基于多源资料的徐州地区气溶胶时空变化特征

作者	单位
罗天阳	南京信息工程大学, 中国气象局气溶胶与云降水重点开放实验室, 江苏南京 210044
许潇锋*	南京信息工程大学, 中国气象局气溶胶与云降水重点开放实验室, 江苏南京 210044
邬昊鹏	南京信息工程大学, 中国气象局气溶胶与云降水重点开放实验室, 江苏南京 210044
杨语迪	南京信息工程大学, 中国气象局气溶胶与云降水重点开放实验室, 江苏南京 210044
熊梓旭	南京信息工程大学, 中国气象局气溶胶与云降水重点开放实验室, 江苏南京 210044

通讯作者:许潇锋* 南京信息工程大学, 中国气象局气溶胶与云降水重点开放实验室, 江苏南京 210044

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中文摘要:

综合利用AERONET、MODIS、CALIPSO、MERRA-2气溶胶反演产品和CHAP PM_2.5产品,对徐州地区2014—2020年的气溶胶光学特性水平和垂直分布、气溶胶组分和PM_2.5质量浓度的时空变化进行了综合分析。分析AERONET数据发现,徐州地区气溶胶光学厚度(AOD,550nm)夏季最高,其次为春季和秋季,冬季最低,而波长指数(AE)则相反;季节平均AOD和AE分别为0.53~0.71和1.11~1.33;2014—2018年平均AOD为0.70~0.47,呈显著下降趋势。粒子谱呈双峰分布,且季节差异显著,其中春夏季主导粒子分别为粗、细粒子,秋冬季的粗、细粒子浓度相当。粒子有效半径在春季最大、夏季最小。冬季单次散射反照率(SSA,440~1 020 nm) 最小,气溶胶吸收光学厚度(AAOD,440 nm) 最大,而夏季相反。气溶胶直接辐射强迫 (ARF) 与AOD呈显著正相关,大气层底部ARF对AOD的变化更敏感,且其辐射强迫效率 (ARFE) 与SSA有较强负相关。分析CALIPSO气溶胶廓线发现,冬春季气溶胶消光系数随高度减小的趋势更显著;受边界层高度影响,夏季气溶胶消光系数随高度减小的趋势显著减缓。近地面气溶胶消光系数有逐年减小趋势,其中冬春季的下降更显著。分析MODIS AOD空间分布发现,AOD总体呈市区高、周边地区低的分布特征。徐州全域AOD年均值呈下降趋势,其中市区下降最快,年下降率约为-0.12。从CHAP PM_2.5空间分布来看,徐州西北部PM_2.5最高,所有区域均呈下降趋势,其中冬季下降幅度最大,年下降率为-6 μg/m³。从MERRA-2再分析资料来看,颗粒物柱质量浓度中沙尘占比最大,其次为硫酸盐。颗粒物柱质量浓度总体呈逐年下降趋势,年下降率为-0.29 mg/m²,其中沙尘气溶胶下降最大。

英文摘要:

The aerosol inversion products of AERONET (Aerosol Robotic Network),MODIS (Moderate-resolution Imaging Spectroradiometer),CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) and MERRA-2 (Modern-Era Retrospective analysis for Research and Applications,Version 2) and CHAP PM_2.5 products were synthetically used to analyze the horizontal and vertical distribution of aerosol optical properties,aerosol components and the spatiotemporal changes of PM_2.5 mass concentration in Xuzhou from 2014 to 2020.Analysis of AERONET data showed that the AOD (Aerosol Optical Depth,550 nm) in Xuzhou was high in summer and low in winter,while the opposite for AE (Ängström Exponent),with the seasonal averages of AOD and AE ranging from 0.53-0.71 and 1.11-1.33,respectively.The average AOD from 2014 to 2018 was 0.70-0.47,showing a significant decreasing trend.The particles showed a clear bimodal size distribution with significant seasonal differences,which showed the dominant of coarse particle in spring and fine one in summer,while both of them were equivalent in autumn and winter.The effective radius of particles presented the largest in spring and the smallest in summer.The smallest SSA (Single Scattering Albedo,440-1 020 nm) and the largest AAOD (Absorption AOD,440 nm) was in winter,while the opposite in summer.The aerosol direct radiative forcing (ARF) was positively correlated with AOD,which was more sensitive at the bottom of the atmosphere (BOA).It appeared a strong negative correlation of the efficiency of ARF (ARFE) with SSA at BOA.From CALIPSO aerosol profiles,it showed a faster decreasing of aerosol extinction coefficient with height in winter and spring,while a much slower one in summer contributed by a higher boundary layer.The near-surface aerosol extinction coefficient decreased during the period,with a faster decline in winter and spring.From MODIS,it showed higher AOD in urban area than that in the surroundings.The mean AOD of Xuzhou showed a significant decreasing trend,with the faster of -0.12 per year in the urban area.From the CHAP product,the highest region of PM_2.5 in Xuzhou was in the northwestern area.It showed a decreasing trend in all seasons,with the fastest annual decline of -6 μg/m³ in winter.According to MERRA-2 reanalysis dataset,the dust contributed the largest proportion in the column mass concentration of aerosols,followed by sulfate.The column mass concentration decreased during the study period,with an annual decline of -0.29 mg/m²,and the dust decreased the fastest.

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