[ARCHIVE] Baltic Sea Level extreme from Observations Reprocessing

'''This product has been archived''' For operationnal and online products, please visit https://marine.copernicus.eu

'''DEFINITION''' The CMEMS BALTIC_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 baltic_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 meter 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 show the tide amplitude spatial variability along the Baltic coast, from 0.42 m above mean sea level in Visby (Gotland Island, south of Stockholm) to 0.82 m in Kemi (northern end of the Gulf of Bothnia), with a standard deviation ranging between 5 cm in Skanor (South) to 11 cm in Hamina (Gulf of Finland). The anomaly of the 99th percentile in 2019 is remarkably negative for all the basin, especially in its central part, where the anomaly reaches around -20 cm for most of the stations. Less negative values are found at the South and Northern areas (-10 cm to -16 cm). These anomalies are twice larger than the climatic variability in all cases.

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

'''DOI (product):''' https://doi.org/10.48670/moi-00203