A Dual-Wavelength In Situ Cloud Lidar with Very Large Sample Volume

Large-volume measurements of cloud microphysical properties are crucial for validating remote measurements from the earth¿s surface and satellites, which are necessary to improve predictions from global climate models. Current airborne in situ instruments are limited to microphysical measurements on scales of cubic centimeters up to a cubic meter. This project will develop a dual-wavelength in situ cloud light detection and ranging (lidar: the optical analog of radar) system capable of measuring volumetric cloud properties over scales of millions of cubic meters. The Phase I project included simulations and laboratory evaluations of components critical for development of the lidar system. SPEC previously developed a signal-wavelength system from which several components will be incorporated into the dual-wavelength (near infrared) system, thereby providing a significant cost savings to the DOE. The development of a near infrared high-power laser system with custom avalanche photodiode detector was a major challenge that was overcome in the Phase I research. In Phase II, SPEC will build the dual-wavelength in situ cloud lidar, and in cooperation with the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS), install it in a research aircraft which will be used in the DOE Atmospheric Radiation Measurement (ARM) field campaign in 2009. Calibration flights will be performed and SPEC staff will deploy to the field program to train CIRPAS personnel on the operation of the equipment. Quick-look data will be placed on the program web site and final data will be placed in the ARM archives after the close of the experiment. Commercial Applications and other Benefits as described by the awardee: The dual-wavelength in situ cloud lidar system will be useful as a tool to quantify the effects of stratus clouds on global climate change and has potential applications on several research aircraft. Military applications include providing information to landing aircraft, such as quantification of cloud properties and boundaries around aircraft carriers. The lidar system installed at uncontrolled airports could warn incoming aircraft of low clouds and fog, which are visually undetectable at night. It would also provide information on cloud boundaries and liquid water content that is critical for in-flight icing precautions. The system, installed in small unmanned aerial vehicles flying off costal areas, could provide critical information on the breakup of marine stratocumulus, resulting in cost savings to airlines by reducing flight delays and cancellations.