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Land Surface Temperature

Description

The "Land Surface Temperature derived from NOAA-AVHRR data (LST_AVHRR)" is a fixed grid map (in stereographic projection ) with a spatial resolution of 1.1 km. The total size covering Europe is 4100 samples by 4300 lines. Within 24 hours of acquiring data from the satellite, day-time and night-time LSTs are calculated. In general, the products utilise data from all six of the passes that the satellite makes over Europe in each 24 hour period. For the daily day-time LST maps, the compositing criterion for the three day-time passes is maximum NDVI value and for daily night-time LST maps, the criterion is the maximum night-time LST value of the three night-time passes. Weekly and monthly day-time or night-time LST composite products are also produced by averaging daily day-time or daily night-time LST values, respectively. The range of LST values is scaled between –39.5 °C and +87 °C with a radiometric resolution of 0.5 °C. A value of –40 °C is used for water. Clouds are masked out as bad values.

Product Example

Night-time (left) and day-time (right) LST. Oceans and lakes are grey, clouds are white.

Methodology:

Numerous factors determine the accuracy of the LST retrieval from satellite thermal data, including sensor radiometric calibration, atmospheric correction, surface emissivity correction, characterisation of spatial variability in land cover, and the combined effects of viewing geometry, background, and fractional vegetative cover.
The technique used for estimating the land surface temperatures from thermal infrared NOAA AVHRR data is the so-called “Split-Window” method. This technique is based on the differential absorption effects in two infrared bands situated close to each other in order to estimate atmospheric water vapour content (channels 4 and 5 of AVHRR are closely related.
Prior to estimating land surface temperature, automatic calibration, interactive georeferencing and interactive cloud masking is performed. Surface emmissivity is estimated based on the vegetation index NDVI which is simultaneously derived from AVHRR solar channels.

Major users:

Scientific Organisations

Publications:

Dech, S., Tungalagsaikhan, P., Preusser, C., & Meisner, R., 1998. Operational value-adding to AVHRR data over Europe: methods, results, and prospects. Aerospace Science and Technology, 5, 335-346.

Relevance:

Land surface temperature (LST) is an important factor controlling most physical, chemical, and biological processes of the Earth (e.g. evapotransiration of canopies). This product is thus used by scientists modelling biogenic emission from vegetation or modelling the hydrological cycle.

Data Access

Contact: Dr. Kurt P. Günther