Incorporating human-induced land-cover/land-use change in dust emission prediction: Implications for air quality in Central Asia

In recent decades, an increasing frequency of sand/salt dust events has been a major air quality and environmental health problem in the Central Asian region. Land desertification and salinization, such as the dry-up of Aral Sea, caused by improper agricultural practices and water resource exploitation has resulted in vast areas of sandy and solonchak deserts which are highly susceptible to wind erosion. The dust storms may carry large amounts of salt and toxic chemicals which are a serious threat to region's air quality. However, man-made dust sources are poorly represented in regional and global models. Here, we aim to examine how land degradation, along with variations in meteorological conditions (e.g., surface wind), affects the threshold friction velocity and dust emission strength in Central Asia between the 1950s and 2010s. This work is conducted using a coupled dust model, WRF-Chem-DuMo, which includes two different physically-based parameterizations of threshold friction velocity and dust vertical flux. A georeferenced dataset of land surface input parameters for Asian dust sources and meteorological fields from the NCAR/NCEP reanalysis data are used in model initialization. The model also incorporates historical land use datasets of the annual agricultural (i.e., cropland and pasture) fraction and surface water body state to reflect the spatiotemporal changes in land cover and surface properties relevant to dust emission processes. Results will be presented on the spatial and temporal variability in threshold friction velocity and dust emission strength of major dust sources in Central Asia for the selected years between the 1950s and 2010s. The anthropogenic proportion of emitted dust will also be estimated using land use datasets and satellite aerosol products from the MODIS and SeaWiFS instruments.