The Imprint of Southern Ocean Stratification on the Isotopic Composition of Antarctic Precipitation

The local temperarturecannot explain the inter-annual variation in δ¹⁸O_precip in the coastal Antarctic in past few decades. To understand this enigmatic variation, we have used long-term modern δ¹⁸O_precip value of three coastal Antarctic sites. Using the δ¹⁸O-d-excess relationship and modelled δ¹⁸O value of vapor at source, we have shown that δ¹⁸O_precip inherits the signature of moisture source parameters (MSPs). Furthermore, the wavelet analysis suggests that the variation in the MSPs impacts the seasonal cycle of δ¹⁸O_precipwhich lead to disparity in the seasonal isotope-temperature relationship. The Southern Ocean surface stratification, due to increase in the freshwater flux by glacier melting, led to alignment of MSPs in such a manner that altogether significantly lowered the isotopic composition of initially formed vapor, which is reflected in δ¹⁸O_precip at inter-annual scale.Our observations suggest that the palaeothermometry will underestimate the Antarctic temperature change for the periods characterized by warming and high glacier-melt.