Coastal and regional marine heatwaves and cold spells in the northeastern Atlantic

Abstract. The latest Intergovernmental Panel on Climate Change (IPCC) report describes an increase in the number and intensity of marine heatwaves (MHWs) a decrease cold spells (MCSs) global ocean. However, these reported changes are not uniform regional to local basis, it remains unknown if coastal areas follow open-ocean trends. Surface ocean temperature measurements collected by satellites (from 1982–2022) 13 buoys 1990–2022) analyzed northeastern Atlantic three subregions: English Channel, Bay Brest Biscay. activity metric, combining events, intensity, duration spatial extent, is used evaluate magnitude extreme events. results from situ satellite datasets for each studied regions quite agreement, although dataset underestimates amplitude both MHWs MCSs. This supports applicability method data, albeit with caution Also, this localized study European water highlights that similar being seen open oceans regarding events temperature, more frequent longer extending over larger areas, while opposite These trends can be explained mean variance sea-surface temperature. In addition, pace evolution dynamics differ among subregions. Among subregions, Channel region experiencing strongest summer MHW last 4 decades. Summer were very active 2022 due long Biscay 2018 intense 2017 high occurrence Winter MCSs largest 1987 1986 Channel. Finally, our findings suggest at interannual timescale, positive North Oscillation favors generation strong Atlantic, low-pressure conditions northern Europe off Iberian Peninsula winter dominate A preliminary analysis air–sea heat fluxes suggests that, region, reduced cloud coverage key parameter MHWs, winds increased important