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The Chinese University of Hong Kong (2016)

Investigating the spatial and interannual variability of springtime East Asian dust emission over 1982-2010 using a modeling approach

CHOW, Ming Keung

Titre : Investigating the spatial and interannual variability of springtime East Asian dust emission over 1982-2010 using a modeling approach

Auteur : CHOW, Ming Keung

Université de soutenance : The Chinese University of Hong Kong

Grade : Master of Philosophy in Earth and Atmospheric Sciences 2016

Résumé
Dust emission is important because it modulates the global radiation budget byinputting aerosol into the atmosphere, and that it alters the terrestrial and oceanbiogeochemistry by acting as a nutrient fertilizer. However, little is known aboutits variability under climate change, in particular in East Asia where intenseland cover change occurs in recent decades. In this study, we optimize the dustemission model in GEOS-Chem for vegetation dynamics and obviate the need of adust source function by using a novel dust emission scheme. The optimized modelis then validated by AERONET in-situ daily AOD and MISR monthly AOD. Wealso perform sensitivity simulation of the impact of climate variability and landcover variability, on the dust emission variability over 1982-2010 in Teklimakan,Gobi and the whole East Asia domain. We discover that in Gobi the change indust emission (-22%) is mostly due to climate change (-23%) and that due to landcover changes is negligible (+1%) between 1982-1986 and 2006-2010. However inTeklimakan land cover change contributes 5% of the decrease of dust emissionwhile climate change offset the decrease by 3%, such that the dust emission hasi no significant change. Besides the budget change, over 95% of the dust emissionvariability is attributed to climate change, whereas land cover change contributesvery little to the variability in both deserts. We also perform principal componentregression (PCR) on the dust emission variability due to the changing climate,with the latter represented by three atmospheric variables, namely surface windspeed, total precipitation and surface temperature. We find that over 50% ofthe dust emission variability in Teklimakan is controlled by the decrease of windtogether with the increase of temperature and the decrease of precipitation. InGobi, increase of precipitation and decrease of wind speed together lead to a 60%decrease of dust emission

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Page publiée le 20 décembre 2022