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Indirect Measurement of the Mean Meridional Circulation in the Southern Hemisphere

出版	Massachusetts Institute of Technology, Department of Meteorology, 1963
URL	http://books.google.com.hk/books?id=abV-No-SqzUC&hl=&source=gbs_api

註釋Using IGY data analyses of Obasi (1963), the mean meridional circulations for the southern hemisphere are measured indirectly, using the method of characteristics. It is found that the slope of the characteristic curves is proportional to the ratio of the zonal vertical wind shear to the dynamic stability. The characteristic curves may be approximately identified with the curves of constant absolute angular momentum. The horizontal and vertical momentum convergences enter as forcing functions, in a manner similar to that of Kuo (1956), and Mintz and Lang (1955). Certain simplifying assumptions are made about the vertical convergences. The expression for [W], the vertical component of the circulation, strongly resembles the integrated form of the continuity equation, the difference being attributable entirely to the inclusion of the baroclinicity of the atmosphere. Both methods give similar overall [W] patterns, but there are differences in details, particularly in the winter season. The calculations generally confirm Obasi's directly measured three cell pattern, but there are strong differences in cell intensity and position. Comparison with northern hemisphere indirect measurements of Mintz and Lang (1955) shows strong similarities in position and intensity, but with the much stronger southern hemisphere polar direct cell a marked exception. Vertical eddy convergences of momentum in the "free" atmosphere are calculated using the directly measured mean meridional circulations. Large areas of negative eddy viscosity result, always in a region including the mid-latitude jet. Similar calculations for the northern hemisphere using data of Buch (1954) give the same general result. The negative signs do not appear to be implausible if large scale vertical eddies dominate at higher levels, but the magnitudes may be too large