scholarly journals PROTEVS-MED field experiments: Very High-Resolution Hydrographic Surveys in the Western Mediterranean Sea

2019 ◽  
Author(s):  
Pierre Garreau ◽  
Franck Dumas ◽  
Stéphanie Louazel ◽  
Stéphanie Correard ◽  
Solenn Fercocq ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Field Experiments ◽  
Theoretical Work ◽  
Horizontal Resolution ◽  
Western Mediterranean ◽  
Surface Salinity ◽  
Data Set ◽  
Western Mediterranean Basin ◽  
Very High

Abstract. From 2015 to 2018 four field experiments (7 legs) have been performed in the Western Mediterranean Basin during winter or early spring. The main objectives were the assessment of high-resolution modelling, the observation of mesoscale structure and associated ageostrophic dynamics. Thanks to the intensive use of a towed vehicle undulating in the upper oceanic layer between 0 and 400 meter depth (a SeaSoar), a large amount of very high resolution hydrographic transects (about 10.000 km) have been performed, observing mesoscale dynamics (slope current and its instabilities, anticyclonic eddies, sub-mesoscale coherent vortices, frontal dynamics convection events, strait outflows) and sub-mesoscale processes like stirring, mixed layer or symmetric instabilities. When available, the data were completed with velocities recorded by Vessel Mounted Acoustic Doppler Current Profiler (VMADCP) and by surface salinity and temperature recorded by ThermosalinoGraph (TSG). CTD casts have also been performed giving the background hydrography of the deeper layers when focusing on peculiar objects. In 2017, a free fall profiler (an MVP-200) has been deployed to manage even higher horizontal resolution. The aim of the survey was the dynamics and attention were paid to temperature, salinity and currents. Nevertheless, biological sensors (Chlorophyll a, Turbidity, Dissolved Oxygen etc.) have been opportunely carried out as they are able to provide complementary observations about the circulation. This data set is an unprecedented opportunity to investigate the very fine scale processes as the Mediterranean Sea is known for its intense and contrasted dynamics. It should be useful for modellers (who reduce the grid size below a few hundred meters) and expect to properly catch finer scale dynamics. Likewise, theoretical work could also be illustrated by in situ evidence embedded in this data set. The data are available through SEANOE repository (https://doi.org/10.17882/62352; Dumas et al., 2018).

scholarly journals PROTEVS-MED field experiments: very high resolution hydrographic surveys in the Western Mediterranean Sea

2020 ◽  
Vol 12 (1) ◽  
pp. 441-456
Author(s):  
Pierre Garreau ◽  
Franck Dumas ◽  
Stéphanie Louazel ◽  
Stéphanie Correard ◽  
Solenn Fercocq ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Field Experiments ◽  
Acoustic Doppler Current Profiler ◽  
Free Fall ◽  
Theoretical Work ◽  
Western Mediterranean ◽  
Surface Salinity ◽  
Western Mediterranean Basin ◽  
Very High

Abstract. From 2015 to 2018 four field experiments (seven legs) were performed in the Western Mediterranean basin during winter or early spring. The main objectives were the assessment of high-resolution modeling and the observation of mesoscale structure and associated ageostrophic dynamics. Thanks to the intensive use of a towed vehicle undulating in the upper oceanic layer between 0 and 400 m depth (SeaSoar), a large number of very high resolution hydrographic transects (total length about 10 000 km) were measured, observing mesoscale dynamics (slope current and its instabilities, anticyclonic eddies, submesoscale coherent vortices, frontal dynamics, convection events, strait outflows) and submesoscale processes like stirring, mixed-layer or symmetric instabilities. When available, the data were completed with velocities recorded by a vessel-mounted acoustic Doppler current profiler (VMADCP) and by surface salinity and temperature recorded by a thermosalinograph (TSG). Classical full-depth CTD (conductivity, temperature, depth) stations were also used, providing the background hydrography of the deeper layers when focusing on peculiar structures. In 2017, a free-fall profiler (MVP-200; MVP – moving vessel profiler) was deployed to manage even higher horizontal resolutions. In 2018, another free-fall profiler (a rapidCAST) was tested. When available, biological sensors (chlorophyll a, turbidity, dissolved oxygen, etc.) were used. They provided useful complementary observations about the circulation. This dataset is an unprecedented opportunity to investigate the very fine scale processes, as the Mediterranean Sea is known for its intense and contrasting dynamics. It should be useful for modellers (who reduce the grid size below a few hundred meters) and should properly resolve finer-scale dynamics. Likewise, theoretical work could also be illustrated by in situ evidence embedded in this dataset. The data are available through the SEANOE repository at: https://doi.org/10.17882/62352 (Dumas et al., 2018).

