scholarly journals Intrusion of coastal waters into the pelagic eastern Mediterranean: in situ and satellite-based characterization

2013 ◽  
Vol 10 (5) ◽  
pp. 3349-3357 ◽  
Author(s):  
S. Efrati ◽  
Y. Lehahn ◽  
E. Rahav ◽  
N. Kress ◽  
B. Herut ◽  
...  
Keyword(s):  
High Resolution ◽  
Coastal Waters ◽  
Eastern Mediterranean ◽  
Propagation Speed ◽  
Surface Currents ◽  
Sampling Strategies ◽  
Open Sea ◽  
Levantine Basin ◽  
Transport Barriers

Abstract. A combined dataset of near-real-time multi-satellite observations and in situ measurements from a high-resolution survey is used for characterizing physical-biogeochemical properties of a patch stretching from the coast to the open sea in the Levantine Basin (LB) of the eastern Mediterranean (EM). Spatial analysis of the combined dataset indicates that the patch is a semi-enclosed system, bounded within the mixed layer and separated from ambient waters by transport barriers induced by horizontal stirring. As such, the patch is characterized by physical-biogeochemical properties that significantly differ from those of the waters surrounding it, with lower salinity and higher temperatures, concentrations of silicic acid and chlorophyll a, and abundance of Synechococcus and picoeukaryote cells. Based on estimates of patch dimensions (∼40 km width and ∼25 m depth) and propagation speed (∼0.09 m s−1), the volume flux associated with the patch is found to be on the order of 0.1 Sv. Our observations suggest that horizontal stirring by surface currents is likely to have an important impact on the ultra-oligotrophic Levantine Basin ecosystem, through (1) transport of nutrients and coastally derived material, and (2) formation of local, dynamically isolated niches. In addition, this work provides a satellite-based framework for planning and executing high-resolution sampling strategies in the interface between the coast and the open sea.

scholarly journals Intrusion of coastal waters into the pelagic Eastern Mediterranean: in situ and satellite-based characterization

2012 ◽  
Vol 9 (12) ◽  
pp. 17975-17997
Author(s):  
S. Efrati ◽  
Y. Lehahn ◽  
E. Rahav ◽  
N. Kress ◽  
B. Herut ◽  
...  
Keyword(s):  
High Resolution ◽  
Coastal Waters ◽  
Eastern Mediterranean ◽  
Propagation Speed ◽  
Surface Currents ◽  
Sampling Strategies ◽  
Open Sea ◽  
Levantine Basin ◽  
Transport Barriers

Abstract. A combined dataset of near real time multi-satellite observations and in situ measurements from a high-resolution survey, is used for characterizing physical-biogeochemical properties of a patch stretching from the coast to the open sea in the Levantine basin of the Eastern Mediterranean. Spatial analysis of the combined dataset indicates that the patch is a semi-enclosed system, bounded within the mixed layer and separated from ambient waters by transport barriers induced by horizontal stirring. As such, the patch is characterized by physical-biogeochemical properties that significantly differ from those of the waters surrounding it, with lower salinity, higher temperatures, higher concentrations of silicic acid and chlorophyll a, and higher abundance of Synechococcus and Picoeukaryotes cells. Based on estimates of patch dimensions (~ 40 km width and ~ 25 m depth) and propagation speed (~ 0.09 m s−1), the volume flux associated with the patch is found to be in the order of 0.1 Sv. Our observations suggest that horizontal stirring by surface currents is likely to have an important impact on the ultra-oligotrophic Levantine basin ecosystem, through (1) transport of nutrients and coastal derived material, and (2) formation of local, dynamically isolated, niches. In addition, this work provides a satellite-based framework for planning and executing high resolution sampling strategies in the interface between coast and the open sea.

scholarly journals High-resolution nested model for the Lebanese coastal area, Eastern Mediterranean: implementation and climatological runs

2006 ◽  
Vol 3 (3) ◽  
pp. 373-396 ◽  
Author(s):  
N. Kabbara ◽  
R. Sorgente ◽  
S. Natale ◽  
D. R. Hayes ◽  
G. Zodiatis
Keyword(s):  
High Resolution ◽  
Eastern Mediterranean ◽  
Ocean Model ◽  
Levantine Basin ◽  
Resolution Model ◽  
Coarse Model ◽  
Shelf Region ◽  
Horizontal Grid ◽  
Lebanese Coast ◽  
Circulation Characteristics

