AUTHOR: Tim Baltzer
Apply atmospheric correction to a previously generated composite image.
A new algorithm for ATMOCOR which includes correction for water vapor has been created. Consequently, there is a need to reprocess composite images using the new ATMOCOR. Since there is data from multiple acquisition days within a composite, a single water vapor image/ ozone image must be created before it is used as input to ATMOCOR. Also, the archived water vapor and ozone images reside in a different projection (Geographic) than the typical composite product (Goodes projection). These as well as other complexities make the need for REATMO necessary.
REATMO will be written to apply atmospheric correction to previously computed composite images. Once REATMO has processed all existing composites, it will no longer be a necessary software tool (future composites will have atmospheric correction with water vapor effects already applied).
Inputs to REATMO: ------------------
Outputs from REATMO: ---------------------
Body
Call REATMOINFO to return the necessary information from the date band log file.
Inputs to REATMOINFO: ------------------
Outputs from REATMOINFO: ---------------------
for each acquisition date doCall GETWATER to return a filled TOVS water vapor image (global image in geographic space).
end for each
Inputs to GETWATER: ------------------
Outputs from GETWATER: ---------------------
Call GETATM to generate an elevation image in composite space, and a line and sample band in composite space. The line and sample band values will be used as indices into the water vapor/ozone images which are in geographic space.
Inputs to GETATM: ------------------
Outputs from GETATM: ---------------------
Call COMPATM to generate a water vapor image which represents the entire composite (involves a reprojection as well as integrating water vapor data for each day used in the composite). COMPATM will also generate an ozone image which represents the entire composite (involves a reprojection as well as integrating ozone data for each month used in the composite). COMPATM will also generate a QC band which represents the entire composite (including the solar zenith flag). All of the above images will be in composite space.
Inputs to COMPATM: ------------------
Outputs from COMPATM: ---------------------
Finally, we are ready to call ATMOCOR to apply atmospheric correction!
Inputs to ATMOCOR: ------------------
Outputs from ATMOCOR: ---------------------
Call NORMD to regenerate the NDVI band, since AVHRR channels 1 and 2 have changed with the new atmospheric correction.
Inputs to NORMD: ------------------
Outputs from NORMD: ---------------------
NOTE: Delete all intermediate files ASAP during the processing flow to minimize the amount of disk space required by this routine!
End (Body)
- IN
- Input image. IN must be a two band LAS image and may be of any data type. Band one must contain AVHRR channel 1 and band two must contain AVHRR channel 2. The image cannot be subwindowed. Only one image may be specified. The values contained within IN must represent percent reflectance or radiance for calibrated AVHRR data, such as those produced by AVHRRCAL.
- SCALE
- Scale method. Scaling method used to store IN, ANGLES, and OUT. The data type indicated in the image's DDR will be used to determine the scaling factor and offset value to use when scaling/unscaling the data.
- GLOBAL: Global scaling
- NONE: No scaling
- US: US scaling
- RADOPT
- Radiance flag. Flag to indicate if IN contains radiance or reflectance values. = RADIANCE: Input radiance = REFLECTANCE: Input reflectance
- DATEBAND
- Date band. Image containing the date band from the compositing process. This image must be the same size and in the same projection space as IN.
- DATELOG
- Date log. The log file associated with the DATEBAND image which specifies the scenes used to generate the composite.
- ANGLES
- Angles image. The image containing the necessary view angles. Three bands are expected, the first band being satellite zenith angles, the second band being solar zenith angles, and the third band being relative azimuth angles. This image must be the same size and projection as IN. Subwindowing is not allowed.
- ELEV
- Elevation image. A single band image containing elevation in kilometers. The image must be in geographic projection with units of degrees.
- WATERBASEDIR
- Water directory. The base directory in which the water vapor climatology images are stored.
- SILOBASEDIR
- Water silo directory. The base directory on the silo in which the water vapor acquisition images are stored.
- OZONEBASEDIR
- Ozone directory. The base directory in which the ozone images are stored.
- WORKDIR
- Working directory. The directory wherein processing should occur.
- NDVI
- Output NDVI image. The image containing the resulting normalized difference image computed from the atmospherically corrected AVHRR channels 1 and 2.
- OUT
- Output image containing the atmospherically corrected AVHRR channels 1 and 2. The output image is the same size, data type, and in the same projection as the input image specified by IN. Output values are expressed as a percentage of surface reflectance with atmospheric correction applied.
- QC
- Quality control. The quality control output image. This image is in the same size and projection as IN.