1998年青藏高原臭氧低值中心异常及其背景环流场的分析

采用TOMS和SAGE II臭氧卫星观测资料,对1998年青藏高原臭氧低值中心异常变化的过程和垂直结构进行了分析。为了探讨1998年这个低值中心出现异常的原因,利用NCEP/NCAR再分析资料,通过1998年高原附近上空位势场和位温的变化,分析了1998年臭氧低值中心异常期间高原上空对流层上层到平流层下层的流场和垂直运动的变化特征。结果表明,1998年11月,青藏高原上空对流顶比正常年份高,无论是对流层上层还是平流层下层,上升运动都比正常年份强。同时高原上空南亚高压也比正常年份强,于是使得1998年高原上空的强臭氧低值中心一直维持到11月。

Anomaly of the Ozone Low Center over the Tibetan Plateau in 1998 and the Surrounding Flow Field

Based on the data sets from TOMS and SAGE II,the anomaly of ozone low center over the Tibetan Plateau in 1998 has been analyzed both in its variation process and in its vertical distribution.In order to investigate the cause for the anomaly,the variation of the flow field and the vertical motion in 1998 over the plateau was analyzed through the changes of the geopotential height and potential temperature by using the NCEP/NCAR monthly mean reanalysis data.The result shows that the tropopause over the plateau in November 1998 was much higher than normal and the ascend motion over the plateau both in the upper troposphere and in the lower stratosphere was stronger than the normal in November 1998;In the same period,the South Asian High was also stronger than the normal.These are the reason for the strong ozone low center over the plateau in 1998 maintained to November.