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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
C09030,
doi:10.1029/2005JC002956,
2006
On the steric and mass-induced contributions to the annual sea level variations in the Mediterranean Sea
David García
Space Geodesy Laboratory, Applied Mathematics Department, University of Alicante, Alicante, Spain
Benjamin F. Chao
Space Geodesy Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
Jorge Del Río
Department of Applied Physics II, University of Malaga, Malaga, Spain
Isabel Vigo
Space Geodesy Laboratory, Applied Mathematics Department, University of Alicante, Alicante, Spain
Jesús García-Lafuente
Department of Applied Physics II, University of Malaga, Malaga, Spain
Abstract
The sea level variation (SLV
total) is the sum of two major contributions: steric and mass-induced. The steric SLV
steric is that resulting from the thermal and salinity changes in a given water column. It only involves volume change, hence has
no gravitational effect. The mass-induced SLV
mass, on the other hand, arises from adding or subtracting water mass to or from the water column and has direct gravitational
signature. We examine the closure of the seasonal SLV budget and estimate the relative importance of the two contributions
in the Mediterranean Sea as a function of time. We use ocean altimetry data (from TOPEX/Poseidon, Jason 1, ERS, and ENVISAT
missions) to estimate SLV
total, temperature, and salinity data (from the Estimating the Circulation and Climate of the Ocean ocean model) to estimate SLV
steric, and time variable gravity data (from Gravity Recovery and Climate Experiment (GRACE) Project, April 2002 to July 2004) to
estimate SLV
mass. We find that the annual cycle of SLV
total in the Mediterranean is mainly driven by SLV
steric but moderately offset by SLV
mass. The agreement between the seasonal SLV
mass estimations from SLV
total – SLV
steric and from GRACE is quite remarkable; the annual cycle reaches the maximum value in mid-February, almost half a cycle later
than SLV
total or SLV
steric, which peak by mid-October and mid-September, respectively. Thus, when sea level is rising (falling), the Mediterranean Sea
is actually losing (gaining) mass. Furthermore, as SLV
mass is balanced by vertical (precipitation minus evaporation, P–E) and horizontal (exchange of water with the Atlantic, Black Sea, and river runoff) mass fluxes, we compared it with the P–E determined from meteorological data to estimate the annual cycle of the horizontal flux.
Received 15
March
2005;
accepted 31
January
2006;
published 26
September
2006.
Keywords: sea level;
Mediterranean Sea;
mass transport.
Index Terms: 1240 Geodesy and Gravity: Satellite geodesy: results (6929, 7215, 7230, 7240); 1222 Geodesy and Gravity: Ocean monitoring with geodetic techniques (1225, 1641, 3010, 4532, 4556, 4560, 6959); 1217 Geodesy and Gravity: Time variable gravity (7223, 7230).
Read Full Article (file size: 2263463 bytes) Cited by
Citation: García, D., B. F. Chao, J. Del Río, I. Vigo, and J. García-Lafuente
(2006),
On the steric and mass-induced contributions to the annual sea level variations in the Mediterranean Sea,
J. Geophys. Res.,
111,
C09030,
doi:10.1029/2005JC002956.
Copyright 2006 by the American Geophysical Union.
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