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Abstract Transformation of light to dense waters by atmospheric cooling is key to the Atlantic Meridional Overturning Circulation in the Subpolar Gyre. Convection in the center of the Irminger Gyre contributes to the formation of the densest waters east of Greenland. We present a 19‐year (2002–2020) weekly time series of hydrography and convection in the central Irminger Sea based on (bi‐)daily mooring profiles supplemented with Argo profiles. A 70‐year annual time series of shipboard hydrography shows that this mooring period is representative of longer‐term variability. The depth of convection varies strongly from winter to winter (288–1,500 dbar), with a mean March mixed layer depth (MLD) of 470 dbar and a mean maximum density reached of 27.70 ± 0.05 kg m⁻³. The densification of the water column by local convection directly impacts the sea surface height in the center of the Irminger Gyre and thus large‐scale circulation patterns. Both the observations and a Price‐Weller‐Pinkel mixed layer model analysis show that the main cause of interannual variability in MLD is the strength of the winter atmospheric surface forcing. Its role is three times as important as that of the strength of the maximum stratification in the preceding summer. Strong stratification as a result of a fresh surface anomaly similar to the one observed in 2010 can weaken convection by approximately 170 m on average, but changes in surface forcing will need to be taken into account as well when considering the evolution of Irminger Sea convection under climate change. 

Abstract Observations indicate that symmetric instability is active in the East Greenland Current during strong northerly wind events. Theoretical considerations suggest that mesoscale baroclinic instability may also be enhanced during these events. An ensemble of idealized numerical ocean models forced with northerly winds shows that the short time‐scale response (from 10 days to 3 weeks) to the increased baroclinicity of the flow is the excitation of symmetric instability, which sets the potential vorticity of the flow to zero. The high latitude of the current means that the zero potential vorticity state has low stratification, and symmetric instability destratifies the water column. On longer time scales (greater than 4 weeks), baroclinic instability is excited and the associated slumping of isopycnals restratifies the water column. Eddy‐resolving models that fail to resolve the submesoscale should consider using submesoscale parameterizations to prevent the formation of overly stratified frontal systems following down‐front wind events. The mixed layer in the current deepens at a rate proportional to the square root of the time‐integrated wind stress. Peak water mass transformation rates vary linearly with the time‐integrated wind stress. Mixing rates saturate at high wind stresses during wind events of a fixed duration which means increasing the peak wind stress in an event leads to no extra mixing. Using ERA5 reanalysis data we estimate that between 0.9 Sv and 1.0 Sv of East Greenland Coastal Current Waters are produced by mixing with lighter surface waters during wintertime due to down‐front wind events. Similar amounts of East Greenland‐Irminger Current water are produced.