Networkable Automated Water Vapor Lidar for Tropospheric Profiling

Measurement of the vertical profile of H2O vapor in the lower atmosphere can provide new understanding of the dynamics of H2O vapor mass transport. Such measurements can improve predictive capability for precipitation forecasts as well as lead to increased understanding of complex feedback mechanisms involving H2O vapor, temperature, radiative balance, and precipitation and therefore are important to global climate change modeling. While techniques exist to measure vertical profiles of H2O vapor in the atmosphere, there is a need for a compact and economical sensor that can make these measurements in an automated manner as part of a network. A compact Differential Absorption Lidar can measure vertical profiles of H2O vapor in the lower atmosphere. Based on mature telecom components, the proposed system will have the capability to make round-the-clock measurements in a network environment. The Phase I program enhanced the measurement performance of the system by increasing the transmit power and by decreasing the range of the first measurement. The Phase I program enhanced the long term stability of the system by creating a rugged mechanical design and subjecting it to thermoelastic analysis. The Phase II program will fabricate an engineering prototype and demonstrate it at the DoE Southern Great Plains site for several months. It will be intercompared with balloon-borne radiosondes and with the sites Raman Lidar facility. Measurements of water vapor flux will be demonstrated by operating in collaboration with the sites Doppler lidar. Commercial Applications and Other Benefits: The primary market for the compact water vapor differential absorption lidar system is for routine water vapor measurements for meteorology. The increased data volume is expected to lead to improved general weather forecasts, as well as those for extreme events.