【摘要】 我们根据1965年1月—1984年12月共20年平均的50hPa高度场资料作出的沿各经度的纬度-高度时间剖面图和逐月纬间高度梯度值表,分析得到如下结论: 1、50hPa上从冬到夏的季变,北带(60—90°N)和南带(10—30°N)中最早的时间都在3—4月,这比中带(30—60°N)各经度上和北、南带其余各地区完成季变都要早一个月。 2、50hPa上从夏到冬的季变,北带最早,大多出现在7—月,少数出现在8—9月;中带全在8—9月完成季变,南带更晚些。显然北带早于中带,中带又早于南带。 3、北半球平流层50hPa的季变,从冬到夏是来自极地和赤道两个方向共同发动的,而自夏到冬,其发动方向仅来自极地。更多还原

【Abstract】 In this paper, according to both the charts of averaged latitude-time of height at every 10 ° longitudes and the tables of averaged longitudinal height gradient taken over 20 years (from January 1965 through December 1984) on 50 hPa the following conclusions were drawn:① For the seasonal variations of the circulations from winter to summer on the 50 hPa level over Northern Hemisphere, the earliest ones occur on about 90 ° E and 170 ° E longitudes over both the northern belt (60-90 ° N) and southern belt (10-30 ° N) and in March-April. It is one month earlier over above areas than all longitudes of the middle belt (30-60 ° N) and the rest of both northern and south belts.② For the seasonal variations of the circulations from summer to winter, the earliest ones occur over northern belt and in July-August; the next ones, over middle belt and in August-September; the southern belt is much more late than northern and middle belts.⒔The seasonal variations from winter to summer at 50 hPa level start with both the Pole and Equator sides simutaneously; but the ones from summer to winter start with only the Pole side.更多还原