Numerical modeling study of the momentum deposition of small amplitude gravity waves in the thermosphere
Numerical modeling study of the momentum deposition of small amplitude gravity waves in the thermosphere
复制标题
热层小振幅重力波动量沉积的数值模拟研究
DOI：
10.5194/angeo-31-1-2013
复制
发表时间：
2013-01
期刊：
影响因子：
--
通讯作者：
S. L. Vadas
中科院分区：
文献类型：
--
作者：
刘晓;J. Xu;J. Yue;S. L. Vadas
本文利用完全非线性二维可压缩数值模式研究了小振幅重力波在波包内耗散引起的热层动量沉积。该模型求解了不同普朗特数下，具有真实分子粘性和热扩散率的GW包从平流层到热层的非线性传播和耗散。对初始垂直波长（z）为5 ~ 50 km的GW分组进行了数值模拟。我们发现，随着GW包在热层中消散，z随时间减小，与Vadas和Fritts（2005）（VF 05）的射线追踪结果一致。对于初始z为2 H的GWs，在等温无风背景下，我们的模拟结果与VF 05的模拟结果在动量通量峰值高度（zdiss）上也有很好的一致性，其中H是密度尺度高度。我们还证实，zdiss随着普朗特数的增加而增加。我们在模式中考虑了涡旋扩散，发现动量沉积发生在较低的高度，对于初始z较小的GW包，动量沉积有两个独立的峰值。我们还模拟GW包在非等温大气中。净z分布是粘度降低和背景温度升高引起的净z分布增加之间的竞争。我们发现，在非等温大气中，波包的色散更大，并且对于初始z为10 km的GW波包，其动量通量和z谱在早期和晚期都发生了变化。这些效应是由热层中T的增加和中层顶附近T的减小引起的。
We study the momentum deposition in the ther- mosphere from the dissipation of small amplitude gravity waves (GWs) within a wave packet using a fully nonlinear two-dimensional compressible numerical model. The model solves the nonlinear propagation and dissipation of a GW packet from the stratosphere into the thermosphere with re- alistic molecular viscosity and thermal diffusivity for various Prandtl numbers. The numerical simulations are performed for GW packets with initial vertical wavelengths ( z) rang- ing from 5 to 50 km. We show that z decreases in time as a GW packet dissipates in the thermosphere, in agreement with the ray trace results of Vadas and Fritts (2005) (VF05). We also find good agreement for the peak height of the mo- mentum flux (zdiss) between our simulations and VF05 for GWs with initial z 2H in an isothermal, windless back- ground, where H is the density scale height. We also confirm that zdiss increases with increasing Prandtl number. We in- clude eddy diffusion in the model, and find that the momen- tum deposition occurs at lower altitudes and has two sep- arate peaks for GW packets with small initial z. We also simulate GW packets in a non-isothermal atmosphere. The net z profile is a competition between its decrease from vis- cosity and its increase from the increasing background tem- perature. We find that the wave packet disperses more in the non-isothermal atmosphere, and causes changes to the mo- mentum flux and z spectra at both early and late times for GW packets with initial z 10 km. These effects are caused by the increase in T in the thermosphere, and the decrease in T near the mesopause.
登录
查看更多内容
影响因子：
--
作者：
M. Hickey;G. Schubert;R. Walterscheid
通讯作者：
M. Hickey;G. Schubert;R. Walterscheid
影响因子：
--
作者：
C. Hines
通讯作者：
C. Hines
影响因子：
5.2
作者：
Qihou H. Zhou;Y. Morton
通讯作者：
Qihou H. Zhou;Y. Morton
影响因子：
3.1
作者：
Hock Lim;Chih-Pei Chang
通讯作者：
Hock Lim;Chih-Pei Chang
影响因子：
--
作者：
Jiyao Xu;Anne K. Smith;R. Ma
通讯作者：
Jiyao Xu;Anne K. Smith;R. Ma