Cold surface temperature in the Nordic. Seas during MIS 11. Kandiano et al., Palaeo3, 2012;. Thibodeau et al., EPSL, 2017 ...
The Sensitivity of Nordic Seas Upper-Ocean Stratification to Freshwater Input Benoit Thibodeau1, Henning Bauch2, Tom Pedersen3 & Andreas Schmittner4 1The
University of Hong Kong, 2Alfred Wegener Institute, 3University of Victoria, 4Oregon State University
Modes of the Atlantic meridional overturning circulation (AMOC)
Strength of the current
Presence of North Atlantic water
Böhm et al., Nature, 2015
MIS 11: Strong AMOC • Minimal difference in d13C = Strong(er)
AMOC • Large difference in d13C = Weak(er) AMOC
Vazquez Riveiro et al., EPSL, 2013
Cold surface temperature in the Nordic Seas during MIS 11
Kandiano et al., Palaeo3, 2012; Thibodeau et al., EPSL, 2017
Where the warm water went during MIS11? Tracing the mixed-layer depth through time
Thibodeau et al., EPSL, 2017
Nitrogen isotope to trace N-utilization and mixed-layer depth
Using d15N in sub-polar North Atlantic and Arctic Ocean
Straub et al., Paleoceanography, 2013 Schubert et al., Paleoceanography, 2001
Core PS1243
6.4 5.2
4.8
Thibodeau et al., EPSL, 2017
Mixed-layer variations throughout the last interglacials based on d15N and NPs abundance
Why the summer mixed-layer would be thicker during MIS 11? • dDA(C37:2, C37:3)
Kandiano et al., GRL, 2017
OSUVic 2.9 • Climate model of intermediate complexity including a GCM at
coarse resolution and a biogeochemical component (including d15N & d13C)
Schmittner and Somes, Paleoceanography, 2016
Freshwater effect on d15N-NO3 at our coring site
Mixed-layer depth increased by about 20%
d15N-NO3
Red = control Green = 400 yrs hosing Black = 1400 yrs hosing
N-utilization
d15N-NO3
Seasonality in the d15N and nitrate utilization
Any relevance to AMOC intensity?
Thibodeau et al., unpublished (GRF-proposal), 2016
MIS 11 strong AMOC or weak AMOC? • Indication of strong AMOC • But…we can’t model a strong AMOC with a thick and fresh
mixed-layer over the Nordic Seas
Schmittner & Lund, 2015, Clim Past
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