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Global Land 1-KM AVHRR Project

Advanced Very High Resolution Radiometer (AVHRR) Sensor Characteristics


Background
Extent of Coverage
Spatial Resolution
Temporal Coverage
Spectral Range
Applications and Related Data Sets
Reference

Background

The Advanced Very High Resolution Radiometer (AVHRR) is a broad-band, four or five channel (depending on the model) scanner, sensing in the visible, near-infrared, and thermal infrared portions of the electromagnetic spectrum. This sensor is carried on NOAA's Polar Orbiting Environmental Satellites (POES), beginning with TIROS-N in 1978.

AVHRR data are acquired in three formats:



HRPT data are full resolution image data transmitted to a ground station as they are collected. The average instantaneous field-of-view of 1.4 milliradians yields a HRPT ground resolution of approximately 1.1 km at the satellite nadir from the nominal orbit altitude of 833 km (517 mi).

LAC are full resolution data that are recorded on an on board tape for subsequent transmission during a station overpass. The average instantaneous field-of-view of 1.4 milliradians yields a LAC ground resolution of approximately 1.1 km at the satellite nadir from the nominal orbit altitude of 833 km (517 mi).

GAC data are derived from a sample averaging of the full resolution AVHRR data. Four out of every five samples along the scan line are used to compute one average value and the data from only every third scan line are processed, yielding 1.1 km by 4 km resolution at the subpoint.

Extent of Coverage

The AVHRR sensor provides global (pole to pole) on board collection of data from all spectral channels. Each pass of the satellite provides a 2399 km (1491 mi) wide swath. The satellite orbits the Earth 14 times each day from 833 km (517 mi) above its surface.

Spatial Resolution

The average instantaneous field-of-view (IFOV) of 1.4 milliradians yields a LAC/HRPT ground resolution of approximately 1.1 km at the satellite nadir from the nominal orbit altitude of 833 km (517 mi). The GAC data are derived from an on board sample averaging of the full resolution AVHRR data yielding 1.1-km by 4-km resolution at nadir.

Temporal Coverage

Satellite
Number
Launch
Date
Ascending
Node
Descending
Node
Service
Dates

TIROS-N 10/13/78 1500 0300 10/19/78 - 01/30/80
NOAA-6 06/27/79 1930 0730 06/27/79 - 11/16/86
NOAA-7 06/23/81 1430 0230 08/24/81 - 06/07/86
NOAA-8 03/28/83 1930 0730 05/03/83 - 10/31/85
NOAA-9 12/12/84 1420 0220 02/25/85 - Present
NOAA-10 09/17/86 1930 0730 11/17/86 - Present
NOAA-11 09/24/88 1340 0140 11/08/88 - 09/13/94
NOAA-12 05/14/91 1930 0730 05/14/91 - Present
NOAA-14 12/30/94 1340 0140 12/30/94 - Present


An ascending node would imply a northbound Equatorial crossing while a descending node would imply a southbound Equatorial crossing.

NOAA-B, launched May 29, 1980, failed to achieve orbit. NOAA-13 launched August 9, 1993, failed due to an electrical short circuit in the solar array.

Spectral Range

Band
#
Satellites:
NOAA-6,8,10
Satellites:
NOAA-7,9,11,12,14
IFOV
1 0.58 - 0.68 0.58 - 0.68 1.39
2 0.725 - 1.10 0.725 - 1.10 1.41
3 3.55 - 3.93 3.55 - 3.93 1.51
4 10.50 - 11.50 10.3 - 11.3 1.41
5 band 4 repeated 11.5 - 12.5 1.30
  (micrometers) (micrometers) (milliradians)

Applications and Related Data Sets

AVHRR data provide opportunities for studying and monitoring vegetation conditions in ecosystems including forests, tundra, and grasslands. Applications include agricultural assessment, land cover mapping, producing image maps of large areas such as countries or continents and tracking regional and continental snow cover. AVHRR data are also used to retrieve various geophysical parameters such as sea surface temperatures and energy budget data.

Reference

Kidwell, Katherine B., comp. and ed., 1995, NOAA Polar Orbiter Data (TIROS-N, NOAA-6, NOAA-7, NOAA-8, NOAA-9, NOAA-10, NOAA-11, NOAA-12, and NOAA-14) Users Guide : Washington, D.C., NOAA/NESDIS.


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