Reorganization of atmospheric circulation between 1400-1700 CE as
recorded in a South Pole ice core
Abstract
Here we present an ~2000 year high-resolution
glaciochemical record from the South Pole. Significant changes in
chemical concentrations, accumulation rate, stable water isotopes and
deuterium excess records are captured during the period
~1400-1700 CE, indicating a reorganization of
atmospheric circulation that occurred in two steps:
~1400-1425 CE and ~1650-1700 CE. Major
declines in dust and SO42- concentrations are observed
~1400 CE suggesting poleward contraction of the southern
circumpolar vortex and potential intensification of westerly air flow,
accompanied by a sea ice decrease in the Weddell Sea and potentially
also in the Indian sector of the Southern Ocean. The changes in stable
water isotopes, deuterium excess, NO3- concentration and accumulation
rate characterize a second shift in atmospheric reorganization between
1650-1700 CE, reflecting increased marine air mass intrusions and
subsequent reduction of the katabatic winds, and a shift to a colder
moisture source for South Pole precipitation. These internally
consistent changes involving atmospheric circulations and sea ice
conditions are also in line with those identified for the recent period,
and include associations with the large-scale teleconnections of El Niño
Southern Oscillation (ENSO) and the Southern Annular Mode (SAM).