[gradsusr] SeaWIFS NDVI data

[Huddleston, John]

Matt, see the following for the specifications.

http://oceancolor.gsfc.nasa.gov/DOCS/Ocean_Level-3_SMI_Products.pdf

The control file is something like:

dset ^S20100652010072.L3m_8D_LAND_NDVI_4km
dtype hdf4
title SeaWiFS Level-3 Standard Mapped Image
undef -1 Fill
unpack Slope Intercept
options yrev
xdef 8640 linear -179.9791667   0.04166666667
ydef 4320 linear -89.97916667    0.04166666667
zdef 1 linear 1 1
tdef 1  linear 00:00Z23apr2006 1dy
vars 1
l3m_data=>sea  1 y,x l3m_data
endvars