Linear Relation Between Shifting ITCZ and Dust Hemispheric Asymmetry

Mineral dust is emitted primarily from arid regions, which may shrink or expand in one or both hemispheres, producing a complex and asymmetric pattern of radiative forcing that varies on interannual to millennial timescales. We assess the impact of hemispheric dust asymmetry on tropical precipitation. Using the Geophysical Fluid Dynamics Laboratory (GFDL) coupled climate model CM3 to simulate dust emission, we vary source strength in each hemisphere individually. Hemispherically asymmetric dust emission produces asymmetric dust load and radiative forcing. We find that the Intertropical Convergence Zone (ITCZ) shifts away from the hemisphere with enhanced dust load in response to the forcing asymmetry. We find significant linear relationships between the hemispheric imbalance and the latitude of tropical precipitation globally, in the Pacific, and especially in the Atlantic basin. This relationship offers a first-order estimation of dust effects on the hydrological cycle when investigating records of paleodust and for accurately predicting dust effects and feedbacks on future climate.