avcalnl [ inputfile ]
No Parameters.
This routine is used for initial AVHRR calibration purposes only. The need for this routine began with noaa-12 when we began to incorporate the non-linearity of the channel responses into the calibration. It can facilitate the 'seaspace' computation of the non-linear corrections by printing out the list of radiance vs delta radiances for each of the 4 target temperatures. These data can then be put into a regression routine to compute the 2nd degree polynomial or this routine can be enhanced to do that calculation also. The 2nd order polynomial coefficients are put into the final version of the calinput.raw file and subsequently through the use of newavcal3 put into the avhrr sensor file.
The sequence of steps is the following:
1) Create the avhrr sensor file using newsensor.
2) Create the preliminary version of the calinput.raw file from the NESDIS issued documentation. See file for format.
3) Modify the source of avcalnl.c to include the proper coefficients and then run avcalnl on the preliminary calinput.raw file. This process produces radiance vs delta radiance data.
4) By some other means compute best fit 2nd order polynomial to fit above data.
5) Add these coefficients to the end of the calinput.raw file in the manner shown in the noaa-12 version.
6) Run newavcal3 on the calinput.raw file and sensor file. This will add to the sensor file all the calibration data. Additionally, it will print to the screen the radiance versus temperature data. This can be appended to the calinput.raw file for documentation purposes (see calinput.raw file for noaa-12).
$SATDATA/noaa-xx/avhrr and $SATDATA/noaa-xx/calinput.raw files. Note differences in format beginning with noaa-12. Use noaa-12 format for all future calibrations.
This documentation is for internal SeaSpace use only. Additional documentation and necessary calibration information is released through NOAA/NESDIS documentation. A SeaSpace Notebook contains our current archive for each of the NOAA satellites.
Last Update: $Date: 2000/11/20 19:00:12 $