Fig. 3 Global patterns of submesoscale vertical heat transport. Values are spatially smoothed over 3° × 3° square boxes; positive values indicate upward. The heat fl ux is calculated at 40 m depth ( a , b ) and 200 m depth ( c , d ) during the winter or summer seasons: a , c Jan – March mean and b , d Jul – Sep mean. In most area of mid-latitudes, vertical heat transport at submesoscales is ~20 – 100 W/m 2 and is systematically