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Title: A subtropical fate awaited freshwater discharged from glacial Lake Agassiz

The 8.2 kyr event is the largest abrupt climatic change recorded in the last 10,000 years, and is widely hypothesized to have been triggered by the release of thousands of kilometers cubed of freshwater into the North Atlantic Ocean. Using a high-resolution (1/6°) global, ocean-ice circulation model we present an alternative view that freshwater discharged from glacial Lake Agassiz would have remained on the continental shelf as a narrow, buoyant, coastal current, and would have been transported south into the subtropical North Atlantic. The pathway we describe is in contrast to the conceptual idea that freshwater from this lake outburst spread over most of the sub-polar North Atlantic, and covered the deep, open-ocean, convection regions. This coastally confined freshwater pathway is consistent with the present-day routing of freshwater from Hudson Bay, as well as paleoceanographic evidence of this event. In this study, using a coarse-resolution (2.6°) version of the same model, we demonstrate that the previously reported spreading of freshwater across the sub-polar North Atlantic results from the inability of numerical models of this resolution to accurately resolve narrow coastal flows, producing instead a diffuse circulation that advects freshwater away from the boundaries. To understand the climatic impact of freshwatermore » released in the past or future (e.g. Greenland and Antarctica), the ocean needs to be modeled at a resolution sufficient to resolve the dynamics of narrow, coastal buoyant flows.« less
Authors:
 [1] ;  [2]
  1. Univ. of Massachusetts, Amherst, MA (United States)
  2. Univ. of Alaska Fairbanks, Fairbanks, AK (United States)
Publication Date:
OSTI Identifier:
1159310
Grant/Contract Number:
FG02-09ER64725
Type:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 38; Journal Issue: 3; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Research Org:
Univ. of Alaska, Fairbanks, AK (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES