FY-3A/MERSI、MODIS C5.1和C6气溶胶光学厚度产品在中国区域与地面观测站点的对比分析

Comparison of FY-3A/MERSI, MODIS C5.1, C6 and AERONET aerosol optical depth in China

  • 摘要: 准确获取气溶胶光学厚度对于气候变化研究和大气环境监测具有重要意义。通过波长插值和时空匹配方法,利用气溶胶自动观测站网(AERONET)观测的气溶胶光学厚度(AOD)对风云3A/中分辨率光谱成像仪(FY-3A/MERSI)、Terra(Aqua)/MODIS的C5.1(Collections 5.1)和C6(Collections 6)气溶胶光学厚度产品在中国区域的反演精度进行验证分析。结合一次发生在中国境内的沙尘天气与一次严重雾霾天气个例,分析上述卫星气溶胶光学厚度的分布特征。研究结果表明,(1)FY-3A/MERSI AOD的反演精度较高(R=0.887,RMSE=0.234),其值低于AERONET的观测值(Bias=-0.293)。(2)在不同的下垫面下,各种卫星暗像元算法AOD产品反演精度有差异,植被覆盖情况越好,反演精度越高,而植被很少的地区,即亮地表甚至没有反演值。(3)MODIS C5.1深蓝算法产品能在亮地表地区反演AOD,但效果不佳。MODIS C6中的深蓝算法产品在不同下垫面的反演精度都很高(RMSE为0.096-0.127)。(4)在不同季节的对比中,各种卫星AOD产品在夏季的反演精度最差,而反演最好的季节各有不同。(5)在一次沙尘天气污染与一次严重雾霾天气个例中,中国西部与北部区域,MODIS C6深蓝算法AOD的监测效果优于其他算法AOD;MERSI AOD产品在此区域的分布不连续。总体而言,MODIS C6 AOD分布比MODIS C5.1产品连续,MODIS 3 km产品在相同区域的AOD值高于其他产品。以上结论可为卫星AOD产品在中国区域的使用提供参考。

     

    Abstract: Obtaining accurate aerosol optical depth (AOD) information is important for climate change study and atmospheric environment monitoring. By using the method of band interpolation and temporal-spatial matching, the inversion accuracy of AOD products obtained from FY-3A/MERSI and from the C5.1 (Collections 5.1) and C6 (Collections 6) of Terra (Aqua)/MODIS are verified against AOD observations from AErosol RObotic NETwork (AERONET). Besides, the AOD distribution characteristics from the satellite observations for a case of dust weather and a case of severe haze occurred in China are analyzed. The results indicate that:(1) the inversion accuracy of FY-3A/MERSI is better (R=0.887, RMSE=0.234), but the values of AOD are generally smaller than observations of AERONET (Bias=-0.293); (2) with different underlying surfaces, the inversion accuracy varies between different satellite AOD products obtained from dark target algorithm (DT). The accuracy is higher where the vegetative cover is high, and lower in areas with small vegetation fractions. The inversion value is even missing over the so-called bright surface, where there is no vegetation cover; (3) MODIS C5.1 deep blue algorithm (DB) can retrieve AOD in areas of bright surface, but the effect is poor. In MODIS C6, the inversion accuracy in different underlying surfaces is better (RMSE:0.096-0.127); (4) among all the seasons, summer has the worst inversion accuracy, while the optimal accuracy may occur in any other seasons; (5) in the case of sand and dust storms, the monitoring effect of MODIS C6 AOD from DB is superior to other algorithms in western and northern regions of China, and the MERSI AOD distribution is discontinuous in this area. In general, MODIS C6 AOD distributes more continuously than MODIS C5.1 AOD. At the same time, the AOD value of MODIS 3 km is more accurate than other products. The conclusions above can provide references for the application of satellite AOD products in China.

     

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