Tidal Records as Liquid Climate Archives for Large-Scale Interior Mediterranean Variability

Abstract

Characterization of interior ocean variability is necessary for understanding climate. Water mass evolution shapes ocean-atmosphere interactions and contributes to determine timescales for global and regional climate variability. However, a robust assessment of past state and variability of the ocean interior is prevented by sparseness/shortness of historical subsurface observations and uncertainties affecting proxy-based reconstructions. Here, we propose a novel approach to infer past large-scale interior ocean variability with unprecedented accuracy and temporal resolution. It exploits links between stratification determined by “large-scale” water mass distributions and local dynamics. We characterize interannual interior ocean variability in the Mediterranean Sea in the early 20th century contained in tidal measurements in the Strait of Messina, and demonstrate the general applicability of our method, paving the way to a new approach to analyze historical oceanographic records: Regions where different water masses are known to collide can thus act as magnifying glasses for basin-scale interior ocean variability, hence providing “liquid archives” for climatology.

New Insights of the Sicily Channel and Southern Tyrrhenian Sea Variability

“…The anticyclonic vorticity of the NSA is reduced during the anticyclonic circulation modes of the northern Ionian (1993-1996, 2006-2010, 2017-2018), whereas it is enhanced during the cyclonic circulation modes (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2011)(2012)(2013)(2014)(2015)(2016). This result supports the relationship between the large-scale interior ocean variability in the central Mediterranean Sea and the local dynamics, suggested by Reference [27]. More specifically, these authors suggest a link between the inversions of the surface circulation in the northern Ionian and the local tidal observations in the area of the Strait of Messina.…”

“…This anticyclone, although located in the southern Tyrrhenian Sea, is affected by the decadal variability induced by the adjacent Ionian Sea ( Figure 6). This result, as suggested by Reference [27], opens to a new interpretation of the link between different Mediterranean sub-basins and underlines the importance of internal processes on the variability of the mesoscale structures.…”

Review article: Sea-level rise in Venice: historic and future trends

“…Fukumori et al, 2007;Menemenlis et al, 2007;Gomis et al, 2008;Calafat et al, 2012;Landerer and Volkov, 2013;Tsimplis et al, 2013;Volkov et al, 2019). Nonetheless, the imprint of the NAO on Mediterranean coastal sealevel variability in 2010 remains clear from tide-gauge data (Rubino et al, 2018). Zanchettin et al (2009) estimate that about half of the variability of detrended winter Venetian RSL can be explained linearly by the NAO.…”

Experimental evidence of long-term oceanic circulation reversals without wind influence in the North Ionian Sea

“…Modes of variability in such miniature oceans are of special interest: understanding their emergent spatio-temporal features in relation to the basin's characteristics can disclose a host of processes and relations of paramount importance for the comprehension of the world ocean functioning and evolution. Especially when such modes connect surface, interior and deep ocean, they can be pivotal in entangling the intricate interactions involved in the basin's long-term variability and in paving the way to an increased near-term predictability of interior dynamics 6 .…”

“…Moreover, the area is subjected to broader climate shifts, encompassing the replacement of waters of Adriatic origin by waters of Aegean origin in the Ionian abyss, like, e.g., the so-called Eastern Mediterranean Transient (EMT) 25 . Recent studies have presented evidence on occurrences of other EMT-like phenomena in the last centuries 6,26 .…”