Abstract. As a part of the project Mediterranean Network to Assess and Upgrade Monitoring and Forecasting Activity in the Region (MAMA) we implemented a high resolution nested hydrodynamic model (1/40° horizontal grid, 16 sigma levels) for the coastal, shelf and open sea areas off the Lebanese coast, East Levantine Basin of the Eastern Mediterranean Sea. The Lebanese Shelf Model (LSM) is a version of the Princeton Ocean Model (POM). It is nested in a coarse resolution model the Aegean Levantine Eddy Resolving Model (1/20° horizontal grid, 25 sigma levels), ALERMO, that covers the Eastern Mediterranean. The nesting is one way so that velocity, temperature, and salinity along the open boundaries are interpolated from the relevant coarse model variables. Numerical simulations have been carried out under climatological surface and lateral forcing. Due to the relatively small domain, the results closely follow the simulation of the intermediate model with more details especially over the narrow shelf region. Simulations reproduce main circulation features and coastal circulation characteristics over the eastern Levantine shelf. This paper describes the modeling system setup, compares the simulations with the corresponding results of the coarse model ALERMO, and with the observed climatological circulation characteristics in the Levantine Basin off the Lebanese coast.

Enhancing WRF Model Forecasts by Assimilating High-Resolution GPS-Derived Water-Vapor Maps combined with METEOSAT-11 Data 

2021 ◽  
Author(s):  
Yuval Reuveni ◽  
Anton Leontiev ◽  
Dorita Rostkier-Edelstein
Keyword(s):  
Water Vapor ◽  
High Resolution ◽  
Numerical Models ◽  
Eastern Mediterranean ◽  
Wrf Model ◽  
In Situ Measurements ◽  
Suggested Approach ◽  
Positioning Systems ◽  
The Mediterranean

<p>Improving the accuracy of numerical weather predictions still poses a challenging task. The lack of sufficiently detailed spatio-temporal real-time in-situ measurements constitutes a crucial gap concerning the adequate representation of atmospheric moisture fields, such as water vapor, which are critical for improving weather predictions accuracy. Information on total vertically integrated water vapor (IWV), extracted from global positioning systems (GPS) tropospheric path delays, can enhance various atmospheric models at global, regional, and local scales. Currently, numerous existing atmospheric numerical models predict IWV. Nevertheless, they do not provide accurate estimations compared with in-situ measurements such as radiosondes. In this work, we demonstrate a novel approach for assimilating 2D IWV regional maps estimations, extracted from GPS tropospheric path delays combined with METEOSAT satellite imagery data, to enhance Weather Research and Forecast (WRF) model predictions accuracy above the Eastern Mediterranean area. Unlike previous studies, which assimilated IWV point measurements, here, we assimilate quasi-continuous 2D GPS IWV maps, augmented by METEOSAT-11 data, over Israel and its surroundings. Using the suggested approach, our results show a decrease of more than 30% in the root mean square error (RMSE) of WRF forecasts after assimilation relative to the standalone WRF when verified against in-situ radiosonde measurements near the Mediterranean coast. Furthermore, substantial improvements along the Jordan Rift Valley and Dead Sea Valley areas are achieved when compared to 2D IWV regional maps. Improvements in these areas suggest the importance of the assimilated high resolution IWV maps, in particular when assimilation and initialization times coincide with the Mediterranean Sea Breeze propagation from the coastline to highland stations.</p>

scholarly journals Improving HF Radar Estimates of Surface Currents Using Signal Quality Metrics, with Application to the MVCO High-Resolution Radar System

2012 ◽  
Vol 29 (9) ◽  
pp. 1377-1390 ◽  
Author(s):  
Anthony R. Kirincich ◽  
Tony de Paolo ◽  
Eric Terrill
Keyword(s):  
High Resolution ◽  
Hf Radar ◽  
Signal Quality ◽  
Surface Currents ◽  
High Frequency Radar ◽  
New Methods ◽  
Resolution System ◽  
High Resolution Radar ◽  
Coastal Observatory

Abstract Estimates of surface currents over the continental shelf are now regularly made using high-frequency radar (HFR) systems along much of the U.S. coastline. The recently deployed HFR system at the Martha’s Vineyard Coastal Observatory (MVCO) is a unique addition to these systems, focusing on high spatial resolution over a relatively small coastal ocean domain with high accuracy. However, initial results from the system showed sizable errors and biased estimates of M2 tidal currents, prompting an examination of new methods to improve the quality of radar-based velocity data. The analysis described here utilizes the radial metric output of CODAR Ocean Systems’ version 7 release of the SeaSonde Radial Site Software Suite to examine both the characteristics of the received signal and the output of the direction-finding algorithm to provide data quality controls on the estimated radial currents that are independent of the estimated velocity. Additionally, the effect of weighting spatial averages of radials falling within the same range and azimuthal bin is examined to account for differences in signal quality. Applied to two month-long datasets from the MVCO high-resolution system, these new methods are found to improve the rms difference comparisons with in situ current measurements by up to 2 cm s−1, as well as reduce or eliminate observed biases of tidal ellipses estimated using standard methods.

