Micro-Pulse DIAL for Atmospheric Water Vapor Profiling

Water vapor plays a key role in Earth’s climate and weather patterns. Accurate, high resolution measurements of the water vapor vertical profiles in a region have been found to significantly improve the numerical weather prediction models’ short-term forecasts, precipitation forecasts, as well as severe weather forecasts. However, current measurement techniques provide very coarse resolution in space, time, and/or altitude. A network of continuously sampling water vapor profilers would greatly expand the scientific knowledge of the atmosphere and serve as a valuable input into numerical weather models. This would be of interest not only to the Department of Energy’s Environmental Sciences Division but to other institutions such as the National Weather Service, the National Center for Atmospheric Research, the Federal Emergency Management Agency, and the military. Differential absorption lidar has the potential to greatly improve the resolution and accuracy of atmospheric water vapor measurements when integrated into a global network, but, while there are some research-grade systems, there doesn’t exist a commercial one with the potential for deployment into a sensing network. One promising research-grade lidar system is based on two narrow-linewidth amplified laser-diodes micro- pulsed at high repetition rates with state-of-the-art optical filtering in the photon-counting receivers. This instrument has already demonstrated strong performance in field campaigns. This proposal outlines a workplan to adapt this proven architecture to a commercialized product. Such a system promises to provide continuous monitoring of water vapor vertical profiles in an autonomous, eye-safe instrument that can be deployed in a network of sensors at relatively low cost and requiring minimal maintenance. In addition to the water vapor sensor, this architecture can be easily applied to a variety of other wavelengths in the visible and near-IR for profiling different atmospheric properties including temperature profiles (via molecular oxygen dial) and aerosol backscatter profiles (via a high spectral resolution lidar). Any system innovations developed under this proposed workplan can be incorporated into these potential sensors. The Phase I work will progress along two main fronts. First, several innovations will be tested to reduce the system complexity and cost to allow for a competitive, commercial product. Secondly, market research will be performed on both this base water vapor lidar system, as well as other atmospheric profiling sensors based on a similar architecture, to determine the level of interest in a system with performance specifications demonstrated in previous work and cost-point and ruggedness demonstrated by the Phase I improvements. The results of this market research will be used to guide a Phase II follow-up contract to develop and implement a lidar system that will directly meet a market demand for autonomous atmospheric profiling. Successful completion of this Phase I program will result in the development of plans for this commercialized product based on the needs of the potential customers.