Forecasting the Mediterranean Sea marine heatwave of summer 2022

Abstract

Abstract. Early warning of marine heatwaves requires short-term forecasts to provide precise information on timings, local-scale coverage, and intensities of coming events. Here, we describe our successful efforts to track the onset, peak, and decay of the Mediterranean Sea marine heatwave of summer 2022 with the Copernicus MedFS short-term (10 d) forecast system. First, we show that the 2022 event eclipses the economically and ecologically damaging event of 2003 in terms of marine heatwave (MHW) activity (a measure of intensity and duration). Forecasts of MHW area and activity provide a means of basin-wide validation, highlighting the capability of MedFS to capture regional behaviour. On local scales, we found that the MHW occurrence in the Ligurian Sea and Gulf of Taranto, two regions of economic and ecological importance, was also reliably forecast. Encouragingly, we note that the forecast has demonstrated skill in capturing not just the season-long MHW cycle but also breaks in MHW persistence and abrupt changes in local activity. Subseasonal forecasts do not yet demonstrate the capacity to predict MHW response to short-lived weather patterns, but this study confirms that short-term forecasts, at least in the Mediterranean Sea, can fill this gap.