An application of the satellite derived NDVI to improve dust emission in the GOCART model

Dust is the major atmospheric aerosol that affects to the Earth environmental and climate systems. While regional scale numerical models have successfully predicted dust outbreaks, global scale models also have shown reasonable agreement when they were compared against surface, air, and space born observations. Unlike regional scale models that are focusing on specific deserts, however, global models have to deal with all kinds of desert and they usually make higher level simplifications in various processes. Dust erodibility remains uncertain among the several physical and chemical processes that control dust cycle during emission, transport, and removal process. The Normalized Difference Vegetation Index (NDVI) is defined as the ratio of the difference between Near IR radiation and Visible radiation to the sum and it is a useful tool to describe the surface bareness because of its sensitivity to the vegetation cover. The NDVI from the Moderate Resolution Imaging Spectroradiometer (MODIS) is applied to a global aerosol model to investigate the impact of NDVI and soil bareness to the dust emission. The Goddard Chemistry Aerosol Radiation and Transport (GOCART) model used in this study captures most of the major dust sources over the Earth. The erodibility probability map in the GOCART model is based on only the topographic depression and the additional surface type information might be helpful for the dust emission. The modeled Aerosol Optical Depth (AOD) from GOCART was compared with the AERONET (AErosol RObotic NETwork) and MODIS AOD. Simulation results indicate that there are significant changes in regional scale and it also affects the global distributions. More results will be discussed further.