Interaction of the Lofoten Vortex with a Satellite Cyclone

Abstract

The Lagrangian-particles simulation in the Lofoten Basin area in the Norwegian Sea, based on the GLORYS12V1 reanalysis for the period from 2016-05-31 to 2016-06-28, was used to track the vortex pair consisting of the large quasi-permanent Lofoten Vortex (LV) and a cyclone generated nearby the LV. We show that the cyclone is a part of a shield around the LV. The core of the cyclone is partly located inside the LV. This structure forms an uneven vortex pair. We provide a complementary analysis of Lagrangian maps with temperature, salinity, and relative vorticity at 75 horizons from the surface to the bottom, consider the evolution of the vortex pair and obtain its characteristics. The cyclone moves around the LV passing along its periphery 348.97 km with a speed of 14 cm/s, which is comparable 23 cm/s, the orbital velocity of the LV during the study period. The orbital velocity of the satellite cyclone is 15 cm/s. The mean amplitude of the LV in the period from 2016-05-31 to 2016-06-28 is 12.50 cm, and the mean amplitude of the satellite cyclone for the same period is − 2.92 cm. The average radius of the LV is 57.48 km and 13.42 km for its satellite cyclone. The orbital velocities of the LV and its satellite cyclone (with their mean values of amplitude and radii) are 0.23 m/s and 0.15 m/s, respectively. The average integral (in a volume) relative vorticity of the eddies in the vortex pair is − 1.41 × 1018 c−1 for the LV and 3.19 × 109 c−1 for the satellite cyclone.