On the Theory of the Extratropical High Pressure Belt

[摘要] There are at present two dominant theories of essentially differnet mechanism on the existence of the high pressure belt of subtrooical latitude (subtropische Hochdruckgürtel, for brevity hereafter will be call “subtropical high”), whose development and decaying of intensity and migration of the location in the course of year have unseparably intimate relation with our climatic circumstances, in conjunction with the high and low pressure system developing over the continent and ocean (High and Low of Monsoons). This is the very reason why we n_??_me it “the active center of the atmosphere”. Thus it is one of the most important problem in the the_??_ry of the general circulation of the atmosphere to investigate the mechanism of subtropical high. One of them is the theory inheren from W. Ferrel, in which he assumes the conservation of angularmomentum referred to the rotation axis of the earth in spetially fixed coordinate and the complete rest of the atmosphere relative to the rotating earth at a certain stage of the earth's history. In this theory the effect of friction is discar_??_el. Indeel W. Ferrel succeeded in determining the location of subtropical high, but his hypothetical conditions are generally unrealizable on our globe. (This throry will be named “dynamical theory, dynamische Theorie” in the present paper).The other is the theory by Oberbeck and others, in which the distribution of air temperature constitutes the cssential factor in deciding the subtropical high (This theory will be named “thermic theory, thermische Theorie”).In this paper the latter thermic theory is supported, and finally the mechanism of subtropical high and that of high and low pressure system accompanying monsoon wind are condcluded to be essentially the same.Next, in order to explain the mechanism of monsoon high and low has seen introduced the term “Cyclo-and Anticyclogenesis of Oberbeck's type”, in consideration of the analogy with that in the theory of air mass.This means “in the northern hemisphere, the current system of warm air in the south and cold air in the north results in the formation of anticyclonic motion and that of cold air in the south and warm in the north result in the formation of cyclonic motion (This result has been derived in my previous pa_??_er. On the Effect of the Distribution of Continent and Ocean upon the Geaeral Circulation of the Atmosphere and the Theory and the Theory of Monsoons, Geophys. Mag. Vol. IX).”The above theme is the generalized one of Oberbeck's theory. Here warm and cold air mean that of positive and negative deviation from normal temperature respectively, viz. in the problem of planetary circulation the normal temperature denotes the equilibrium temperature and in the problem of non-planetary circulation the normal temperature has to be replaced by the temperature corresponding to the planetary circulation.As annual mean, in the tropical region the air temperature ove the continent is higher than that over the ocean on the same hatitude and reversed in higher latitude, the critical latitude being supposed to be about 45°, as is evident from, say, Spitaler's formula.Such a distribution of non-planetary temperature constitutes the essential factor in determining the high and low pressure system developing over continent and ocean, namely on the continent warm air exists in the south and cold air in the north, the location of juxtaposition of both currents being at latitude 45°.This distribution of current system corresponds to anticyclogenesis of Oberbeck's type and may be compared to the Siberian High in win'er seasons.The same is said of cyclonic motion over the ocean.

[学科分类] 大气科学