Climatology and Seasonal Variations of Temperatures and Gravity Wave Activities in the Mesopause Region Above Ft. Collins, CO (40.6°N, 105.1°W)
Climatology and Seasonal Variations of Temperatures and Gravity Wave Activities in the Mesopause Region Above Ft. Collins, CO (40.6°N, 105.1°W)
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DOI：
10.1029/2021jd036291
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发表时间：
2022-05
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影响因子：
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通讯作者：
C. She;Zhaoai Yan;C. Gardner;D. Krueger;Xiong Hu
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文献类型：
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作者：
C. She;Zhaoai Yan;C. Gardner;D. Krueger;Xiong Hu
利用在20年期间（1990年3月至2010年3月）在柯林斯堡（40.6°N，105.1°W）获得的956个夜晚的Na激光雷达夜间中层顶区域温度剖面，我们推导出背景夜间平均温度T <$（z）$\bar{T}（z）$和浮力频率N2（z）的平方，分辨率为2 km，在83和105 km之间。温度气候学揭示了两层中层顶结构，具有清晰和急剧的中层顶转换，导致从一年的第121天到第222天有102天的夏季。在10 min和1 km分辨率下分析的相同数据集给出了85和100 km之间的重力波（GW）温度扰动Ti '（z）和波方差Var（T'（z））以及GW势能Epm（z）。90 ~ 100 km的GWVar（T′（z））和Epm（z）的季节平均值表明，春季和秋季的Var（T′）相当，但低于夏季和冬季。主要由于夏季背景稳定度较高或N2（z）较大，85 ~ 100 km的Epm（z）在春、夏、秋三季基本相当，但比同海拔冬季的Epm（z）小30%~ 45%。冬季的不确定性约为4%，其他三个季节约为5%。在85 km处的Epm值（春、夏、秋和冬）分别为（156.0、176.2、145.6和186.2 J/kg），在93 km处分别为（125.4、120.2、115.2和168.7 J/kg），在100 km处分别为（207.5、180.5、213.1和278.6 J/kg）。随着海拔的升高，所有的廓线都是先减小后增大，这表明在气候上，全球变暖在85 km以下发生。
Utilizing 956 nights of Na lidar nocturnal mesopause region temperature profiles acquired at Fort Collins, CO (40.6°N, 105.1°W) over a 20‐year period (March 1990–2010), we deduce background nightly mean temperature T¯(z) $\bar{T}(z)$ and the square of the buoyancy frequency N2(z) 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 102 days of summer from Days 121 to 222 of the year. The same data set analyzed at 10‐min and 1‐km resolution gives the gravity wave (GW) temperature perturbations Ti'(z) and the wave variance Var(T′(z)) and GW potential energy Epm(z) between 85 and 100 km. Seasonal averages of GW Var(T′(z)) and Epm(z) between 90 and 100 km, show that Var(T′) for spring and autumn are comparable and lower than for summer and winter. Due mainly to the higher background stability, or larger N2(z) in summer, Epm(z) 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 three seasons. The values for Epm 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, GWs break below 85 km.