Articles | Volume 17, issue 18
Atmos. Chem. Phys., 17, 11331–11353, 2017
Atmos. Chem. Phys., 17, 11331–11353, 2017

Research article 25 Sep 2017

Research article | 25 Sep 2017

Effect of sea breeze circulation on aerosol mixing state and radiative properties in a desert setting

Yevgeny Derimian1, Marie Choël2, Yinon Rudich3, Karine Deboudt4, Oleg Dubovik1, Alexander Laskin5, Michel Legrand1, Bahaiddin Damiri1,6, Ilan Koren3, Florin Unga1,2, Myriam Moreau2, Meinrat O. Andreae7,8, and Arnon Karnieli9 Yevgeny Derimian et al.
  • 1Laboratoire d'Optique Atmosphérique, UMR8518 CNRS, Universiteé de Lille 1, Villeneuve d'Ascq, 59655, France
  • 2Laboratoire de Spectrochimie Infrarouge et Raman, Université de Lille 1, Villeneuve d'Ascq, 59655, France
  • 3Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
  • 4Laboratoire de Physico-Chimie de l'Atmosphère, Université du Littoral Côte d'Opale, Dunkirk, 59140, France
  • 5Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084, USA
  • 6Cimel Electronique, Paris, 75011, France
  • 7Biogeochemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, 55020 Mainz, Germany
  • 8Department of Geology, King Saud University, P.O. Box 2455, 11451 Riyadh, Saudi Arabia
  • 9Remote Sensing Laboratory, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boker 84990, Israel

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.

Short summary
We present influence of daily occurrence of the sea breeze flow from the Mediterranean Sea on physicochemical and optical properties of atmospheric aerosol deep inland in the Negev Desert of Israel. Sampled airborne dust was found be internally mixed with sea-salt particles and reacted with anthropogenic pollution, which makes the dust highly hygroscopic and a liquid coating of particles appears. These physicochemical transformations are associated with a change in aerosol radiative properties.
Final-revised paper