scholarly journals Analysis of Wave Height Variability Using Altimeter Measurements: Application to the Mediterranean Sea

2007 ◽  
Vol 24 (12) ◽  
pp. 2078-2092 ◽  
Author(s):  
Pierre Queffeulou ◽  
Abderrahim Bentamy
Keyword(s):  
Mediterranean Sea ◽  
Interannual Variability ◽  
Wave Height ◽  
Measurement Data ◽  
Altimeter Data ◽  
Mean Values ◽  
The Mediterranean ◽  
Standard Deviations ◽  
Wave Models ◽  
Ocean Topography

Abstract Altimeter significant wave height (SWH) measurement data from six satellite missions covering 14 yr were analyzed over the Mediterranean Sea. First, data correction and screening were performed using the same method for the six altimeters [European Remote Sensing Satellites (ERS-1 and ERS-2), Ocean Topography Experiment (TOPEX), Geosat Follow-On, Jason, and Environmental Satellite (Envisat)]. The data from the TOPEX and Jason missions enabled the construction of seasonal maps of along-track SWH mean values and standard deviations. These reveal the regional short-scale sea state features associated with the specific meteorological patterns of the various geographical basins. Time series of monthly SWH mean values and standard deviations from each satellite and over the whole Mediterranean Sea were calculated and seen to be in good agreement, thus demonstrating interannual variability. The six altimeter missions used together enable the investigation of the monthly annual cycle at the short scales of the various subbasins. Significant differences are observed between the western and eastern parts of the Mediterranean Sea. The annual SWH cycle changes in both shape and amplitude depending on the subbasin. Analysis of the seasonal interannual variability confirms the existence of some degree of independence between the subbasins. Thanks to multisatellite missions and homogeneous corrections of the altimeter data, SWH time and space characteristics were able to be obtained at regional short scales. These results are independent of numerical wind and wave models. This method can be applied to any geographical region.

scholarly journals Assimilation of radar altimeter data in numerical wave models: an impact study in two different wave climate regions

2007 ◽  
Vol 25 (3) ◽  
pp. 581-595 ◽  
Author(s):  
G. Emmanouil ◽  
G. Galanis ◽  
G. Kallos ◽  
L. A. Breivik ◽  
H. Heiberg ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Mediterranean Sea ◽  
European Space Agency ◽  
Wave Climate ◽  
Altimeter Data ◽  
Radar Altimeter ◽  
The Indian Ocean ◽  
Numerical Wave ◽  
The Mediterranean ◽  
Wave Models

Abstract. An operational assimilation system incorporating significant wave height observations in high resolution numerical wave models is studied and evaluated. In particular, altimeter satellite data provided by the European Space Agency (ESA-ENVISAT) are assimilated in the wave model WAM which operates in two different wave climate areas: the Mediterranean Sea and the Indian Ocean. The first is a wind-sea dominated area while in the second, swell is the principal part of the sea state, a fact that seriously affects the performance of the assimilation scheme. A detailed study of the different impact is presented and the resulting forecasts are evaluated against available buoy and satellite observations. The corresponding results show a considerable improvement in wave forecasting for the Indian Ocean while in the Mediterranean Sea the assimilation impact is restricted to isolated areas.

Use of Numerical Wind-Wave Models for Assessment of the Offshore Wave Energy Resource

1997 ◽  
Vol 119 (3) ◽  
pp. 184-190 ◽  
Author(s):  
M. T. Pontes ◽  
S. Barstow ◽  
L. Bertotti ◽  
L. Cavaleri ◽  
H. Oliveira-Pires
Keyword(s):  
Mediterranean Sea ◽  
North Atlantic ◽  
Wave Energy ◽  
Wind Wave ◽  
Energy Resource ◽  
Altimeter Data ◽  
The North ◽  
The North Atlantic ◽  
The Mediterranean ◽  
Wave Models

In the last two decades the performance of numerical wind-wave models has improved considerably. Several models have been routinely producing good quality wave estimates globally since the mid-1980s. The verifications of wind-wave models have mainly focused on the evaluation of the error of the significant wave height Hs estimates. However, for wave energy purposes, the main parameters to be assessed are the wave power Pw and the mean (energy) period Te. Since Pw is proportional to Hs2 Tc, its expected error is much larger than for the single-wave parameters. This paper summarizes the intercomparison of two wind-wave models against buoy data in the North Atlantic and the Mediterranean Sea to select the most suitable one for the construction of an Atlas of the wave energy resource in European waters. A full verification in the two basins of the selected model—the WAM model implemented in the routine operation of the European Centre for Medium-Range Weather Forecasts—was then performed against buoy and satellite altimeter data. It was found that the WAM model accuracy is very good for offshore locations in the North Atlantic; but for the Mediterranean Sea the results are much less accurate, probably due to a lower quality of the input wind fields.

scholarly journals Links of the significant wave height distribution in the Mediterranean sea with the Northern Hemisphere teleconnection patterns

