LAND/SEA MASK


     The Land/Sea Mask file is a half degree resolution grid consisting of
zeros (for sea or coastal interface) and ones (for land).  (Satellite and
in situ data are discarded over land in the SST analyses.)  The mask is
derived from a NESDIS low resolution land/sea tag data set.

     The mask can be read by the following statements if the array IMASK is
dimensioned (720, 361):

             READ(1,10)((IMASK(I,J),I=1,720),J=1,361)
          10 FORMAT(80I1)

     Here, IMASK is the land/sea mask.  The location of the IMASK array is
defined by the first index, I, for longitude and the second index J for
latitude.  For I=1 the grid is centered at 0.0, I=2 at 0.5E and so on eastward
to I=720 at 0.5W (359.5E).  For J=1 the grid is centered at 90.0S, J=2 at
89.5S and so on northward to J=361 at 90.0N.