Satellite Data and Processing at CAPITA

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Satellite Data and Processing at CAPITA
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GOES 8

• Images for every ½ hour processed daily
• Processing includes georeferencing and gamma
  correction

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MODIS

• High resolution (250 m) color images
• Data collected as needed

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SeaWiFS Global Images

• Images collected daily
• 4 km resolution
• Processing includes joining two images to create
  global view of a single day

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High Resolution SeaWiFS Processing

• In addition to the global data, processing is
  done on 1 km resolution SeaWiFS data gathered
  from various receiving stations
• Daily images are downloaded in raw Level 1a
  form and are processed in several steps
• Conversion from L1a engineering values to L1b
  scientific values
• Georeferencing
• Calculation of angle data for each pixel
• Splicing multiple images and cropping to achieve
  the desired geospatial coverage
• Rayleigh correction to remove Rayleigh scattering
  (the blue sky)
• A batch of daily images is then used to form a
  composite minimum reflectance image
• The minimum image is compared with the daily
  images to create daily aerosol optical depth maps

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SeaWiFS Processing - Rayleigh Correction
Spliced, georeferenced L1b image without Rayleigh
correction
Rayleigh corrected image
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SeaWiFS Processing Minimum Image Generation
At each pixel, the darkest value from a series of
daily images is used to create the composite
minimum image. This removes clouds and haze.
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SeaWiFS Processing - Aerosol Optical Depth

• This is a measure of the excess reflectance at a
  location on a given day
• Cloudy areas are ignored

Daily image and cloud mask
Retrieved aerosol optical depth (band 1)
Minimum image
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Retrieved Optical Depth
2000.08.12
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Retrieved Optical Depth
2000.08.15
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Retrieved Optical Depth
2000.08.18