Abstract. Ice cores at Siple Dome, West Antarctic receive the majority of their precipitation from Pacific Ocean moisture sources. Pacific climate patterns, particularly in response to the El Niño-Southern Oscillation, affect local temperature, atmospheric circulation, snow accumulation, and water isotope signals at Siple Dome. We examined borehole temperatures, accumulation, and water isotopes from a number of shallow ice cores recovered from a 60 km north–south transect of the Dome. The data (with coverage from 1920–1995) reveal a microclimate heavily influenced by ENSO and the location of the Amundsen Sea Low Pressure Area. The Dome Summit and Pacific Flank respond to La Niña conditions by warming, increased isotope ratios, higher deuterium excess, and increased snowfall. The Inland Flank responds to El Niño conditions and cold interior air masses by cooling, decreased isotope ratios, lower deuterium excess, and decreased snowfall. ENSO-type spectral signatures (2–7 yr) are present in all water isotope records, but are not similar in their power structures. A longer 300 yr wavelet analysis record from the Dome Summit shows a late 19th-century climate shift similar to that seen in South Pacific coral isotope records. Our analyses suggest that while an ENSO signal is evident at Siple Dome, the microclimate effect makes climate reconstruction problematic, a conclusion which should be considered at other West Antarctic coastal dome locations.
Climate reconstruction using data assimilation of water isotope ratios from ice cores
