Study On Micrometeorological Observation Of Tall Sand Ridges In The Hinterland Of Taklimakan Desert

The topographic structure drives the changes of key parameters in the process of surface-atmosphere exchange,which in turn affects atmospheric processes.In ord-er to reveal the change rules of meteorological elements near the surface of the desert sand ridge,this study used the data of the micro-meteorological observation test car-ried out on the tall sand ridge in the hinterland of the Taklimakan Desert in summer2019 from June to August.With the flat sand surface as the background,this study analyzed and quantify the variation characteristics of total radiation,air temperatur-e,surface soil temperature,specific humidity,wind speed and wind direction at the bottom and top of sand ridges.The changes of meteorological elements under differ-ent weather conditions and the characteristics of dust aerosol mass concentration we-re also analyzed.The conclusions are as follows:(1)According to the comparative analysis of the station at the bottom of sand ridge,Tazhong station and Tazhong West station,there is no obvious difference in meteorological elements,but there is obvious difference compared with the top of sand ridge,which shows that the influence of topographic undulation of tall sand ridge on the change of meteorological elements is not consistent with that of flat sand surface.Compared with Tazhong West Station,the C station at the top of sand ridge has a total daily radiation difference of 1.4 MJ·m^-2,an average surface soil temperature difference of 2.2?,an average air temperature difference of 0.7?,an average wind speed difference of 0.3 m·s^-1,and average specific humidity difference is 0.01 g·kg^-1.Compared with Tazhong Station,the C station at the top of sand ridge has a total daily radiation difference of 1.1 MJ·m^-2,an average surface soil temperature difference of 1.0?,an average air temperature difference of 1.3?,an average wind speed difference of 1.1 m·s^-1,and average specific humidity difference is 0.61 g·kg^-1.(2)The total radiation at the bottom of tall sand ridges is higher than that at the top,and the difference of total radiation at different sites of sand ridges is less than60W·m^-2.The difference of surface radiation energy directly affects the difference between land surface temperature and atmospheric thermal condition,the surface temperature at the top is higher than the bottom at night,but it is on the contrary in the daytime,the difference of air temperature and specific humidity between the bottom and the top of sand ridge is less than 3?and 0.5 g·kg^-11 respectively,the difference of air temperature and specific humidity is mainly reflected in the night,and the difference is obviously reduced in the process of sand and dust weather.The wind speed is different in the sand ridge topography(the top is greater than the bottom),the wind speed difference is less than 3 m·s^-1,the prevailing wind direction(NE,ENE)is the same in all parts of the sand ridge,and the prevailing wind direction at the top of the sand ridge is more concentrated.(3)In different weather,the mass concentration of PM_2.5.5 and PM₁₀0 of tall sand ridge was different.The average mass concentration of PM_2.5.5 at the bottom of sand ridge was higher than that at the top of sand ridge,and the average mass concentration of PM₁₀0 at the top of sand ridge was higher than that at the bottom of sand ridge.On a sunny day,the average mass concentration of PM_2.5.5 the station A at the bottom of sand ridge(1.33?g·m^-3)>the station E at the bottom of sand ridge(0.17?g·m^-3)>the station C at the top of sand ridge(0.14?g·m^-3),and the average mass concentration of PM₁₀0 the station C at the top of sand ridge(2.40?g·m^-3)>the average mass concentration bottom E station(2.06?g·m^-3)>the average mass concentration bottom A station(1.58?g·m^-3).In floating dust weather,the average mass concentration of PM_2.5.5 the station E at the bottom of the sand ridge(40.15?g·m^-3)>the station C at the top of the sand ridge(38.29?g·m^-3),and the average mass concentration of PM₁₀0 at the station C at the top of the sand ridge(81.35?g·m^-3)>the Station E at the bottom of the sand ridge(71.80?g·m^-3).In sand blowing weather,the average mass concentration of PM_2.5.5 the station E at the bottom of the sand ridge(32.73?g·m^-3)>the C station at the top of the sand ridge(30.57?g·m^-3),and the average mass of the PM₁₀0 at the top station of the sand ridge(65.05?g·m^-3)>the Station E at the bottom of the sand ridge(58.21?g·m^-3).