Sea surface circulation variability in the Ionian-Adriatic Seas. (November 2020)

• Record Type: Journal Article
• Authors: Kalimeris, Anastasios; Kassis, Dimitris
• Is Part Of: Progress in oceanography. Volume 189(2020)
• Publication Date: 2020-11
• Subjects: Circulation -- Central Mediterranean -- Surface currents -- Mediterranean climatic variability; AdDW Adriatic Deep Water -- AdSW Adriatic Surface Water -- AIS Atlantic Ionian Stream -- AW Atlantic Water -- BiOS Adriatic‐Ionian Bimodal Oscillation System -- CAd Central Adriatic -- CDW Cretan Deep Water -- CIW Cretan Intermediate Water -- CMEMS Copernicus Marine Environment Monitoring Service -- COI Cone of Influence -- CWT Cross-Wavelet Transform -- DWF Dense Water Formation -- EIon Eastern Ionian -- EMDW Eastern Mediterranean Deep Water -- EMed Eastern Mediterranean -- EMT Eastern Mediterranean Transient -- ExtIon Extended Ionian domain -- ISV Ionian Shelfbreak Vortex -- ISW Ionian Surface Water -- LIW Levantine Intermediate Water -- LSW Levantine Surface Water -- MCC Maltese Channel Crest -- MED REA Mediterranean Sea Physical Reanalysis -- MIJ Mid-Ionian Jet -- MRV Malta Rise Vortex -- NAd Northern Adriatic -- NIG North Ionian Gyre -- NIon Northern Ionian -- NIR Northern Ionian Reversal -- PG Pelops Gyre -- SAd Southern Adriatic -- SEIon Southeastern Ionian -- SIon Southern Ionian -- SSH Sea Surface Height -- SWIon Southwestern Ionian -- TW Transitional Water -- WCC Western Cretan Cyclone -- WGI Western Greece - Ionian Islands zone -- WIon Western Ionian -- WMed Western Mediterranean; Oceanography -- Periodicals; 551.4605
• DOI: 10.1016/j.pocean.2020.102454
• Languages: English
• ISSNs: 0079-6611

Abstract

Highlights: The sea-surface circulation variability in the Ionian-Adriatic region is studied. Two alternative circulation indices are used to quantify the surface current variations. The circulation sense and strength is analyzed over a period of 60 years. The significant variability modes of the surface circulation are resolved. Circulation regime shifts associated with different dynamical epochs are detected. Abstract: The surface circulation of the Ionian and Adriatic Seas is explored by the re-analysis of available datasets that estimate the mean monthly ocean state for the 60 years-long time period 1955–2015. Emphasis is given to the major recurrent and transitional events in the area. Two circulation indices are utilized for the quantification of the cyclonic or anticyclonic circulation modes and intensity, one based on the vorticity flux of the reconstructed mean monthly surface velocity field, and another based on an appropriately modified version of the velocity field. Such quantification consequently allows for a detailed analysis of the surface circulation variability for the entire Ionian and Adriatic basins, as well as for sub-regions of particular interest. Discontinuities associated with possible regime shifts of the examined flow field were identified by time-series analysis of the circulation indices and compared to well-documented events in the hydrography of the studied area. Subsequently, the statistically significant components of the surface circulation variability were resolved out of a red noise background in the time–frequency domain and their evolution was studied. The results highlight the presence of various circulation modes and reversals in different temporal scales (mainly seasonal and decadal to inter-decadal) which are discussed in reference to the dynamics of both the sub-regional (Western, Northern, Eastern, and Southern Ionian, as well as Northern and Southern Adriatic), and of the basin-wide (Ionian or Adriatic) spatial scales. The relationships of the surface circulation variability between the Ionian and the Adriatic basins are also assessed through wavelet coherence.