CALL SEQUENCE...
       gsmslp  GSTEMP GLNSP GPHIS GPMSL INPUT OUTPUT [ -n VAL1 -a VAL2 ]
 
 
      DESCRIPTION...
       gsmslp - COMPUTES MEAN-SEA-LEVEL PRESSURE FROM SIGMA T, LNSP, PHIS
 
 
      AUTHOR  - R. Laprise, MAY 06/81.
      LAST REVISION: $Header: /home/cvs/RMNLIB/utils/rdiag/lspgm/gsmslp.ptn,v 4.8 2014/09/25 20:20:49 dugas Exp $
 
 
      PURPOSE - FROM A SERIES OF SIGMA LEVEL TEMPERATURES (=GSTEMP) AND
                LN(PS) (=GLNSP), COMPUTE  A  SERIES  OF  MEAN-SEA-LEVEL
                PRESSURES (=GPMSL), USING THE MOUNTAIN FIELD PHIS (=GPHIS).
 
 
      INPUT FILES...
       GSTEMP = SIGMA LEVEL GRID SETS OF TEMPERATURE (DEG K).
       GSLNSP = CORRESPONDING GRIDS OF LN(SF.PRES.)
       GPHIS  = GRID OF SURFACE GEOPOTENTIAL.
 
      OUTPUT FILE...
       GPMSL  = MEAN-SEA-LEVEL PRESSURE GRIDS (IN MB).
 
 
      INPUT PARAMETERS...
 
       GAM    (a) = LOW LEVEL LAPSE RATE (DEFAULT .0065).
       NLVLUP (n) = NUMBER OF LEVELS BETWEEN REFERENCE
                    AND LOWEST LEVEL TEMP (DEFAULT 1).
 
       READ(5,5010) GAM,NLVLUP
 5010  FORMAT(10X,E10.0,I5)
 
 
      EXAMPLE OF INPUT CARD...
 
 * GSMSLP      .0065    1
 
         0123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7
 
 
      EXIT CONDITIONS...
        0 NO PROBLEMS
        1 NOT ENOUGH OR TOO MANY VERTICAL LEVELS
        2 UNABLE TO READ GPHIS
        3 GPHIS NOT THE SAME SIZE AS GSTEMP
        4 UNABLE TO READ GSTEMP
        5 MORE THAN ONE SIZE FOUND IN GSTEMP
        6 UNABLE TO READ GLNSP
        7 GLNSP NOT THE SAME SIZE AS GSTEMP
        8 HAVING PROBLEMS READING DIRECTIVE CARD
        9 GSTEMP DOES NOT CONTAIN A KNOWN TEMPERATURE