Fig. 4: Linear trends of the potential temperature and horizontal velocity vertically-averaged within the surface mixed layer in the North Atlantic for NAGA and HIST.

Linear trends in the DJF mean horizontal current (vector) and velocity (colors) [cm s⁻¹ decade⁻¹] for a HIST and b NAGA. The horizontal velocity is vertically averaged within the surface mixed layer. The hatching and black vectors indicate statistically significant linear trend. The black solid box shows the area in which SST anomalies are restored to the observations in NAGA. c–h As in a and b, but for c and d for potential temperature [°C decade⁻¹], e and f oceanic contribution to the mixed layer temperature tendency [Ks⁻¹ decade⁻¹] (Eq. 3), and g and h atmospheric contribution to the mixed layer temperature tendency [Ks⁻¹ decade⁻¹] (Eq. 3).