Numerical Insights Into Gobi Wind-Blown Sand: Deriving a Saltation Flux Scheme

Abstract

Dust emissions from land-air interaction in arid and semi-arid regions are crucial for predicting the global dust cycle. However, a comprehensive understanding of the complex physical mechanisms contributing to dust emissions from Gobi surfaces remains elusive. The expansive Gobi Desert, spanning northern China and Mongolia, significantly intensifies sandstorms in East Asia. Although researchers use models to study global dust transport, current models primarily depend on the aerodynamic roughness of the Gobi Desert. They often overlook the particle-bed collision processes unique to the Gobi bed surface, which differ significantly from those of desert surfaces, thus compromising the accuracy of global dust cycle simulations. In this article, we establish a numerical model for drift sand in the Gobi based on existing theoretical and experimental studies. The model accurately simulates the wind-blown sand in the Gobi and been used to investigate the saltation structure of sand transport. Simulations reveal an exponential decay of mass concentration with height, with an average attenuation rate of 0.00385 in the Gobi compared to 0.00806 in sandy deserts. The horizontal velocity of saltating particles increases with height following a power law. Through quantitative analysis of this structure, we present a saltation flux formula suitable for the Gobi.