TITLE: POES NOAA AVHRR AMSU-B Data [NCAR/EOL] CONTACTS: Steve Williams NCAR/EOL P.O. Box 3000 Boulder, CO 80307-3000 phone: 303-497-8164 email: sfw@ucar.edu 1.0 DATA SET OVERVIEW This data set contains AMSU-B (Advanced Microwave Sounding Unit-B) data from the NOAA POES satellites (K/L/M/N). These data were retrieved from the NOAA CLASS archive. The data are in Level 1-b format and cover the T-REX period (1 March to 30 April 2006). They cover the region from 34-40 N and 115-126 W. 2.0 INSTRUMENT DESCRIPTION Complete information on the NOAA POES AMSU-A instumentation is available from the NOAA KLM User's Guide: http://www2.ncdc.noaa.gov/docs/klm/ The Advanced Microwave Sounding Unit-B (AMSU-B) is a 5 channel microwave radiometer. The purpose of the instrument is to receive and measure radiation from a number of different layers of the atmosphere in order to obtain global data on humidity profiles. It works in conjunction with the AMSU-A instruments to provide a 20 channel microwave radiometer. AMSU-B covers channels 16 through 20. Channels 18, 19 and 20 span the strongly opaque water vapor absorption line at 183 GHz to provide data on the atmosphere's humidity level. Channels 16 and 17, at 89 GHz and 150 GHz, respectively, penetrate through the atmosphere to the Earth's surface. AMSU-B is a cross-track, line scanned instrument designed to measure scene radiances in 5 channels. At each channel frequency, the antenna beamwidth is a constant 1.1 degrees (at the half power point). Ninety contiguous scene resolution cells are sampled in a continuous fashion. Each scan covers roughly 50 degrees on each side of the subsatellite path. The scan pattern and geometric resolution translate to a 16.0 km diameter cell at nadir at a nominal altitude of 833 km. 3.0 DATA COLLECTION AND PROCESSING NCAR/EOL conducted no processing or quality control on these data. The NOAA ATOVS processing flow begins with sensor data receipt by the Command and Data Acquisition (CDA) stations where the data are re-broadcast via communications satellites to NOAA/NESDIS in Suitland, MD where they are processed. Earth location and calibration data are appended, but not applied, to the data as part of the Level 1b processing. The earth locations are computed for specific pixels using the data time corrected for clock drift, if any. Shortly after arriving at NOAA/NESDIS, the data are made available at the Comprehensive Large Array-data Stewardship System (CLASS). Global coverage is available for the AMSU-B data which have an Instantaneous Field of View (IFOV) of approximately 1.1 degrees. From an altitude of 833 kilometers, this translates into a ground IFOV encompassing an area of 16.0 kilometers in diameter at nadir on the Earth. At scan end, a 51.6 km cross-track by 26.9 km along-track footprint is registered, again assuming a nominal altitude of 833 km. At the equator, the 97.9 degree scan equates to a swath width of 2,178.8 km to the far edge of the outer FOV centered on the subsatellite track. The instrument is automatically calibrated each data cycle by measuring both warm and cold calibration targets. Once every 8/3 seconds, the AMSU-B measures 90 Earth views, four space views and four internal blackbody target views. 4.0 DATA FORMAT AND FILE NAMING 4.1 File Naming conventions NSS.AMBX.NM.D06119.S1836.E2008.B1998990.GC.L7200831 where: AMBX is the data type (AMSU-B) NM is the satellite (NOAA-M) D06119 is the year (06) and Julian day (119) S1836 is the scan start time (UTC) E2008 is the scan end time (UTC) 4.2 Data Format These data are in Level 1-b format. Complete information on the NOAA POES AMSU-B format is available from the NOAA KLM User's Guide: http://www2.ncdc.noaa.gov/docs/klm/ 5.0 DATA REMARKS 6.0 REFERENCES None.