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Ann. Geophys., 21, 833-846, 2003
www.ann-geophys.net/21/833/2003/
© European Geosciences Union 2003
Sound speed in the Mediterranean Sea: an analysis from a climatological data set
S. Salon1, A. Crise1, P. Picco2, E. de Marinis3, and O. Gasparini3
1Istituto Nazionale di Oceanografia e di Geofisica Sperimentale–OGS, Borgo Grotta Gigante 42/C, I-34010 Sgonico–Trieste, Italy
2Centro Ricerche Ambiente Marino, CRAM-ENEA, S.Teresa, Località Pozzuolo di Lerici, I-19100, La Spezia, Italy
3DUNE s.r.l., Via Tracia 4, I-00183 Roma, Italy
Abstract. This paper presents an
analysis of sound speed distribution in the Mediterranean Sea based on
climatological temperature and salinity data. In the upper layers, propagation
is characterised by upward refraction in winter and an acoustic channel in
summer. The seasonal cycle of the Mediterranean and the presence of gyres and
fronts create a wide range of spatial and temporal variabilities, with relevant
differences between the western and eastern basins. It is shown that the
analysis of a climatological data set can help in defining regions suitable for
successful monitoring by means of acoustic tomography. Empirical Orthogonal
Functions (EOF) decomposition on the profiles, performed on the seasonal cycle
for some selected areas, demonstrates that two modes account for more than 98%
of the variability of the climatological distribution. Reduced order EOF
analysis is able to correctly represent sound speed profiles within each zone,
thus providing the a priori knowledge for Matched Field Tomography. It is also
demonstrated that salinity can affect the tomographic inversion, creating a
higher degree of complexity than in the open oceans.
Key words. Oceanography: general
(marginal and semi-enclosed seas; ocean acoustics)
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