Monday, 3 June 2002
A Global Lidar Observation Database for Cloud and Aerosol Radiative Study
The Micropulse Lidar Network (MPL-Net) was created at NASA/GSFC to establish long-term cloud and aerosol monitoring sites around the world and support similarly motivated short-term field campaigns. The project marks a significant step in the evolution of the lidar technology. The development of autonomous, eye-safe instruments suitable for remote long-term deployment has had a great effect on the overall practicality of lidar systems (bridging somewhat the cavernous gap with its analogous counterpart radar). The MPL instrument is a single-channel (523 nm), elastic backscatter lidar able to profile nearly all significant tropospheric cloud and aerosol to the limit of transmitted pulse attenuation. Eye-safety is achieved through rapid pulse transmission and subsequent expansion through a dual-purpose transmit-receive Cassegrain telescope. MPL-Net sites are chosen to coincide with existing AEROENT sun-photometer sites, as well as supplementary passive radiometric arrays if possible. Four current program sites are in operation, with two new sites planned for 2002. In accordance with the Atmospheric Radiation Measurement Program, MPL-Net provides data analysis and instrument support for instruments operated at each of their four central CART facilities. MPL instruments have been recently deployed for numerous global field campaigns, including INDOEX, SAFARI-2000 and ACE-Asia.
Analysis of the normalized MPL signal yields macrophysical properties of the incident atmosphere (i.e. particulate layer boundary heights) and optical characteristics of cloud and aerosol layers. Global climatological characterization of many radiatively significant atmospheric parameters will benefit greatly from long-term MPL datasets. In this presentation we discuss recent relevant examples of their application, including the radiative forcing of biomass smoke events over southern Africa through comparisons of observed surface flux measurements to model calculations, a similar inquiry focusing on elevated dust layers observed in the eastern Caribbean Sea and over central Maryland, and seasonal variations of polar cloud coverages and optical depths.