Simulation of dust emissions in Hebei Province based on CLM4.5 soil wind erosion model

With the continuous development of the economy and society, the problem of air pollution in China is becoming more and more serious especially in Hebei Province. Currently, Hebei Province has been one of the most serious areas of air pollution in China. The wind-blown dust, emitted from the earth's surface to the atmosphere, has become one of the main components of air pollutants. The wind-blown dust has significant impacts on atmospheric phenomena and consequently on air quality. The wind-blown dust not only causes atmospheric pollution, but also changes the radiation balance of the ground and the acidity or alkalinity of the aerosol. It not only affects human health but also causes changes in the global climate system and ecosystem. In order to evaluate the PM10 of atmospheric pollutants in Hebei Province caused by wind-blown dust, the article set up parameters system of wind-blown dust production by Community Land Model 4.5 (CLM4.5) using remote sensing data, the ground meteorological data, the Land Data Assimilation System data and the land surface characteristic parameters production data with 1 km spatial resolution. The factors affecting the wind-blown dust include soil texture, wind speed, soil moisture, surface roughness, and the proportion of bare soil determined by vegetation coverage, surface freezing ratio, snow cover ratio, lakes and wetland ratio. Wind speed, soil moisture, vegetation coverage, snow cover area and freezing ratio change greatly with the seasons, so they are the sensitive factors of the wind-blown dust. This study provides the first estimates of the fine-scale spatial and temporal distribution of dust emissions from Hebei Province. The result shows that: The wind-blown dust annual emission flux of PM10 is 1.02 t/hm2 in 2013. The highest monthly emission flux is 0.28 t/hm2 in March, accounting for 27.6% of the whole year, and the lowest is July, accounting for only 0.2%. The dust emission flux of spring is 0.55 t/hm2, the summer is 0.015 t/hm2, the autumn is 0.18 t/hm2, and the winter is 0.28 t/hm2. That shows spring is the highest season and summer is the lowest season for wind-blown dust emission flux. There are obvious regional differences about wind-blown dust emissions in Hebei Province, the coastal plain of Cangzhou and Bashang plateau are the highest areas for dust emission flux, annual emission flux of which is 5.365 and 3.542 t/hm2 respectively, and Taihang Mountain piedmont plain is the lowest area, annual emission flux of which is 0.20 t/hm2. The result above shows CLM4.5 wind-blown dust model can well simulate the characteristics of spatial and temporal change in Hebei Province. Comparing the initial data of CLM4.5 with our study data, it presents the spatial resolution of initial data is very low, and not suitable for the simulation of the small area, in contrast, the local parameters we used including vegetation coverage, wind speed, soil moisture, the proportion of bare soil, lakes and wetland ratio data with high spatial resolution (1 km) have improved the accuracy of the simulation result. This paper is not only meaningful for evaluating the PM10 from wind-blown dust in Hebei Province, but also the first application to estimate wind-blown dust in the fine scale by CLM4.5 model. © 2018, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.