Fraction strong zenith angle dep. For example, 1.5 is Greenwich noon on January 1st, 2.0 is Greenwich midnight of January 2nd. 31.5 and 32.5 are GMT noontimes for January 31st and February 1st, respectively.
Longitude is specified in degrees east of Greenwich.
The CRM uses the specified year, latitude, longitude and GMT to compute the correct Sun-Earth distance and solar zenith angle. The CRM does not apply the equation of time, see the FAQ for details. Pressure data is on mid-levels, like temperature, moisture, and winds. The radiation code requires the interface pressures between layers. These are computed as simple averages of adjacent level pressures.