Coastal Trapped Waves and Other Subinertial Variability along the Southeast Greenland Coast in a Realistic Numerical Simulation

Abstract

Ocean currents along the Southeast Greenland Coast play an important role in the climate system. They carry dense water over the Denmark Strait sill, fresh water from the Arctic and the Greenland Ice Sheet into the subpolar ocean, and warm Atlantic water into Greenland’s fjords, where it can interact with outlet glaciers. Observational evidence from moorings shows that the circulation in this region displays substantial subinertial variability (typically with periods of several days). For the dense water flowing over the Denmark Strait sill, this variability augments the time-mean transport. It has been suggested that the subinertial variability found in observations is associated with Coastal Trapped Waves, whose properties depend on bathymetry, stratification, and the mean flow. Here, we use the output of a high-resolution realistic simulation to diagnose and characterize subinertial variability in sea surface height and velocity along the coast. The results show that the subinertial signals are coherent over hundreds of kilometers along the shelf. We find Coastal Trapped Waves on the shelf and along the shelf break in two subinertial frequency bands—at periods of 1–3 days and 5–18 days—that are consistent with a combination of Mode I waves and higher modes. Furthermore, we find that northeasterly barrier winds may trigger the 5–18 day shelf waves, whereas the 1–3 day variability is linked to high wind speeds over Sermilik Deep.

The Annual Salinity Cycle of the Denmark Strait Overflow

“…However, we appreciate that this is logistically challenging due to the fishing activity and very strong currents, and may not be possible at present. In light of these observational difficulties, the continued use of ocean circulation models to understand the contribution of different sources to the overflow (e.g., Koszalka et al., 2013), the mixing of overflow with other water masses (e.g., Koszalka et al., 2017) and the drivers of high frequency variability at Denmark Strait (e.g., Gelderloos et al., 2021) is vital for future progress.…”

Intermittent Reduction in Ocean Heat Transport Into the Getz Ice Shelf Cavity During Strong Wind Events

“…Due to the small internal Rossby radius of a few kilometers, this process can only be captured by moorings located close to the ice front (such as GW 6 F ) and by numerical models with a high enough resolution. Coastal trapped waves are a well‐known phenomenon and have been observed along various coasts (e.g., Battisti & Hickey, 1984; Gelderloos et al., 2020; Inall et al., 2015; Robinson, 1964). Our results indicate that they are of particular importance around the coast of Antarctica, where the waves may block the inflow of warm bottom water into the ice shelf cavities as they travel along ice fronts.…”

Import of Atlantic Water and sea ice controls the ocean environment in the northern Barents Sea

“…Given the short timescales of the forcing and the ocean response, it is likely that the resulting ocean adjustment process involves the generation and propagation of topographically trapped waves (Mysak, 1980). Such waves are commonly observed as a result of wind anomalies along shelf breaks in the high-latitude ocean, where they contribute to elevated energy in the sub-inertial frequency band (Inall et al, 2015;Gelderloos et al, 2021). The complicated bathymetry means that the propagation of such waves might be rather complex in the study region, but waves generated upstream in the FSAW or even in the WSC might propagate into Kvitøya Trough and perhaps also the northern Barents Sea.…”