10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Cloud and Aerosol Optical Analysis for Temperate Zona
Ibtissam Marsli, MOHAMMED DIOURI, Djamaleddine Chaabane, Atmospheric Physic, LME, University of Oujda, Morocco
Abstract Number: 1040 Working Group: Clouds and Climate
Abstract Cloud and aerosol are of high importance in understanding the variability of radiative balance; they can also clarify the atmospheric evolution and remove the still significant uncertainties in climate change models. From the AERONET/PHOTONS network the data processing of about thirty sites distributed over the temperate zone allowed a precise characterization of the optical properties of clouds (optical thicknesses and occurrence frequencies) and aerosols (PSDs, single scattering albedo, optical depths and radiative forcing). This study concerns the analysis of data of the following sites: Maryland (38.99 °N, 76.83 °W), ARM_Graciosa (39.09°N, 28.02°W), La_Laguna (28.48°N, 16.32°W), Carpentras (44.08 °N,5.05°E), Weizmann_Institute (31.90°N, 34.81°E) , CEILAP-RG(51.60°S, 69.32°W) and Durban_UKZN(29.81°S, 30.94 °E). These seven sites are a sample representing the temperate zone from 77°W to 35 °E.
The histograms of the occurrence frequencies of the cloud optical depths reveal the dominance, as in the equatorial zone, and of identical way, of those included between 20 and 100 relating to low clouds as Stratus and Altostratus with 57%. For values below 20, the histograms are different and the appearance is dependent on the weather conditions of the considered region. The seasonal average of aerosol PSD show larger amplitudes with a maximum total volume concentration of 110, 58 10-3 (µm3/µm2) observed in Southeast of Mediterranean Sea. The corresponding accumulation and coarse modes determined for all the sites show median radii near 0.17 and 2.56 μm respectively.
The spectral time series (0.87 and 0.44μm) of the aerosol single scattering albedo appear to be relatively similar and vary on average between 0.6 and 0.98; this variability can be explain by the meteorological conditions of each region and local air pollution. The aerosol radiative forcing shows a tendency towards low local cooling, with annual average values near -125 W/m2 at the bottom and -15 W/m2 at the top of the atmosphere. The monthly averages of aerosol optical depth at 0.5 μm shows that the highest values are often record on summer with a maximum reaching 0.4. As on Equatorial area, the time series of the occurrence frequencies of the aerosol optical depths and those of the clouds indicate certain links to be confirm by a statistical approach, which requires a long-term monitoring.