Effect of sea breeze circulation on aerosol mixing state and radiative properties in a desert setting
Effect of sea breeze circulation on aerosol mixing state and radiative properties in a desert setting
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DOI：
10.5194/acp-17-11331-2017
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发表时间：
2017-09
影响因子：
6.3
通讯作者：
Y. Derimian;M. Choël;Y. Rudich;K. Deboudt;O. Dubovik;A. Laskin;M. Legrand;B. Damiri;I. Koren;F. Unga;M. Moreau;M. Andreae;A. Karnieli
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文献类型：
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作者：
Y. Derimian;M. Choël;Y. Rudich;K. Deboudt;O. Dubovik;A. Laskin;M. Legrand;B. Damiri;I. Koren;F. Unga;M. Moreau;M. Andreae;A. Karnieli
摘要。发现以色列内盖夫沙漠内陆深处大气气溶胶的化学成分、微物理和光学特性受到来自地中海的每日海风流的影响。在夏季距离海岸至少80公里处系统地记录到，与风速和大气含水量增加有关的气溶胶体积浓度突然增加和尺寸分布向较大尺寸转移。气溶胶样品的化学成像显示，在海风入侵期间，高吸湿性颗粒的贡献增加。在海风期，除海洋气溶胶显著增加外，内部混合的海洋和矿物粉尘颗粒的数量也有所增加。PM1-2海风中海洋和内部混合颗粒的数量占比高达88%。在pm2.5中高达62%。5-10的大小范围。此外，SEM/EDX分析还观察到大量带有液体涂层残留物的颗粒。拉曼显微光谱证实了富钙粉尘颗粒与人为硝酸盐发生反应。所得的吸湿颗粒可以在非常低的相对湿度下潮解。我们的观测表明，内盖夫沙漠的气溶胶吸湿性增长是由每日海风的到来引起的。不同的气溶胶微物理和光学特性干扰了太阳和热红外辐射。根据一个案例研究的评估，海风引起的气溶胶特性的变化，相对于背景情况，使地表短波辐射冷却增加了一倍（从- 10到- 20.5 W m−2），使大气变暖增加了近3倍（从5到14 W m−2）。考虑到观测到的粒子液体包覆的重要价值，我们还研究了粒子均匀性假设对气溶胶微物理特征反演的可能影响。试验表明，如果反演算法具有后向散射和偏振测量，则对涂层的敏感性会出现。这可能对遥感应用中气溶胶微物理特性的检索具有重要意义。
Abstract. Chemical composition, microphysical, and optical properties of atmospheric aerosol deep inland in the Negev Desert of Israel are found to be influenced by daily occurrences of sea breeze flow from the Mediterranean Sea. Abrupt increases in aerosol volume concentration and shifts of size distributions towards larger sizes, which are associated with increase in wind speed and atmospheric water content, were systematically recorded during the summertime at a distance of at least 80 km from the coast. Chemical imaging of aerosol samples showed an increased contribution of highly hygroscopic particles during the intrusion of the sea breeze. Besides a significant fraction of marine aerosols, the amount of internally mixed marine and mineral dust particles was also increased during the sea breeze period. The number fraction of marine and internally mixed particles during the sea breeze reached up to 88 % in the PM1–2. 5 and up to 62 % in the PM2. 5–10 size range. Additionally, numerous particles with residuals of liquid coating were observed by SEM/EDX analysis. Ca-rich dust particles that had reacted with anthropogenic nitrates were evidenced by Raman microspectroscopy. The resulting hygroscopic particles can deliquesce at very low relative humidity. Our observations suggest that aerosol hygroscopic growth in the Negev Desert is induced by the daily sea breeze arrival. The varying aerosol microphysical and optical characteristics perturb the solar and thermal infrared radiations. The changes in aerosol properties induced by the sea breeze, relative to the background situation, doubled the shortwave radiative cooling at the surface (from −10 to −20.5 W m−2) and increased by almost 3 times the warming of the atmosphere (from 5 to 14 W m−2), as evaluated for a case study. Given the important value of observed liquid coating of particles, we also examined the possible influence of the particle homogeneity assumption on the retrieval of aerosol microphysical characteristics. The tests suggest that sensitivity to the coating appears if backward scattering and polarimetric measurements are available for the inversion algorithm. This may have an important implication for retrievals of aerosol microphysical properties in remote sensing applications.