Research on threshold friction velocities during dust events over the Gobi Desert in northwest China

摘要

Dust emission generated by wind erosion is the largest source of tropospheric aerosols. The Gobi Desert in northwest China has one of highest dust storm frequencies in northeast Asia. In this paper, a simple method is proposed to distinguish local dust emissions. A lag correlation coefficient R_(lag) of wind speed and dust concentration is introduced. Using observational data obtained from a 20 m monitoring tower in the Gobi Desert, the characteristics of dust concentration and friction velocities u_* during various dust emission periods were investigated. The threshold friction velocities u_(*t) were estimated to be 0.34–0.42 m/s over the Gobi area for four local dust events in April 2006. The values of u_(*t) were slightly smaller than those in previous results, but they were proven to be reasonable through validation based on additional dust events in April 2008 over the same area.