Parent Topic: AVHRRAD

PARAMETERS

AVHRRAD is controlled by the following global parameters: 

Name     Prompt                                  Count     Type
FILI     Database Input File Name                1-64      Char
FILO     Database Output File Name               1-64      Char
DBIC     Database Input Channel List             1-1024    Int
DBOC     Database Output Channel List            1-1024    Int
AVHRRSEG AVHRR Calibration/Orbit Text Segment    0-1       Int
TIMEMULT Multiplier for Start Scan Date Interval 0-1       Int
CTYPE    Corr/Calib: SOL/VIS/THE/ALL/ANG         3         Char
REPORT   Report Mode: TERM/OFF/filename          1-64      Char

FILI

Specifies the name of the input file which contains the raw AVHRR image data and the AVHRRSEG text segment. The input file must be a PCIDSK file (created using FIMPORT or MIAVHRR) or an actual AVHRR disk file (for solar zenith angle correction, FILI can be a Level 1b AVHRR disk file but not any other AVHRR disk file format). If FILI and FILO are the same, FILI must be a PCIDSK file (it cannot be an AVHRR disk file). 

 EASI>FILI="filespec"

FILO

Specifies the name of the PCIDSK file which will receive the corrected (or calibrated) image data. FILO must be specified and it must exist. AVHRRAD does not create a new output file. FILO can be the same as FILI as long as the file type is PCIDSK. 

 EASI>FILO="filespec"

DBIC

Specifies the image channels in the input file (FILI) to correct (or calibrate). 

 EASI>DBIC=i,j,...,n
Ranges of channels can be specified with negative values. For example: {1,-3,4} is internally expanded to {1,2,3,4}.

When the "ALL" CTYPE option is chosen, 5 input channels must be specified in DBIC. The first two input channels are expected to be the visible channels. The other three channels are expected to be the thermal channels.

When the "ANG" CTYPE option is chosen, DBIC is ignored and does not have to be set.

DBOC

Specifies the channels in the output file (FILO) to receive the corrected (or calibrated) image data. 

 EASI>DBOC=i,j,...,n
Ranges of channels can be specified with negative values. For example: {1,-3,4} is internally expanded to {1,2,3,4}.

For each channel specified in DBIC, an output channel must be specified in DBOC (unless the "ANG" CTYPE option was chosen). Duplicate output channels are not allowed.

AVHRRSEG

Specifies the text segment which contains AVHRR calibration and orbital data. This segment is automatically created when FIMPORT or MIAVHRR is used to read in an AVHRR image (from disk or tape, respectively). If AVHRRSEG is not set, AVHRRAD will try to find a valid AVHRR text segment in the input file to use. 

 EASI>AVHRRSEG=j     | Use segment number j
 EASI>AVHRRSEG=      | AVHRRAD will try to find a valid text segment
Alternatively, one can create a new text segment (or edit an existing one) for use with AVHRRAD. Please see the section describing the text segment format for details.

TIMEMULT

This parameter is only applicable to radiometric correction. It specifies a multiplication factor which can be used to increase the search time interval in which AVHRRAD tries to look for the exact starting scan date of the input image. The starting scan date refers to the exact instant just before the top-left pixel in the input image was scanned. By default, TIMEMULT is set to 1, which indicates that a default search interval of 60 minutes should be used. 

 EASI>TIMEMULT=        | Defaults to a search interval of 60 minutes
 EASI>TIMEMULT=2       | Use a search interval of 120 minutes
AVHRRAD looks for date and time information in the text segment of the input PCIDSK file. It uses this date as an approximation to the exact starting scan date. The format of the date information in the text segment is described in the text segment format section.

CTYPE

Specifies the correction/calibration type. Valid choices are: SOL (solar zenith angle correction), VIS (visible channel calibration), THE (thermal channel calibration), and ALL (perform all corrections/calibrations). There is also a "ANG" option for generating satellite zenith angles, solar zenith angles, and relative azimuth angles. 

 EASI>CTYPE="SOL"      | Perform a solar zenith angle correction
 EASI>CTYPE="VIS"      | Perform a visible channel calibration
 EASI>CTYPE="THE"      | Perform a thermal channel calibration
 EASI>CTYPE="ALL"      | Perform all three corrections/calibrations
 EASI>CTYPE="ANG"      | Generate satellite zenith, solar zenith,
                       | and relative azimuth angles.

REPORT

Specifies the file to which to append the generated report. 

 EASI>REPORT="filename"
The following names have special meaning: 

 EASI>REPORT="TERM"     | Generates a report on your terminal
 EASI>REPORT="OFF"      | Cancels report generation
Parent Topic: AVHRRAD
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