Fig. 4 Sensitivity of the global heat budget to model resolution. Global maps of the annual-mean difference of a submesoscale vertical heat fl ux, b ocean surface temperature, c net air – sea heat fl ux, and d mixed layer depth between the 1/48° model and the 1/24° model (1/48° model minus 1/24° model). Values are spatially smoothed over 3° × 3° square boxes. The two models have identical setups except for the horizontal resolution. The model differences here are mainly caused by submesoscale at 10 – 20 km range. In most area of mid-latitudes, the 1/48° model exhibits upward heat transport at submesoscales larger than the 1/24° model, by ~4 – 10 W/m 2 ( a ; about 14% larger, as in Supplementary Figure 5d). This results in a sea surface warming of ~0.06 – 0.3 °C (see b ). This is ultimately compensated by a stronger upward ocean – atmosphere heat exchange (~4 – 10 W/m 2 , c vs a ). The 1/48° model generally has a shallower mixed layer depth than the 1/24° model (see d ). This is due to a stronger restrati fi cation in the 1/48° model (i.e., heat fl ux as in a ) and is linked to most of the difference in sea surface temperature (see b ). This is illustrated further in Supplementary Figure