Evolution of Maud Rise Polynya during the last 250 years – a multiproxy ice core reconstruction from coastal Dronning Maud Land, Antarctica

Abstract. Open ocean polynyas drive deep ocean convection, influencing regional carbon and heat budgets, which in turn influence the ocean circulation and overall climate of Antarctica. The Maud Rise Polynya (MRP), also known as the Weddell Polynya, is one such polynya that forms in the Southern Ocean during early spring or winter months. The extensively studied MRP opening, which occurred during 2016–2017 and 1974–1976, triggered intense convection, ventilating heat from the deep ocean and modifying water mass properties. However, polynya evolution beyond the satellite era remains poorly understood. Here, we develop a polynya index using multiple proxy records from an ice core in coastal Dronning Maud Land, East Antarctica. Our approach – integrating records of snow accumulation, δ¹⁸O, deuterium excess, Na flux, and Na/SO₄ ratios – enhances polynya reconstruction, thereby overcoming the limitations of single-proxy methods. The index replicates the 1974–1976 polynya and extends the record to 1774, revealing three major events comparable to the 1974–1976 great polynya event, in the past 250 years, totalling 47 polynya years. We identified distinct clusters of polynya activity, possibly corresponding to a specific combination of atmospheric circulation patterns and oceanographic preconditioning for MRP development. This study offers a long-term perspective on MRP variability, providing insights into its drivers and climate-related impacts.