Interconnectivity Between Volume Transports Through Arctic Straits

Abstract

Arctic heat and freshwater budgets are highly sensitive to volume transports through the Arctic‐Subarctic straits. Here we study the interconnectivity of volume transports through Arctic straits in three models; two coupled global climate models, one with a third‐degree horizontal ocean resolution (High Resolution Global Environmental Model version 1.1 [HiGEM1.1]) and one with a twelfth‐degree horizontal ocean resolution (Hadley Centre Global Environment Model 3 [HadGEM3]), and one ocean‐only model with an idealized polar basin (tenth‐degree horizontal resolution). The two global climate models indicate that there is a strong anticorrelation between the Bering Strait throughflow and the transport through the Nordic Seas, a second strong anticorrelation between the transport through the Canadian Arctic Archipelago and the Nordic Seas transport, and a third strong anticorrelation is found between the Fram Strait and the Barents Sea throughflows. We find that part of the strait correlations is due to the strait transports being coincidentally driven by large‐scale atmospheric forcing patterns. However, there is also a role for fast wave adjustments of some straits flows to perturbations in other straits since atmospheric forcing of individual strait flows alone cannot lead to near mass balance fortuitously every year. Idealized experiments with an ocean model (Nucleus for European Modelling of the Ocean version 3.6) that investigate such causal strait relations suggest that perturbations in the Bering Strait are compensated preferentially in the Fram Strait due to the narrowness of the western Arctic shelf and the deeper depth of the Fram Strait.

The Evaluation of the North Atlantic Climate System in UKESM1 Historical Simulations for CMIP6

“…Generally we find Arctic to North Atlantic oceanic volume and freshwater transports simulated with UKESM1 compare well with the available observational estimates and are accurate enough for the model to simulate the historical state of the Arctic‐North Atlantic exchanges. The mean volume transport through the Fram Strait in UKESM1 simulated over 1997–2014 of 2.4 ± 0.98 Sv is well within the observational range of 2.2 ± 2.1 Sv (de Boer et al., 2018). Observational estimates of the Fram Strait fresh water transport depend on the reference salinity, whether shelf or Atlantic water component are accounted for, on the layout of the moored instruments, and on the data interpolation strategy (as highlighted by the observed uncertainty in Figures 21d and 21e).…”

“…The key reasons for this are the large distance between the moorings, changes in instrumental layout from year‐to‐year, and absence of the observations on the Greenland continental shelf. The later requires the gap in the shelf transports to be filled with model estimates or extrapolate the data from nearest moorings (e.g., de Boer et al., 2018). The differences in the interpolation procedures can also introduce a large uncertainty in transport calculations.…”

The Response of the Nordic Seas to Wintertime Sea Ice Retreat

“…They show that in the Nordic seas, the climatology of the model is an improvement over its lower-resolution counterpart and is consistent with observations in terms of ocean volume transport (Hansen and Østerhus 2000;Fahrbach et al 2001;Jónsson and Briem 2003;Macrander et al 2005), precipitation (Xie and Arkin 1997), winter sea ice, sea level pressure (Uppala et al 2005), and sea surface temperature and salinity (Conkright et al 2002). Several other studies have also demonstrated that HiGEM has a good representation of the Arctic when compared with observations (Lique et al 2015;de Boer et al 2018).…”

Heat Balance in the Nordic Seas in a Global 1/12° Coupled Model

“…More recently, Muilwijk et al (2018) analyzed the variability in a century-long forced simulation of the same model. de Boer et al (2018) studied the variability of volume transports through the Arctic straits and their correlations using both a 1/38 and a 1/128 coupled model similar to GC3. The ongoing HighResMip experiments (Roberts et al 2019) will provide new opportunities to investigate the multidecadal variability of the AW inflow into the Arctic.…”