A numerical simulation on gravity waves generated by thermal source and their influences on mean flow

作者：Ding Xia^*; Zhang Shao-Dong; Yi Fan

来源：Acta Geophysica Sinica, 2011, 54(7): 1701-1710.

DOI：10.3969/j.issn.0001-5733.2011.07.002

• Gravity waves
• Thermal source
• Jet
• Numerical simulation
• Wave scale

In this study, a time- and space-dependent thermal forcing is introduced into a compressible and isothermal two-dimensional atmosphere. Stationary background and monthly averaged eastward horizontal wind at middle latitude in January are employed as two different background flows, respectively. The propagation and characteristics of gravity waves generated by thermal source in these two different background flows are numerically simulated. Gravity waves generated by thermal source have wide spectra in the earlier stage, but the spectra of horizontal and vertical wavelengths shrink when the excited waves propagate in the atmosphere. Small-scale and low-frequency parts in the excited downwind waves are easily absorbed by the eastward jet which will be enhanced consequently. Whereas the excited upwind (westward-propagating) waves can easily go through the jet, which will induce an enhancement of westward background in the mesosphere. This indicates that troposphere jet will influence the wind structure in the mesosphere. It is also found that the wavelengths/frequencies of the excited waves are dependent on the temporal and spatial scale of the thermal source; the vertical and temporal scales of the excited waves are more sensitive to the changes of thermal forcing than the horizontal scale of excited waves.

• 出版日期2011-7
• 单位武汉大学