Strong ENSO variability in the Drake Passage in the 1990s

Decadal variability in the El-Niño-Southern Oscillation (ENSO) signal affecting the Drake Passage (30-90oS, 30-150oW) region between southern South America and the Antarctic Peninsula is demonstrated. Both station observations and National Centers for Environmental Prediction Reanalysis 2 show that the ENSO teleconnection is much more pronounced in the 1990s than the 1980s from the Drake Passage westwards to the 120ºW meridian along the 55ºS parallel.

Mean sea level pressure (MSLP) observations from Orcadas and Faraday stations on the Antarctic Peninsula are contrasted with the Southern Oscillation Index (SOI) to place the 1990s into the long-term perspective. The goal is to identify whether this decade represents climate variability or climate change, especially in view of the recent dramatic collapse of parts of the Larsen Ice Shelf. Very similar results are obtained from the Orcadas and Faraday records for the period of overlap, 1950-2000. Comparing the Orcadas MSLP record (starts in 1903) to the SOI shows that the 1990s and the 1920s are similar decades. Thus, the ENSO teleconnection to the Drake Passage region strongly varies on the multi-decadal to nearly centennial time scales.