Regionalizing the Impacts of Wind- and Wave-Induced Currents on Surface Ocean Dynamics: A Long-Term Variability Analysis in the Mediterranean Sea

205 pages, 12 figures, 1 table, 3 appendixes.-- Data Availability Statement: All data are accessible from https://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=sfc/, https://www.cpc.ncep.noaa.gov/data/teledoc/telecontents.shtml and from https://resources.marine.copernicus.eu/?option=com_csw&view=details&product_id=SEALEVEL_MED_PHY_L4_REP_OBSERVATIONS_008_051Effects of wind and waves on the surface dynamics of the Mediterranean Sea are assessed using a modified Ekman model including a Stokes-Coriolis force in the momentum equation. Using 25 years of observations, we documented intermittent but recurrent episodes during which Ekman and Stokes currents substantially modulate the total mesoscale dynamics by two nonexclusive mechanisms: (a) by providing a vigorous input of momentum (e.g., where regional winds are stronger) and/or (b) by opposing forces to the main direction of the geostrophic component. To properly characterize the occurrence and variability of these dynamical regimes, we perform an objective classification combining self-organizing maps and wavelet coherence analyses. It allows proposing a new regional classification of the Mediterranean Sea based on the respective contributions of wind, wave, and geostrophic components to the total mesoscale surface dynamics. We found that the effects of wind and waves are more prominent in the northwestern Mediterranean, while the southwestern and eastern basins are mainly dominated by the geostrophic component. The resulting temporal variability patterns show a strong seasonal signal and cycles of 5–6 years in the total kinetic energy arising from both geostrophic and ageostrophic components. Moreover, the whole basin, specially the regions characterized by strong wind- and wave-induced currents, shows a characteristic period of variability at 5 years. This can be related to climate modes of variability. Regional trends in the geostrophic and ageostrophic currents show an intensification of 0.058 ± 1.43 · 10−5 cm/s per yearAuthors acknowledge financial support from MINECO/FEDER through projects MOCCA (RTI2018-093941-B-C31) and from the Balearic Islands Goverment Project ADAPTA. V. Morales-Márquez is supported by an FPI grant from the Ministerio de Ciencia, Innovación y Universidades. I. Hernandez-Carrasco acknowledges the Vicenç Mut contract funded by the Government of the Balearic Island and the European Social Fund (ESF) Operational Programme and the financial support from the Fundacion Universidad Empresa de las Islas Baleares, Spain, through project ALERTA (REF-190121). V. Rossi acknowledges financial support from the European project SEAMoBB, funded by ERA-Net Mar-TERA and managed by ANR (number ANR_17_MART-0001_01, P.I.: A.C.). This work was partially performed while V. Morales-Márquez was staying in MIO (Marseille, France) with the support of FPI grant from the Ministerio de Ciencia, Innovación y Universidades. In addition, this work was carried out in part when A. Orfila was a visiting scientist at the Earth, Environmental and Planetary Sciences Department at Brown University through a Ministerio de Ciencia, Innovación y Universidades fellowship (PRX18/00218)With the institutional support of the ‘Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe