Freshwater input and vertical mixing in the Canada Basin’s seasonal halocline: 1975 versus 2006-2012

Type Article
Date 2022-07
Language English
Author(s) Rosenblum EricaORCID1, 2, Stroeve Julienne1, 3, 4, Gille Sarah T5, Tremblay L Bruno2, Lique CamilleORCID6, Fajber Robert7, Galley Ryan8, Barber David1, Loureiro Thiago9, Lukovich Jennifer1
Affiliation(s) 1 : Centre for Earth Observation Science, University of Manitoba, Winnipeg, Manitoba, Canada
2 : Department of Atmospheric Science, McGill University, Montreal, Quebec, Canada
3 : Centre for Polar Observation and Modelling, University College London, Earth Sciences, London, United Kingdom
4 : National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
5 : Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
6 : University of Brest, CNRS, IRD, Ifremer, Laboratoire d‘Oceanographie Physique et Spatiale (LOPS), IUEM, Brest, France
7 : Department of Physics, University of Toronto, Toronto, Ontario, Canada
8 : Department of Environment and Geography, University of Manitoba, Winnipeg, Manitoba, Canada
9 : Toronto, Ontario, Canada
Source Journal Of Physical Oceanography (0022-3670) (American Meteorological Society), 2022-07 , Vol. 52 , N. 7 , P. 1383-1396
DOI 10.1175/JPO-D-21-0116.1
Note This is a preprint and has not been peer reviewed. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints
Keyword(s) Ocean, Arctic, Ocean dynamics, Mixed layer, Seasonal variability, Multidecadal variability

The seasonal halocline impacts the exchange of heat, energy, and nutrients between the surface and the deeper ocean, and it is changing in response to Arctic sea ice melt over the past several decades. Here, we assess seasonal halocline formation in 1975 and 2006-2012 by comparing daily, May to September, below-ice salinity profiles collected in the Canada Basin. We evaluate differences between the two time periods using a one-dimensional (1D) bulk model to quantify differences in freshwater input and vertical mixing. The 1D model metrics indicate that two separate factors contribute similarly to stronger stratification in 2006-2012 than in 1975: (1) larger surface freshwater input and (2) less vertical mixing of that freshwater. The first factor is mainly important in August-September, consistent with a longer melt season in recent years. The second factor is mainly important from June until mid-August, when similar levels of freshwater input in 1975 and 2006-2012 are mixed over a different depth range, resulting in different stratification. These results imply that decadal changes to ice-ocean dynamics, in addition to freshwater input, significantly contribute to the stronger seasonal stratification in 2006-2012 than in 1975. The findings highlight the need for near-surface process studies to elucidate the roles of lateral processes and ice-ocean momentum exchange on vertical mixing.

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Rosenblum Erica, Stroeve Julienne, Gille Sarah T, Tremblay L Bruno, Lique Camille, Fajber Robert, Galley Ryan, Barber David, Loureiro Thiago, Lukovich Jennifer (2022). Freshwater input and vertical mixing in the Canada Basin’s seasonal halocline: 1975 versus 2006-2012. Journal Of Physical Oceanography, 52(7), 1383-1396. Publisher's official version : , Open Access version :