1 引言
2 数据来源与方法介绍
2.1 观测资料
2.2 再分析数据
2.3 研究方法
2.3.1 光学特性计算
2.3.2 libRadtran辐射模型介绍
表1 libRadtran模型使用参数Table 1 Parameters used in the libRadtran model |
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3 结果与讨论
3.1 PM2.5 及碳组分浓度变化特征
表2 各季节PM2.5 、 碳组分浓度及EC/TC、 TC/PM2.5 比值与相关气象要素Table 2 Seasonal averages of PM2.5, carbon component concentrations, ratios of EC/TC and TC/PM2.5 and related meteorological factors |
| 季节 | PM2.5、 碳组分浓度(均值±标准差)/(μg·m-3) | EC/TC、 TC/PM2.5比值与相关气象要素(均值±标准差) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 | TC | OC | BC | EC | EC/TC | TC/PM2.5 | T/℃ | RH/% | WS/(m·s-1) | |
| 春 | 42.29±18.82 | 7.21±3.31 | 4.48±2.02 | 3.41±1.74 | 2.73±1.39 | 0.36±0.06 | 0.19±0.06 | 18.06±3.94 | 76.25±7.69 | 1.06±0.27 |
| 夏 | 25.20±13.17 | 5.67±2.48 | 3.73±1.56 | 2.41±1.30 | 1.93±1.04 | 0.33±0.05 | 0.24±0.05 | 25.84±2.39 | 78.36±9.21 | 1.00±0.23 |
| 秋 | 32.41±25.11 | 6.43±3.78 | 4.31±2.62 | 2.65±1.50 | 2.12±1.20 | 0.32±0.04 | 0.23±0.07 | 17.53±5.67 | 88.53±7.89 | 0.90±0.30 |
| 冬 | 60.11±29.68 | 11.57±5.45 | 8.65±4.29 | 3.68±1.73 | 2.94±1.38 | 0.26±0.05 | 0.20±0.04 | 8.14±2.17 | 83.64±9.50 | 0.87±0.28 |
春、 夏、 秋、 冬季的计算样本数分别为92、 92、 91、 90 (the calculation sample numbers for spring, summer, autumn and winter are 92, 92, 91 and 90, respectively) |
3.2 气溶胶光学特性
3.2.1 单散射反照率
图2 550 nm处吸收系数(a)、 散射系数(b)以及单散射反照率(c)的季节变化特征 箱线图从上至下依次为: 最大值、 75%分位数、 中位数、 25%分位数、 最小值Fig.2 Seasonal variations characteristics of β abs,550 (a), β sca,550 (b), and SSA550 (c).The box plots are arranged from top to bottom as: maximum value, 75th percentile, median, 25th percentile, minimum value |
3.2.2 不对称系数
3.2.3 气溶胶光学厚度
表3 各季节PM2.5 与AOD的相关系数Table 3 Correlation coefficients between PM2.5 and AOD for each season |
| | 春季 | 夏季 | 秋季 | 冬季 |
|---|---|---|---|---|
| PM2.5~EAC-4 AOD | 0.461* | 0.303* | 0.528* | 0.724* |
| PM2.5~MERRA-2 AOD | 0.062 | 0.101 | 0.401* | 0.048 |
| EAC-4~MERRA-2 | 0.702* | 0.606* | 0.581* | 0.306* |
*表示在0.05水平(双侧)上显著相关 [* indicates a significant correlation at the 0.05 level (bilateral)] |
图5 各季节(a~d)黑碳气溶胶光学厚度与质量浓度逐日变化Fig.5 Daily variations of BC AOD and m(BC) for each season (a~d) |
表4 各季节BrC_AOD、 BC_AOD及其与 m (BC)相关的相关系数Table 4 Seasonal variations of BrC_AOD, BC_AOD, and their correlation coefficients with m (BC) |
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*表示在0.05水平(双侧)上显著相关 [* indicates a significant correlation at the 0.05 level (bilateral)] |
3.3 气溶胶辐射效应
3.3.1 模型参数验证
3.3.2 总气溶胶辐射强迫的季节效应
图8 总气溶胶对地表、 天顶以及大气中的辐射强迫逐月变化Fig.8 Monthly variations of Total_RF BOA, Total_RF TOA, and Total_RF ATM |
表5 各季节Total_RF BOA 与光学参数的相关性Table 5 Correlations between Total_RF BOA and optical properties for each season |
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*表示在0.05水平(双侧)上显著相关 [* indicates a significant correlation at the 0.05 level (bilateral)] |
3.3.3 碳质气溶胶辐射强迫
表8 各季节 r (BC/PM2.5 )、 RF BOA (BC/Total)、 RF ATM (BC/Total)Table 8 Seasonal variations of r (BC/PM2.5 ), RF BOA (BC/Total), and RF ATM (BC(BC/Total) |
| 季节 | r(BC/PM2.5) | | |
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表9 各季节 RF BOA (BrC/Total)、 RF ATM (BrC/Total)Table 9 Seasonal variations of RF BOA (BrC/Total) and RF ATM (BrC/Total) |
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