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The Advanced Very High Resolution Radiometer (AVHRR) instrument flies on the
NOAA Polar Operational Environmental Satellites (POES) and the European
MetOp Satellites. AVHRR is used to image a large variety of Earth phenomena,
including vegetation, clouds, dust, snow, ice, fire, and surface temperature.
Sea surface temperature (SST) is measured using AVHRR's infrared channels.
CoastWatch SST images are produced in near real-time for each operational
POES and MetOp satellite for the coastal waters of the United States.
East coast overpasses for each satellite (swath data) are
available for several days.
Daily, 3-day, and 7-day composite data (average of all overpasses) are
available indefinitely.
The AVHRR sensor measures radiance from the Earth in five channels
with 1.1 km spatial resolution at nadir. Satellite estimates of SST are
made by converting the radiance measured in the infrared channels to
brightness temperature and then using a multichannel technique to
calculate SST. Cloud identification masks are
also created using visible and infrared channels with a series of
spectral gradient, difference, and threshold tests.
Information on the algorithm and validation of the satellite SST's against
in-water buoys can be found
here.
| Channel Number |
Wavelength (Band)
(microns) |
Primary use |
|
| 1 |
0.58-0.68 (visible) |
daytime cloud, snow and ice mapping data |
| 2 |
0.72-1.10 (near-IR) |
surface water delineation, vegetation and agriculture assessments |
| 3 |
3.55-3.93 (infrared) |
nighttime cloud mapping, sea
surface temperature measurements, land and water distinctions, and
hot spot detection such as volcanic activity or forest fires |
| 4 |
10.30-11.30 (infrared) |
cloud mapping, sea and land
surface temperature measurements, and soil moisture and volcanic
eruption data |
| 5 |
11.50-12.50 (infrared) |
sea surface temperature measurements and soil moisture data |
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