First used on TIROS-N
in October 1978.
SPECTRAL
REGION: |
Bands
1-5: |
580-12500
nm (range) |
TEMPORAL
COVERAGE
RANGES: |
Ascending
Node: |
1340-1930 |
|
Descending
Node: |
0140-0730 |
INSTANTANEOUS
FIELD OF VIEW: |
1.4
mrad |
GROUND
RESOLUTION
CELL: |
1.1
km |
The
AVHRR Concept
Background
Advanced Very High Resolution
Radiometer (AVHRR) is
carried on NOAA's Polar Orbiting
Environmental Satellites (POES),
beginning with TIROS-N in
1978. This series of
satellites commenced with TIROS-N
(launched in October 1978) and
continued with NOAA-A (launched
in June 1979 and renamed
NOAA-6), NOAA-C (launched in
June 1981 and renamed NOAA-7),
NOAA-E (launched in March1983
and renamed NOAA-8), NOAA-F
(launched in December 1984 and
renamed NOAA-9), NOAA-G
(launched in September 1986 and
renamed NOAA-10), NOAA-H
(launched in September 1988 and
renamed NOAA-11), NOAA-D
(launched in May 1991 and
renamed NOAA-12), NOAA-I
(launched in August 1993 and
renamed NOAA-13) and NOAA-J
(launched in December 1994 and
renamed NOAA-14). This series of
satellites (TIROS-N and NOAA-6
through NOAA-14) will henceforth
be referred to in this document
as the TIROS-N series
(technically, TIROS-N through
NOAA-D are called the TIROS-N
series and NOAA-E through -N are
called the TIROS ATN series or
Advanced TIROS-N). The complete
TIROS series will eventually
include NOAA-A through -N.
Sensor
The AVHRR sensor 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.
Sensor
Applications
AVHRR is primarily used for
vegetation studies-the study
and monitoring of drought
conditions.:
The 1988 drought on the
United States Corn Belt was
monitored using AVHRR data by
the Foreign Crop Condition
Assessment Division. Vegetation
index numbers were created from
the data and monitored for
changes over the period of the
drought. The use of the data and
technique was successful in
detecting the early drought
conditions and assessing
potential damages and crop
yields. In Niger, the grasslands
are the most important factor in
their economic potential. New
Mexico State University's
International Studies have been
using AVHRR and associated data
to monitor the size of the
grasslands after each rainy
season. By doing this they are
able to help the government of
Niger plan for the economic year
and create resource friendly
policy. There is current work to
help improve the use of AVHRR
data on vegetation studies. One
such effort was conducted on the
vegetation of Mexico. Here
vegetation indexes were created
and compared to the known
vegetation types collected from
ground truth data, in hopes of
refining the system.
AVHRR is used for other mapping
and ecological projects as
well.:
Data obtained from the AVHRR
sensor can be used to create
land use maps and land cover
maps. This is very helpful when
trying to create maps of large
continents and areas that are
remote or inaccessible. AVHRR
data is being used in a study to
determine the amount of
inundation in the Florida
everglades. The inundation
affects the amount of greenhouse
gases being produced in the
everglades area. This study will
help determine the amounts of
gasses that can potentially be
produced in the area. The sensor
is used to track the continental
snow cover amounts over seasons
and years. It also helps provide
data on ice sheets and related
phenomena such as iceberg
movements.
AVHRR is currently being used
to map out global near surface
temperatures. This data is
useful in monitoring agriculture
and forestry resources and is
important in calculating global
energy budgets. AVHRR is also
used in the monitoring of the
sea surface temperatures. These
temperatures have bearings on
the global climate and marine
resources.
Orbital
Characteristics
Orbits |
Circular,sun-synchronous |
Altitude |
approx
833 km |
Orbital
period |
102
minutes |
Orbits
per day |
14 |
Swath |
2399
km |
Band
Characteristics
Band |
Wavelength
(microns)
NOAA 6,8,10,12 |
Wavelength
(microns)
NOAA 7,9,11 |
IFOV
(millirads) |
Principal
Applications |
1 |
0.58-0.68 |
0.58-0.68 |
1.39 |
Daytime
cloud/surface mapping. |
2 |
0.725-1.10 |
0.725-1.10 |
1.41 |
Surface
water delineation, ice
and snow melt. |
3 |
3.55-3.93 |
3.55-3.93 |
1.51 |
Sea
surface temperature,
night-time cloud
mapping. |
4 |
10.5-11.5 |
10.3-11.3 |
1.41 |
Sea
surface temperature, day
and night cloud mapping. |
5 |
Band
4 repeated |
11.5-12.5 |
1.30 |
Sea
surface temperature, day
and night cloud mapping. |
Data
Acquisition
Data is sent to acquisition
stations by three formats:
High Resolution Picture
Transmission (HRPT) - this
is full resolution image data
that is transmitted to the
ground station as it is
collected.
Local Area Coverage (LAC)
data - This form is also
full resolution data, but this
is recorded on-board for later
transmission while over a
station.
Global Area Coverage (GAC)
- This data is the averaged data
for the globe that is
preprocessed by the on-board
computer and stored for later
transmission to ground stations.
|