近10年中国大陆MODIS遥感气溶胶光学厚度特征

应用2001—2010年MODIS大气气溶胶光学厚度(AOD)资料,分析中国550 nm AOD年和季节平均分布。还选取了10个代表性区域,分析AOD变化特征。这些分析建立起了近10年来中国气溶胶光学厚度的气候学特征:中国年平均AOD空间区域分布中心大体呈现两低两高。两低中心位于植被覆盖度高和人烟稀少的(1)黑龙江和内蒙古东北高纬度地区(～0.2);(2)川、滇与青藏高原交界的西南高海拔地区(0.1～0.2)。一个AOD低值带(0.2～0.3)连接这两个低中心,呈东北西南走向跨过中国大陆。在此低值带两侧,各有一片AOD高值中心(～0.8):(1)人口密集和工业化发展带来的大量人为气溶胶形成了一个覆盖了华北、长江流域(从四川盆地,两湖地区到长三角)到华南珠江三角洲相联的大片高AOD中心区域;(2)以沙尘为主的自然气气溶胶造就了西北塔克拉玛干沙漠及周边高AOD区。中国AOD这一两低两高区域分布特征基本保持四季不变,但其中心强度呈现各自区域性季节变化。中国春季AOD高值区的面积最大,其次是夏季,然后是秋季,面积最小的是冬季。南方AOD月变化规律多为双峰型,即3—5和8—9月出现2次高峰,5—7月从南向北先后出现波谷,变化规律与季风响应。北方为单峰型,6—7月为高峰,11到来年2月为低谷。用弱季风年(2002)和强季风年(2003)季风影响区域气象条件和气溶胶数据对比分析表明,大陆AOD的月空间分布和变化与季风气候,以及风速、风向、降水、温度和湿度等的变化有关。

Climatology of aerosol optical depth over China from recent 10 years of MODIS remote sensing data

Using the recent 10 year(2001—2010) MODIS data of aerosol optical depth(AOD),the distributions of 10-year annual and seasonal mean AOD at 550 nm over China are presented,and the seasonal variations in AOD over 10 regions in China are analyzed.A 10-year climatology of AOD over China is constructed.The spatial pattern of annual mean AOD is characterized generally with two low value centers and two high value centers over China.Two low AOD centers are located in the areas with a high vegetation cover and a sparse population in(1) the high-latitude Heilongjiang and Inner Mongolia in Northeast China with the AOD of about 0.2 and(2) the high-altitude Sichuan,Yunnan and Xizang in Southwest China with the AOD from 0.1 to 0.2.These two low AOD centers are connected by a low AOD ozone(0.2-0.3)in a northeast-southwest direction across China.Beside this low AOD ozone,two high centers with the AOD of about 0.8 are situated in(1) the most densely populated and industrialized regions in China with high anthropogenic aerosols stretching from North China Plain,Sichuan Basin,Hubei-Hunan and Yangtze River Delta to South China with Pearl River Delta region and(2) Taklimakan desert and the surrounding area in Northwest China with high natural aerosols dominated by desert dust.The spatial structures of seasonal AOD pattern over China remain unchanged,but the strengths of AOD-centers vary seasonally.Seasonally averaged over China,the area of high AOD is biggest in spring followed by summer and autumn with the minimum in winter.The monthly AOD values in Southern China peak twice respectively from March to May and from August to September and drop between May and July accompanied by Asian summer monsoon rain belt movement from the south to north.The monthly AOD in Northern China change with a single peak in June and July and a low during November and February.Taking example of the AOD anomalies and meteorological data in July 2002 and 2003 for a weak and strong year of south Asian summer monsoon,compared to the 10-year mean,the monthly AOD spatial distribution and change pattern relates to monsoon,wind speed and direction,precipitation,temperature and humidity in mainland of China.