SUN package
===========

Computes the solar zenith angle above the sea surface for all grid center
locations.

Computation follows Patt and Gregg, 1994, Int. J. Remote Sensing.
Code adapted from the Ocean-Atmosphere Spectral Irradiance Model (OASIM).

sun_init_varia    creates arrays of up, north, and east vectors
sun_sfcsolz       computes solar zenith angle above the sea surface
+- sun_jd         converts calendar date to Julian day
+- sun_ephparms   computes ephemeris parameters
+- sun_nutate     computes the nutation in longitude and the obliquity
+- sun_sun2000    computes the sun vector in geocentric inertial coordinates
+- sun_gha2000    computes the Greenwich hour angle in degrees