On the structure of the Lofoten Basin Eddy

• DOI: 10.1002/jgrc.20301
• Publication Date: 2013-07-11T11:50:59Z
• Authors: H. Søiland; T. Rossby
• Keywords: Eddy; Anticyclone; Pycnocline; Mixed layer

A small anticyclonic eddy of extraordinary intensity sits in the center Lofoten Basin near 69°40′N, 3°E. This paper gives a first detailed description its kinematics and lowest‐order dynamic balances. Using 75 kHz vessel‐mounted acoustic Doppler current profiler, hydrography, six RAFOS floats to probe eddy, we document solid body core with 7–8 km radius relative vorticity very close –f, where f is local Coriolis parameter. Maximum orbital velocities 0.8 ms −1 were observed at 18 radius. One float, trapped for 9 months, indicated undiminished strength throughout that period, possibly even intensifying winter. Hydrography revealed adiabatic conditions from bottom shallow seasonal thermocline 1000 m depth early July 2010. Thermal convection winter maintains an already deep pycnostad, may also play key role quite through penetrative deepens sharpens underlying pycnocline. Heat lost atmosphere has be replenished warm eddies shed off eastern branch Norwegian Atlantic Current, but mechanism(s) by which it added remains studied. Examination historical data sets suggests permanent feature Basin. Two hydrocasts 1960s show similar mixed layer albeit 1°C cooler than 2010, perhaps reflecting generally cold prevailed then.