Analysis of Air-Soil Temperature Differences at Five Locations: Application to Passive Standoff Chemical Detection

摘要

For a passive spectral sensor such as CATSI (Compact ATmospheric Sounding Interferometer), the temperature difference ( T) that exists between a chemical cloud and the background scene is of prime importance because it is linked to the radiative contrast of the target. The larger T, the better the radiative contrast and the more accurate is the detection and identification, of the cloud. The purpose of this memorandum is to establish statistics on realistic air-soil temperature differences to be used to estimate the detection performance of CATSI-type sensors in a variety of scenarios and environments. To this end, an analysis of the air-soil temperature differences is presented for five locations around the world; namely, 1- Sanborn Field, Boone County, Missouri, USA, 2- Novelty, Knox County, Missouri, USA, 3- Macquarie University, Sydney, Australia, 4- Murdoch University, Perth, Australia, and 5- Bylot Island, Nunavut, Canada. The results of the analysis indicate that the statistics of the air-soil temperature differences are similar from one location to another. The average statistics over the five locations show a mean air-soil temperature difference of 3.5 C and a median of 2.8 C. An air-soil temperature difference of less than one degree Celsius occurs less than 14% of the time on the average. This suggests that, on average, air-soil temperature contrasts should yield good detection probabilities 86% of the time.