NIRST, a satellite based IR instrument for fire and sea surface temperature measurement

摘要

NIRST is a pushbroom scanning infrared radiometer that makes use of 512x2 arrays of resistive microbolometers. This instrument comprises mainly two cameras, one operating in the spectral band of 3.4-4.2 μm (band 1) and the other in the bands of 10.4-11.3 (band 2) and 11.4-12.3 μm (band 3). It is intended for the retrievals of forest fire and sea surface temperatures in the Aquarius / SAC-D mission. In this mission the satellite will be launched into a Sun Synchronous polar orbit with an ascending node at 6 PM. This orbit suits the need of discriminating forest fires from solar reflections. NIRST is designed to achieve a spatial resolution of 350 m and a swath width of 180 km at nadir. Its field of view can be steered across track up to 500 km on each side to shorten the revisit time. To measure fire intensity temperatures NIRST will perform multispectral scans of ground area in bands 1 and 2 and the acquired data will be analyzed using a double band algorithm . The microbolometer detectors have been designed to exhibit useful dynamic range for this application. It is projected that the detector response in band 1 saturates only when NIRST scans a 350 m ground pixel of average temperature of 700 K. The use of the data acquired in bands 2 and 3 allows for the retrieval of sea surface temperature by means of the split algorithm technique.