Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5753755 | Atmospheric Research | 2017 | 28 Pages |
Abstract
To derive the comprehensive aerosol in situ characteristics at a rural background area in Saudi Arabia, an aerosol measurements station was established to Hada Al Sham, 60Â km east from the Red Sea and the city of Jeddah. The present sturdy describes the observational data from February 2013 to February 2015 of scattering and absorption coefficients, Ã
ngström exponents and single scattering albedo over the measurement period. The average scattering and absorption coefficients at wavelength 525 nm were 109 ± 71 Mmâ 1 (mean ± SD, at STP conditions) and 15 ± 17 Mmâ 1 (at STP conditions), respectively. As expected, the scattering coefficient was dominated by large desert dust particles with low Ã
ngström scattering exponent, 0.49 ± 0.62. Especially from February to June the Ã
ngström scattering exponent was clearly lower (0.23) and scattering coefficients higher (124 Mmâ 1) than total averages because of the dust outbreak season. Aerosol optical properties had clear diurnal cycle. The lowest scattering and absorption coefficients and aerosol optical depths were observed around noon. The observed diurnal variation is caused by wind direction and speed, during night time very calm easterly winds are dominating whereas during daytime the stronger westerly winds are dominating (sea breeze). Positive Matrix Factorization mathematical tool was applied to the scattering and absorption coefficients and PM2.5 and coarse mode (PM10-PM2.5) mass concentrations to identify source characteristics. Three different factors with clearly different properties were found; anthropogenic, BC source and desert dust. Mass absorption efficiencies for BC source and desert dust factors were, 6.0 m2 gâ 1 and 0.4 m2 gâ 1, respectively, and mass scattering efficiencies for anthropogenic (sulphate) and desert dust, 2.5 m2 gâ 1 and 0.8 m2 gâ 1, respectively.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Atmospheric Science
Authors
H. Lihavainen, M.A. Alghamdi, A. Hyvärinen, T. Hussein, K. Neitola, M. Khoder, A.S. Abdelmaksoud, H. Al-Jeelani, I.I. Shabbaj, F.M. Almehmadi,