Size distribution, chemical composition, and optical properties of urban and desert aerosols in Israel.

Measurements of aerosol size distributions, chemical composition, and optical properties were carried out at two locations in Israel, Tel Aviv, an urban region, and Mitzpe Ramon, a desert region. Diurnal variations between day and night are observed in the size distribution of the summertime measurements in Tel Aviv, related to the increase in aerosol size due to absorption of water vapor during high relative humidity periods. During westerly flow, aerosols contain large amounts of NaCl particles, which are not usually found in the desert. During Sharav conditions the aerosols in Tel Aviv are very similar to those found in the desert. Measurements of imaginary refractive index in the 0.3- to 1.7-micrometre spectral region are presented. These measurements are consistently higher by a factor of 2-4 in Tel Aviv as compared to simultaneous samples from the desert site. The size distribution, composition, and imaginary refractive index observations are interpreted in terms of aerosol origins and prevailing local and synoptic scale meteorological conditions.- from Author