Impact of Dust Shortwave Absorption on General Circulation and Energy Transport

Mineral dust aerosols exhibit a distinct non-uniform distribution, characterized by enhanced concentrations meridionally within the subtropics and zonally across the Middle East and North Africa. This distribution profile leads to variability in the top of the atmosphere (TOA) radiative forcing, which potentially modulates both zonal and meridional temperature and energy gradients. Consequently, the general circulation and energy transport, which are strong functions of TOA forcing gradients, should change in response to dust forcing. Moreover, the optical properties of dust differ significantly across regions and carry substantial uncertainty when estimating radiative forcing. Dust can cause either positive or negative TOA forcing, depending on the refractive index. Hence, evaluating how the variability in dust's shortwave absorption (refractive index) affects circulation and energy transport is crucial.

Past investigations into climate change have extensively explored how various factors affect large-scale atmospheric circulations, including noticeable shifts in the Hadley cell, atmospheric jets, storm tracks, Walker circulation, and the Intertropical Convergence Zone (ITCZ). However, there is a scarcity of such studies in the context of dust radiative forcing.

This study focuses on understanding how general circulation characteristics and the meridional energy transport respond to dust radiative forcing, emphasizing the sensitivity to dust shortwave absorption. The study utilizes a high-resolution atmospheric general circulation model (HiRAM) to conduct the study. Preliminary findings highlight substantial changes in overturning circulations and circulation features like jets and storm tracks, with a marked sensitivity to variations in dust's shortwave absorption properties. These changes also impact energy transport.