A study on mesoscale eddies in the Irminger Sea and Iceland Basin using high resolution mooring data and satellite altimetry
Summary
The Irminger Sea and Iceland Basin are the main regions of deep water formation which feed the lower limb of the Atlantic Meridional Overturning
Circulation (AMOC). This deep water formation occurs due to deep convection in winter and restratification in summer. Changes in stratification
have far-reaching effects on the deep water formation, ultimately impacting
the climate of western Europe and the North Atlantic region. Ocean eddies
transport different water masses through the entire ocean outside of large
scale circulations. They have the potential to transport buoyant water to
the convection region, therefore impacting restratification. In this study we
use six years of high resolution mooring observations in the Irminger Sea to
determine the vertical and horizontal structures, temperature and salinity
of anticyclonic eddies. Additionally, we employ a global dataset of eddies
tracked through satellite altimetry to analyze the horizontal structures and
propagation of eddies across the eastern subpolar North Atlantic. Twelve
eddies have been detected through mooring observations. We find that
eddies at the mooring reach depths of up to 850 m with salinity between
35.02 g/kg
and 35.15 g/kg
and temperatures between 5.0° and 6.6°C. The
radii of mooring detected eddies lie between 16.5 km and 33.1 km. Based on
our analysis of globally tracked eddies using satellite altimetry, we observe
no discernible distinction in the characteristics of anticyclonic eddies between the Irminger Sea and Iceland Basin in a mean over a 30-year period.
The tracked eddies have a mean radius of 34 km and a mean lifetime of 60
days. They mainly travel westward over the span of their lifetime. Eddy
propagation is influenced by strong currents and shallow topography, but
independent of the background flow in the basin interior. The findings in
this study enhance our understanding of the characteristics and dynamics
of anticyclonic eddies in the Irminger Sea and Iceland Basin. The insights
gained from this research need yet to be linked to stratification and convection.