Variation Patterns of the ENSO’s Effects on Dust Activity in North Africa, Arabian Peninsula, and Central Asia of the Dust Belt

Abstract

El Niño/Southern Oscillation (ENSO) events produce anomalous oceanographic and atmospheric conditions in regions far from the equatorial central-eastern Pacific, which modulate the atmospheric and surface processes that influence the dust emission, transport, and deposition in many places on Earth. In this study, we examined the MERRA-2 dust column mass density data in five subregions of the “dust belt”: eastern and western Arabian Peninsula, western and eastern Central Asia, and North Africa-Sahara during 1980–2021. We discovered that, while there is a common dust season from April to July, the specific dust seasons in these subregions are different with the peaks of dust activity occurring at different times of the year. In the meantime, the modulating effects of ENSO also peak at different times within the respective dust seasons. For example, ENSO has a persistent effect on dust activity during April-August in the eastern Arabian Peninsula, while its influence in eastern Central Asia lasts from February to November. For different well-recognized factors of dust activities, such as precipitation/humidity, wind, vegetation, and soil moisture, their responses to ENSO are also different in these subregions. For precipitation, humidity, and soil moisture, their responses to ENSO are mostly positive in winter and spring/early summer months during El Niño years, while mean daily maximum wind responded positively in spring, but it did so negatively in summer. During the three months when the ENSO’s effects were strongest, these factors could explain 25.1–58.6% of the variance in the dust column mass density in combination with the ENSO’s modulation effects. However, the highest model-explained variance was obtained for the North Africa–Sahara subregion where the intensity of dust activity was not statistically correlated with ENSO.