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Modelling the atmospheric controls and climate impact of mineral dust in the Sahara Desert

Cavazos Guerra, C.d.C.; (2011) Modelling the atmospheric controls and climate impact of mineral dust in the Sahara Desert. Doctoral thesis , UCL (University College London). Green open access

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Mineral dust aerosols play an important role in climate and the Earth's energy budget. The effect of dust on the radiative forcing is uncertain due to the complexity of particle properties and the complexity to quantify and discriminate preferential dust sources. This research considers the potential of two Regional Climate Models (RCM’s): The Weather Research and Forecasting model (WRF-Chem) and the Regional Climate Model (RegCM3) both with an integrated dust module. Numerical sensitivity experiments are performed to quantify the ability of both models to simulate sources, the magnitude of dust emission, the transport in 3-dimensions and the subsequent impact on the radiative forcing. Particular emphasis is given to preferential source regions within the Sahara and Sahel in North Africa including the Bodélé Depression in Northern Chad. To account for the distribution of preferential dust source regions, soil texture characteristics were modified in dust source regions in RegCM3. As for WRF-Chem GOCART scheme, a new higher resolution erodible fraction map is tested. Moreover, the sensitivity of the results to the specification of aerosol optical properties to evaluate the impacts of optical characteristics on the radiative forcing was considered for the RegCM3. Finally, model outputs are compared to in-situ data: weather stations (WMO) and AERONET and satellite estimates: MODIS, MISR, OMI, CALIPSO and SEVIRI. Results show that both models represent the space/time structure of near-surface meteorology well. The tuning of preferential dust sources tested in this research provides a more realistic representation of local dust sources, emissions and resulting AOT. This suggest that in the absence of truly accurate soil maps at high resolution, further refinements to preferential sources map and its implementation in dust models can lead to useful improvements in simulation of dust processes and dust forecast accuracy.

Type: Thesis (Doctoral)
Title: Modelling the atmospheric controls and climate impact of mineral dust in the Sahara Desert
Open access status: An open access version is available from UCL Discovery
Language: English
UCL classification: UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/1322565
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