Evaluating hydroclimatic persistence signals in Antarctic snowfall accumulation and sea salt sodium records

Abstract

Antarctic ice core proxy records of atmospheric circulation (sea salt aerosol concentrations) and precipitation (annual snowfall accumulation) have potential for estimating long-term hydroclimatic persistence (the tendency for wet and dry years to cluster) and drought risk in the Southern Hemisphere. However, the fidelity of the persistence signal in ice cores has not been examined. While Antarctica lacks long-term, in-situ precipitation/snowfall measurements with which to evaluate persistence signals in ice cores, various hydrological studies have demonstrated that hydroclimatic persistence in long-term rainfall records is similar over mid- to high-latitudes. This similarity means that Antarctic ice core persistence can be compared with long-term, Southern Hemisphere mid-latitude rainfall records. In this study, the persistence signal in Antarctic ice core records from regions with high enough precipitation to be annually resolved were evaluated against extended annual precipitation records from the mid-latitude Southern Hemisphere (23.5°S to 50°S). We found that similar to annual mid-latitude precipitation, annual snowfall accumulation and annual sea salt aerosol records exhibited long-term persistence (with mean Hurst parameters ranging from 0.55 to 0.62). Additionally, persistence in both the annual snowfall accumulation and annual sea salt aerosol records from ice cores was statistically similar to mid-latitude precipitation persistence. These findings suggest that information from Antarctic ice core records can be used to constrain uncertainty in hydroclimatic persistence estimates in the mid-latitude Southern Hemisphere – providing a promising avenue for using insights from paleoclimate data to improve drought resilience and water security.