Interannual Variability of African Dust with Seasonal Distinction in Recent Decades from a Multi-Satellite Analysis

Dust affects key components of the climate system, including energy, water, and carbon cycles, in many ways. The emission and transport of dust is strongly modulated by surface and meteorological conditions that change in a changing climate. Model simulations of dust variability depend strongly on how the dust lifecycle is represented in models, which currently has large uncertainties and is model-dependent. In this study, we acquired an observational understanding of the interannual variability of African dust over the last two decades by analyzing remote sensing measurements from multiple satellites (MODIS, CALIOP, MISR, and IASI) and AERONET. We separate dust from non-dust aerosol by using remote sensing measurements of particle size and shape. All the measurements show a consistent interannual variability of dust optical depth in North Africa and tropical North Atlantic Ocean, which is mainly driven by that in spring. The interannual variability correlates negatively with prior-year Sahelian rainfall anomaly and has become more pronounced since 2009 when Sahelian rainfall varied substantially from year to year. A composite analysis between high-dust years and low-dust years shows that the dust interannual variability in source regions is mainly controlled by surface wind speed, although variability of soil moisture and vegetation cover is also consistent with the dust variability.