   Pressure on potential density surfaces

   The pressure (decibars) on sigma-theta (potential density with respects
   to the surface kg/m^3) isopycnal surfaces 1027.60 and 1027.65 were calculated
   for the Gulf of Mexico.  These surfaces are just above and just below 1000
   meters depth in the area of the wellhead.  The pressure was calculated using
   1/4 degree sigma-theta climatology on extended depths.  This climatology
   is described in the gulf_clim directory.  The sigma-theta surface data are
   in three files for each of the two sigma-theta surfaces (data format described below):

gulf_dsurf_27.60
gulf_dsurf_27.60.deep
gulf_dsurf_27.60.shallow

gulf_dsurf_27.65
gulf_dsurf_27.65.deep
gulf_dsurf_27.65.shallow

The first file (no suffix) contains the pressure on the given density surface for
all 1/4 degree ocean squares in the Gulf of Mexico.  The files are comma-separated
value files with latitude,longitude,pressure on given sigma-theta surface (db)

The .deep file contains all 1/4 degree ocean squares in the Gulf of Mexico for
which the water never reaches the given density (the sigma-theta surface
intersects the ocean bottom).  The file is a comma-separated value file with
latitude,longitude

The .shallow file contains all 1/4 degree ocean squares in the Gulf of Mexico for
which the water is always more dense than the given density (the sigma-theta
surface intersects the ocean surface).  The file is a comma-separated value file
with latitude,longitude.

Graphic representing these isopycnals are provided in sigma2760.png and sigma2765.png

For further question please contact the Ocean Climate Laboratory, National 
Oceanographic data Center.

