期刊名称：Tellus A: Dynamic Meteorology and Oceanography
电子版ISSN：1600-0870
出版年度：1998
卷号：50
期号：1
页码：12-25
DOI：10.3402/tellusa.v50i1.14509
摘要：The linear mountain drag in the presence of trapped lee waves is calculated using a twodimensionallinear anelastic model. In many cases, it is shown that the drag is affected by thewave refraction index aloft, but remains well predicted by the drag due to hydrostatic freelypropagating mountain waves. In contrary, the vertical profile of the waves’ Reynolds stress isvery sensitive to the mean flow variation, and often decays with altitude in the steady case andin the absence of dissipation. This apparent contradiction with the conventional Eliassen-Palmrelation is simply related to the non-zonal, non-periodic geometry of the domain in which themomentum budget is calculated and to the presence of trapped lee-waves. In this context, thespatial average of the pseudo-momentum conservation equation shows that the wave drag atthe ground is equal to the wave pseudo-momentum entering in the domain through its upperand leeward boundaries. In the presence of trapped lee-waves, the amount of pseudo-momentumentering through the leeward boundary represents a significant part of the drag, and explainsthe difference between the Reynolds stress and the surface drag. In this case, the large-scaleflow does not need to be modified inside the physical domain, because the entering pseudomomentumequals the entering momentum transported by the waves across the domain boundaries.It is suggested that conventional gravity wave drag schemes can easily represent thetrapped waves by altering the large scale momentum at low level, when the waves are dissipated.
