平流层中部垂直运动年循环异常的模拟研究

A model simulation for anomalous annual cycle of vertical motion in the middle stratosphere

利用NCAR提供的包含化学、辐射、动力相互作用的二维模式(SOCRATES)进行模拟试验,进一步探讨年循环年际异常的可能成因.模拟结果的分析表明臭氧高值中心相对于赤道准两年移动是年循环的年际异常的一个重要原因.当臭氧高值区离开赤道偏向夏半球时,夏半球的平流层中部将吸收更多的太阳短波辐射,而冬半球的则相反,因此更大的短波加热率将增大夏半球平流层中部的上升运动,导致年循环的增强;相反地,臭氧高值中心接近赤道时则导致了相对较弱的年循环.

There is a pronounced antisymmetry with respect to the equator for the middle stratospheric methane, and it has been attributed to the anomalous annual cycle of vertical motions. The NCAR interactive chemical, dynamical and radiative two- dimensional model （SOCRATES） has been used to simulate and explore the possible cause of the anomalous annual cycle of vertical motions. The simulation results indicate that the quasi-biennial shift to the equator of high concentration ozone center plays an important role in the interannual anomaly of annual cycle. As high concentration of ozone leaves the equator for the summer Hemisphere, there more solar radiation is absorbed in the middle stratosphere, while in the winter Hemisphere the situation is the contrary. Thus enhanced ascending motion is promoted by greater short-wavelength radiation heating in the middle stratosphere over the summer Hemisphere and strengthens the descending motion over the winter Hemisphere as well, which results in a stronger annual cycle. On the contrary, when high concentration of ozone is located close to the equator, there is a relatively weaker annual cycle.