Collaborative Research: Lidar Studies of Middle Atmospheric Dynamics(CEDAR)

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A lidar consortium consisting of Clemson University (CU), Utah State University (USU), the University of Maryland (UMD), and the University of Pittsburgh (UP) jointly propose a 2-year research program on middle atmosphere dynamics based on Doppler Rayleigh and Raman lidar observations combined with other optical measurements obtained at Bear Lake Observatory (BLO) and measurements of winds, densities, and temperatures obtained from balloon and rocket flights. (Proposals have been submitted by three institutions using the same text, but different budgets; UP will support this effort through current NSF funding.) CEDAR funding made possible the installation in Utah of a Nd:YAG Rayleigh lidar system that had been developed at UMD and moved to USU to be part of the BLO facilities. The possible altitude coverage has been extended upward to 75 km with the addition of a 6 times more powerful frequency-stable Nd:YAG laser that was purchased by CU for use with the lidar Consortium system. This upgrade of the Maryland lidar facility also includes one additional detector channel, which is a Raman 607 nm channel that extends profile observations of temperature structure downward to the ground from 30 km. The first year of this proposed effort would continue observations of components - a high-resolution Fabry Perot etalon and a double-axis mirror system - that are necessary for measuring the Doppler shift of the backscattered Rayleigh and Mie lidar spectra to observe line-of-sight winds in the middle atmosphere. A small radar system will be added to observe line-of-sight winds in the middle atmosphere. A small radar system will be added to shut off the laser transmitter when any aircraft is near the beam. A new lidar transmission channel will be added (607 nm) based on Raman-shifting the Nd laser output in a high pressure Raman cell. Upon completion of these instrumental modifications at the beginning of the second year of the grant award, application of the new Doppler lidar would collect vertical profiles of middle atmosphere winds and temperature from clear-air portions of the atmosphere above 10 km by using the laser returns from Mie (particulate) scattering and Rayleigh scattering at 532 nm. These profiles will provide the basis for examining the occurrence, structure, interaction, and variability of the jet stream, planetary waves, tides, and gravity waves in the middle atmosphere above the extended mountainous region of the American Rocky Mountain chain. The oblique propagation of these waves through the middle atmosphere as filtered by the prevailing winds in the middle atmosphere will be related to the dynamic activity simultaneously observed in the mesopause region by several instruments at BLO. Correlative observations of temperature, density, and winds will be made between the lidar and a combination of balloons and rockets. A by- product of the PIs observations will be the measurement of aerosol backscatter and extinction in high clouds, particularly thin cirrus, and the detection of stratospheric aerosols.