Description: Aircraft wake vortices is especially hazardous during the landing and taking-off phases of flight. It is essential to obtain an accurate atmospheric temperature profile in the lower troposphere for a better prediction and understanding of aircraft wake vortex. In this NASA SBIR project, we propose to build a lidar instrument that is capable of measuring both the daytime and nighttime atmospheric temperature profile in the lower troposphere. Atmospheric temperature measurement using Raman Lidar technique is well established and has been implemented by a lot of research groups. The major innovation of our approach is to use a low-power, high-repetitive-rate laser, instead of the high-power, low-repetitive-rate flash-lamp-pumped laser systems commonly used for such instruments. This will allow us to achieve the goals of building an eye-safe, compact, robust, reliable, relatively inexpensive and low maintenance instrument. The proposed lidar will be able to achieve 1K accuracy, good range resolution (~100m) with a range up to 3 km at both daytime and nighttime with under 10 minutes of averaging. We will build a breadboard system for Phase I and perform a proof of concept temperature measurement. We will bring the development to preliminary design so that Phase II may begin with the final system design and begin construction as early as possible. Phase II will provide for delivery of a prototype and culminate in a series of validation field trials, comparing our measured profiles with other measurement techniques.

Benefits: The proposed instrument can be used on helping wake vortex avoidance, which is a primary constraint on the national Airspace System (NAS). More than 30 Joint Planning and Development Office (JPDO) operational improvements (OIs) and SESAR lines of change (LoC) could be impacted by wake considerations. NextGen concept required significant reductions in separations of aircraft wake vortex to achieve capacity goals. When successfully developed, the proposed system can be applied for many other atmospheric trace gas measurements and environmental monitoring and will have numerous markets. Raman Lidar techniques have been demonstrated which provide most valuable descriptions of the evolution of air pollution events. With different optical configuration of the lidar system, the Raman technique provides a robust tool that can be employed to measure a wide range of meteorological and environmental properties, such as the simultaneous profiles of meteorological data, ozone, water vapor optical extinction and measurements of airborne particulate matter.

Temperature is a basic parameter which describe the atmospheric state of many important meteorological phenomena occur in the troposphere, the accurate measurement of temperature in the lower troposphere is of considerable importance for studies in the atmospheric sciences, particularly for research on conditions for atmospheric stability and for circulation models. Since the instrument can be used to measure elastic and other Raman channels, there are numerous non-NASA applications in the market to measure a wide range of meteorological and environmental properties. Potential customers include the NOAA or EPA for environmental monitoring. In addition, with the small size, high rep rate laser instead of using the flash pump laser, the proposed instrument can be easily transported and can be implemented for use at National Weather Service instrument stations. And without complicated modification to the instrument, there are also a number of military / civilian commercial applications of the lidar instrument such as bio/chemical hazard detection, etc.