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Accueil du site → Master → Etats Unis → 2014 → Spatial and Seasonal Variability of Cloud Condensation Nuclei Number Concentrations Over the Extended North African Continent and the Mediterranean

STATE UNIVERSITY OF NEW YORK AT ALBANY (2014)

Spatial and Seasonal Variability of Cloud Condensation Nuclei Number Concentrations Over the Extended North African Continent and the Mediterranean

Hassan, Hesham A.A

Titre : Spatial and Seasonal Variability of Cloud Condensation Nuclei Number Concentrations Over the Extended North African Continent and the Mediterranean

Auteur : Hassan, Hesham A.A

Université de soutenance : STATE UNIVERSITY OF NEW YORK AT ALBANY

Grade : Master of Science (MS) 2014

Résumé
The spatiotemporal variability of cloud condensation nuclei (CCN) number concentration is investigated over the extended domain of the North African continent and Mediterranean which is an essential step for better understanding of aerosol-cloud interactions and associated climate impacts over the region. The study is performed by analyzing the output for the period from 2004 to 2011 from the well-validated global chemistry and aerosol transport model GEOS-Chem-APM. The analysis shows that the dominant aerosol type for CCN number concentration is secondary particles all over the domain. Spatial analysis reveals the existence of four characteristic subdomains of variability : over the Mediterranean and Europe, the Caspian Sea, the Arab Peninsula, and tropical Africa. Temporal analysis shows that each subdomain has its characteristic variability pattern ; the analysis of different aerosol type concentrations shows that secondary particles are the main controller of variability over the Mediterranean and Europe, Caspian Sea, and Arab Peninsula, and have contribution to the variability through the upper layer over tropical Africa. The carbonaceous compounds, especially primary organic carbon, are the main controller of variability over tropical Africa and have significant contribution to variability over the Arab Peninsula, the Caspian Sea, and Mediterranean and Europe. Wind has been shown to play an essential role in particle transportation from Europe and the Mediterranean onto the Caspian Sea and Arab peninsula, which in turn affect the variability pattern over the latter two domains through the competition between local and transported sources, and in rising concentration over central tropical Africa during most seasons, and to enhance dispersion during the summer season. Temperature has been found to affect the variability over Arab Peninsula lower layer through suppressing nucleation during summer. Also, it has been illustrated that the one important source of CCN precursors over the Mediterranean is volcanic activity as well as anthropogenic sources, over both the Caspian Sea and the Arab peninsula is anthropogenic activity as well as transportation, and over tropical Africa is biomass burning and anthropogenic and natural sources of secondary particles. Observations and measurements of CCN in the regions, presently not available, are needed for validating the model results.

Mots clés : Atmospheric chemistry ; Atmospheric sciences

Présentation (GradWorks)

Page publiée le 12 février 2015, mise à jour le 27 décembre 2017