10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Single Scattering Albedo in Coastal Cities
Azhare El Khabbouti, MOHAMMED DIOURI, Atmospheric Physic, LME, University of Oujda, Morocco
Abstract Number: 1480 Working Group: Remote/Regional Atmospheric Aerosol
Abstract Global demographics continue to grow with a human flow increasingly geared towards coastal cities with a strong interest in heat, visibility and air quality. In this study, we analyse PSD, single scattering albedo and induced radiative forcing. These quantities are determined from measurements of the optical thicknesses of the AERONET / PHOTONS network for a sample of coastal sites of great importance at the human activity level composed of Dakar (14.39N, 16.95W), Hong Kong (22.30N, 114 .17E) and Karachi (24.87N, 67.03E) compared with lower activity ones such as Monterey (36.59N, 121.85W) and Santa Monica (34.01N, 118.47W).
The monthly means of PSD show very higher amplitudes of the order of coarse modes and with less degree for fine modes respectively around an average radius of 2.6µm and 0.16µm with a maximum recorded in summer for Karachi, Dakar and Hong Kong expressing an important anthropogenic and maritime mixture, which constitute the main local pollution. For the other sites, we observe very lower amplitudes about 0.04 around the same median radius that indicate healthy air consistent with the registered AOD values.
The monthly averages of single scattering albedo are between 0.8 and 0.97 with the same trend for visible (440 nm) and infrared (1020 nm) for all sites, and with a value close to 1 for the case of Hong Kong. This implies a very important power of Mie diffusion in coherence with the radiative forcing registered. The seasonal averages of radiative forcing observed at sites with a loaded atmosphere are of the order of -67,09 W/m2 at the surface and -28.82 W/m2 at the top of the atmosphere. While for Monterey and Santa Monica, the values are close to zero at the top of the atmosphere and at the surface, thus reflecting the state of radiative equilibrium characteristic of an aerosol-free atmosphere.