Analysis of linear long-term trend of aerosol optical thickness derived from SeaWiFS using BAER over Europe and South China
Analysis of linear long-term trend of aerosol optical thickness derived from SeaWiFS using BAER over Europe and South China
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DOI：
10.5194/acp-11-12149-2011
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发表时间：
2011-12
影响因子：
6.3
通讯作者：
J. Yoon;W. V. Hoyningen-Huene;M. Vountas;J. Burrows
中科院分区：
文献类型：
--
作者：
J. Yoon;W. V. Hoyningen-Huene;M. Vountas;J. Burrows
抽象。本文的主要目的是研究欧洲和中国南方地区443和555 nm气溶胶光学厚度（AOT）的线性长期趋势，同时也揭示无云气溶胶趋势分析中云扰动所引起的不确定性。这些研究区域是人口密集的城市化地区，通常是高度污染的地区。该研究使用的不莱梅AErosol检索（BAER）和海视宽视场传感器（SeaWiFS）的AOT检索数据在指定区域从1997年10月至2008年5月。为了验证单独检索的AOT和相应的趋势，AERONET（AERONET）2.0级数据已被使用。检索出的AOT与AERONET的AOT符合良好（0.79 ≤ R ≤ 0.88，0.08 ≤ RMSD ≤ 0.13）。薄云的气溶胶反演和/或AERONET观测的污染可以显着降低AOT，并导致统计上不具有代表性的月平均值，特别是在多云季节。因此，一种相互校正的方法已经开发和应用。BAER SeaWiFS和AERONET AOT的“校正”趋势相似，平均相对差异为25.19%。总体而言，主要在欧洲地区观测到负趋势（气溶胶含量减少），在443和555 nm处的震级分别达到-0.00453和-0.00484 yr-1。相比之下，珠江三角洲的趋势是积极的，这很可能是由于快速的城市化和工业化。在443和555 nm处，AOT的星等分别增加了+0.00761和+0.00625 yr −1。
Abstract. The main purposes of the present paper are not only to investigate linear long-term trends of Aerosol Optical Thickness (AOT) at 443 and 555 nm over regions in Europe and South China, but also to show the uncertainty caused by cloud disturbance in the trend analysis of cloud-free aerosol. These research areas are the densely urbanised and often highly polluted regions. The study uses the Bremen AErosol Retrieval (BAER) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data for AOT retrievals in the specified regions from October 1997 to May 2008. In order to validate the individually retrieved AOTs and the corresponding trends, AErosol RObotic NETwork (AERONET) level 2.0 data have been used. The retrieved AOTs were in good agreement with those of AERONET (0.79 ≤ R ≤ 0.88, 0.08 ≤ RMSD ≤ 0.13). The contamination of the aerosol retrievals and/or AERONET observations by thin clouds can significantly degrade the AOT and lead to statistically non-representative monthly-means, especially during cloudy seasons. Therefore an inter-correction method has been developed and applied. The "corrected" trends for both BAER SeaWiFS and AERONET AOT were similar and showed in average a relative difference of ∼25.19%. In general terms, negative trends (decrease of aerosol loading) were mainly observed over European regions, with magnitudes up to −0.00453 and −0.00484 yr −1 at 443 and 555 nm, respectively. In contrast, the trend in Pearl River Delta was positive, most likely attributed to rapid urbanization and industrialization. The magnitudes of AOT increased by +0.00761 and +0.00625 yr −1 respectively at 443 and 555 nm.