Observation of aerosol optical depth over the Pearl River Delta
Observation of aerosol optical depth over the Pearl River Delta
复制标题
DOI：
--
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Deng Tao
中科院分区：
文献类型：
--
作者：
Deng Tao
利用多波长太阳光度计检索了2004年1月至2007年6月珠江三角洲气溶胶光学深度（AOD）资料。介绍了一种校准仪器的方法，并对AOD结果进行了分析。将NASA的MODIS AOD产品与从太阳光度计获取的AOD进行比较。结果表明，与其他方法相比，迭代法滤波的数据对Langley图更为合理。部分统计结果表明：珠三角地区的AOD在春季最大，秋季次之，夏季次之，冬季最小。4个观测点AOD的季节变化趋势基本一致。区域年均AOD大于0.7，表明气溶胶可使直接可见辐射衰减50%~60%，造成严重雾霾天气。AOD在频率分布上主要在0.4 ~ 0.6之间。4个观测点的ngstrm波长指数在1.2 ~ 1.6之间占较高比例，频率分布相似。因此，气溶胶颗粒的区域平均有效半径较小，且具有一致性，可归类为城市-工业气溶胶。ngstrm波长指数与AOD之间无显著相关。通过样本统计和典型案例分析，得出无论晴天还是污染天气，气溶胶粒子的类型、大小分布和有效半径都没有明显变化，但粒子的数量密度对消光的影响不同。并将MODIS的AOD与太阳光度计反演的AOD进行了比较。MODIS AOD在珠江三角洲的定量测量中显示出良好的精度。提出了珠江三角洲上空MODIS AOD的初步校正公式。
Multi-wavelength sun-photometers were used to retrieve data on the aerosol optical depth(AOD)over the Pearl River Delta(PRD)from January 2004 to June 2007.A method for calibrating the instruments is described and the AOD results are analyzed.The MODIS AOD products from NASA are compared against retrieved AOD from the sun-photometers.The results reveal that the data filtered by the iterative method is more reasonable for the Langley plot than that from other approaches.Some statistical results are as follows:AOD is largest in spring,followed by autumn and summer and smallest in winter over the PRD region.The seasonal trends of AOD are consistent for the four observation sites.The annual mean regional AOD is greater than 0.7,indicating that the aerosol can attenuate direct visible radiation by 50%～60%,resulting in severely hazy weather.And AOD mainly stays between 0.4 and 0.6 in terms of frequency distribution.The ngstrm wavelength exponent for the four observation sites occupies high proportions between 1.2 and 1.6 with similar frequency distributions.Therefore the regional average effective radii of aerosol particles are small and also consistent and can be classified as urban-industrial aerosols.There is no significant relationship between the ngstrm wavelength exponent and AOD.Through sample statistics and typical case analyses,it can be concluded that the type,size distribution and effective radius of aerosol particles do not change dramatically whether the day is clear or polluted,but the number density of particles is responsible for the different effects on light extinction.MODIS AOD is also compared with the AOD retrieved by the sun-photometer.MODIS AOD is shown to have good precision in quantitative measurement over the PRD.A preliminary correction formula for MODIS AOD over the PRD is suggested.