Arctic Vortex changes alter the sources and isotopic values of precipitation in northeastern US

摘要

Altered atmospheric circulation, reductions in Arctic sea ice, ocean warming, and changes in evaporation and transpiration are driving changes in the global hydrologic cycle. Precipitation isotopic (δ¹⁸O and δ²H) measurements can help provide a mechanistic understanding of hydrologic change at global and regional scales. To study the changing water cycle in the northeastern US, we examined the longest (1968–2010) record of precipitation isotope values, collected at the Hubbard Brook Experimental Forest in New Hampshire, US (43^o56′N, 71^o45′W). We found a significant reduction in δ¹⁸O and δ²H values over the 43-year record, coupled with a significant increase in d-excess values. This gradual reduction in δ¹⁸O and δ²H values unexpectedly occurred during a period of regional warming. We provide evidence that these changes are governed by the interactions among the Atlantic Multidecadal Oscillation, loss of Arctic sea ice, the fluctuating jet stream, and regular incursions of polar air into the northeastern US.