| 海洋-大气过程对南海气溶胶数浓度谱分布的影响 |
| 摘要点击 2184 全文点击 1181 投稿时间：2015-11-01 修订日期：2016-02-25 |
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| 中文关键词 南海 海洋气溶胶 数浓度 粒径谱 气象条件 |
| 英文关键词 South China Sea marine aerosol number concentration particle size distribution meteorological condition |
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| 中文摘要 |
| 利用2012年8月28日至10月13日期间走航观测的气溶胶数据,分析了南海气溶胶数浓度时空分布和粒径谱分布特征,以及海洋-大气过程的影响.结果表明,南海气溶胶数浓度的时空分布和粒径谱分布受海洋和陆地源以及当地气象条件如风速、风向、相对湿度、云量、温度等的共同影响.陆地气团影响下的海域气溶胶数浓度较大,达2300个·cm-3;受陆地影响较小的海域大气较为洁净,气溶胶数浓度在1200个·cm-3以下.观测得到的气溶胶粒径谱包括积聚模态和粗模态,峰值分别位于0.08~0.2μm和0.5~2μm附近.出现频率较高的谱型有3种:陆地型,海洋背景1型和海洋背景2型.陆地型与海洋2型的谱分布形状基本一致,但后者次微米粒子数浓度非常小,是洁净海洋背景下最常见的谱型;海洋1型在0.05~0.1μm粒径段数浓度显著高于海洋2型,并且在大于0.5μm的粗粒子段,海洋1型的气溶胶数浓度超过陆地型气溶胶数浓度,暗示了海洋源对这两个粒径段的粒子数浓度的贡献.0.05~0.12μm的积聚模态粒子数浓度与低云量有明显的正相关关系,且当相对湿度达90%~95%时,0.08μm附近的粒子数浓度增加显著.0.5~6μm的粗模态海洋气溶胶对风速的依赖性较强,相关性达0.7; 0.05~0.12μm气溶胶数浓度与风速呈现弱正相关; 0.12~0.5μm粒子数浓度与风速呈负相关.随着相对湿度的增大,0.08~0.12μm的粒子数浓度降低,而0.05~0.08μm和0.5~6μm的粒子数浓度增大.降水过程中,各粒径段粒子数浓度逐渐降低,但在降水初期,相对湿度达到90%~95%,0.05~0.12μm和0.5~6μm的粒子数浓度显著增大,随后逐渐减小. |
| 英文摘要 |
| The shipboard measurements of aerosol number concentration from August 28th to October 13th, 2012 were conducted to analyze the characteristics of temporal-spatial distribution and number size distribution of marine aerosol in the South China Sea. The impact of meteorological condition on the marine aerosol was also analyzed in this paper. The result showed that the temporal-spatial distribution and number size distribution of marine aerosol were influenced by the backward trajectory of the air masses and the time they spent over the sea, and the meteorological conditions in the local sea area such as wind speed, wind direction, temperature, relative humidity and cloud cover. In terms of temporal-spatial distribution of marine aerosol in the South China Sea, the aerosol in the sea areas under the influence of continental air mass concentration showed much higher concentration than that in the clean maritime air mass (2300 cm-3 vs. 1200 cm-3). During the ship observation, three kinds of number size distribution of marine aerosol were found and classified:polluted type, marine type 1 and marine type 2 (clean). All the distributions had a similar sub-micron mode and a similar coarse mode. The marine type 2 (clean) had the same distribution shape as polluted type except that the value of concentration was much lower. The sub-micron peak of marine type 1 appeared near 0.08 μm and its concentration was significantly higher than that of marine type 2 (clean). Non-precipitating clouds as well as abundant moisture contributed to the growth of ultrafine particles to the size of accumulation mode aerosol (0.05-0.12 μm). Number concentration of particles in this range showed weak positive correlation with wind speed since wind can enhance the efficiency of sea-air exchange and accelerate the release of gas precursors of sulfate aerosol to the atmosphere. The concentration of coarse particles ranging from 0.5-6 μm in diameter strongly depended on the wind speed, and the correlation coefficient reached a value of 0.7. |
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