摘要
利用美国NCAR最新的化学-气候耦合模式WACCM-3对平流层风场、温度场以及平流层臭氧等多种微量气体成分(O_3,CH_4,N_2O,H_2O,HCl,HNO_3)的季节变化进行了数值模拟,并使用ECMWF再分析资料与美国UARS卫星搭载的HALOE,MLS,CLAES等探测器的观测资料,对模式输出的动力、热力及化学成分浓度的气候平均值进行了验证.结果表明,在气候平均海表温度值驱动下,WACCM-3模式能够很好地再现ECMWF资料中平流层纬向平均风场与温度场的季节变化.模拟结果中平流层化学成分的经向-垂直分布及其季节变化与卫星观测结果基本一致.模式的动力、热力场在极地平流层以及热带对流层顶等区域存在一定的偏差.这些偏差对于微量气体成分分布的模拟具有一定影响,特别是南半球冬(7月)、春(10月)季节南极平流层低层极夜急流偏强,造成极地地区附近的输送障碍增强,从而导致CH_4,N_2O,H_2O浓度比观测偏低.此外,WACCM-3缺少热带平流层风场的准两年振荡(QBO)机制,这对于热带平流层东风急流以及低纬度平流层O_3,CH_4,N_2O,H_2O等成分经向输送的模拟结果也有一定影响.
The coupled chemistry-climate model WACCM-3 （Whole Atmosphere Community Climate Model） developed by NCAR is applied to study the seasonal variations of the stratospheric wind, temperature and trace gases such as O3, CH4, N2O, H2O, HCl, HNOa. Comparisons of the ECMWF/ERA-40 dynamics and observed trace gases from HALOE, MLS, CLEAS on UARS satellite show that the WACCM-3 simulation forced by the climatological Sea-Surface Temperature can generally reproduce the observed characteristics in the seasonal cycles of the stratospheric zonal winds, temperatures and chemical tracers. However, some obvious biases exist in model dynamics, which are closely associated with biases in the distributions of trace gases. Especially, the circumpolar westerlies during austral winter （July） and spring （October） in WACCM-3 model are too strong, which can cause a stronger barrier to the poleward transports of warm air and long-lived trace gases （e.g., CH4, N2O, H2O） in Antarctic lower stratosphere. Moreover, this cold bias also enhances the denitrification and dehydration effects during the formation of Polar Stratospheric Cloud （PSC）, on the surface of which more HCl are activated through a series of heterogeneous reactions. As a result, the simulated concentrations of chemical tracers （e.g., CH4, N2O, H2O, HCl, HNO3） are prominently lower than observations in the Antarctic lower stratosphere during wintertime and springtime. In addition, there are also biases in the tropical stratospheric easterlies and the meridional transports of stratospheric tracers （e.g., O3, CH4, N2O, H2O）, since WACCM-3 does not generate a Quasi-Biennial Oscillation （QBO） in tropical stratospheric winds.
出处
《空间科学学报》
CAS
CSCD
北大核心
2009年第6期580-590,共11页
Chinese Journal of Space Science
基金
国家自然科学基金重点项目资助(40633015)
关键词
化学-气候耦合模式
平流层气候
平流层臭氧
微量气体
中层大气
Chemistry-climate model, Stratospheric climate, Stratospheric ozone, Trace gases, Middle atmosphere
