Two-dimensional reconstruction of the Mediterranean sea level over 1970–2006 from tide gage data and regional ocean circulation model outputs

2011 ◽  
Vol 77 (1-2) ◽  
pp. 49-61 ◽  
Author(s):  
B. Meyssignac ◽  
F.M. Calafat ◽  
S. Somot ◽  
V. Rupolo ◽  
P. Stocchi ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Level ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Two Dimensional ◽  
Ocean Circulation Model ◽  
Dimensional Reconstruction ◽  
Tide Gage ◽  
The Mediterranean

A Near-Uniform Basin-Wide Sea Level Fluctuation of the Mediterranean Sea

2007 ◽  
Vol 37 (2) ◽  
pp. 338-358 ◽  
Author(s):  
Ichiro Fukumori ◽  
Dimitris Menemenlis ◽  
Tong Lee
Keyword(s):  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Ocean Circulation ◽  
Large Scale ◽  
Circulation Model ◽  
Level Fluctuation ◽  
Strait Of Gibraltar ◽  
Sea Level Fluctuation ◽  
The Mediterranean

Abstract A new basin-wide oscillation of the Mediterranean Sea is identified and analyzed using sea level observations from the Ocean Topography Experiment (TOPEX)/Poseidon satellite altimeter and a numerical ocean circulation model. More than 50% of the large-scale, nontidal, and non-pressure-driven variance of sea level can be attributed to this oscillation, which is nearly uniform in phase and amplitude across the entire basin. The oscillation has periods ranging from 10 days to several years and has a magnitude as large as 10 cm. The model suggests that the fluctuations are driven by winds at the Strait of Gibraltar and its neighboring region, including the Alboran Sea and a part of the Atlantic Ocean immediately to the west of the strait. Winds in this region force a net mass flux through the Strait of Gibraltar to which the Mediterranean Sea adjusts almost uniformly across its entire basin with depth-independent pressure perturbations. The wind-driven response can be explained in part by wind setup; a near-stationary balance is established between the along-strait wind in this forcing region and the sea level difference between the Mediterranean Sea and the Atlantic Ocean. The amplitude of this basin-wide wind-driven sea level fluctuation is inversely proportional to the setup region’s depth but is insensitive to its width including that of Gibraltar Strait. The wind-driven fluctuation is coherent with atmospheric pressure over the basin and contributes to the apparent deviation of the Mediterranean Sea from an inverse barometer response.

scholarly journals Analytic reconstruction of a two-dimensional velocity field from an observed diffusive scalar

2019 ◽  
Vol 871 ◽  
pp. 755-774
Author(s):  
Arjun Sharma ◽  
Irina I. Rypina ◽  
Ruth Musgrave ◽  
George Haller
Keyword(s):  
Velocity Field ◽  
Ocean Circulation ◽  
Incompressible Flows ◽  
Circulation Model ◽  
Scalar Fields ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Velocity Measurements ◽  
Ocean Circulation Model ◽  
Spatial Domains

Inverting an evolving diffusive scalar field to reconstruct the underlying velocity field is an underdetermined problem. Here we show, however, that for two-dimensional incompressible flows, this inverse problem can still be uniquely solved if high-resolution tracer measurements, as well as velocity measurements along a curve transverse to the instantaneous scalar contours, are available. Such measurements enable solving a system of partial differential equations for the velocity components by the method of characteristics. If the value of the scalar diffusivity is known, then knowledge of just one velocity component along a transverse initial curve is sufficient. These conclusions extend to the shallow-water equations and to flows with spatially dependent diffusivity. We illustrate our results on velocity reconstruction from tracer fields for planar Navier–Stokes flows and for a barotropic ocean circulation model. We also discuss the use of the proposed velocity reconstruction in oceanographic applications to extend localized velocity measurements to larger spatial domains with the help of remotely sensed scalar fields.

scholarly journals Two-dimensional reconstruction of past sea level (1950–2003) from tide gauge data and an Ocean General Circulation Model

2009 ◽  
Vol 5 (2) ◽  
pp. 217-227 ◽  
Author(s):  
W. Llovel ◽  
A. Cazenave ◽  
P. Rogel ◽  
A. Lombard ◽  
M. B. Nguyen
Keyword(s):  
Time Series ◽  
Sea Level ◽  
General Circulation ◽  
Tide Gauge ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Two Dimensional ◽  
Tide Gauges ◽  
Dimensional Reconstruction ◽  
Ocean General Circulation

Abstract. A two-dimensional reconstruction of past sea level is proposed at yearly interval over the period 1950–2003 using tide gauge records from 99 selected sites and 44-year long (1960–2003) 2°×2° sea level grids from the OPA/NEMO ocean general circulation model with data assimilation. We focus on the regional variability and do not attempt to compute the global mean trend. An Empirical Orthogonal Function decomposition of the reconstructed sea level grids over 1950–2003 displays leading modes that reflect two main components: (1) a long-term (multi-decadal), regionally variable signal and (2) an interannual, regionally variable signal dominated by the signature of El Nino-Southern Oscillation. Tests show that spatial trend patterns of the 54-year long reconstructed sea level significantly depend on the temporal length of the two-dimensional sea level signal used for the reconstruction (i.e., the length of the gridded OPA/NEMO sea level time series). On the other hand, interannual variability is well reconstructed, even when only ~10-years of model grids are used. The robustness of the results is assessed, leaving out successively each of the 99 tide gauges used for the reconstruction and comparing observed and reconstructed time series at the non considered tide gauge site. The reconstruction performs well at most tide gauges, especially at interannual frequency.

scholarly journals A nested Atlantic-Mediterranean Sea general circulation model for operational forecasting

