Combined Influence of IPO and AAO on Dust Events in South America

Abstract

Southern South America is an important dust source to Antarctica. However, there is a lack of overall understanding of the dust event variation in recent decades in South America. Here, we analyzed variations in the dust frequency in southern South America (south of 208S) from 1986 to 2020 and its causes with large-scale climatic factors, based on observational station data and reanalysis data. During the austral spring and summer, several stations recorded an average dust frequency exceeding 15 days, with some even surpassing 20 days. The frequency of dust events in spring exhibited a strong association with large-scale climate factors. Negative phases of the interdecadal Pacific oscillation (IPO) and the Antarctic Oscillation (AAO) were more likely to lead to an increase in the dust frequency in southern South America. The negative IPO had a greater impact on the Patagonia dust (south of 408S), resulted from a decrease in the drought index under the influence of downward motion. However, the negative AAO had a greater impact on the dust in South America over 208？408S by increasing strong wind frequency and decreasing the drought index over there. On longer time scales, model outputs from the Coupled Model Intercomparison Project phase 6 (CMIP6) also confirmed the combined influence of the negative IPO and negative AAO phases on southern South American dust.