Large‐scale gravity wave characteristics simulated with a high‐resolution global thermosphere‐ionosphere model
Large‐scale gravity wave characteristics simulated with a high‐resolution global thermosphere‐ionosphere model
复制标题
用高分辨率全球热层-电离层模型模拟大尺度重力波特征
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
R. Schunk
中科院分区：
文献类型：
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作者：
L. Gardner;R. Schunk
[1] 大气层、电离层、磁层和海洋中的波是在整个地球-大气系统中耗散和分配能量的重要机制。内波在大气中极其重要，过去的全球研究利用重力波参数化研究了重力波对热层的影响。相比之下，这里在全球热层-电离层模型中研究了中等规模的重力波，以确定波在热层中向上传播时的 3D 特征。所使用的模型是全球热层-电离层系统的依赖时间的高分辨率数值模型，该模型产生质量密度、温度以及高度90至500公里的中性风的所有三个分量的全球分布。在热层中测量到的重力波水平波长为数百至数千公里，与这些波相关的周期约为一个小时。因此，本研究生成了物理的、存在于热层中且可在全球数值模型中解析的重力波；该波是1000公里水平波长波，周期为3小时。重力波振幅增大，达到临界状态，然后破裂，产生弯曲的波前，并在局部沉积能量。当重力波破裂并储存能量时，原始重力波会产生次级波，水平波长为 4000 至 5000 公里。二次波在全球范围内传播，不像原始重力波只在局部区域传播。原始重力波的密度和温度振幅分别为 35% 和 ±100 K，而次级波的振幅分别为 5% 和 ±20 K。
[1] Waves in the atmosphere, ionosphere, magnetosphere, and oceans are important mechanisms for dissipating and distributing energy throughout the Earth-atmosphere system. Internal waves are extremely important in the atmosphere, and past global studies have looked at the impacts of gravity waves on the thermosphere using gravity wave parameterizations. Here, in contrast, a medium-scale gravity wave is studied in a global thermosphere-ionosphere model, to determine the 3-D characteristics of the wave as it propagated upward through the thermosphere. The model used is a time-dependent, high-resolution, numerical model of the global thermosphere-ionosphere system, which produces global distributions of mass density, temperature, and all three components of the neutral wind at altitudes from 90 to 500 km. The gravity wave horizontal wavelengths that are measured in the thermosphere are hundreds to thousands of kilometers, with periods associated with these waves of about an hour. Therefore, a gravity wave that is physical, present in the thermosphere, and resolvable in the global numerical model was generated for this study; this wave is a 1000 km horizontal wavelength wave with a 3 h period. The gravity wave grows in amplitude, reaches a critical state and then breaks, creating curved wavefronts, and depositing its energy locally. As the gravity wave breaks, depositing its energy, a secondary wave is generated from the original gravity wave, with horizontal wavelengths of 4000 to 5000 km. The secondary wave propagates globally, unlike the original gravity wave, which only propagates in a local area. The original gravity wave had amplitudes for density and temperature of 35% and ±100 K, respectively, while the secondary wave had amplitudes of 5% and ±20 K, respectively.