The Imprint of Southern Ocean Stratification on the Isotopic Composition
of Antarctic Precipitation
The local temperarture cannot explain the inter-annual variation in
δ18Oprecip in the coastal Antarctic in past few decades. To understand
this enigmatic variation, we have used long-term modern δ18Oprecip value
of three coastal Antarctic sites. Using the δ18O-d-excess relationship
and modelled δ18O value of vapor at source, we have shown that
δ18Oprecip inherits the signature of moisture source parameters (MSPs).
Furthermore, the wavelet analysis suggests that the variation in the
MSPs impacts the seasonal cycle of δ18Oprecip which 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 δ18Oprecip 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.