Analysis of horizontal flux and sand collecting efficiency of sand dust near ground surface based on field observations

Abstract: Aeolian sand transport caused by soil wind erosion is a serious problem in many arid regions in the world, and it is considered to be the significant part of global biogeochemical cycles. The dust produced by aeolian sand transport can affect the atmospheric radiation balance, climate, the environment, air quality, and human health. Therefore, widespread attention has been attracted to the significance of aeolian sand transport for geomorphology, climatology, meteorology, ecology and environmental science. Sand sampler is an important instrument to measure the quantity of aeolian sand caused by wind erosion, and there were many sand samplers designed and used in wind tunnel and field experiments for measuring aeolian sand. Sampling efficiency is an important parameter for correcting the quantity of aeolian sand collected by sand sampler, its value depends on the structures of sand sampler, wind speed during measurement process, sand particle size and measuring time. The sand-dust horizontal flux is an important parameter for the study on aeolian sand transport, as well as an important foundation. The research on sand-dust horizontal flux can enhance our understanding of soil wind erosion, aeolian sand transport and wind sand disasters. The Taklimakan Desert is the second largest shifting sand desert in the world, with about 85% of its environment made up of shifting sand dunes, and it is known to be an important dust source area that contributes to the high incidence of dusty weather in China. There is an annual average of more than 100 days of dusty weather in the desert, and in some stations this figure can be over 200. It is a huge testing platform for field experiment of aeolian sand transport.In this study, a field experiment was developed to measure the data of aeolian transport and microclimate during different dust events with a auto sand sampler, a piezoelectric saltation sensor (Sensit, H11B) and a 10 m high meteorological tower in Tazhong, the hinterland of the Taklimakan Desert from July to August in 2010. Then the sampling efficiency of auto sand sampler and horizontal dust flux of near surface were analyzed based on observed data. The results showed that: There was a good linear relationship between the amount of sediment and total saltation particle numbers, and the average value of R2 was 0.605 3. The average sampling efficiency of atuo sand sampler was 94.3% at 5 cm high. The horizontal dust flux of different dust events that passed through a section of 100cm in width and 200cm in height was calculated with formula Q=256 m, the maximum of one dust event was about 190.335kg, and the minimum was 1.2 kg. Overall, the sand transport rate increased with wind speed. However, the changes of sand transport rate did not quite fit in with wind speed during some dust events, and in this case the corresponding surface temperature was significantly higher. The experimental data obtained can provide theoretical basis for regional sand control and enacting effective engineering measures.