  j =  180   lat =  -0.25   lon =   1.75   ChlorA =   0.5495   num =  1
C i =   5  j =  180   lat =  -0.25   lon =   2.25   ChlorA =   0.4269   num =  1
C  
C i =   1  j =  181   lat =   0.25   lon =   0.25   ChlorA =   0.2661   num =  1
C i =   2  j =  181   lat =   0.25   lon =   0.75   ChlorA =   0.3970   num =  1
C i =   3  j =  181   lat =   0.25   lon =   1.25   ChlorA =   0.4552   num =  1
C i =   4  j =  181   lat =   0.25   lon =   1.75   ChlorA =   0.4252   num =  1
C i =   5  j =  181   lat =   0.25   lon =   2.25   ChlorA =   0.4723   num =  1
C  
C  
C host{wd21pw}433> 
C
C----------------------------------------------------------------------C