Freshwater routing in eddy-permitting simulations of the last deglacial: the impact of realistic freshwater discharge

• Published in: Climate of the Past
• Main Authors: Love, Ryan, Andres, Heather J., Condron, Alan, Tarasov, Lev
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: European Geosciences Union 2021
• Subjects: Bering Strait; Dansgaard-Oeschger events; North Atlantic
• Online Access: https://hdl.handle.net/1912/27915

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Love, R., Andres, H. J., Condron, A., & Tarasov, L. Freshwater routing in eddy-permitting simulations of the last deglacial: the impact of realistic freshwater discharge. Climate of the Past, 17(6), (2021): 2327–2341. https://doi.org/10.5194/cp-17-2327-2021. Freshwater, in the form of glacial runoff, is hypothesized to play a critical role in centennial- to millennial-scale climate variability, such as the Younger Dryas and Dansgaard–Oeschger events, but this relationship is not straightforward. Large-scale glacial runoff events, such as Meltwater Pulse 1a (MWP1a), are not always temporally proximal to subsequent large-scale cooling. Moreover, the typical design of hosing experiments that support this relationship tends to artificially amplify the climate response. This study explores the impact that limitations in the representation of runoff in conventional “hosing” simulations has on our understanding of this relationship by examining where coastally released freshwater is transported when it reaches the ocean. We particularly focus on the impact of (1) the injection of freshwater directly over sites of deep-water formation (DWF) rather than at runoff locations (i.e. hosing), (2) excessive freshwater injection volumes (often by a factor of 5), and (3) the use of present-day (rather than palaeo) ocean gateways. We track the routing of glaciologically constrained freshwater volumes from four different inferred injection locations in a suite of eddy-permitting glacial ocean simulations using the Massachusetts Institute of Technology General Circulation Model (MITgcm) under both open and closed Bering Strait conditions. Restricting freshwater forcing values to realistic ranges results in less spreading of freshwater across the North Atlantic and indicates that the freshwater anomalies over DWF sites depend strongly on the geographical location of meltwater ...