All Physics Faculty Publications

Document Type


Journal/Book Title/Conference

Journal of Geophysical Research--Atmospheres


American Geophysical Union

Publication Date



From 1993-2004, 839 nights were observed with the Rayleigh-scatter lidar at Utah State University’s Atmospheric Lidar Observatory. They were reduced to obtain nighttime mesospheric temperatures between 45 and ~90 km, which were then combined to derive composite annual climatologies of mid-latitude temperatures and geophysical temperature variability. At 45 km, near the stratopause, there is a ~250 K temperature minimum in mid-winter and a 273 K maximum in mid-May. The variability behaves oppositely, being 7-10 K in winter and 2.5 K in summer. At 85 km, there is a 215 K temperature maximum at the end of December and a 170 K mesopause minimum in early June. In contrast, the variability is roughly constant at ~20 K. At both low and high altitudes, the temperatures change much more rapidly in spring than in fall. The transition between these opposite temperature behaviors is 65 km. Distinctive temperature structures occur in all regions. In mid-winter, between 45 and 50 km, a 6 K warm region appears, most likely from occasional sudden stratospheric warmings. Above that, a “cold valley” extends to 70 km, which may be related to the bottom side of intermittent inversion layers. Both regions have increased variability. Near 85 km, there is a very rapid heating event of 25 K/month in August with high variability. In October, a temperature minimum, a “cold island”, occurs from 78–86 km with low variability, indicating a regular feature. These USU results are compared extensively to those from other mid-latitude lidars in Canada and France.