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Daily Global Observations of the Earth: From AVHRR To MODIS And On To VIIRS. Chris Elvidge NOAA National Geophysical Data Center chris.elvidge@noaa.gov. MODIS Blue Marble – From GSFC. Why:. The earth systems are in constant motion.
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Daily Global Observations of the Earth: From AVHRR To MODIS And On To VIIRS Chris Elvidge NOAA National Geophysical Data Center chris.elvidge@noaa.gov
Why: • The earth systems are in constant motion. • Long term daily observation of the entire earth which can be used to establish baselines, from which it is possible detect and measure regional to global scale environmental changes.
How: • Imaging sensors on polar orbiting satellites provide consistent sun-synchronous observation of the earth at a spatial and spectral resolution suitable for observing: • Clouds and aerosols. • Snow and ice. • Ocean color and temperature. • Land surface, vegetation and fire.
Disadvantages of Geostationary Satellite Data: • Orbits at 35,000 km make it difficult to acquire sub-kilometer resolution imagery. • Global constellation with spectral bands suitable for air, land, sea and ice observations has not been achieved. • No polar coverage.
A Long Term Record Of Daily Global Observations of the Earth: • AVHRR – Advanced Very High Resolution Radiometer flown on NOAA’s Polar Orbiting Environmental Satellites from 1978 to the present. • MODIS – MODerate resolution imaging spectrometer flown on NASA Earth Observing System (Terra and Aqua satellites since December 1999. • VIIRS – Visible Infrared Imaging Radiometer Suite – to be flown on the NOAA-NASA-DOD National Polar Orbiting Environmental Satellite System (NPOESS) with first launch expected in 2008-09.
Science Driven Improvements From AVHRR - Spectral Resolution AVHRR Five Bands Vis, NIR, MIR, and two TIR MODIS 36 Bands VIIRS 20 Bands “The best of the MODIS Bands.”
Science Driven Improvements From AVHRR – Spatial Resolution AVHRR Four km GAC One km LAC & HRPT MODIS Internested Bands at 250 m 500 m And 1 km VIIRS 15 bands at 800 m Five bands At 400 m
Science Driven Improvements From AVHRR – Geolocation Accuracy AVHRR Variable. GCP’s Frequently Utilized. MODIS Sub- Kilometer. VIIRS Sub- Kilometer.
Science Driven Improvements From AVHRR – Radiometric Calibration AVHRR Inadequate On-board calibration. MODIS Very good On-board Calibration. VIIRS Very good On-board calibration.
Raw Data Volume. AVHRR 4 GB / day. MODIS 70 GB /day. VIIRS 150 GB / day.
Who Started Archiving AVHRR Data? • NASA. NOAA started its archiving effort year’s later.
Who Pioneered the Non-Meteorological Applications For AVHRR Data? • NASA. NOAA focused on the weather community, who needed global observations in near real time.
Summary • NASA and NOAA have built a long record of daily global observations of the earth. • The NASA-MODIS instrument provides data that are substantially better than the NOAA-AVHRR. • The VIIRS instruments will continue MODIS style observations into the next decade and beyond. • Establishing and operating new archives for MODIS and VIIRS for global environmental change research would require a very large effort in data transfer, data storage, and data processing.