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Emin Özsoy
,
Ümit Ünlüata
, and
Mustafa Aral

Abstract

Numerical modeling techniques are used to study tsunami propagation in the eastern Mediterranean. In addition to the propagation patterns, the amplification due to the geometries of the continental shelf and the basin are studied in detail. The surface displacement at selected strategic locations is frequency-analyzed to obtain the resonances and their modal shapes. Coupled resonances are identified in the Cilician Basin-Gulf of Iskenderun system.

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Ümit Ünlüata
,
Temel Oguz
, and
Emin Özsoy

Abstract

Along the southern Turkish continental shelf, the intensity of the observed mean flow has a considerable degree of variability. The relatively strong currents along the straight portion of the coast is reduced significantly in the nearshore region upon encountering irregularities in the form of bays and headlands. As a possible explanation of such blockage by coastal irregularities, a linear, homogeneous wind-stress free model is presented incorporating the constraints of topographic steering and linear bottom friction. Solutions are given for an idealized case of an abrupt indentation on a straight coast adjoining a linearly deepening shelf. The directions preference of blocking and the applicability of boundary layer approximations am discussed. Numerical solutions are obtained for the realistic bathymetry and coastal configuration along the southern Turkish continental shelf. The concepts developed are applied to the observed blocking features.

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Temel Oguz
,
Emin Özsoy
,
Mohammed A. Latif
,
Halil I. Sur
, and
Ümit Ünlüata

Abstract

Recent hydrographic observations obtained in the Bosphorus Strait illustrate several features of the flow that may be related with the internal hydraulics. A two-layer numerical model indicates that the two-way exchange flow may indeed be subject to a series of internal hydraulic adjustments along the strait due to morphological features such as sills, a contraction and abrupt expansion of the width of the strait. The model identifies three distinct regions of the supercritical flow. The lower-layer flow of the Marmara Sea origin is directed to the north towards the Black Sea in a progressively thinning layer and is controlled by the sill located near the Black Sea entrance of the strait. The upper-layer water of the Black Sea origin flows in the opposite direction and is controlled upon reaching the constricted region located about 10–12 km away from the Marmara end of the strait. The upper-layer flow is then matched to the subsequent subcritical conditions by undergoing an internal hydraulic jump and becomes subject to another critical transition near the abruptly widening exit section into the Marmara Sea. The controls exerted by the northern sil and the contraction are connected by a subcritical region whereas the supercritical conditions downstream of these controls isolate the two way exchange from the conditions in the adjacent regions. In this way, the requirement for the maximal exchange is met implying that the Bosphorus Strait achieves the maximum possible transports in the layers depending on the magnitude of net barotropic transport.

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Nadia Pinardi
,
Emin Özsoy
,
Mohammed Abdul Latif
,
Franca Moroni
,
Alessandro Grandi
,
Giuseppe Manzella
,
Federico De Strobel
, and
Vladyslav Lyubartsev

ABSTRACT

The first in situ measurements of seawater density that referred to a geographical position at sea and time of the year were carried out by Count Luigi Ferdinando Marsili between 1679 and 1680 in the Adriatic Sea, Aegean Sea, Marmara Sea, and the Bosporus. Not only was this the first investigation with documented oceanographic measurements carried out at stations, but the measurements were described in such an accurate way that the authors were able to reconstruct the observations in modern units. These first measurements concern the “specific gravity” of seawaters (i.e., the ratio between fluid densities). The data reported in the historical oceanographic treatise Osservazioni intorno al Bosforo Tracio (Marsili) allowed the reconstruction of the seawater density at different geographic locations between 1679 and 1680. Marsili’s experimental methodology included the collection of surface and deep water samples, the analysis of the samples with a hydrostatic ampoule, and the use of a reference water to standardize the measurements. A comparison of reconstructed densities with present-day values shows an agreement within 10%–20% uncertainty, owing to various aspects of the measurement methodology that are difficult to reconstruct from the documentary evidence. Marsili also measured the current speed and the depth of the current inversion in the Bosporus, which are consistent with the present-day knowledge. The experimental data collected in the Bosporus enabled Marsili to enunciate a theory on the cause of the two-layer flow at the strait, demonstrated by his laboratory experiment and later confirmed by many analytical and numerical studies.

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