2023-08-16 ブラウン大学
◆この研究結果は、アークティック海氷の予測モデルの改善や、気候変動がアークティックに及ぼす影響の理解に役立つ可能性があります。アークティックの急速な温暖化と、その海氷が地球の気候に果たす役割も明らかにされています。
＜関連情報＞
- https://www.brown.edu/news/2023-08-16/sea-ice-motion
- https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023GL103558
東グリーンランド限界氷帯における海氷力学的レジーム間の突然の遷移の証拠 Evidence of Abrupt Transitions Between Sea Ice Dynamical Regimes in the East Greenland Marginal Ice Zone
Daniel M. Watkins, Angela C. Bliss, Jennifer K. Hutchings, Monica M. Wilhelmus
Geophysical Research Letters Published: 31 July 2023
DOI:https://doi.org/10.1029/2023GL103558
Abstract
Sea ice modulates the energy exchange between the atmosphere and the ocean through its kinematics. Marginal ice zone (MIZ) dynamics are complex and are not well resolved in routine observations. Here, we investigate sea ice dynamics in the Greenland Sea MIZ using in situ and remote sensing Lagrangian drift datasets. These datasets provide a unique view into ice dynamics spanning spatial scales. We find evidence of tidal currents strongly affecting sub-daily ice motion. Velocity anomalies show abrupt transitions aligned with gradients in seafloor topography, indicating changes in ocean currents. Remote-sensed ice floe trajectories derived from moderate resolution satellite imagery provide a view of small-scale variability across the Greenland continental shelf. Ice floe trajectories reveal a west-east increasing velocity gradient imposed by the East Greenland Current, with maximum velocities aligned along the continental shelf edge. These results highlight the importance of small scale ocean variability for ice dynamics in the MIZ.
Key Points
- Ice dynamics measured with two new Lagrangian datasets show strong bathymetry dependent differences over short spatial scales
- Wind variability is insufficient to describe drift variability in regions with abrupt changes in bathymetry and large gradients in currents
- Drifting buoy observations show a spatially heterogeneous imprint of tidal currents on ice dynamics
Plain Language Summary
Sea ice in the Arctic Ocean plays an important role in climate due to its influence on ocean circulation and air-sea energy exchange. Ice motion results from competing and interacting effects of winds, ocean currents, and internal ice stresses. This study uses two novel observational datasets to analyze ice motion in the Greenland Sea and Fram Strait marginal ice zones. We find abrupt changes in the primary causes of ice motion associated with seafloor topography. In shallow seas, strong tidal currents affect ice drift, resulting in repeated opening and closing of the ice. Near the shelf edge, boundary currents increase ice drift speeds, causing ice pack shear. Sea ice models that ignore small-scale ocean currents will underestimate ice deformation.