2008 ◽  
Vol 17 ◽  
pp. 13-18 ◽  
Author(s):  
P. Lionello ◽  
M. B. Galati
Keyword(s):  
Mediterranean Sea ◽  
Northern Hemisphere ◽  
Wave Height ◽  
Significant Wave Height ◽  
Height Distribution ◽  
East Atlantic ◽  
Significant Wave ◽  
Teleconnection Patterns ◽  
Wave Height Distribution ◽  
The Mediterranean

Abstract. This study analyzes the link between the SWH (Significant Wave Height) distribution in the Mediterranean Sea during the second half of the 20th century and the Northern Hemisphere SLP (Sea Level Pressure) teleconnection patterns. The SWH distribution is computed using the WAM (WAve Model) forced by the surface wind fields provided by the ERA-40 reanalysis for the period 1958–2001. The time series of mid-latitude teleconnection patterns are downloaded from the NOAA web site. This study shows that several mid-latitude patterns are linked to the SWH field in the Mediterranean, especially in its western part during the cold season: East Atlantic Pattern (EA), Scandinavian Pattern (SCA), North Atlantic Oscillation (NAO), East Atlantic/West Russia Pattern (EA/WR) and East Pacific/ North Pacific Pattern (EP/NP). Though the East Atlantic pattern exerts the largest influence, it is not sufficient to characterize the dominant variability. NAO, though relevant, has an effect smaller than EA and comparable to other patterns. Some link results from possibly spurious structures. Patterns which have a very different global structure are associated to similar spatial features of the wave variability in the Mediterranean Sea. These two problems are, admittedly, shortcomings of this analysis, which shows the complexity of the response of the Mediterranean SWH to global scale SLP teleconnection patterns.

scholarly journals New Evidence of Mediterranean Climate Change and Variability from Sea Surface Temperature Observations

2020 ◽  
Vol 12 (1) ◽  
pp. 132 ◽  
Author(s):  
Andrea Pisano ◽  
Salvatore Marullo ◽  
Vincenzo Artale ◽  
Federico Falcini ◽  
Chunxue Yang ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Mediterranean Sea ◽  
Sea Surface ◽  
Western Basin ◽  
Mean Values ◽  
The Mediterranean ◽  
The Impact ◽  
Northeastern Atlantic

Estimating long-term modifications of the sea surface temperature (SST) is crucial for evaluating the current state of the oceans and to correctly assess the impact of climate change at regional scales. In this work, we analyze SST variations within the Mediterranean Sea and the adjacent Northeastern Atlantic box (west of the Strait of Gibraltar) over the last 37 years, by using a satellite-based dataset from the Copernicus Marine Environment Monitoring Service (CMEMS). We found a mean warming trend of 0.041 ± 0.006 ∘ C/year over the whole Mediterranean Sea from 1982 to 2018. The trend has an uneven spatial pattern, with values increasing from 0.036 ± 0.006 ∘ C/year in the western basin to 0.048 ± 0.006 ∘ C/year in the Levantine–Aegean basin. The Northeastern Atlantic box and the Mediterranean show a similar trend until the late 1990s. Afterwards, the Mediterranean SST continues to increase, whereas the Northeastern Atlantic box shows no significant trend, until ~2015. The observed change in the Mediterranean Sea affects not only the mean trend but also the amplitude of the Mediterranean seasonal signal, with consistent relative increase and decrease of summer and winter mean values, respectively, over the period considered. The analysis of SST changes occurred during the “satellite era” is further complemented by reconstructions also based on direct in situ SST measurements, i.e., the Extended Reconstructed SST (ERSST) and the Hadley Centre Sea Ice and Sea Surface Temperature dataset (HadISST), which go back to the 19th century. The analysis of these longer time series, covering the last 165 years, indicates that the increasing Mediterranean trend, observed during the CMEMS operational period, is consistent with the Atlantic Multidecadal Oscillation (AMO), as it closely follows the last increasing period of AMO. This coincidence occurs at least until 2007, when the apparent onset of the decreasing phase of AMO is not seen in the Mediterranean SST evolution.

scholarly journals On the mesoscale monitoring capability of Argo floats in the Mediterranean Sea

2016 ◽  
Author(s):  
Antonio Sánchez-Román ◽  
Simón Ruiz ◽  
Ananda Pascual ◽  
Baptiste Mourre ◽  
Stéphanie Guinehut
Keyword(s):  
Mediterranean Sea ◽  
Large Scale ◽  
Spatial Scales ◽  
Altimeter Data ◽  
Simulation Experiments ◽  
Argo Data ◽  
Sea Level Anomalies ◽  
The Mediterranean ◽  
Observing System Simulation Experiment ◽  
Initial Objective

