Does Ground Surface Soil Aggregation Affect Transition of the Wind Speed Threshold for Saltation and Dust Emission?

抄録

A new dust observation site was built in Tsogt-Ovoo, which is located in the northern Gobi Desert in Mongolia, to clarify wind erosion processes. Ten dust events were detected from March 24 to May 4, 2012. Strong winds (greater than 20 m s^-1 at an altitude of 3 m) blew predominantly from the west. Clear relationships among wind speed, saltation and particulate matter concentrations less than 10 μm (PM₁₀) were detected. A transition in the wind speed threshold for saltation was observed at Julian day (JD) 111 (April 20); before JD 111, the threshold was 14.0 m s^-1, but it decreased to 8.8 m s^-1 after JD 111. We discuss the reason for this threshold discontinuity, focusing on the ground surface conditions. It is hypothesized that this discontinuity is caused by the destruction of the surface soil aggregation.