Numerical Simulation Study Of Sand-dust Process In Northern China And Sand Emission Flux Under Future Climate Change Scenarios

The deserts in Northern and Northwestern China are the largest sources of dust in East Asia,which exert important impacts on China's weather and climate.In this paper,WRF-Chem model is first employed to study the applicability of the five dust emission parameterization schemes and the physical mechanism of the dust process,and then to predict the future changes of dust emission in Northern China through dynamic downscaling.The effects of aerosols,greenhouse gases and land use on weather,climate and dust emission processes are considered comprehensively in the prediction,which makes the results more reliable.The main conclusions are as listed as follows:(1)Among the five dust emission schemes,the Shao01 scheme shows the strongest ability to simulate the emission flux,the spatial pattern of source region,as well as the spatiotemporal variation of dust in the studied process.The different performance of the Shao11 scheme in various dust process simulations may mainly come from the difference of soil types in dust source regions.(2)In China's two major dust source regions,Northern China's dust process is greatly affected by the deposition and diffusion dilution,its climate and environment effects are mostly strong but short.Northwestern China is surrounded by mountains on three sides,the dust here tend to accumulate on the edges of the mountains,and reach higher altitude due to the uplift of dynamic,thermal and topographic.It can stay in the atmosphere for relatively long time,has broader and lasting effects on climate and environment.(3)The prediction shows that from 2016 to 2029,the dust emission flux in the northwest is higher than that in the north,and the annual mean dust emission fluxes in the two regions show fluctuating decreasing trends.The mean dust emission flux in each season of the two regions will decrease overall,while increase in some seasons.The fluxes in the northwest decrease in summer,autumn and winter,and weakly increase in spring.The fluxes in the north decrease in the spring,summer and winter,and weakly increase in the autumn.The variation trend of dust emission flux in the two regions is dominated by near-surface wind speed,while vegetation fraction,precipitation and surface temperature have important effects on the interannual fluctuation of dust emission flux.(4)The prediction shows that from 2016 to 2029,the most severe dust emission processes in the northwest occur in the spring of 2028-2029,the summer of 2023-2024,and the autumn of2016,2023,and 2025.The most severe dust emission processes in the north occur in the spring of 2020?2021 and 2023?2024,the autumn of 2021 and 2029,and the winter of 2017.