The Microwave Radiometer (MWR) -or Microwave Sounder (MWS)- is part of the Along Track Scanning Radiometer and Microwave Sounder (ATSR) instrument on-board the European Remote Sensing Satellites (ERS-1 and ERS-2) launched by the European Space Agency on 17 July 1991 and 20 April 1995. The ATSR incorporates two separate instruments: an advanced four- channel infrared radiometer (the ATSR-IRR, commonly called the ATSR) used for measuring sea surface temperature and cloud top temperatures, and a two-channel Microwave Sounder (the ATSR-MWR, commonly called the MWR) designed to measure total precipitable water vapour and the total liquid water content of the atmosphere. The MWR is a passive two-channel radiometer. The footprints of the two channels are not coincident on the Earth's surface, as one channel views slightly forward of the nadir point and the other slightly behind, although both are on the sub_satellite track. The footprints are 22.4 km for the forward view and 21.2 km for the rear view, with a 60 km separation. The calibration is achieved by ambient loads within the instrument, consisting of terminated waveguides and a set of skyhorns viewing space. MWR characteristics: ------------------------------------------------------------ Channels: 23.8 and 36.5 GHz Beam width: 3 dB IFOV: 20 and 22 km Antenna: 60 cm off-axis paraboloid Cassegrain Receiver: Dicke ------------------------------------------------------------ The ATSR was designed to provide the following: - global sea surface temperature, accurate to better than 0.5K (absolute) with a spatial resolution of 50 Km in conditions of up to 80% cloud cover - images of surface temperature, accurate to 0.1K (relative) with 1 km resolution and 500 km swath width - total water vapour content of the atmosphere - observations of clouds, aerosols, haze, land-ice and sea-ice surface emissivity - tropospheric range correction of the radar altimeter measurements to better than 5 cm The ATSR provides important information in scientific disciplines such as oceanography, climatology and meteorology. When combined with observations of cloud top temperatures, cloud cover, haze, aerosol and total water vapour content of the atmosphere, significant improvements may be expected in the accuracy of medium range weather forecasting. Also accurate sea surface temperatures can be of use to a number of commercial users, particularly those involved in fishing and the management of fishing areas. In the field of research, potential applications of the ATSR include distinguishing thin new ice from open water, identifying surface type, and the accumulation rate of land ice. Online sensor information: "http://www.arm.gov/docs/instruments/static/mwr.html" Related URL: "http://earth.esa.int/mwr/" Reference online documentation: "http://earth.esa.int/services/esa_doc/doc_ats.html" For any query, please refer to: ESA/ESRIN Earth Observation Help Desk "http://earth.esa.int" E-mail: eohelp&#64esa.int Phone: +39 06 94180777 Fax: +39 06 94180292 Address: ESA/ESRIN Via G.Galilei 00044 Frascati Italy
Radiometers