Ocean Science ◽  
2009 ◽  
Vol 5 (4) ◽  
pp. 461-473 ◽  
Author(s):  
P. Oddo ◽  
M. Adani ◽  
N. Pinardi ◽  
C. Fratianni ◽  
M. Tonani ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
General Circulation Model ◽  
Ocean Circulation ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Lateral Boundary ◽  
The Mediterranean ◽  
The Impact

Abstract. A new numerical general circulation ocean model for the Mediterranean Sea has been implemented nested within an Atlantic general circulation model within the framework of the Marine Environment and Security for the European Area project (MERSEA, Desaubies, 2006). A 4-year twin experiment was carried out from January 2004 to December 2007 with two different models to evaluate the impact on the Mediterranean Sea circulation of open lateral boundary conditions in the Atlantic Ocean. One model considers a closed lateral boundary in a large Atlantic box and the other is nested in the same box in a global ocean circulation model. Impact was observed comparing the two simulations with independent observations: ARGO for temperature and salinity profiles and tide gauges and along-track satellite observations for the sea surface height. The improvement in the nested Atlantic-Mediterranean model with respect to the closed one is particularly evident in the salinity characteristics of the Modified Atlantic Water and in the Mediterranean sea level seasonal variability.

scholarly journals 2-D reconstruction of past sea level (1950–2003) using tide gauge records and spatial patterns from a general ocean circulation model

2009 ◽  
Vol 5 (2) ◽  
pp. 1109-1132 ◽  
Author(s):  
W. Llovel ◽  
A. Cazenave ◽  
P. Rogel ◽  
A. Lombard ◽  
M. Bergé-Nguyen
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Ocean Circulation ◽  
Tide Gauge ◽  
Circulation Model ◽  
Global Ocean ◽  
Tide Gauges ◽  
Ocean Circulation Model ◽  
Tide Gauge Records ◽  
Function Decomposition

Abstract. A two-dimensional reconstruction of past sea level is proposed at yearly interval over the period 1950–2003 using tide gauge records at 99 selected sites and 44-year long (1960–2003) 2°×2° gridded dynamic heights from the OPA/NEMO global ocean circulation model with data assimilation. An Empirical Orthogonal Function decomposition of the reconstructed sea level over 1950–2003 displays leading modes that reflect two main components: a long-term (multi-decadal) but regionally variable signal and interannual fluctuations dominated by the signature of El Nino-Southern Oscillation. Tests show that spatial trend patterns of the 54-year long reconstructed sea level (1950–2003) significantly depend on the length of the gridded OPA/NEMO time series used to compute spatial covariance signal used for the reconstruction (i.e., the length of the gridded OPA/NEMO time series). On the other hand, the interannual variability is well reconstructed, even with ~10-year long of the OPA/NEMO model or satellite altimetry-based sea level grids. The robustness of the results is assessed, leaving out successively each of the 99 tide gauges when reconstructing the sea level signal and then comparing observed and reconstructed time series at the non contributing tide gauge site. The reconstruction performs well at most tide gauges, especially at interannual frequency.

scholarly journals A nested Atlantic-Mediterranean Sea general circulation model for operational forecasting

2009 ◽  
Vol 6 (2) ◽  
pp. 1093-1127 ◽  
Author(s):  
P. Oddo ◽  
M. Adani ◽  
N. Pinardi ◽  
C. Fratianni ◽  
M. Tonani ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
General Circulation Model ◽  
Ocean Circulation ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Lateral Boundary ◽  
The Mediterranean ◽  
The Impact

Abstract. A new numerical general circulation ocean model for the Mediterranean Sea has been implemented nested within an Atlantic general circulation model within the framework of the Marine Environment and Security for the European Area project (MERSEA, Desaubies, 2006). A 4-year twin experiment was carried out from January 2004 to December 2007 with two different models to evaluate the impact on the Mediterranean Sea circulation of open lateral boundary conditions in the Atlantic Ocean. One model considers a closed lateral boundary in a large Atlantic box and the other is nested in the same box in a global ocean circulation model. Impact was observed comparing the two simulations with independent observations: ARGO for temperature and salinity profiles and tide gauges and along-track satellite observations for the sea surface height. The improvement in the nested Atlantic-Mediterranean model with respect to the closed one is particularly evident in the salinity characteristics of the Modified Atlantic Water and in the Mediterranean sea level seasonal variability.

scholarly journals A one-way nested eddy resolving model of the Aegean and Levantine basins: implementation and climatological runs

2003 ◽  
Vol 21 (1) ◽  
pp. 205-220 ◽  
Author(s):  
G. Korres ◽  
A. Lascaratos
Keyword(s):  
Mediterranean Sea ◽  
Ocean Circulation ◽  
Mediterranean Region ◽  
General Circulation ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Circulation Model ◽  
Surface Boundary ◽  
Data Set ◽  
The Mediterranean

Abstract. The present study deals with the implementation of an eddy resolving model of the Levantine and Aegean basins and its one-way nesting with a coarse resolution (1/8° × 1/8°) global Mediterranean general circulation model. The modelling effort is done within the framework of the Mediterranean Forecasting System Pilot Project as an initiative towards real-time forecasting within the eastern Mediterranean region. The performed climatological runs of the nested model have shown very promising results on the ability of the model to capture correctly the complex dynamics of the area and at the same time to demonstrate the skill and robustness of the nesting technique applied. A second aim of this study is to prepare a comprehensive climatological surface boundary conditions data set for the Mediterranean Sea. This data set has been developed within the framework of the same research project and is suitable for use in ocean circulation models of the Mediterranean Sea or parts of it. The computation is based on the ECMWF 6-h atmospheric parameters for the period 1979–1993 and a calibrated set of momentum and heat flux bulk formulae resulted from previous studies for the Mediterranean region. Key words. Oceanography: general (numerical modelling); physical (general circulation; air-sea interactions)

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