Consequences of future increased Arctic runoff on Arctic Ocean stratification, circulation, and sea ice cover

Aleksi Nummelin*, Mehmet Ilicak, Camille Li, Lars H. Smedsrud

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119 Atıf (Scopus)

Özet

The Arctic Ocean has important freshwater sources including river runoff, low evaporation, and exchange with the Pacific Ocean. In the future, we expect even larger freshwater input as the global hydrological cycle accelerates, increasing high-latitude precipitation, and river runoff. Previous modeling studies show some robust responses to high-latitude freshwater perturbations, including a strengthening of Arctic stratification and a weakening of the large-scale ocean circulation; some idealized modeling studies also document a stronger cyclonic circulation within the Arctic Ocean itself. With the broad range of scales and processes involved, the overall effect of increasing runoff requires an understanding of both the local processes and the broader linkages between the Arctic and surrounding oceans. Here we adopt a more comprehensive modeling approach by increasing river runoff to the Arctic Ocean in a coupled ice-ocean general circulation model, and show contrasting responses in the polar and subpolar regions. Within the Arctic, the stratification strengthens, the halocline and Atlantic Water layer warm, and the cyclonic circulation spins up, in agreement with previous work. In the subpolar North Atlantic, the model simulates a colder and fresher water column with weaker barotropic circulation. In contrast to the estuarine circulation theory, the volume exchange between the Arctic Ocean and the surrounding oceans does not increase with increasing runoff. While these results are robust in our model, we require experiments with other model systems and more complete observational syntheses to better constrain the sensitivity of the climate system to high-latitude freshwater perturbations.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)617-637
Sayfa sayısı21
DergiJournal of Geophysical Research: Oceans
Hacim121
Basın numarası1
DOI'lar
Yayın durumuYayınlandı - 1 Oca 2016
Harici olarak yayınlandıEvet

Bibliyografik not

Publisher Copyright:
© 2015. The Authors.

Finansman

We wish to thank M. Bentsen and I. Bethke for help with the model setup and B. Tremblay, L. Renaud-Desjardins, and E. Lambert for insightful discussions and helpful comments. We would also like to thank C. Lique, one anonymous reviewer, and the Editor for useful comments that helped improve the manuscript. We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, for data, and we thank the climate modeling groups (listed in supporting information Table S1 of this paper) for producing and making available their model output. For CMIP, the U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. All the data, model setup, and analysis scripts used in this study are available through the corresponding author by e-mail at [email protected]. M. Ilicak is supported by Ice2Ice project that has received funding from the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement 610055. This work was supported by the Bjerknes Centre projects DYNAWARM and BASIC and the Centre for Climate Dynamics (SKD) at the Bjerknes Centre (C. Li).

FinansörlerFinansör numarası
BASIC
Bjerknes Centre projects DYNAWARM
U.S. Department of Energy
Seventh Framework Programme
European Research Council610055

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