On the Rapid Warming in the Subtropical North Atlantic in 2011–2021

Abstract A rapid warming trend was observed in the upper 2,000 m of the subtropical North Atlantic in 2011–2021, with significant heat accumulation not only in the upper ocean layers (0–300 m, 300–700 m) but also in the mid‐depth layer (700–2,000 m). Warming in the mid‐depth layer accounted for approximately 40% of the upper‐2000 m warming, exceeding the global average in this layer. Our analysis indicates that warming in the upper 700 m was primarily driven by isopycnal heave changes, closely linked to anomalous anticyclonic atmospheric circulation. In contrast, warming in the mid‐depth layer was mainly attributed to spice variability, influenced by advection and water mass changes in both the subtropical and subpolar regions. Overall, this study highlights the importance of mid‐depth ocean heat uptake in shaping the ocean heat content variability in the subtropical North Atlantic and reveals the combined impact of local and remote processes.