Potential impact of spatial patterns of future atmospheric warming on Asian dust emission

摘要

Spatial patterns of future atmospheric warming presented by climate model projections indicate that the temperatures of the lower troposphere will increase markedly at high latitudes in the Northern Hemisphere and also the upper troposphere at low-middle latitudes. In this study, potential impacts of the spatial patterns of future atmospheric warming on Asian dust emission were investigated by performing numerical experiments using a dynamical downscaling method. After three significant Asian dust outbreak events were reproduced as control runs, initial and boundary conditions of the control runs were updated by adding differences in atmospheric variables between the future climate (2091-2100) and the recent climate (1991-2000) to execute pseudo global warming runs. The results showed that the dust emission fluxes in the main Asian dust sources (MADSs), i.e., the Taklimakan and Gobi deserts, decrease markedly in the future climate condition. The future decreases in the dust emission fluxes are likely to be caused by a combination of the relatively large increases in sea level pressures (SLPs) in MADSs and the small SLP changes to the north of MADSs, which reduces the meridional SLP gradients between the two areas and consequently weakens cold air outbreaks. The large SLP increases in MADSs may be due to a northward shift of storm tracks and increased atmospheric stabilities caused by the large upper-tropospheric warming at low-middle latitudes. The small SLP changes to the north of MADSs corresponded to the large increases in surface air temperatures, which would be influenced by the large lower-tropospheric warming at high latitudes.