[ARCHIVE] Mediterranean Sea Surface Temperature extreme from Observations Reprocessing

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'''DEFINITION''' The CMEMS MEDSEA_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 Mediterranean Sea has showed a constant increase of the SST in the last three decades across the whole basin. Deep analyses of the variations have displayed a non-uniform rate in space, being the warming trend more evident in the eastern Mediterranean Sea with respect to the western side. This variation rate is also changing in time over the three decades with differences between the seasons (e.g. Pastor et al. 2018; Pisano et al. 2020), being higher in Spring and Summer, which would affect the extreme values.

'''CMEMS KEY FINDINGS''' The mean 99th percentiles showed in the area present values from 26º in the Ligurian Sea, around 27ºC in the Iberian Peninsula to 28.6ºC in the Coast of Slovenia. The standard deviation ranges from around 0.4/0.8ºC in the Iberian Peninsula and Ligurian Sea to 0.9ºC in the Coast of Slovenia. Results for this year show a little positive anomaly in the Spanish Coast (0/+0.5ºC), +0.7ºC in the Coast of Slovenia (+0.3ºC) being both areas below their corresponding standard deviation and around 1ºC in the Ligurian 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-00267