Validation of the Lidar In-Space Technology Experiment: stratospheric temperature and aerosol measurements

Abstract

The Lidar In-Space Technology Experiment (LITE) was flown on STS-64 in September 1994. The LITE employed a Nd:YAG laser operating at 1064, 532, and 355 nm to study the Earth's lower atmosphere. In this paper we investigate the nighttime stratospheric aerosol and temperature measurements derived from the 532- and 355-nm channels. The observations are compared with lidar observations obtained at Arecibo Observatory, Puerto Rico, and Starfire Optical Range, New Mexico, and with balloonsondes launched from the San Juan and Albuquerque airports. The backscatter ratios derived from the LITE and Arecibo data between 15 and 30 km differ by less than 5%. The Angstrom coefficients of the stratospheric aerosols derived from the 532- and 355-nm LITE channels exhibited only slight variation in altitude. The mean value between 15 and 30 km derived from three different orbital segments at approximately 20 degrees N and 35 degrees N was 1.7. The mean standard deviation was approximately 0.3. Temperature profiles were derived from the LITE data by correcting the 355-nm channel for aerosol scattering with the 532-nm signal and an assumed Angstrom coefficient. The rms differences between the corrected profiles and the balloonsonde data were as low as 2 K in the 15-30-km height range. The results were not particularly sensitive to the choice of the Angstrom coefficient and suggest that accurate temperature profiles can be derived from the LITE data in the upper troposphere and lower stratosphere provided that the aerosol loading is light.