Abstract: Sand particles in saltation are the main part of wind-blown sand, and features of their vertical distribution is a vital research content in aeolian physics, which is of reference significance for aeolian engineering. Restricted by research condition and observation instruments, the research on features of the saltating sand flux profile over near gobi surface in real time observation is relatively weak, especially in gobi area with strong wind. In this study, wind erosion sensors in five different heights and a gradient sand trap were applied to measure the real-time distribution characteristic of saltating particles in different heights in Yandun Wind District, Xinjiang, China. Results revealed that the threshold velocity for saltation in a height of 2 m in the study area reached 12 m·s^-1 with a threshold friction velocity of 0.65 m·s^-1, and sand transport over gobi was of intermittency, which was below 50% in value during the whole observation period. The intermittency of sand transport was in relation to the average wind speed in the height of 2 m, while it had no significant correlation with the pulsation intensity of wind in a period of 10 min. Also, sand in saltation was mainly transported in a surface layer of 50 cm in a moderate gale, and the curve of the sand flux profile presented an elephant trunk outline, with a maximum mass flux in the heights of 2.5-5 cm. Besides, the saltation height of sand particles increased exponentially with wind speed in the height of 2 m, and in a moderate gale, sand particles could saltate to a height of 2 m. Thus, the sand fence cannot fully intercept wind-blown sand over gobi may be one of the main reasons for the sand deposition on rails of the Lanzhou-Xinjiang high-speed railway in Yandun Wind District.

Key words: gobi, saltation, sand flux profile, intermittency of sand transport, Yandun Wind District