Abstract

Since the first report on the temperature measurements in the mesopause region using the new two-frequency narrowband Na temperature lidar [1], active research continues and several publications have already appeared in the literature [2, 3]. In order to reveal the seasonal variations and the thermal structure of the mesopause region, long-term routine Na temperature measurements at different locations should be made. Unlike at polar latitudes, investigations of the nighttime temperature structures of the mesopause region on regular basis are possible year-round at a midlatitude. Such investigations are now in progress at both Fort Collins, CO (40.60N, 1050W) and Urbana, IL (400N, 880W) [4], using a new two-frequency narrowband Na temperature lidar in each location. From 1991 to the end of 1992, 106 nights of observations (22,138 files) have been conducted at Fort Collins, CO. In this paper, we report the results deduced from 88 nights of quality data with 4 to 9 hours of observation each night. Our data set covers a nearly continuous period of two years. The thermal structure of the mesopause region at a midlatitude location and its seasonal variation can be established from our observations.

© 1993 Optical Society of America