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| 2013～2018年武汉市降水和BC的时间演变特征分析 |
| Characteristics of the Temporal Evolution of Precipitation and BC Aerosols in Wuhan from 2013 to 2018 |
| 投稿时间：2021-08-19 修订日期：2021-10-19 |
| DOI：10.14050/j.cnki.1672-9250.2022.50.024 |
| 中文关键词: 降水 BC 时间演变 降水强度 武汉 |
| 英文关键词: precipitation BC temporal evolution precipitaiton intensity Wuhan |
| 基金项目:国家自然科学基金项目（41830965、42075186、41805096）。 |
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| 中文摘要: |
| 湿清除是大气气溶胶重要的去除机制，由于降水过程和气溶胶本身的复杂性，针对城市地区降水与气溶胶的相互关系还有待开展深入研究。基于2013～2018年武汉市气象要素和黑碳（BC）质量浓度小时数据，分析了不同等级降水和BC的年际、季节等时间演变特征。结果表明：2013～2018年武汉市共出现785个降水日，降水日占总观测日的35.8%，降雨以小雨为主，占总降雨日的72.0%。随着降水强度的增强，BC质量浓度逐渐降低，在大暴雨时最低，为4 001.5 ng/m3，仅为晴天时浓度的42.9%。随着降水强度的增加，吸收Ångström指数（AAE）先减小后增加。武汉市BC气溶胶主要来自化石燃料的燃烧。2013～2018年武汉市暴雨和大雨日数、降雨量逐渐减少，而中雨和小雨天日数、降雨量逐渐增加。暴雨和大雨天数平均每年减少0.7天和0.6天，中雨和小雨天数平均每年增加1.3天和4天。不同降雨等级过程中BC和AAE的年际变化特征和季节分布特征不同。BC质量浓度在春季和夏季，随着降水强度的增加逐渐降低，AAE在秋季随降雨强度的增强而逐渐降低。降水过程对大气污染物的清除作用持续时间较短，降雨结束后，大气污染物开始堆积，经过十几小时后就可恢复到降水前的浓度。 |
| 英文摘要: |
| The wet scavenging is an important removal mechanism for atmospheric aerosols. However, there are many uncertainties due to the complexities of precipitaion processes and aerosol. Based on the hourly meteorological data and black carbon (BC) mass concentration data in Wuhan from 2013 to 2018, the characteristics of inter-annual and seasonal variations of the different precipitation intensities and BC are analyzed. The results showed that there were 785 precipitation days in Wuhan from 2013 to 2018, and precipitation days accounted for 35.8% of the total observation days. Precipitation was dominated by light rain grade, accounting for 72.0% of the total precipitation days. As the precipitation intensity increases, the mass concentration of BC gradually decreases, and being the lowest mass concentration during heavy rain days, with concentration of 4 001.5 ng/m3, which is only 42.9% of the mass concentration during sunny days. As the precipitation intensity increases, the value of absorption Ångström exponent (AAE) decreases first and then increases. BC aerosols mainly come from the fossil fuels burning in Wuhan. From 2013 to 2018, the amount and days of rainstorm and heavy intensity rainfalls gradually decreased in Wuhan, while the amount and days of moderate rain and low intensity rainfalls gradually increased. The number of rainstorm and heavy intensity rainfalls days decreased by 0.7 and 0.6 days per year on average, and the number of moderate rain and light rain days increased by 1.3 and 4 days per year on average. The interannual and seasonal variations of BC and AAE are different in the different rainfall intensities. The mass concentration of BC gradually decreases with the increase of rainfall intensity in spring and summer, and the AAE gradually decreases with the increase of rainfall intensity in autumn. The rainfall scavenging of atmospheric pollutants during the precipitation process lasts for a short time. After the rainfall ends, the mass concentrations of atmospheric pollutants begin to accumulate, and after more than ten hours, they can return to the mass concentration before the precipitation. |
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