1995~2004年东亚沙尘气溶胶的模拟源汇分布及垂直结构

利用全球气溶胶模式GEM-AQ/EC的1995~2004年10年沙尘气溶胶模拟,探讨了东亚地区沙尘气溶胶源汇分布和垂直结构特征.结果表明,东亚大陆沙尘气溶胶源区主要集中在东亚的沙漠地区,有两大沙尘主要源区:覆盖蒙古国南部及中国内蒙中西部的沙漠地区和南疆的塔克拉玛干沙漠.东亚沙尘排放量春季最大,占全年排放总量的66.81%,四月份达15.29Mt,夏季下降,秋季小幅度回升,冬季最小;东亚沙尘排放量呈现明显的年际变化及增强的趋势.东亚沙尘沉降高值区与源区一致,源区及附近以干沉降为主,远距离传输到中国东北、长江以南及西太平洋包括日本、朝鲜半岛,湿沉降占主导地位;沙尘沉降具有季节变化,其趋势与东亚沙尘排放量的季节变化大致相同,且模拟的10年沉降量呈上升趋势.东亚沙漠地区排放的沙尘主导了东亚沙尘气溶胶的变化,最大的净沙尘汇区集中在紧邻净沙尘源区的黄土高原及华北平原西部.东亚地区春夏秋3个季节均是沙尘的净源区,而冬季强西风急流输入东亚以外的沙尘使东亚整体上为沙尘净接收区.东亚大陆大部分地区,沙尘垂直分布主要集中在对流层低层3km高度以下,在西太平洋地区包括日本、朝鲜半岛沙尘高值中心位于在对流层中层5km高度上下,在沙漠以北地区沙尘垂直廓线的高值出现在对流层中上层6~8km高度.

A simulation of dust aerosols source and sink distributions and vertical profiles in East Asia over 1995~2004.

Based on the 10-years (1995~2004) aerosol simulations of the global aerosol model GEM-AQ/EC, Asian dust aerosol in respect of source and sink distributions and vertical profiles was investigated. Two major dust source regions in East Asia were distributed 1) over the desert areas from southern Mongolia to the middle and west Inner Mongolia; 2) the Taklimakan Desert in southern Xinjiang; Dust emissions reached the peak in spring, accounting for 66.81% of the annual dust emissions with the maximum value of 15.29 Mt in April. The Asian dust emissions weaken in summer, level up in autumn and bottom in winter. The significant inter-annual variations and an increasing trend in East Asian dust emissions were experienced over 1995~2004. The high dust depositions were found over East Asian emission areas. Dry dust deposition was a dominant dust removal process over deserts and the surrounding regions, while wet dust deposition was the major process over the long range transport path ways from Northeast China, Southern China, Korea, Japan to West Pacific. Dust deposition had the same seasonal variation to the dust emission and but an increasing trend over the 10 years. The regional dust emissions from East Asian dominated changes of East Asian dust aerosol, the maximum net dust sink areas were concentrated over the immediate downwind regions from the Loess Plateau to the western part of the North China Plain. Taking Asian East region as a whole, East Asian region were the net source of dust aerosol in spring, summer and autumn and but a dust sink in winter, when the strongest westerly jets import dust aerosol from dust sources beyond East Asia into East Asia. Over the most regions of East Asian continent, the vertical profiles of dust aerosols were structured with the high values below 3km in the lower troposphere, while the high dust concentrations were centered around 5km height in the mid-troposphere over the western Pacific and between 6km and 8km in the mid-and upper troposphere north of the desert areas.