Drivers of anomalous surface melting over Ingrid Christensen Coast, East Antarctica

Abstract

Antarctica contains 90% of the Earth's ice; if it melts, it can significantly contribute to the rise in global sea levels. Over Antarctica, short-term atmospheric warming events have led to significant surface melt in summer. Understanding the conditions of such warming events and subsequent surface melt is highly prioritized in Polar Research. The austral summer of 2016-17 witnessed the largest melt duration of the 21^st century over Ingrid Christensen Coast (ICC), East Antarctica. Being situated on the grounded ice near four research stations, understanding the melt over the region has both scientific and operational importance. Here, we investigate the drivers of four major melt events identified over ICC for the austral summer of 2016-17 using the reanalysis dataset, ERA5. The first melt event, coinciding with the season's highest air temperature, was triggered by high turbulent heat flux from strong katabatic winds, while the rest of the events were triggered by low-level, liquid cloud-induced longwave radiation. During the melt events, anomalous high pressure ridges were present over the continent causing low pressure systems to remain stationary for an extended period and direct warm, moist air towards the ICC, facilitating melting. The present study observed melting occurring above the grounding zone, and if such melting extends to a larger scale beyond ice shelves, it could raise significant concerns regarding the hydrodynamics and stability of ice sheets in the future.