Spatial distribution and temporal variation of aerosol optical depth in the Sichuan basin, China, the recent ten years

Publication date: December 2016
Source:Atmospheric Environment, Volume 147
Author(s): Xinyu Liu, Quanliang Chen, Huizheng Che, Renjian Zhang, Ke Gui, Huan Zhang, Tianliang Zhao
The applicability of the MODIS (Moderate Resolution Imaging Spectroradiometer) aerosol optical depth (AOD) product was verified using CE-318 sun photometric data for the Sichuan area. The results show that MODIS_3K AOD agrees well with the AOD derived from the CE-318 sun photometer, with a high correlation coefficient (R² = 0.91). And we used the MODIS AOD product analyzed the spatial distribution and temporal variation of the annual, seasonal and monthly distribution of AOD in the Sichuan area over the last ten years (2006–2015). In the Sichuan area, the mean change of AOD over the 10-year period showed a significant decreasing trend, reaching its maximum in 2010 and its minimum in 2015. Considering only the first five years, the lowest value was reached in 2008 and the overall trend was a standard symmetrical "V" type. Over the later five years, the annual average AOD value showed an overall decreasing trend. The monthly averaged AOD indicated a "double peaks" fluctuation trend; the two peaks appeared in March and August, and AOD changes were relatively small between September and January. Overall, the average value of AOD reached its highest values in spring, and its lowest values in autumn. In the city of Chengdu, the monthly and seasonal changes in the trend were essentially the same as those of the whole Sichuan area; However, the Chengdu AOD monthly and seasonal average change rate was higher than that of Sichuan as a whole. This shows that Chengdu is still the main contributor to the enhanced AOD value for the entire Sichuan region. The spatial distribution of AOD values indicates an "east high, west low" situation across the Sichuan area and Chengdu is one of three cities with the highest AOD values. However, the spatial variation of AOD trend value indicated an "east low, west high" the spatial distribution across the Sichuan region, opposite to the spatial distribution. Moreover, in the past 10 years, the overall AOD changes in Sichuan showed a downward trend, especially in Chengdu, suggesting that environmental remediation measures have achieved initial improvements. But, average AOD of some parts of western Sichuan is increasing, indicating that other regions in Sichuan should strengthen their management and remediation of haze weather.



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