The Advanced Along-Track Scanning Radiometer is on board the European Space Agency (ESA) satellite ENVISAT. It is the most recent in a series of instruments designed to measure Sea Surface Temperature (SST) to the high levels of accuracy and precision required for the monitoring and detection of climate change.

ATSR-1 was launched on the ESA satellite ERS-1 in July 1991 and operated until March 2000. ATSR-2 was launched on ERS-2 in April 1995 and is expected to continue to operate at least until the end of the ENVISAT commissioning phase. Together this family of instruments will establish a unique fifteen year data set supporting not only oceanographic and climate research, but also a wide range of land surface, cryosphere and atmospheric applications.

Objectives

The primary scientific objective of the AATSR is to establish continuity of the ATSR-1 and ATSR-2 data sets of precise Sea Surface Temperature (SST), thereby ensuring the production of a unique 10 year near-continuous data set at the levels of accuracy required (0.5 K or better) for climate research and for the community of operational as well as scientific users developed through the ERS-1 and ERS-2 missions.

The second objective is to perform quantitative measurements over land surfaces. The land and cloud measurement objectives will be met through the use of an additional visible focal plane assembly, which will lead to indications of

• vegetation biomass,
• vegetation moisture,
• vegetation health and growth stage

The visible channels will also contribute to the measurement of cloud parameters, like water/ice discrimination and aerosol distribution.

Instrument

ATSR-1 measured in the infra-red at 1.6 µm, 3.7 µm, 11 µm and 12.0 µm and had no visible channels. ATSR-2 and AATSR include the same four infra-red channels of ATSR-1 and three additional channels at 0.55 µm, 0.67 µm and 0.87 µm.

The ATSR-2 instrument is largely the same as ATSR-1, differing only in the inclusion of the extra channels and an on-board visible calibration system.

The ENVISAT Platform

In March 2002, the European Space Agency launched ENVISAT, an advanced polar-orbiting Earth observation satellite which provides measurements of the atmosphere, ocean, land, and ice. ENVISAT data supports earth science research and allows monitoring of the evolution of environmental and climatic changes. Furthermore, the data will facilitate the development of operational and commercial applications.

ENVISAT flies in a sun-synchronous polar orbit of about 800-km altitude. The repeat cycle of the reference orbit is 35 days.

Data Access

General Data Product Level Definition

The ESA Data Distribution Policy governs the distribution of AATSR data. Under this policy data use is foreseen to fall within one of two categories:

• Category 1 use: research and applications development use in support of the mission objectives, including research on long term issues of Earth System science, research and development in preparation for future operational use, certification of receiving stations as part of the ESA functions, and ESA internal use
• Category 2 use: all other uses that do not fall into Category 1, including operational and commercial use.

An overview of avaiaible data is found on the European Space Agency website.

Links

• AATSR Product Handbook
• ESA MERIS/AATSR Workshop: Focus on Envisat Sensors Measuring Heat and Light

Contact

If you would like to have more information about the AATSR data, please contact wdc@dlr.de