scholarly journals High-Resolution Observations in the Western Mediterranean Sea: The REP14-MED Experiment

2016 ◽  
Author(s):  
Reiner Onken ◽  
Heinz-Volker Fiekas ◽  
Laurent Beguery ◽  
Ines Borrione ◽  
Andreas Funk ◽  
...  
Keyword(s):  
Time Series ◽  
High Resolution ◽  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Data Set ◽  
Western Mediterranean Sea ◽  
Huge Data ◽  
Operational Forecasting ◽  
Surface Drifters ◽  
Lagrangian Flow

Abstract. The observational part of the REP14-MED experiment was conducted in June 2014 in the Sardo-Balearic Sea west of Sardinia Island (Western Mediterranean Sea). Two research vessels collected high-resolution oceanographic data by means of hydrographic casts, towed systems, and underway measurements. In addition, a vast amount of data was provided by a fleet of 11 gliders, time series were available from moored instruments, and information on Lagrangian flow patterns were obtained from surface drifters and one profiling float. The spatial resolution of the observations encompasses a spectrum over four orders of magnitude from O(101 m) to O(105 m), and the time series from the moored instruments cover a spectral range of five orders from O(101 s) to O(106 s). The objective of this article is to provide an overview of the huge data set which is utilized by various ongoing studies, focusing on (i) sub-mesoscale and mesoscale pattern analyses, (ii) operational forecasting in terms of the development and assessment of sampling strategies, assimilation methods, and model validation, (iii) modeling the variability of the ocean, and (iv) testing of new payloads for gliders.

scholarly journals High-resolution observations in the western Mediterranean Sea: the REP14-MED experiment

Ocean Science ◽  
2018 ◽  
Vol 14 (2) ◽  
pp. 321-335 ◽  
Author(s):  
Reiner Onken ◽  
Heinz-Volker Fiekas ◽  
Laurent Beguery ◽  
Ines Borrione ◽  
Andreas Funk ◽  
...  
Keyword(s):  
Time Series ◽  
High Resolution ◽  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Data Set ◽  
Western Mediterranean Sea ◽  
Huge Data ◽  
Operational Forecasting ◽  
Surface Drifters ◽  
Lagrangian Flow

Abstract. The observational part of the REP14-MED experiment was conducted in June 2014 in the Sardo-Balearic Basin west of Sardinia (western Mediterranean Sea). Two research vessels collected high-resolution oceanographic data by means of hydrographic casts, towed systems, and underway measurements. In addition, a vast amount of data was provided by a fleet of 11 ocean gliders, time series were available from moored instruments, and information on Lagrangian flow patterns was obtained from surface drifters and one profiling float. The spatial resolution of the observations encompasses a spectrum over 4 orders of magnitude from 𝒪(101 m) to 𝒪(105 m), and the time series from the moored instruments cover a spectral range of 5 orders from 𝒪(101 s) to 𝒪(106 s). The objective of this article is to provide an overview of the huge data set which has been utilised by various studies, focusing on (i) water masses and circulation, (ii) operational forecasting, (iii) data assimilation, (iv) variability of the ocean, and (v) new payloads for gliders.

scholarly journals Development of coccolithophore-based transfer functions in the western Mediterranean sea: a sea surface salinity reconstruction for the last 15.5 kyr

