On the Stationary Cyclones and Anticyclones

[摘要] According to the statistical research by European investigators the travelling cyclone and anticyclone may be divided in two classes. One is called high type, and includes all the travelling disturbances which reach the height of the stratosphere. In this type the height of tropopause is lower over a cyclone and is higher over an anticyclone than the normal state. The other is called low type and its height is generally confined to the lower level of the troposphere. In an area of cyclone of high type air temperature is lower than the normal environment in the troposphere and this circumstance is reversed in the stratosphere. On the contrary, in an anticyclonic area of high type air temperature is higher than the normal distribution in the troposphere and reversed in the stratosphere.Thus the difference of air temperature of, a high cyclone from a high anticyclone is conspicuously marked, therefore the former may be called a cold cyclone and the latter a warm anticyclone. This relation is reversed in the stratosphere, but the three-quarters of the whole atmosphere belongs to the troposphere, therefore the air temperature of high anticyclone is definitely higher than that of high cyclone.The cyclone and anticyclone of low type, roughly speaking, have warmer and colder air temperature respectevely, whose type of structure is considered to directly induce the lower and higher pressure anomaly.In short we may say that a cold anticyclone and a warm cyclone belong to the low type and a warm anticyclone and a cold cyclone belong to the high type.The above description concerns the travelling disturbance. Here the author intends to extend the above classification concerning the travelling disturbance to the cyclone and anticyclone of stationary type, such as the equatorial low, the subtropical anticyclone, the low of middle latitudes (locates at about latitude 60°), the polar cap and monsoon high and low.The stationary pressure anomaly may also be classfied as high and low type, and warm and cold type. The classification due to the present scheme is as follows: the equatorial low is cold and high; the subtropical anticyclone is warm and high; the polar cap (if exist) is cold and low; the low of middle latitudes is cold and high; the low and high of monsoons are warm and cold respectively and belong to the low type.We have already learned that over the travelling disturbance of high type there occurs the fluctuation of height of the tropopause. It is generally supposed that such a change of tropopause-level has some important relation with the mechanism of pressure anomaly from the study of travelling disturbance. The extension of this analogy to the stationary cyclone and anticyclone may naturally lead to the provisional conclusion that the inclination of the tropopause has some important relation with the pressure anomaly of high type.In the light of observational fact we see that over the subtropical anticyclone the height of tropopause is about two times greater than that of the low of middle latitudes and the distribution of air temperature has the same tendency as that of travelling disturbance both in the tropopause and in the stratosphere. Thus the analogy between the travelling and stationary pressure anomaly holds fairly good within the scope of the present aim.

[学科分类] 大气科学