Vertical diffusion and oxygen consumption during stagnation periods in the deep North Aegean
Zervakis, V.; Krasakopoulou, E.; Georgopoulos, D.; Souvermezoglou, E. (2003). Vertical diffusion and oxygen consumption during stagnation periods in the deep North Aegean. Deep-Sea Res., Part 1, Oceanogr. Res. Pap. 50: 53-77
In: Deep-Sea Research, Part I. Oceanographic Research Papers. Elsevier: Oxford. ISSN 0967-0637; e-ISSN 1879-0119, more
Ventilation of the deep basins of the North Aegean Sea takes place during relatively scarce events of massive dense water formation in that region. In the time intervals between such events, the bottom waters of each sub basin are excluded from interaction with other water masses through advection or isopycnal mixing and the only process that changes their properties is diapycnal mixing with overlying waters. In this work we utilize a simple one-dimensional model in order to estimate the vertical eddydiffusion coefficient Kro based on the observed rate of change of densityand stratification. Vertical diffusivityis estimated for each of three sub-basins of the North Aegean, one of convex shape of the seabed and the other two of concave topography. It is noteworthy that the convex sub basin exhibited much higher vertical diffusivity than the two concave sub basins, a fact consistent with theoretical predictions that internal-wave- induced mixing is higher over the former shape of seabed. Furthermore, the estimates of Kro are exploited in computing the vertical transport of dissolved oxygen through diffusion and the rate of oxygen consumption by decaying organic matter. The different levels of the estimated diffusion and oxygen consumption rates testify to the dynamical and biogeochemical characteristics of each basin.
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