Basin-wide and coastal modes of north tropical Atlantic variability have distinct impacts on hurricanes

Warm sea surface temperature anomalies in the north tropical Atlantic are conducive to increased intensity and frequency of Atlantic hurricanes. The period 2023-2024 saw two consecutive warm events but with distinct anomaly patterns. Here we use observations and model outputs over the past several decades to determine whether there exists inherent diversity in north tropical Atlantic surface temperature spatial structures and impacts. We find two distinctive modes of variability: a basin-wide mode and a coastal mode, underpinned by differing relationships between air-sea heat flux and sea surface temperature anomalies. The basin-wide mode has a stronger influence on Atlantic hurricane activity due to its more westward and persistent anomaly pattern. Since the 1990s, the well-known impact from El Niño-Southern Oscillation on the north tropical Atlantic is felt through its influence on the basin-wide mode. Our results highlight the importance of distinguishing the two distinctive modes in assessing and predicting their impacts. Sea surface temperature variability in the tropical North Atlantic exhibits a basin-wide mode and a coastal mode, with the former having a stronger impact on Atlantic hurricane activity, according to an analysis of climate data from remote sensing and reanalyses over the period 1982–2024.