[ARCHIVE] North West Shelf Mean Sea Level extreme from Observations Reprocessing

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'''DEFINITION''' The CMEMS NORTHWESTSHELF_OMI_SL_extreme_var_slev_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 level measured by tide gauges along the coast. The use of percentiles instead of annual maximum and minimum values, makes this extremes study less affected by individual data measurement errors. The annual percentiles referred to annual mean sea level are temporally averaged and their spatial evolution is displayed in the dataset northwestshelf_omi_sl_extreme_var_slev_mean_and_anomaly_obs, 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 level (SLEV) is one of the Essential Ocean Variables most affected by climate change. Global mean sea level rise has accelerated since the 1990’s (Abram et al., 2019, Legeais et al., 2020), due to the increase of ocean temperature and mass volume caused by land ice melting (WCRP, 2018). Basin scale oceanographic and meteorological features lead to regional variations of this trend that combined with changes in the frequency and intensity of storms could also rise extreme sea levels up to one metre by the end of the century (Vousdoukas et al., 2020). This will significantly increase coastal vulnerability to storms, with important consequences on the extent of flooding events, coastal erosion and damage to infrastructures caused by waves.

'''CMEMS KEY FINDINGS''' The mean 99th percentiles for the stations available in the area present a large variability related to the different tidal ranges, from nearly 3 m above mean sea level in Dunkerque (near the Dover Strait), with a standard deviation of 3 cm, to around 0.6 m in the other stations along the Swedish west coast, where the standard deviation ranges between 7 and 8 cm. The anomaly for 2019 is practically null in Dunkerke (-2mm) and clearly negative for the Swedish stations in the Eastern part of the basin, where it reaches -9 cm (Smogen). This negative anomaly is coherent with the values observed for the Baltic Sea this year (see CMEMS BALTIC_OMI_SL_extreme_var_slev_mean_and_anomaly_obs OMI).

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

'''DOI (product):''' https://doi.org/10.48670/moi-00272