Preliminary Studies Of Dust Emission Model From Farmland In Northwest Semiarid Areas

In this study we compare the observations and simulation value of surface dust release flux from farmland in Xi'an,Yulin and Yan'an.We analysis and research the applicability of DPM model in northwest semiarid areas,and then we preliminary improve the model.Main conclusions are as follows:(1) The results of the grain size analysis of soil micro aggregate show that:there are two normal distributions in each soil of the three observation areas.The soil of Yulin observation area belong to powder sand loam,and there are many powder sand and fine sand but little coarse sand in it;The soil of Xi'an and Yan'an observation areas belong to sandy loam,and there are many coarse sand and fine sand in it.(2) Assuming the atmosphere is neutral,we use the wind profiling method to determine the surface roughness of each observation area.Yulin,Xi'an and Yan'an observation areas' surface roughness are respectively 0.0036cm,0.0797cm and 0.0601cm.(3) According to the particle size distribution and surface roughness of each observation area,we can calculate that Yulin,Xi'an and Yan'an observation areas' surface starting friction velocity are respectively 7.39cm/s,29.05cm/s and 26.01cm/s.(4) The observations and simulation value of surface dust release flux are respectively 5-39μg/m~2-s and 21025-μ/m~2·s.Simulation value is about 2-5 times of observations.(5) The variation trend of observations and simulation value of surface dust release flux is consistent.So we initially thought that DPM model can be used to simulate farmland surface dust release flux of northwest semiarid areas.(6) Because of the soil moisture content,we can improve DPM model like this: We use N_i=β/ne_i×interal from n=0~p_i(D_p)dF_h(D_p) instead of formula.The coefficient n of Yulin, Xi'an and Yan'an are respectively 3.04,2.53 and 2.01.