北半球平流层高层极涡变化特征的模拟研究

Simulation Study on Variation Characteristics of Polar Vortex in Upper Stratosphere of Northern Hemisphere

应用一个包含完整平流层的谱元大气模式(SEMANS),对平流层高层极涡进行模拟研究,并系统地讨论了位于平流层高层北半球极涡面积及位置的年际变化特征。结果表明:模式能再现平流层高层及中间层大气温度场及风场的特征,温度在平流层高层随高度的增加而增加,冬季温度变化幅度比夏季大;还可再现1月和7月平流层高层中纬向风随高度的分布特征。平流层高层的极区环流系统9月至次年4月为气旋,6月和7月为反气旋。位于北半球平流层高层的极涡面积在全年过程中呈现先扩大后收缩的趋势,极涡位置在秋冬季变动幅度最大,呈现明显的偏心结构偏向亚洲大陆区,只有夏季表现为绕极环流。位于平流层高层10 h Pa的极涡面积的变化要提前相对于它更高的层次,各层极涡变化相互影响,关系紧密。

The spectral element model with atmospheric near space resolved (SEMANS) which contains a completed stratospheric is applied to simulate and study about the polar vortexes in upper stratosphere. The interannual variation characteristics of the polar vortex area and location in the stratosphere of the northern hemisphere are systematically discussed. The results show that SEMANS can reproduce the characteristics of temperature and wind fields in upper stratosphere and mesosphere. The temperature increases with the increase of height in the upper stratosphere, and the temperature variation in winter is larger than that in summer. SEMANS can also reproduce the distribution characteristics of zonal wind with height in the upper stratosphere from January to July. The polar circulation system located in upper stratosphere is cyclonic from September to April and anticyclonic from June to July. The polar vortex area located in upper stratosphere of the northern hemisphere shows a tendency to expand first and then shrink during the whole year. The position of the polar vortex has greatest changes in autumn and winter, showing a distinct eccentric structure that is biased towards the Asian continent. And it shows a circumpolar circulation in summer only. The polar vortex area at 10 hPa has the most intense varies with the season during the year. Each level polar vortex influences each other.