Abstract. In this work an Observing System Simulation Experiment (OSSE) approach is used to investigate the Argo array spatial sampling necessary in the Mediterranean Sea to recover the mesoscale signal as seen by altimetry. The monitoring of the mesoscale features is not an initial objective of the Argo network. However, it is an interesting question in the perspective of future network extensions in order to improve the ocean state estimates. A quality assessment of the performances of the altimeter product is carried out to quantify the differences between Argo and altimetry needed to conduct the simulation experiments. The method used here to evaluate the altimeter data is based on the comparison of Sea Level Anomalies (SLA) from altimetry and Dynamic Height Anomalies (DHA) referred to both 400 and 900 dbar computed from the in-situ Argo network. A standard deviation of the differences between SLA and DHA of 4.92 cm is obtained when comparing altimetry and Argo data referred to 400 dbar. The simulation experiments show that a configuration similar to the current Argo array in the Mediterranean (with a spatial resolution of 2° × 2°) is only able to recover the large-scale signals of the basin. On the contrary, the SLA field reconstructed from a 0.75° x 0.75° Argo network can retrieve most of the mesoscale signal. Such an Argo array of around 450 floats in the Mediterranean Sea would be enough to recover the SLA field with an RMSE of 3 cm for spatial scales higher than 150 km, similar to those captured by the altimetry.

scholarly journals Characterization of turbulence and validation of fine-scale parametrization in the Mediterranean Sea during BOUM experiment

2011 ◽  
Vol 8 (5) ◽  
pp. 8961-8998 ◽  
Author(s):  
Y. Cuypers ◽  
P. Bouruet-Aubertot ◽  
C. Marec ◽  
J.-L. Fuda
Keyword(s):  
Energy Dissipation ◽  
Mediterranean Sea ◽  
Fine Scale ◽  
Data Set ◽  
Mean Values ◽  
The Mediterranean ◽  
Microstructure Measurements ◽  
High Level ◽  
Anticyclonic Eddies

Abstract. One main purpose of BOUM experiment was to give evidence of the possible impact of submesoscale dynamics on biogeochemical cycles. To this aim physical as well as biogeochemical data were collected along a zonal transect through the western and eastern basins. Along this transect 3 day fixed point stations were performed within anticyclonic eddies during which microstructure measurements were collected over the first 100 m. We focus here on the characterization of turbulent mixing induced by internal wave breaking. The analysis of microstructure measurements revealed a high level of turbulence in the seasonal pycnocline and a moderate level below with energy dissipation mean values of the order of 10−6 W kg−1 and 10−8 W kg−1, respectively. Fine-scale parameterizations developed to mimic energy dissipation produced by internal wavebreaking were then tested against these direct measurements. Once validated a parameterization has been applied to infer energy dissipation and mixing over the whole data set, thus providing an overview over a latitudinal section of the Mediterranean sea. The results evidence a significant increase of dissipation at the top and base of eddies associated with strong near inertial waves. Vertical turbulent diffusivity is increased both in these regions and in the weakly stratified eddy core.

scholarly journals Interannual variability of the Mediterranean trophic regimes from ocean color satellites

2015 ◽  
Vol 12 (17) ◽  
pp. 14941-14980 ◽  
Author(s):  
N. Mayot ◽  
F. D'Ortenzio ◽  
M. Ribera d'Alcalà ◽  
H. Lavigne ◽  
H. Claustre
Keyword(s):  
Spatial Distribution ◽  
Mediterranean Sea ◽  
Interannual Variability ◽  
Deep Convection ◽  
Regional Scale ◽  
Ocean Color ◽  
Run Off ◽  
The Mediterranean ◽  
The One ◽  
The Impact

Abstract. D'Ortenzio and Ribera d'Alcalà (2009, DR09 hereafter) divided the Mediterranean Sea into "bioregions" based on the climatological seasonality (phenology) of phytoplankton. Here we investigate the interannual variability of this bioregionalization. Using 16 years of available ocean color observations (i.e. SeaWiFS and MODIS), we analyzed the spatial distribution of the DR09 trophic regimes on an annual basis. Additionally, we identified new trophic regimes, with seasonal cycles of phytoplankton biomass different from the DR09 climatological description and named "Anomalous". Overall, the classification of the Mediterranean phytoplankton phenology proposed by DR09 (i.e. "No Bloom", "Intermittently", "Bloom" and "Coastal"), is confirmed to be representative of most of the Mediterranean phytoplankton phenologies. The mean spatial distribution of these trophic regimes (i.e. bioregions) over the 16 years studied is also similar to the one proposed by DR09. But at regional scale some annual differences, in their spatial distribution and in the emergence of "Anomalous" trophic regimes, were observed compared to the DR09 description. These dissimilarities with the DR09 study were related to interannual variability in the sub-basin forcing: winter deep convection events, frontal instabilities, inflow of Atlantic or Black Sea Waters and river run-off. The large assortment of phytoplankton phenologies identified in the Mediterranean Sea is thus verified at interannual level, confirming the "sentinel" role of this basin to detect the impact of climate changes on the pelagic environment.

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