Interpreting recent accumulation records through an understanding of the regional synoptic climatology: an example from the southern Antarctic Peninsula

In this study we correlate temporal features within the electrical conductivity (acidity) traces of four shallow firn cores obtained from the southern Antarctic Peninsula to synoptic-scale variations in the regional climate, as depicted by a numerical weather prediction model. It is demonstrated that the three high-acidity features present within the 1992-93 accumulation correspond to periods of significant precipitation, a hypothesis supported by the association of these events with strong onshore winds, ideal for transporting the biogenically derived sources of precipitation acidity to the core sites. The longitudinal location of depressions within the Bellingshausen Sea is shown to be the principal factor governing the volume of precipitation that they give over the western Peninsula. Annual accumulation in the model is ~25% lower than revealed by the cores; although there are too many uncertainties to provide a definite reason for the deviation, the smoothed model orography and inaccurate land-sea mask are believed to be significant factors. It is postulated that the acidity pattern within southern Peninsula cores may reveal an El Niño-Southern Oscillation signal.