Modeling the Ventilation of the Vortex Periphery for Anticyclonic Quasi-Permanent Lofoten Vortex

Abstract

This study examines the structure of the Lofoten Anticyclone, located in the Lofoten Basin of the Norwegian Sea. The high-resolution ROMS model is used for hydrodynamic modeling of the Lofoten Basin circulation. The dynamics of the Lofoten Vortex are investigated using the Lagrangian methods, where trajectories of passive tracers advected by the model velocity field are calculated, and Lagrangian indicators are computed for the studied region. Lagrangian markers initially located both in the core and on the periphery of the Lofoten Vortex are considered, showing different behaviors. Lagrangian markers in the core move along closed trajectories with angular velocities depending on their distance from the eddy's center. Those initially on the periphery form a series of S-shaped folds and twists, entering and exiting the eddy. We refer to this process as “ventilation of the vortex periphery”. We demonstrated that particles leave the core and periphery of the eddy intermittently rather than uniformly over time, and the statistics of this process are analyzed. Additionally, it was found that the center of the Lofoten Vortex not only drifts cyclonically at an average speed of 3.8 cm/s but also oscillates in the horizontal plane, with the amplitude increasing in the eastern part of the Vortex’s movement area.