precals - Get the calibration coefficients for the AVHRR visual channels from the degradation table

SYNTAX

FUNCTION precals(hostbl, satnum, ayear, aday, Kval, ocoeffs)

    char 	 *hostbl;
    long 	 satnum;
    long 	 ayear;
    long 	 aday;
    float	 Kval[];
    long 	 ocoeffs[];

PARAMETERS

hostbl (char *, input)

The host file name of the calibration degradation table.

satnum (long, input)

The number of the satellite acquiring the pass (for example, 11 for NOAA-11).

ayear (long, input)

The year of acquisition (ie. 94 for 1994).

aday (long, input)

The julian acquisition day.

Kval (float [], output)

The K value for AVHRR channels 1 and 2 of this satellite. These values are used to convert radiance to albedo.

ocoeffs (long [], output)

The calibration coefficients for the AVHRR visual channels (channels 1 and 2).

DESCRIPTION

For NOAA-06 satellite data, prelaunch calibration coefficient values will be returned (because NOAA-06 maintained nearly constant calibration over its lifespan). Otherwise, calibration coefficients will be computed from values retrieved from the degradation table.

RETURN VALUE

precals() returns

    E_SUCC --> Successful completion
    E_FAIL --> Operation failed