Climatology and Seasonal Variations of Temperatures and Gravity Wave Activities in the Mesopause Region Above Ft. Collins, CO (40.6˚N, 105.1˚W)

Utilizing 956 nights of Na lidar nocturnal mesopause region temperature profiles acquired at Fort Collins, CO (40.6oN, 105.1oW) over a 20 year period (Mar 1990-Mar 2010), we deduce background nightly mean temperature and the square of the bouyancy frequency at 2-km resolution between 83 and 105 km. The temperature climatology reveals the two-level mesopause structure with clarity and sharp mesopause transitions, resulting in a 102 days of summer from Day 121 to Day 222 of the year. The same dataset analyzed at 10-min and 1-km resolution gives the gravity wave temperature perturbations and the wave variance and gravity wave potential energy between 85 and 100 km. Seasonal averages of gravity wave and between 90 and 100 km, show that for spring and autumn are comparable and lower than for summer and winter. Due mainly to the higher background stability, or larger in summer, between 85 and 100 km is comparable in spring, summer, and autumn seasons, but ∼ 30 - 45% smaller than the winter values at the same altitude. The uncertainties are about 4% for winter and about 5% for the other 3 seasons. The values for are (156.0, 176.2, 145.6 and 186.2 J/kg) at 85 km for (spring, summer, autumn and winter) respectively, (125.4, 120.2, 115.2, and 168.7 J/kg) at 93 km, and (207.5, 180.5, 213.1, and 278.6 J/kg) at 100 km. Going up in altitude, all profiles first decrease and then increase, suggesting that climatologically, gravity waves break below 85 km. This article is protected by copyright. All rights reserved.