Langley DAAC Version Number:   LD_008_024_001_00_00_0_19990615
                                               
                                               


PRABHAKARA SMMR ATMOSPHERIC LIQUID WATER DATA SET

     1.0  Introduction

     This README file contains information on the structure
     of the Prabhakara Scanning Multichannel Microwave Radiometer
     (SMMR) atmospheric liquid water data, sample software to
     read the data files, and pertinent scientific references.

     The Prabhakara SMMR Atmospheric Liquid Water  files were generated
     by Dr. Prabhakara Cuddapah at the Goddard Space Flight Center
     (GSFC) using the SMMR Antenna Temperatures.  A discussion of the
     SMMR Antenna Temperatures is available from the Langley Research 
     Center Distributed Active Archive Center (DAAC) User Services Office 
     at 804-864-8656 or e-mail at larc@eos.nasa.gov.  Each Atmospheric 
     Liquid Water file contains one month of 3 degree by 5 degree gridded 
     mean liquid water.  The data spans the period from February 1979 to 
     May 1984.  For a discussion of the data, see the scientific references 
     in section 4.0.

     2.0  Monthly Atmospheric Liquid Water File Structure

     Each data file contains 1 header record and integer values in a
     72 x 32 element array  (see Table 1).  Each element represents a
     gridded mean for a 3 x 5 degree grid, beginning at 48N,180W and
     progressing to 48S,180E.

     EXAMPLES:

          Element (1,1) corresponds to the mean for the grid
          defined as 45-48N, 175-180W.

          Element (32,72) corresponds to the mean for the grid
          defined as 45-48S, 175-180E.


                                Table 1.

        180E                                                      180W
     48N--------------------------------------------------------------
        |    ----------- 72 grids ----------                         |
        |    |                                                       |
        |    32 grids                                                |
        |    |                                                       |
        |    |                                                       |
     48S--------------------------------------------------------------


     Each element of data is in units of mg/cm2.  Since the data are
     only computed over ocean, a value of 999.9 represents a land grid.


     3.0  Sample Software

     The following sample software to read the data is provided by
     Dr. Prabhakara Cuddapah.

     C
     C  SAMPLE PROGRAM TO READ AND WRITE HEADER RECORD
     C  AND LIQUID WATER DATA FOR ONE FILE FROM TAPE
     C
            INTEGER LIQ(32,72), HDR(20)
     C
            READ(10,1000)(HDR(K),K=1,20)
      1000  FORMAT(20A4)
            WRITE(6,1000)(HDR(KK),KK=1,20)
     C
            DO 10 I=1,32
             READ(10,1100)(LIQ(I,J),J=1,72)
             WRITE(6,1100)(LIQ(I,JJ),JJ=1,72)
      1100   FORMAT(72I4)
        10  CONTINUE
     C
            STOP
            END

    4.0  Scientific References

    Prabhakara, C., G. Dalu, J. J., Nucciarone, and G. L. Liberti, 1992:
    Rainfall over Oceans:  Remote Sensing from Satellite Microwave
    Radiometers.  Meteorol. Atmos. Phys., 47, 177-192.

    Prabhakara, C., D. A. Short, W. Wiscombe, and R. S. Fraser, 1986:
    Rainfall over Oceans Inferred from Nimbus 7 SMMR:  Application to
    1982-83 El Nino.  J. Climate Appl. Meteor., 25, 1464-1474.