ATSR-1/2 UBT Archive

See also (A)ATSR common-format archive

Introduction

ATSR-1 was launched as part of the payload of ESA's ERS-1 satellite on 17th July 1991, and was the test-bed for the along track scanning concept (see Fig. 1). It carries an Infrared Radiometer (IRR) with four infrared channels at 1.6µm, 3.7µm, 10.8µm and 12.0µm, measuring sea-surface temperature (SST). Routine ATSR-1 operations stopped when ERS-1 was put into hibernation in June 1996, but the instrument is still capable of operation. The other instrument is the Microwave Radiometer (MWR), which measures the integrated (vapour and liquid) atmospheric water content. The IRR was developed by Rutherford Appleton Laboratory (RAL, UK) and the MWR by the Centre de Recherche en Physique de l'Environment Terrestre et Planetaire (CRPE, F).

For the ATSR-2 on ERS-2, the IRR has been upgraded by adding three more bands in the visible part of the spectrum at 0.55µm, 0.67µm and 0.87µm. The MWR is identical to that used on ERS-1, but is provided by Schrack Aerospace of Austria. For AATSR see AATSR article. (source: ATSR User Guide).

See the ERS-1/2 fact sheet for details of other instruments on these platforms. 

Fig. 1 ATSR Viewing Geometry (Source: ATSR User Guide)

Fig. 1 ATSR Instruments (Source: ATSR User Guide)

Latest News: A major project is underway at NEODC to create a common-format archive of (A)ATSR data products, see the (A)ATSR multi-mission archive fact sheet.

Platform Parameters

IRR Sensor

The ATSR sensor uses low-noise infrared detectors, continuous on-board radiometric calibration and the along-track scanning technique as shown in Fig. 1, which makes two observations of the same point on the Earth's surface through differing amounts of atmosphere. The "along-track" view passes through a longer atmospheric path and so is more affected by the atmosphere compared to the nadir view. First, the ATSR views the surface along the direction of the orbit track at an incidence angle of 55 degrees as it flies towards the scene. Then, some 150s later, ATSR records a second observation of the scene at an angle close to the nadir. By combining the data from these two views a direct measurement of the effect of the atmosphere is obtained, which yields an atmospheric correction for the surface data set.

MWR Sensor

The MWR instrument uses a 60cm Cassegrain offset-fed antenna to view the Earth in the nadir direction at frequencies of 23.8 and 36.5 GHz. The signals received are compared with that from the reference source at a known temperature in order to minimise the effects of short-term variations in the receiver-chain gain. To calibrate the MWR, additional features are used. The sky-horn antenna is pointed towards the very low cosmic background radiation of deep space at about 4 K for 'cold reference' measurements, while the 'hot reference' is obtained from measurements within the instrument itself.

Sea Surface Temperature

In this global SST image temperature is represented on a scale ranging from purple/blue (coldest) through green to red (warmest). The continents have been masked in black. To the right of the East coast of the USA a thin tongue of warm water can be seen stretching northwards - the famous Gulf Stream. A relatively cool (yellow) region extends westwards from Peru into the warm equatorial waters of the Pacific - this is the surface temperature 'signature' of the El Nino event. In non El Nino years this cool tongue does not appear.

Fig. 3 Global monthly and spatial averaged SST, September 1993 (source: University of Leicester EOSG)

Data availability

NEODC archive

Click here to search NEODC holdings of ATSR UBT (Ungridded Brightness Temperature) data.

Click here to browse NEODC (A)ATSR multimission archive 

Other suppliers

Infoterra

Eurimage

Further Information

ERS-1/2 Website

Main page

ATSR-1/2 Website

Main page

Data products page