Seasonal Variation of Vertical Heat and Energy Fluxes due to Dissipating Gravity Waves in the Mesopause Region Over the Andes
Seasonal Variation of Vertical Heat and Energy Fluxes due to Dissipating Gravity Waves in the Mesopause Region Over the Andes
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DOI：
10.1029/2020jd033825
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发表时间：
2021-02
期刊：
影响因子：
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通讯作者：
Yafang Guo;A. Liu
中科院分区：
文献类型：
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作者：
Yafang Guo;A. Liu
利用位于智利Cerro Pachón（30.25°S，70.73°W）的安第斯山脉激光雷达观测站（ALO）的窄带钠风温激光雷达获得的400多小时观测数据，分析了中层顶区域（85-100 km）重力波耗散引起的垂直能量输运。感热通量直接估计使用实测温度和垂直风;能量通量估计的垂直波数和温度扰动的频谱;和焓通量的基础上，它与感热和能量通量的关系推导。感热通量在整个区域主要是向下的。焓通量呈现出年度振荡，最大的向下输送在7月90公里以上。能量通量的主要特征是随着海拔从85 km增加到100 km，能量通量从10−2到10−4 W m−2呈指数下降，并且在南半球冬季更大。由焓通量推断的年平均热扩散率从85 km处的303 m2 s−1降低到90 km处的最小值221 m2 s−1，然后增加到99 km处的350 m2 s−1。结果还表明，较短的周期重力波往往消散在较高的高度，并产生更多的热量输送。高频、中频和低频波的平均垂直群速度分别为4.15 m s-1、1.15 m s-1和0.70 m s-1。重力波热输运在中层顶区域带来显著的冷却，平均冷却速率为6.7 ± 1.1K/天。
Vertical energy transports due to dissipating gravity waves in the mesopause region (85–100 km) are analyzed using over 400 h of observational data obtained from a narrow‐band sodium wind‐temperature lidar located at Andes Lidar Observatory (ALO), Cerro Pachón (30.25°S, 70.73°W), Chile. Sensible heat flux is directly estimated using measured temperature and vertical wind; energy flux is estimated from the vertical wavenumber and frequency spectra of temperature perturbations; and enthalpy flux is derived based on its relationship with sensible heat and energy fluxes. Sensible heat flux is mostly downward throughout the region. Enthalpy flux exhibits an annual oscillation with maximum downward transport in July above 90 km. The dominant feature of energy flux is the exponential decrease from 10−2 to 10−4 W m−2 with the altitude increases from 85 to 100 km and is larger during austral winter. The annual mean thermal diffusivity inferred from enthalpy flux decreases from 303 m2 s−1 at 85 km to minimum 221 m2 s−1 at 90 km then increases to 350 m2 s−1 at 99 km. Results also show that shorter period gravity waves tend to dissipate at higher altitudes and generate more heat transport. The averaged vertical group velocities for high, medium, and low frequency waves are 4.15 m s−1, 1.15 m s−1, and 0.70 m s−1, respectively. Gravity wave heat transport brings significant cooling in the mesopause region at an average cooling rate of 6.7 ± 1.1 K per day.