AVHRR Sea Surface Temperature

The very talented AVHRR

AVHRR stands for Advanced Very High-Resolution Radiometer.

“Very high resolution” is a bit of a misnomer. This is because its spatial resolution is actually very coarse at 1.1 km.

So the “very high resolution” refers to its day temporal resolution and revisit times.

Because of its high temporal resolution, AVHRR offers services in monitoring wildfires, flooding risk, and even volcanic eruptions.

AVHRR spectral bands and specifications

The Advanced Very High Resolution Radiometer is a multispectral sensor with six spectral bands.

This includes red, thermal, mid, and near-infrared bands. But over time, their spectral ranges have varied.

For example, AVHRR/3 channel characteristics are as follows:

Band Name Spectral Range Applications
Band 1 Red 0.58-0.68 Urban, vegetation, snow/ice, daytime clouds
Band 2 Near IR 0.725-1.00 Vegetation, land/water boundaries, snow/ice, flooding
Band 3A Mid IR 1.58-1.64 Vegetation, snow/ice detection, dust monitoring
Band 3B Thermal 3.55-3.93 Surface temperature, wildfire detection, nighttime clouds, volcanic eruptions
Band 4 Thermal 10.30-11.30 Surface temperature, wildfire detection, nighttime clouds, volcanic eruptions
Band 5 Thermal 11.5-12.50 Sea surface temperature, water vapor path radiance

AVHRR uses and applications

Because of AVHRR’s quick revisit times, it has several monitoring applications. For example, AVHRR monitors vegetation change, active wildfires, flooding risk and even volcanic eruptions.

AVHRR is the backbone for the 1km global land cover product. We use global land cover to understand the human footprint on the land and its environmental impact.

The AVHRR land cover product differentiates forest types, grass, shrub, cropland, and water.

AVHRR Global Land Dataset
AVHRR Global Land Cover Dataset – Image courtesy of NOAA

By using its red and NIR band, AVHRR applies normalized difference vegetation index (NDVI).

Because of its high revisit time, it’s capable of monitoring vegetation change daily.

We can interpret vegetation change over time by comparing NDVI over decades of data.

AVHRR NDVI Composite
AVHRR NDVI Composite – Image Courtesy of NOAA.

Other remote sensing applications and uses from AVHRR include measuring regional soil moisture, climate change, physiographic features.

By using the thermal bands, we get a better understanding of sea surface temperatures (pictured below).

AVHRR Sea Surface Temperature
AVHRR Sea Surface Temperature – Image courtesy of NASA/JPL

40+ year history of AVHRR data

From NOAA-6 to NOAA-19, NOAA Polar-Orbiting Environmental Satellite (POES) satellites have been the primary carrier of AVHRR. But there have been other satellites equipped with Advanced Very High Resolution Radiometer.

For example, Television and Infrared Observation Satellite (TIROS) was the first to use AVHRR in 1978. The 4-channel radiometer on TIROS was later replaced with the 5-channel AVHRR/2.

Finally, MetOp-A and B have been launched with this sensor. To this day, AVHRR still collects satellite imagery of our changing planet. That makes it more than 40 years AVHRR has been in orbit making it one of the longest-running sensors.

Satellites equipped with AVHRR

The table below lists all of the satellites that have carried the AVHRR instrument.

Satellite Launch Day End Mission
Television and Infrared Observation Satellite (TIROS) October, 1978 January, 1980
NOAA-6 June, 1979 November, 1986
NOAA-7 June, 1981 June, 1986
NOAA-8 March, 1983 October, 1985
NOAA-9 December, 1984 May, 1994
NOAA-10 September, 1986 September, 1991
NOAA-11 September, 1988 September, 1994
NOAA-12 May, 1991 December, 1994
NOAA-14 December, 1994 May, 2007
NOAA-15 May, 1998 Present
NOAA-16 September, 2000 June, 2014
NOAA-17 June, 2002 April, 2013
NOAA-18 May, 2005 Present
NOAA-19 February, 2009 Present
MetOp-A October, 2006 Present
MetOp-B September, 2012 Present
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