2014 CEDAR Workshop
A Rayleigh-scatter lidar operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W), part of Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU), collected extensive data between 1993 and 2004. From the Rayleigh lidar photon-count profiles, relative densities were determined throughout the mesosphere, from 45 to 90 km. Using these relative densities three climatologies were derived, each using a different density normalization at 45 km. The first normalized the relative densities to a constant; the second to the NRL-MSISe00 empirical model which has a strong annual component; and the third to the CPC analyses model, which is similar to MSIS in that it has a strong annual oscillation. In each case the density profile for every night of a composite year was found by averaging the nighttime density profiles over a 31-day by 11-year window centered on that day. For each of the cases, the average annual density profile was found by averaging all the days. Then the daily percent differences were found relative to the annual density profile. Despite the different normalizations at 45 km, many common features were found in the seasonal behavior of the density profiles, a large seasonal variation maximizing in June at ~70 km, Another above 80 km is a large shift in the maximum to earlier in the year, and lastly sharp density fall off at almost all altitudes in early October. While these density normalizations provide initial information about mesospheric behavior, the current lidar upgrade will enable us to add an absolute scale to the density profiles.
Barton, D., Wickwar, V., Sox, L., & Herron, J. (2014, June 22). Seasonal Variations of Relative Neutral Densities between 45 and 90 km Determined from USU Rayleigh Lidar Observations. Presented at the 2014 CEDAR Workshop, University of Washington, Seattle, WA.