Calibration of AVHRR Reflectance Channels

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Calibration of AVHRR Reflectance Channels

• NOAA Office of Global Programs has funded STAR to
  lead an effort to derive a consensus historical
  AVHRR reflectance calibration. The availability
  of MODIS data now makes this feasible.
• Simultaneous Nadir Observations (SNO) occur when
  the ground track of two satellites cross at the
  same time. (see cartoon on right)
• SNOs offer a new tool for calibrating the
  reflectance channels on the AVHRR which have no
  onboard calibration. SNOs occur between all
  polar orbiting satellites.
• For example, SNOs between AVHRR and MODIS allow
  for transfer of the MODIS calibration to the
  AVHRR
• SNOs also allow for monitoring of the relative
  calibration for historic AVHRR data and greatly
  improves its potential for climate studies.

Example Results from MODIS/AVHRR SNO
Verification of Results Stability of
Greenlands Reflectance over last 25 years