1. NOAA National Geophysical Data Center
Daily Global Observations of the Earth: From AVHRR To MODIS And On To VIIRS
Chris Elvidge
NOAA National Geophysical Data Center

2. MODIS Blue Marble – From GSFC

3. 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.

4. 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.

5. 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.

6. Fourteen orbits per day – global coverage

7. 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

8. Science Driven Improvements From AVHRR - Spectral Resolution
Five Bands
Vis, NIR,
MIR, and
two TIR
MODIS
36 Bands
VIIRS
20 Bands
“The best of
the MODIS
Bands.”

9. Science Driven Improvements From AVHRR – Spatial Resolution
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

10. Science Driven Improvements From AVHRR – Geolocation Accuracy
Variable.
GCP’s
Frequently
Utilized.
MODIS
Sub-
Kilometer.
VIIRS
Sub-
Kilometer.

11. Science Driven Improvements From AVHRR – Radiometric Calibration
Inadequate
On-board
calibration.
MODIS
Very good
On-board
Calibration.
VIIRS
Very good
On-board
calibration.

12. Raw Data Volume. MODIS AVHRR 4 GB / day. VIIRS 150 GB / day.

13. Who Started Archiving AVHRR Data?
NASA. NOAA started its archiving effort year’s later.

14. Who Pioneered the Non-Meteorological Applications For AVHRR Data?
NASA. NOAA focused on the weather community, who needed global observations in near real time.

15. MODIS Imagery Ice, frozen land & clouds

16. MODIS Imagery British Columbia

17. MODIS Imagery Mozambuique Channel

18. MODIS Imagery Florida

19. 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.