[ARCHIVE] North West Shelf Sea Surface Temperature extreme from Observations Reprocessing

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'''DEFINITION''' The CMEMS NORTHWESTSHELF_OMI_TEMPSAL_extreme_var_temp_mean_and_anomaly_obs OMI indicator is based on the computation of the 99th and the 1st percentiles from in situ data (observations). It is computed for the variable sea surface temperature measured by in situ buoys at depths between 0 and 5 meters. The use of percentiles instead of annual maximum and minimum values, makes this extremes study less affected by individual data measurement errors. The percentiles are temporally averaged, and the spatial evolution is displayed, jointly with the anomaly in the target year. This study of extreme variability was first applied to sea level variable (Pérez Gómez et al 2016) and then extended to other essential variables, sea surface temperature and significant wave height (Pérez Gómez et al 2018).

'''CONTEXT''' Sea surface temperature (SST) is one of the essential ocean variables affected by climate change (mean SST trends, SST spatial and interannual variability, and extreme events). In Europe, several studies show warming trends in mean SST for the last years. An exception seems to be the North Atlantic, where, in contrast, anomalous cold conditions have been observed since 2014 (Mulet et al., 2018; Dubois et al. 2018). Extremes may have a stronger direct influence in population dynamics and biodiversity. According to Alexander et al. 2018 the observed warming trend will continue during the 21st Century and this can result in exceptionally large warm extremes. Monitoring the evolution of sea surface temperature extremes is, therefore, crucial. The North-West Self area comprises part of the North Atlantic, where this refreshing trend has been observed, and the North Sea, where a warming trend has been taking place in the last three decades (e.g. Høyer and Karagali, 2016).

'''CMEMS KEY FINDINGS''' The mean 99th percentiles showed in the area present a range from 14ºC in the North West of the British Isles, 18-19ºC in the English Channel and North Sea to 20-21ºC in the Kattegat Sea. The standard deviation ranges from 0.6ºC in the English Channel and 0.8ºC in the North West of the British Isles to 1.2/1.5ºC in the buoys around Denmark. Results for this year show a general positive anomaly between +0.3ºC and +0.7ºC in the North West of the British Isles, English Channel and the Kattegat Sea, around their corresponding standard deviation and a higher positive anomaly (+1.7ºC) in Helgoland (North Sea) slightly above the standard deviation.

""Note: The key findings will be updated annually in November, in line with OMI evolutions.

'''DOI (product):''' https://doi.org/10.48670/moi-00274