| 北京一次污染过程气溶胶光学特性及辐射效应 |
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| 引用本文： | 梁苑新,车慧正,王宏,彭玥,张养梅,陶法.北京一次污染过程气溶胶光学特性及辐射效应[J].应用气象学报,2020,31(5):583-594. |
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| 作者姓名： | 梁苑新 车慧正 王宏 彭玥 张养梅 陶法 |
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| 作者单位： | 1.中国气象科学研究院灾害天气国家重点实验室, 中国气象局大气化学重点开放实验室, 北京 100081 |
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| 摘 要： | 利用地面激光雷达、太阳光度计观测反演气溶胶光学特性参数，结合PM2.5观测数据，分析了2018年1月25—28日北京一次完整污染过程中气溶胶光学特性变化。基于观测数据，利用短波辐射传输模式计算了不同程度污染日，晴空背景下气溶胶对辐射加热率的改变程度。结果表明:清洁日（25日），PM2.5日平均质量浓度为19.00 μg·m-3，440 nm气溶胶光学厚度为0.13，单次散射反照率为0.87，整层气溶胶消光系数低于0.10 km-1，短波辐射均为增温效应；污染期间（26—27日），PM2.5日平均质量浓度为83.21 μg·m-3，气溶胶光学厚度为2.48，气溶胶散射能力增强，单次散射反照率达到0.94，气溶胶主要消光层厚度提升至3.00 km高度，消光系数平均值为0.43 km-1，气溶胶在垂直方向的变化导致气溶胶中上层（1.50~3.00 km高度）加热作用强烈，短波辐射加热率平均值达到13.89 K·d-1，而低层（1.50 km高度以内）加热作用较弱，加热率平均值仅为0.99 K·d-1。气溶胶散射能力增强导致加热作用减弱，污染日加热率对于气溶胶散射能力变化更敏感。
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| 关 键 词： | 激光雷达 气溶胶消光系数 垂直廓线 辐射加热率 北京 |
| 收稿时间： | 2020-03-04 |
Aerosol Optical Properties and Radiative Effects During a Pollution Episode in Beijing |
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| Affiliation: | 1.State Key Laboratory of Severe Weather (LASW) & CMA Key Laboratory for Atmospheric Chemistry, Chinese Academy of Meteorological Sciences, Beijing 1000812.CMA Meteorological Observation Center, Beijing 100081 |
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| Abstract: | Based on continuous observations of aerosol optical properties from sun-photometer and PM2.5 concentration, the variation of aerosol optical depth, single scattering albedo and asymmetry factor during a pollution episode in Beijing from 25 January to 28 January in 2018 are analyzed. Combined with Raman-Mie Lidar vertical detection, the vertical variation of aerosol extinction coefficient is analyzed in detail. Based on ground-based observations, using a shortwave radiative transfer model, the shortwave radiative heating rates under the clear sky background during the pollution episode are calculated. Results show that under clean condition (25 January 2018), the average daily PM2.5 concentration is 19.00 μg·m-3, aerosol optical depth at 440 nm is 0.13, single scattering albedo is 0.87, and the extinction coefficient of aerosol is less than 0.10 km-1. During the pollution episode (26-27 January 2018), the average daily PM2.5 concentration is 83.21 μg·m-3, aerosol optical depth is 2.48, single scattering albedo increases to 0.94, the main aerosol extinction layer height increases to 3.00 km and the mean extinction coefficient of the whole layer is 0.43 km-1. The aerosol layer can heat the atmosphere evidently, the magnitude of radiative heating rates by aerosol depends on distribution of the aerosol in the vertical direction, and the heating rate under the concentrated heating layer decreases rapidly. Under clean condition, extinction coefficient is less than 0.1 km-1 which causes the shortwave radiative heating rate of aerosol layer within 10.00 K·day-1. During the pollution episode, the strong heating effect in the middle and upper aerosol layers (1.50-3.00 km) where the average shortwave radiative heating rate reaches 13.89 K·day-1, while the lower aerosol layer (within 1.50 km) has a weak heating effect, and the average shortwave radiative heating rate within 1.50 km is only 0.99 K·day-1. Heating rate accuracy is affected by single scattering albedo, the increased aerosol scattering ability would weaken the heating effect on the atmosphere, and the heating rate in pollution condition is more sensitive to changes of aerosol scattering ability. With the mean extinction coefficient of the whole layer being 0.43 km-1, the increase of single scattering albedo from 0.87 to 0.94 cause the heating rate of the upper and middle aerosol layers decreases by 3.74 K·day-1, while the heating rate of the lower aerosol layer increases by 0.81 K·day-1 on 27 January 2018. |
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