Understanding the mechanisms of dust impacts on climate and nonlinear characteristics of climate responses to global dust loading using CESM

Dust aerosols represent typical absorbing aerosols, as they are responsible for modifying incoming solar radiation, causing surface cooling, and atmosphere heating. While dust accounts for approximately 30 percent of total aerosol loading at a global scale, its spatial and temporal patterns are heterogeneous. The many impacts of dust on climate are currently poorly understood. We conducted five sensitivity experiments of the present-day climate with a fully coupled climate model, the Community Earth System Model (CESM). For each experiment, the dust module in the CESM was modified to yield 10x, 5x, 0.5x and 0.2x surface dust emission at the global scale. An additional set of sensitivity experiments with prescribed sea surface temperature was carried out to investigate radiative forcing due to climate perturbation. We have found that dust impacts to climate have nonlinearity, especially in the western tropical Pacific. Increase in dust emission over the Sahara Desert triggers additional transport of dust particles to the tropical Atlantic. Dust impact over the tropical Atlantic propagates to the sub-tropical Atlantic. Thus, the large scale impacts of dust appear to be associated with the variation of the Atlantic Multi-decadal Oscillation (AMO). Our research suggests that the mechanisms of dust impacts include the generation of an opposite sign from the AMO phase by changes over the Atlantic. Our study shows to what extent increased dust loading in the future can amplify the AMO in the opposite way. Our results will give insight to the impacts of dust on global monsoons.