Study On The Land Surface Process Characteristics Of The Snow Underlying Surface In The Hinterland Of The Taklimakan Desert In Winter

In this paper,by using 10 m gradient detection system and turbulent flux detection system data from the Taklimakan Desert atmosphere and environment observation station,studied the characteristics of Taklamakan Desert hinterland of snow underlying micro weather,surface radiation,energy balance,surface heating field and surface albedo and multilayer soil temperature and moist and their relationship in the winter of 2016-2017.The results show that:1)The micro meteorological features of the winter snow cover in the hinterland of the Taklimakan Desert:?The average daily variation characteristics of meteorological elements of 10m each gradient in the near stratum under snow cover:The wind speed of each gradient is characterized by a single peak,and the wind speed is obviously greater than that of the night.The temperature was sinusoidal,which was the same as that on the surface of non-snow cover,but the temperature was significantly lower than that of the previous year.The relative humidity relatively overall improved when there is no snow.?Vertical profile characteristics of meteorological elements within 10m height under snow cover:The wind speed of the whole day is changed at the height of2m.The temperature of the whole day increases with the elevation of the height,and the inversion is significant.The strongest inversion appears at 21:00,vertical temperature lapse rate up to 41.8?/100 m.It means that the presence of snow blocks the transfer of heat from the earth's surface to the air,keeping the temperature below the upper level all day.The whole day is in reverse humidity,and the evening to early morning reverse-wetness is stronger than morning to afternoon.It is found that the gradient and intensity change of the reverse wetness is correspond to the change of the inversion temperature,and the two have obvious positive correlation.2)The features of surface radiation balance in the winter snow cover in the heart of the Taklamakan Desert:Each component of the radiated under the snow cover is characterized by unimodal daily variation,and the radiation budget is dominated by total radiation and reflected radiation.The effect of ground snow on the net short wave radiation is mainly reflected in the increase of reflected radiation,which leads to the reduction of the absorption of net short wave radiation.At the same time,the coverage of the snow reduces the surface effective radiation,resulting in the decrease of the radiation emitted by the ground.In general,the ground radiation balance is still decreasing due to the reduction of effective radiation from the ground,which is not enough to compensate for the reduction of net short wave radiation absorption.During the winter,the albedo is the main factor of net radiation on the snow cover ground,while the total radiation is the main factor of net radiation on the absence of snow cover ground.3)Energy balance and ground heating field characteristics of winter snow cover in the winter of the Taklamakan Desert:Sand surface snow cover,net radiation,surface soil heat flux has obvious unimodal type diurnal variation characteristics and trends are also similar,both H and LE is show greater volatility and LE amplitude is bigger,the daily average change form also assumes unimodal type;The average daily accumulation of net radiation,H,LE and soil heat flux is:1.20,0.37,0.06,-3.65 MJ/m².In winter,the surface energy balance is obviously not closed,and the energy closure rate of snow cover and no snow cover is 43%and 60%respectively.During the 17 days of continuous snow cover in January 2017,the average daily heating intensity of the ground was 4.86 MJ·m^-2,with a value greater than zero indicating that the surface of the snow cover was still a heat source.4)Surface albedo and soil temperature and humidity characteristics of winter snow cover in the heart of the Taklimakan Desert:?The surface albedo daily changes between 0.25 and 0.73 during snow cover,the average value is 0.60;The daily variation of surface albedo tends to reverse"J"and the value in the morning is bigger than in the evening,the average difference is0.13.?Snow makes the 0-40 cm depth soil temperature decreased,the layers of soil temperature are close to each other when soil moisture increases after the snow;The existence of snow makes the daily variation range of 0cm,10cm,20cm soil temperature decreased except the layer of 40cm depth,decreased respectively41%,39%,39%??There is a negative correlation relationship between surface albedo and surface temperature in snow underlying surface;Namely,high surface albedo is corresponding to low surface temperature,the correlation coefficient is-0.71;On the snow underlying surface albedo and 5 cm depth soil moisture present a negative correlation,the high surface albedo is corresponding to low soil moisture,and low surface albedo is corresponding to high soil moisture,the correlation coefficient is-0.74.