Unraveling the 2023 record high temperatures in the eastern subtropical North Atlantic

During 2023, record high, widespread sea surface temperature (SST) anomalies of up to 1.5 °C developed in the North Atlantic, with a core located in the eastern subtropics. In a warming climate, extreme temperature events like this are increasing in frequency and intensity, having profound implications for marine life. The 2023 SST anomalies may have been driven by a combination of elements, such as weak winds, increased heat fluxes into the ocean, and basin-scale changes in circulation and heat transport. Yet, the relative importance of these factors has not been investigated. We use observational datasets, both in-situ and remotely sensed, as well as atmospheric reanalysis to provide long-term context and examine how different potential drivers contributed to the recent SST anomalies. Preliminary results show that throughout spring 2023, the eastern subtropical North Atlantic experienced anomalously high heat fluxes from the atmosphere to the ocean. Interestingly, large SST anomalies appeared almost instantly in regions of weaker wind speeds across the subtropics. We further explore connections between a general increase in upper ocean heat content, potential oceanic preconditioning over the prior two decades, and the North Atlantic Oscillation, contributing to favorable forcing conditions. We highlight the relative roles played by regional forcing and large-scale variability in the study region. Understanding the mutual importance of these roles is necessary when studying temperature extremes in the North Atlantic, especially as these events become more common and intense.