scholarly journals Distribution Patterns of Floating Microplastics in Open and Coastal Waters of the Eastern Mediterranean Sea (Ionian, Aegean, and Levantine Seas)

2021 ◽  
Vol 8 ◽  
Author(s):  
Argyro Adamopoulou ◽  
Christina Zeri ◽  
Francesca Garaventa ◽  
Chiara Gambardella ◽  
Christos Ioakeimidis ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Coastal Waters ◽  
Spectroscopic Analysis ◽  
Eastern Mediterranean ◽  
Distribution Patterns ◽  
Sea Surface ◽  
Morphological Properties ◽  
Eastern Mediterranean Sea ◽  
Surface Circulation ◽  
Open Sea

Microplastic pollution is a pervasive anthropogenic phenomenon at the ocean surface. Numerous studies have been performed worldwide; nevertheless, the distribution patterns, morphological properties, and sources of origin in the Eastern Mediterranean Sea are still poorly explored. The purpose of this study is to investigate the distribution patterns of surface floating microplastics (MPs) in the Ionian, Aegean, and Levantine Seas in relation to their sources and sea surface circulation. In total, eighty-four samples were collected using manta nets from 2014 to 2020, covering open waters, coastal waters, and enclosed gulfs (Corfu and Saronikos). MPs concentration measurements revealed high variability ranging from 0.012 to 1.62 items m–2 and did not present maximum concentrations close to MPs hotspot areas. The presence of sea surface slicks, as recorded visually during our samplings, seems to play a key role on the distribution pattern of MPs, and highest concentrations were recorded in samples affected by these formations. The dominant MPs shape type identified were fragments (50–60%), whilst filaments (1–23%), films (3–26%), and foams (0–34%) varied among the studied areas. The majority of MPs in open waters had sizes ≤2 mm peaking between 0.6 and 1.4 mm. Spectroscopic analysis of MPs revealed the presence of 11 polymer types in both open sea and gulfs; the most abundant type was polyethylene (PE), followed by polypropylene (PP), and polystyrene (PS). The relative abundance of polymer types was more diverse in Saronikos Gulf, compared to the open sea due to the proximity to major urban and industrial sources. Our findings suggest that the vicinity to coastal population centers determined the properties, size and polymer types of MPs and highlight that MPs concentrations are affected significantly by local oceanographic conditions, such as surface slicks.

scholarly journals High-resolution regional modelling of natural and anthropogenic radiocarbon in the Mediterranean Sea

2017 ◽  
Vol 14 (5) ◽  
pp. 1197-1213 ◽  
Author(s):  
Mohamed Ayache ◽  
Jean-Claude Dutay ◽  
Anne Mouchet ◽  
Nadine Tisnérat-Laborde ◽  
Paolo Montagna ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Deep Water ◽  
Thermohaline Circulation ◽  
Eastern Mediterranean ◽  
Dynamical Model ◽  
Major Influence ◽  
Western Basin ◽  
The Impact

Abstract. A high-resolution dynamical model (Nucleus for European Modelling of the Ocean, Mediterranean configuration – NEMO-MED12) was used to give the first simulation of the distribution of radiocarbon (14C) across the whole Mediterranean Sea. The simulation provides a descriptive overview of both the natural pre-bomb 14C and the entire anthropogenic radiocarbon transient generated by the atmospheric bomb tests performed in the 1950s and early 1960s. The simulation was run until 2011 to give the post-bomb distribution. The results are compared to available in situ measurements and proxy-based reconstructions. The radiocarbon simulation allows an additional and independent test of the dynamical model, NEMO-MED12, and its performance to produce the thermohaline circulation and deep-water ventilation. The model produces a generally realistic distribution of radiocarbon when compared with available in situ data. The results demonstrate the major influence of the flux of Atlantic water through the Strait of Gibraltar on the inter-basin natural radiocarbon distribution and characterize the ventilation of intermediate and deep water especially through the propagation of the anthropogenic radiocarbon signal. We explored the impact of the interannual variability on the radiocarbon distribution during the Eastern Mediterranean Transient (EMT) event. It reveals a significant increase in 14C concentration (by more than 60 ‰) in the Aegean deep water and at an intermediate level (value up to 10 ‰) in the western basin. The model shows that the EMT makes a major contribution to the accumulation of radiocarbon in the eastern Mediterranean deep waters.

scholarly journals High resolution regional modeling of natural and anthropogenic radiocarbon in the Mediterranean Sea

