第七届青年地学论坛

Abstract: The Southern Hemisphere westerlies (SHW) play an important role in regulating the sea ice extent of Antarctic Southern Ocean (ASO). They modulate northward and upwelling of the Ekman current, which determine the sea surface temperature (SST) and the sea ice extent of this area. Some models indicate that the current strengthening and poleward shift of these winds is account for the observed Antarctic sea ice expansion in 1979-2015. However,  evidence from paleoclimatic archives is still scarce for understanding the mechanism between SHW and Antarctica sea ice on centennial to millennial timescales. Here we present a 11,500-year reconstruction of wind strength based on peat Macro-fossils and δ¹³C of peat cellulose from Andorra peatbog in southernmost Patagonia. The Macro-fossils results suggest a rapid Fen to Bog transition at 2900 cal yr BP which may be triggered by the subsequent intensification of SHW. Combined with  peat cellulose δ¹³C data, we found several centennial to millennial variations of SHW. Comparison of our SHW paleoclimate records with data tracking the Antarctic sea ice and SST reveals clearly synchronous in-phase Antarctic sea ice and SHW dynamics during past 11,500 years. This observation is consistent with model inferences of enhanced SHW contributing to the long-term (centennial to millennial) expansion of Antarctic sea ice extent.
 

δ13C of peat cellulose,peat macro-fossil analysis,Southern hemisphere westerlies,Antarctic sea ice extent