École Nationale Supérieure de
Techniques Avancées

Résumé

We investigated changes in the hydrography and circulation over the Northern Nordic Seas. Horizontal AW pathways, Polar Waters (PW) and Modied Atlantic Water (MAW) out ows are examined through Mercator Physical System. Low frequency changes between 2007 and 2019 have been highlighted over the area. At the surface, the Transpolar Drift (TPD) shifted along the north-south axis and Polar Waters salinity has increased while southward PW velocities have decreased. At depth, surroundings of the Yermak Plateau and region of the Greenland Sea Gyre (GSG) have shown important temperature and salinity increases. The AW circulation along the Mohn Ridge (MR) and the Knipovitch Ridge (KR) is intensi- ed. The latest shows an increase of 74%, from 1.25Sv over the 2007/13 period to 2.17 Sv on average over the 2014/19 period. At the same time, PSY4 documents along the KR an activation of the mesoscale activity from 2015 onward. Mean circulation and eddy activity increases have led to increased lateral exchanges between warm and salty AW from the east and PW to the west. These exchanges have contributed to increase salinity and temperature in the GSG. Further north, westward recirculations at both 78.5oN (srB) and 80.10 oN (nrB) have decreased thus reducing the AW in ow to the EGC south of Fram Strait. Therefore southward velocities have weakened in the southern branch of the EGC although they have strengthened in its northern branch (north of Fram Strait). Finally, we have highlighted a northward shift of the heat and salt turbulent uxes north of 82oN.