Temporal controls on global dust emissions: The role of surface gustiness

Abstract

Topographic depressions serve as the key spatial control on large global dust sources. In contrast, the temporal control on these hotspots has remained elusive. We provide the first global observational evidence that the annual cycle of emissions from dust hotspots is determined by an erosivity feature in the form of wind gustiness. We use TOMS AI and an aridity index to define 131 global dust hotspots. The correlation between the annual cycle of hotspot dust and the annual cycle of gustiness is 70% stronger than the corresponding correlation with wind. The mean significant correlation with wind (n = 106 hotspots) is 0.37 (σ = 0.24) and the mean of significant correlation (n = 118 hotspots) with gustiness is 0.63 (σ = 0.12). Whereas most model simulations of dust have relied on the broadscale wind, gustiness holds overwhelmingly more power in explaining the annual cycle of dust emissions from global dust hotspots.