Local Wintertime Tropospheric Response to Oceanic Heat Anomalies in the Nordic Seas Area

A regression analysis between observed summertime Atlantic water temperature anomalies at the entrance to the Barents Sea and atmospheric fields in the following winter from the NCEP–NCAR reanalysis in the period 1982–2006 is carried out. It shows that the ocean plays a key role in shaping wintertime tropospheric variability in the Nordic seas (Greenland–Iceland–Norwegian and Barents Seas) region. The oceanically driven atmospheric circulation anomaly around the Nordic seas marginal ice zone is intensified at the surface as a result of a thermally direct baroclinic adjustment. Frictional convergence in the cyclonic disturbance corresponding to warm ocean temperature anomalies forces ascending motion at the top of the planetary boundary layer and a compensating divergence aloft, which over the Barents Sea is extreme at the tropopause. A quasi-meridional overturning circulation anomaly is closed by descending motion south of the cyclonic disturbance. In addition, an equivalent barotropic flow anomal...