Ocean Heat Content in the Iberian-Biscay-Ireland regional seas

The ocean has the largest heat capacity of any single component of the climate system and plays a key dominant role in global heat content changes. Several recent studies have found that the Ocean Heat Content (OHC) has increased during the last decades, not only at a global scale, but also at regional/basin scales. To analyse OHC variability in the Iberia-Biscay-Ireland (IBI) region, several Copernicus Marine model and observed derived products are used together to provide multi-product estimations of OHC anomalies over the water column (at layers upper 150 m, 700 m, and 2000 m). This work provides an exhaustive analysis of spatial and temporal variability of OHC in the Northeast Atlantic region providing an analysis of area-averaged time series, trend maps, and trends linked with the main water masses found in the IBI region. The analysis of trends reveals that, despite a significant warming of the region in the period 1993–2020 (at rates of 0.4 W/m2), the thermohaline variability of subsurface water masses mainly dominates the OHC variability over the upper 2000 m. Additionally, vertical profiles of OHC trends are investigated, linking them with the vertical distribution of water masses; and describing how coupled inter-annual variability of Sub-Artic Intermediate Water, Mediterranean Outflow Water, and Labrador Sea Water accounts for an important part of the total OHC variability in the region.