乌鲁木齐市气溶胶光学厚度时空分布特征及潜在来源分析

依据2009年1月—2019年7月MODIS/AQUA C6.1 MYD04_L2 气溶胶光学厚度（Aerosol Optical Depth， AOD）日数据，在宏观视角下对乌鲁木齐市AOD时空分布特征进行分析，利用后向轨迹模式（Hybrid Single Particle Lagrangian Integrated Trajectory，HYSPLIT）和潜在源贡献作用分析方法（Potential Source Contribution Function， PSCF）讨论气溶胶运输的季节性变化，并揭示研究不同季节对AOD影响较为明显的潜在源空间分布.结果表明：①乌鲁木齐市AOD呈显著的季节性差异，四季均值依次为：春季（0.328） > 夏季（0.310） > 秋季（0.273） > 冬季（0.137），AOD高值区主要集中在市区.②AOD年内呈双峰分布，峰值分别对应为4月（0.402）和8月（0.346）；10 a间AOD呈弱下降趋势，其中2014年最高（0.316），2017年最低（0.235），AOD均值为0. 276.③春季和冬季乌鲁木齐市气团输送主要来自中亚地区，夏季和秋季则来自于天山周边地区；AOD主要潜在源区为乌鲁木齐市及其周边地区，对乌鲁木齐市空气质量具有显著影响.

Spatiotemporal distribution characteristics and potential sources of aerosol optical depth in Urumqi

In this study, collection 6.1 MODIS/AQUA MYD04_L2 products of Urumqi from January 2009 to July 2019 were used to analyze the AOD spatiotemporal variation characteristics. HYSPLIT model and Potential Source Contribution Function (PSCF) was used to evaluate the transport pathways and identify the potential source-zones and its contribution to Urumqi AOD in different seasons during the study period. The results show that the mean AOD values of the four seasons were: spring (0.328) > summer (0.310) > autumn (0.273) > winter (0.137), AOD high value were mainly concentrated in the urban areas of Urumqi. The monthly mean AODs in Urumqi were bimodal distribution, with a peak value of 0.402 in April and 0.346 in August. The yearly mean AOD ranged from 0.235 to 0.316, and showed a weak downward trend, average value of AOD during the 10 years was 0.276. The airflows transported to Urumqi in spring and winter mainly come from Central Asia, while in summer and autumn the airflows come from the areas around Tianshan Mountains. Major potential sources of AOD in the study period were mainly centralized in local and surrounding regions, which has a significant impact on air quality in Urumqi.