Multivariate analysis of sea level and thermohaline characteristics in the Mediterranean Sea

The estimation of three-dimensional oceanic parameters, such as temperature and salinity, presents significant challenges. The coarse sampling of in situ observations restricts our ability to directly analyze the thermohaline structure of the oceans. Satellite remote sensing offers great spatial coverage, but it is limited to surface data. Reanalyses merge model outputs with both in situ and satellite observations. This research intends to study how to improve them by identifying optimal techniques for extracting subsurface structural information from satellite data.The methodology adopted is based on the framework established by Ezer and Mellor and Adani et al. The problem is addressed by employing correlation factors that establish a connection between anomalies in sea surface elevation and anomalies in subsurface temperature and salinity profiles. These correlation factors are derived from time averages, making the selection of an appropriate time averaging interval crucial. This study explores various time intervals to determine which one yields the most favorable outcomes. Moreover Adani et al. (2011) utilizes Empirical Orthogonal Functions to derive the correlation factors. Specifically, bi- or tri-variate EOFs are applied to surface elevation data and vertical profiles of temperature and salinity. The various methodologies have been applied to investigate the reconstructions of salinity and temperature profiles for the years 2019-2020 across four distinct locations in the Mediterranean Sea, (Alboran, Tyrrhenian, Adriatic, and Levantine Seas) as well as to examine the structures of two different mesoscale eddies, specifically anticyclonic and cyclonic. The reconstruction of tri-variate EOFs, utilizing monthly correlation coefficients derived solely from data spanning 2019 to 2020, demonstrates optimal results. This finding implies that the multi-variate statistics and a small temporal range connected to our target reconstructions is the optimal choice.