An observational study of soil moisture effects on wind erosion at a gobi site in the Taklimakan Desert

The measurements at a gobi site suggest that (1) saltation mass flux q(z) is particle size and soil moisture-dependent and (2) a simple relationship exists between q and wind speed u and threshold wind speed u(t)(theta). The u(t)(theta) in wet conditions (theta=0.009 m(3) m(-3)) was estimated to be 9.5 m s(-1) at a height of 3.8 m. This value is 1.27 times larger than that in dry condition, which corresponds to Fecan et al.'s theoretical result. The (q) over cap (D) in wet conditions was smaller than that in dry conditions for the particles of 69-203 mu m in diameter. However, for 38 and 54 mu m particles, the (q) over cap did not change in both dry and wet conditions. Furthermore, long-term monitoring showed that (1) the ground surface was dry during Aeolian Dust Experiment on Climate Impact (ADEC)-Intensive Observation Period (IOP) 1 (8-21 April 2002), whereas it was wet during ADEC-IOP2 (16-27 March 2003) because of snowfall at the beginning of March, and (2) the visibility frequently became worse during warm season when strong winds over the threshold wind speed blew and was dry.