Temporal Evolution Of The Boundary Layer Height And The Contribution Of Dust Devils To Atmospheric Dust Aerosol In Arid Areas

Dust aerosol is an important component of tropospheric aerosol. It is one of the key factors that affect the global climate change through the sand emission, transport and settlement. Sandstorm mainly with dynamic sand emission has been extensively studied, and the contribution of sand emission of dust devils mainly with thermal sand emission in the year may exceed the sandstorm, showing that dust devils may also be the key elements of environment and climate change. According to the theory of thermodynamics, the height of convective boundary layer is important to the sand volume of dust devils. How to estimate the daily variation of the height of the boundary layer with the long-term sounding data is of great importance to the accurate calculation of the sand volume of dust devils. With the temperature profilemethod, the daily maximum convective boundary layer height (CBLmax) in arid area is obtained and the possible influencing factors are analyzed, then the sand volume of dust devils and its contribution to the total amount of sand volume were calculated. Finally, the distribution of dust in the Dunhuang area was simulated by WRF and the results of calculated were verified. The results are as follows:1) Calculation and analysis the CBLmax in Dunhuang and Minqin The daily CBLmax has very significant annual variation characteristics, showing a single-peak positive skew distribution, the lowest in Dunhuang in December, the highest in May; Minqin lowest in January, the highest in June, an annual mean height of 2 to 2.4km and an extreme near-6km. The contribution of thermal factors to CBLmax is decisive, and the amount of cloudiness can affect the variation of CBLmax·2) The sand volume of dust devils and the annual average contribution to the total of atmospheric.The thermodynamic efficicency and the monthly average sand volume of dust devils are all showing single-peak distribution in Dunhuang and Minqin. The thermodynamic efficiency is the highest in May of Dunhuang, Minqin highest in June. The sand volume of dust devils in the two places are all reached the maximum in June. The sand volume of dust devils is consistent with the aerosol index of Aura(Aura-Al). Dust devils contributes at least 54.4% to the annual dust aerosol in Dunhuang and 54.1% in Minqin.3) The daily CBLma. and the sand volume of dust devils in Dunhuang was simulated with WRF model.This paper put the dry adiabatic curve method into the WRF model to calculate the CBLmax, reducing the mode error from 50.5% to 18%. The annually average sand volume of dust devils shows a characteristic that high in the western region and the eastern region is low. The sand volume in the desert is higher than that in Gobi. The simulated dust devils sand volume and the actual monthly error is 6.7%.