The influence of Saharan Dust Radiative Forcing on Wave Activity over the Tropical Atlantic Ocean

Abstract:

Tropical Atlantic easterly waves, also known as African Easterly Waves (AEWs), are synoptic-scale disturbances that often serve as seeds of tropical Atlantic cyclogenesis. Previous studies have shown that Saharan dust aerosols have robust influences on the thermal and dynamical behaviors of the AEWs (Hosseinpour and Wilcox, 2014). Using the NCAR global climate model as well as NASA’s satellite observations and reanalysis datasets, we provide evidence of dust-induced changes on the characteristics of these waves across the tropical Atlantic Ocean.

The main goal of this study is to investigate the causality underlying the impacts of Saharan dust on the development of the waves. We have implemented advanced diagnostic methods to explore the role of dust on the eddy kinetic energy of the waves. We show that dust radiative forcing has the capability to act as an additional source of energy to fuel the development of the eddies over the ocean. We suggest mechanisms that explain the coupling of wave activity with dust radiative forcing that motivate variations in instability and evolution of tropical waves in a region of the world that is vulnerable to impacts from such variability. Because the AEWs contribute to the formation of hurricanes, the results of this study may have implications for tropical Atlantic cyclogenesis.