TITLE: POES NOAA ATOVS HIRS/3 Data [NCAR/EOL] CONTACTS: Steve Williams NCAR/EOL P.O. Box 3000 Boulder, CO 80307-3000 phone: 303-497-8164 email: email@example.com 1.0 DATA SET OVERVIEW This data set contains HIRS/3 (High Resolution Infrared Radiation Sounder) 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 HIRS/3 instumentation is available from the NOAA KLM User's Guide: http://www2.ncdc.noaa.gov/docs/klm/ The High Resolution Infrared Radiation Sounder (HIRS/3) is part of the ATOVS instrument suite flown onboard the NOAA KLM series of satellites. The HIRS/3 is a discrete stepping, line-scan instrument designed to measure scene radiance in 20 spectral bands to permit the calculation of the vertical temperature profile from the Earth's surface to about 40 km. Multispectral data from one visible channel (0.69 micrometers), seven shortwave channels (3.7 to 4.6 micrometers) and twelve longwave channels (6.5 to 15 micrometers) are obtained from a single telescope and a rotating filter wheel containing twenty individual filters. An elliptical scan mirror provides cross-track scanning of 56 increments of 1.8 degrees. The mirror steps rapidly (<35 msec), then holds at each position while the 20 filter segments are sampled. This action takes place each 100 msec. The instantaneous FOV for each channel is approximately 1.4 degrees in the visible and shortwave IR and 1.3 degrees in the longwave IR band which, from an altitude of 833 kilometers, encompasses an area of 20.3 kilometers and 18.9 kilometers in diameter, respectively, at nadir on the Earth. 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 HIRS/3 data which have an Instantaneous Field of View (IFOV) of approximately 1.4 degrees in the visible and shortwave IR and 1.3 degrees in the longwave IR band. From an altitude of 833 kilometers, these translate into a ground IFOV encompassing an area of 20.3 kilometers and 18.9 kilometers in diameter, respectively, at nadir on the Earth. At scan end, a 68.3 km cross-track by 34.8 km along-track footprint is registered for the visible and shortwave IR channels, again assuming a nominal altitude of 833 km. The HIRS/3 instrument provides a global (pole-to-pole) on-board collection of data from all 20 spectral channels. At the equator, the 99 degree scan equates to a swath width of 2,248.8 km to the far edge of the outer FOV centered on the subsatellite track. As a result of the scan geometry, there is variable underlap between steps and scans. 4.0 DATA FORMAT AND FILE NAMING 4.1 File Naming conventions NSS.HIRX.NN.D06119.S1832.E2027.B0485456.GC.L7210371 where: HIRX is the data type (HIRS/3) NN is the satellite (NOAA-N) D06119 is the year (06) and Julian day (119) S1832 is the scan start time (UTC) E2027 is the scan end time (UTC) 4.2 Data Format These data are in Level 1-b format. Complete information on the NOAA POES HIRS/3 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.