Decadal to multi-decadal variability in Antarctic climate system as evidenced from high-resolution ice core records of coastal Dronning Maud Land, East Antarctica

Abstract:

Coastal regions of Antarctica receive significantly higher precipitation than the interiors and therefore, coastal ice core records are ideal for assessing decadal and multi-decadal climate variability in Antarctica during the last millennia. However, recent study has revealed that extreme precipitation events can dominate the seasonal and interannual variability of snowfall across the Antarctic continent, especially in the coastal areas. A careful examination of multiple proxy records with reliable chronological constraints is therefore, imperative for reconstruction of decadal to multi-decadal climate variability. While high-resolution ice cores representing the last millennia are better-distributed in West Antarctica, the ice core records from East Antarctica are sparse and are not consistent among themselves. Here, we review the decadal and multi-decadal modes of Antarctic climate variability during the past few centuries through the analysis of ice core records from Dronning Maud Land (DML). Our study revealed that such short-term variability in the past was linked to the changes in Southern Annular Mode (SAM), El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Since SAM is the dominant mode of climate variability across the southern hemisphere, it had a significant impact on the mean surface temperature over the DML region in the past. Over longer periods, the interaction between SAM and ENSO influenced the DML temperature variability. Although the temperature signals at ENSO band were persistent throughout the past two centuries, a systematic increase in high frequency bands were apparent since the mid-20^th century. Prior to this, low frequency variability at PDO band dominated the DML climate. The SAM also controlled the transport of dust flux to DML, through its influence over the westerlies that facilitate the dust transport from Southern South America. The present study also revealed that changes in ENSO and PDO phase relationships have influenced the aridity over the Southern South America and resultant dust transport to the DML region.