NASA LASE water vapor differential absorption lidar measurementsand performance evaluation

摘要

The Lidar Atmospheric Sensing Experiment (LASE) is a highlynengineered and autonomous Differential Absorption Lidar (DIAL) systemndeveloped at NASA Langley Research Center (LaRC) to measurenhigh-resolution water vapor and aerosol profiles in the troposphere.nLASE is being developed as a precursor to the deployment of a spacebornenDIAL system for global measurement of high-resolution water vapornprofiles. The LASE system uses a tunable Ti:sapphire laser that isnfrequency locked to pre-selected water vapor lines in the 815-nm region.nLASE is undergoing a series of engineering test flights onboard anhigh-altitude ER-2 aircraft to evaluate its initial performance beforendeployment on field programs. During the first engineering test flightnconducted near NASA Ames Research Center in May 1994, LASE was operatednin the backscattered lidar mode and obtained high-quality aerosolnprofiles in the 0-20 km altitude region. During a subsequent engineeringnflight series conducted near NASA Wallops Flight facility in Septembern1994, water vapor and aerosol profiles were obtained simultaneouslynunder a variety of cloud and background conditions. This paper discussesnthe results of the water vapor and aerosol measurements made duringnthese flights. These measurements will be used to evaluate thenperformance of the instrument and for comparison with predicted valuesnof atmospheric signals and water vapor profiles derived from in situnmeasurements from radiosondes launched in the vicinity of LASEnmeasurements. These results will be used to refine the LASE system for anfinal engineering test series planned for early 1995. Plans for thenvalidation of the LASE instrument with other in situ and remote sensorsnand the anticipated field program participation are also discussed