天山北坡城市群气溶胶光学特性时空分布特征

Temporal and Spatial Distribution Characteristics of Aerosol Optical Properties in Urban Agglomerations on the North Slope of the Tianshan Mountains

为探究天山北坡城市群大气气溶胶光学特性时空分布特征,本文利用卫星遥感MCD19-A2气溶胶产品分析了2000~2019年研究区气溶胶光学厚度(aerosol optical depth,AOD)时空分布特征及变化趋势,针对AOD较为稳定的2016~2019年,利用多波段太阳光度计地基遥感技术,对AOD及Angstr9m波长指数(α)等参数进行特征分析.结果表明:(1)空间上,研究区AOD空间分布与地形呈现较好的一致性,高值现象主要分布在低海拔地区;AOD空间分布表现出较强烈季节变化,春季(0.15±0.03)>秋季(0.14±0.03)>夏季(0.14±0.02);(2)时间上,2000~2019年间研究区AOD年均值为0.12,年增幅1.03%,整体呈现增加趋势;AOD月均值的年际变化表现为双峰型,5月和11月为第一峰值和第二峰值,自然尘源粉尘的释放和传输以及人类社会燃煤供暖是造成AOD增加的主要原因;(3)受沙尘天气的影响,春季AOD的变化幅度较为剧烈,气溶胶主控粒子粒径及变化幅度均大于夏季;研究区AOD高值主要受粗模态粒子气溶胶的影响,细模态粒子吸湿增长会引起AOD的波动,但不易导致AOD高值.

In order to explore the temporal and spatial distribution characteristics of atmospheric aerosol optical depth( AOD) in the urban agglomeration on the northern slope of the Tianshan Mountains,the temporal and spatial distribution characteristics and trends of changes in the AOD in the study area from 2000 to 2019 were analyzed by MODIS aerosol products( MCD19-A2). For 2016-2019,when the AOD was relatively stable,the parameters such as the AOD and Angstr?m m wavelength index( α) were analyzed using multiband sun photometer ground-based remote sensing technology. The results showed that(1) the spatial distribution of AOD in the study area was consistent with the topography,and high values were mainly distributed in the low altitude area. The spatial distribution of AOD in the four seasons showed a strong seasonal change from spring( 0. 15 ± 0. 03) > autumn( 0. 14 ± 0. 03) > summer( 0. 14 ±0. 02) .(2) In terms of time,the annual average AOD value of the study area was 0. 12 from 2000 to 2019 with an annual growth rate of 1. 03%,thereby showing an overall increasing trend. The annual variation in the monthly mean value of AOD was bimodal;the first and second peaks were in May and November. The main reason for the increase in AOD was the release and transmission of dust from natural sources and heating.(3) Under the influence of dust weather,the AOD changed sharply in spring,and the size and change range of aerosol particles were larger than those in summer. The high value of AOD in the study area was mainly affected by coarse mode particles. The moisture absorption growth of fine mode particles caused a fluctuation in the AOD,but it was not the cause of the high value of AOD.