2016 ◽  
Author(s):  
Mohamed Ayache ◽  
Jean-Claude Dutay ◽  
Anne Mouchet ◽  
Nadine Tisnérat-Laborde ◽  
Paolo Montagna ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Deep Water ◽  
Thermohaline Circulation ◽  
Eastern Mediterranean ◽  
Dynamical Model ◽  
Major Influence ◽  
Transient Event ◽  
The Impact

Abstract. A high-resolution dynamical model (NEMO-MED12) was use to give the first simulation of the distribution of radiocarbon (14C) across the whole Mediterranean Sea. The simulation provides a descriptive overview of both the natural pre-bomb 14C and the entire anthropogenic radiocarbon transient generated by the atmospheric bomb tests performed in the 1950s and early 1960s. The simulation was run until 2010 to give the post-bomb distribution. The results are compared to available in-situ measurements and proxy-based reconstructions. The radiocarbon simulation allows an additional and independent test of the dynamical model, NEMO-MED12, and its performance to produce the thermohaline circulation and deep-water ventilation. The model produces a generally realistic distribution of radiocarbon when compared with available in-situ data. The results demonstrate the major influence of the flux of Atlantic water through the strait of Gibraltar on the inter-basin natural radiocarbon distribution, and characterize the ventilation of intermediate and deep water ventilation especially through the propagation of the anthropogenic radiocarbon signal. We explored the impact of the interannual variability on the radiocarbon distribution during the Eastern Mediterranean transient event (EMT). It reveals a significant increase in 14C concentration (by more than 60 ‰) in the Aegean deep water, and at intermediate level (value up to 10 ‰) in the western basin. The model shows that the EMT makes a major contribution to the accumulation of radiocarbon in the eastern Mediterranean deep waters.

scholarly journals Operational Assimilation of glider temperature and salinity in a mesoscale flow field: Eastern Mediterranean test case

2016 ◽  
Author(s):  
Daniel R. Hayes ◽  
Srdjan Dobricic ◽  
Hezi Gildor
Keyword(s):  
Eastern Mediterranean ◽  
Background Field ◽  
Test Case ◽  
Surface Currents ◽  
Predictive Capacity ◽  
In Situ Data ◽  
Operational Data ◽  
Data Assimilation System ◽  
Assimilation System

Abstract. An operational data assimilation system for the Eastern Mediterranean is described and evaluated for a 6-month twin experiment. In the assimilative run, glider profiles of temperature and salinity are assimilated daily into a high resolution ocean forecast, after an initial spin up of one week. In the control run, the same initial and boundary conditions are used to produce an operational forecast, but without assimilation of in situ data. While both runs were similar for most of the time and most of the domain, significant differences were found near the region of assimilation, particularly when the glider passed through the anticyclonic Cyprus eddy. Root mean square differences of the misfits between the temperature and salinity observations and the model background field at those locations (before any assimilation) were approximately 15% lower in the assimilative run. Improvements in the forecasting capability of surface currents were found, and would provide a significant improvement of predictive capacity for applications such as pollutant spreading or offshore operational safety.

scholarly journals Immense variability in the sea surface temperature near macro tidal flat revealed by high-resolution satellite data (Landsat 8)

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Seung-Tae Lee ◽  
Yang-Ki Cho ◽  
Duk-jin Kim
Keyword(s):  
High Resolution ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Tidal Flat ◽  
Sea Water ◽  
Sea Surface ◽  
Landsat 8 ◽  
Open Sea ◽  
In Situ Observations

AbstractSea surface temperature (SST) is crucial for understanding the physical characteristics and ecosystems of coastal seas. SST varies near the tidal flat, where exposure and flood recur according to the tidal cycle. However, the variability of SST near the tidal flat is poorly understood owing to difficulties in making in-situ observations. The high resolution of Landsat 8 enabled us to determine the variability of SST near the macro tidal flat. The spatial distribution of the SST extracted from Landsat 8 changed drastically. The seasonal SST range was higher near the tidal flat than in the open sea. The maximum seasonal range of coastal SST exceeded 23 °C, whereas the range in the open ocean was approximately 18 °C. The minimum and maximum horizontal SST gradients near the tidal flat were approximately − 0.76 °C/10 km in December and 1.31 °C/10 km in June, respectively. The heating of sea water by tidal flats in spring and summer, and cooling in the fall and winter might result in a large horizontal SST gradient. The estimated heat flux from the tidal flat to the seawater based on the SST distribution shows seasonal change ranging from − 4.85 to 6.72 W/m2.

Results in coastal waters with high resolution in situ spectral radiometry: The Marine Optical System ROV

2007 ◽  
Author(s):  
Mark Yarbrough ◽  
Michael Feinholz ◽  
Stephanie Flora ◽  
Terrance Houlihan ◽  
B. Carol Johnson ◽  
...  
Keyword(s):  
High Resolution ◽  
Optical System ◽  
Coastal Waters
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