Chapter 1
The AATSR Products User Guide

The Advanced Along Track Scanning Radiometer (AATSR) is one of the Announcement of Opportunity (AO) instruments on board 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. In order to achieve this, the (A)ATSR instruments include several innovative features in their design:

• An along track scanning technique 1.1.3.1. ;
• Continuous on-board calibration of the thermal channels;
• An on-board calibration system for the visible and near infrared channels;
• Low-noise infrared detectors, cooled to near-optimum operating temperatures;
• A multi-channel approach to SST retrieval.

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.

The purpose of this User Guide is to introduce users to the capabilities of the AATSR instrument and its data products. It provides a brief overview of the instrument, the geophysical measurements it retrieves and the measurement principles employed. It also provides information to help users select, read and understand AATSR data. Also included are a list of links and references for further reading, and a selection of example images in the form of an image gallery. The User Guide is intended to help users "get started" with AATSR data.

The AATSR User Guide has been produced in conjunction with an AATSR Reference Guide. The Reference Guide provides more detailed information on the heritage and evolution of the (A)ATSR series of instruments, the AATSR instrument itself and its products and data processing system. The Reference Guide is designed for use when more specific scientific or engineering information is required, and covers AATSR Products and Algorithms(Chapter 2. ), The AATSR Instrument(Chapter 3. ), Frequently Asked Questions(Chapter 4. ), a Glossary(Chapter 5. ) and detailed Data Format information(Chapter 6. ).