Northern Hemisphere Stratospheric Circulation Transition, Causes, And Its Relationship With The Tropospheric Circulation Study

The remarkable transition of circulation type from winter to summer in middle stratosphere is from cyclonic type to anticyclone type. This is also the notable characteristic which is different from the transition in low stratosphere and troposphere. The transition from negative to positive of the spherical function coefficient A20 reflects it impersonally and quantificationally. With NCEP/NCAR day-to-day height field analysis data ,the coefficient of spherical function A02 is calculated. The transition dates of circulation type in middle stratosphere are determinated based on the dates that A02 have transited from negative to positive steadily. Then all of the following work is done:1. The average values of the transition dates in middle stratosphere andtheir variations with height. The climatic variability and the interannual and interdecadal variation rule of the transition dates. In this paper, the circulation of 20hPa transits to anticyclone type first (at April the twenty-fourth averagely ) and then the transition transmit downwards, 54 days later it arrive to 70hPa (at June the seventeenth averagely ). The interannual variation of transition dates in higher layers of middle stratosphere (10hPa 20hPa and 30hPa) is more remarkable than in lower ones ( 50hPa and 70hPa). The transition dates of 50hPa and 70hPa have notable interdecadal variation feature: they are sooner before 1978 and later after 1978.2. The correlation between the transition dates in middle stratosphere and the quasi-biennial oscillation in stratosphere . The correlation between the transition dates in middle stratosphere and the ozone quantity in stratosphere. The correlation between the zonal wind of 10hPa and 70hPa and the transition dates of these two layers is remarkable. When the zonal wind of 10hPa is Apheliotes(Zephyrus) and that of 70hPa is Zephyrus(Apheliotes), the transition delays(advances).The correlation between the ozone quantity and the transition dates in middle stratosphere is opposite. When the ozone quantity is excessive(lack), the transition advances (delays).3. The relation between the transition dates in middle stratosphere and the important systems in troposphere such as polar vortex and the subtropical high in West Pacific. Some relation is found between the transition dates of 70hPa and the subtropical high in West Pacific. When the transition advances (delays), the intensity of the subtropical high is weak(strong) and the position is partial to the east(west). When the transition of 10-70hPa advances (delays), the area of polar vortex in Asia is big(small) and the intensity of polar vortex in Northern Hemisphere is strong(weak).When the transition of 10-30hPa advances (delays), the intensity of polar vortex in April is weak(strong).