| Summary: | Presented at the GHRSST XXIII international science team meeting, 27 June-1 July 2022, online and in-person (Barcelona). #GHRSST23 Short abstract The North Atlantic is characterised by dipole sea surface temperature (SST) differences that result from the regional segments of the global thermohaline circulation: While such Sea Surface Temperature (SST) patterns are well documented, more recently, attention has also been drawn to the urgency of detecting and predicting marine heatwaves (MHW). Like their atmospheric counterparts, MHWs have been associated with anthropogenic climate change, impacting both the marine fauna (e.g., coral bleaching, megafauna mortality, species-range shift) and flora (e.g., dieback of kelp forests, harmful algal blooms). In this study, 39 years of remotely sensed SST observations are used to identify spatio-temporal patterns of MHWs in the N. Atlantic (1982-2020 period). The 0.25˚ spatial resolution data is subject to MHW detection using the deviation from the climatological 90th percentile during at least 5 days as the criteria to measure pixel-wise anomalies. Results show that MHW events are becoming more frequent in the westernmost North Atlantic region, particularly in the Gulf Stream - this zonal pattern agrees with the typical N. Atlantic dipole SST gradient, which is shown to be increasing. Conversely, MHW intensity trends – both mean magnitude and maximum amplitude – reveal the polar amplification signal, i.e., the greatest increases are detected in the northernmost region, where the mean rate of intensity reaches up to 1ºC change, per decade.
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