Characteristics of Dust Outbreaks and their Relation to Strong Wind and Land Surface Conditions in the Gobi Desert and Northern China, 1999-2013

Abstract

The arid and semi arid regions in the Gobi Desert and northern China are one of the main source regions for Asian dust events. The aim of this study is to understand the spatial and temporal characteristics of spring dust outbreaks that occurred during the period from 1999 to 2013. Spatial distributions show that dust outbreaks occurred most frequently in the Gobi Desert, followed by the Loess Plateau. In those regions, strong wind also occurred frequently, and the dry land surfaces were characterized by sparse vegetation and snow cover. However, dust outbreaks occurred infrequently in the Inner Mongolian grassland, even though frequent strong wind was observed. Temporal variations show that the occurrence of dust outbreaks was highest between 2000 and 2002, followed by 2006, and then decreased significantly between 2007 and 2013. Statistically significant correlations were found between the frequency of dust outbreaks and strong wind (r=0.80, p<0.01), and the spring normalized difference vegetation index (NDVI) (r=-0.67, p<0.01). Thus, the frequency of dust outbreaks increased with the occurrence of strong wind, and was inhibited by abundant spring vegetation. Since the condition of vegetation coverage is connected with the condition of land degradation and desertification, the effect of anthropogenic factors (e.g., grazing) on vegetation is also discussed. Due to the limitation of available data, this study region is restricted in Inner Mongolia. The results suggest that the expansion of fenced grassland areas, and a plateauing of the amount of land being cultivated and the livestock population were related to the increase in the NDVI, especially from 2007 to 2013, which in turn was responsible for the recent decline in the frequency of dust outbreaks.