2015 ◽  
Vol 11 (12) ◽  
pp. 1635-1651 ◽  
Author(s):  
B. Ausín ◽  
I. Hernández-Almeida ◽  
J.-A. Flores ◽  
F.-J. Sierro ◽  
M. Grosjean ◽  
...  
Keyword(s):  
Transfer Function ◽  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Partial Least Square ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Weighted Averaging ◽  
Surface Salinity ◽  
Data Set ◽  
Western Mediterranean Sea

Abstract. A new data set of 88 marine surface sediment samples and related oceanic environmental variables (temperature, salinity, chlorophyll a, oxygen, etc.) was studied to quantify the relationship between assemblages of coccolithophore species and modern environmental conditions in the western Mediterranean Sea and the Atlantic Ocean, west of the Strait of Gibraltar. Multivariate statistical analyses revealed that coccolithophore species were primarily related to sea surface salinity (SSS), explaining an independent and significant proportion of variance in the coccolithophore data. A quantitative coccolithophore-based transfer function to estimate SSS was developed using the modern analog technique (MAT) and weighted-averaging partial least square regression (WA-PLS). The bootstrapped regression coefficient (R2boot) was 0.85MAT and 0.80WA-PLS, with a root-mean-square error of prediction (RMSEP) of 0.29MAT and 0.30WA-PLS (psu). The resulting transfer function was applied to fossil coccolithophore assemblages in the highly resolved (~ 65 years) sediment core CEUTA10PC08 from the Alboran Sea (western Mediterranean) in order to reconstruct SSS for the last 25 kyr. The reliability of the reconstruction was evaluated by assessing the degree of similarity between fossil and modern coccolithophore assemblages and by a comparison of reconstructions with fossil ordination scores. Analogs were poor for the stadials associated with Heinrich events 2 and 1 and part of the Last Glacial Maximum. Good analogs indicate a more reliable reconstruction of the SSS for the last 15.5 kyr. During this period, several millennial and centennial SSS changes were observed and associated with sea-level oscillations and variations in the Atlantic Water entering the Alboran.

scholarly journals High-resolution neodymium characterization along the Mediterranean margins and modelling of <i>ε</i><sub>Nd</sub> distribution in the Mediterranean basins

2016 ◽  
Vol 13 (18) ◽  
pp. 5259-5276 ◽  
Author(s):  
Mohamed Ayache ◽  
Jean-Claude Dutay ◽  
Thomas Arsouze ◽  
Sidonie Révillon ◽  
Jonathan Beuvier ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Thermohaline Circulation ◽  
Eastern Mediterranean ◽  
Horizontal Resolution ◽  
Data Set ◽  
Isotopic Signatures ◽  
Interesting Insight ◽  
Geographical Variations ◽  
The Mediterranean

Abstract. An extensive compilation of published neodymium (Nd) concentrations and isotopic compositions (Nd IC) was realized in order to establish a new database and a map (using a high-resolution geological map of the area) of the distribution of these parameters for all the Mediterranean margins. Data were extracted from different kinds of samples: river solid discharge deposited on the shelf, sedimentary material collected on the margin or geological material outcropping above or close to a margin. Additional analyses of surface sediments were done in order to improve this data set in key areas (e.g. Sicilian strait). The Mediterranean margin Nd isotopic signatures vary from non-radiogenic values around the Gulf of Lion, (εNd values  ∼  −11) to radiogenic values around the Aegean and the Levantine sub-basins up to +6. Using a high-resolution regional oceanic model (1/12° of horizontal-resolution), εNd distribution was simulated for the first time in the Mediterranean Sea. The high resolution of the model provides a unique opportunity to represent a realistic thermohaline circulation in the basin and thus apprehend the processes governing the Nd isotope distribution in the marine environment. Results are consistent with the preceding conclusions on boundary exchange (BE) as an important process in the Nd oceanic cycle. Nevertheless this approach simulates a too-radiogenic value in the Mediterranean Sea; this bias will likely be corrected once the dust and river inputs will be included in the model. This work highlights that a significant interannual variability of εNd distribution in seawater could occur. In particular, important hydrological events such as the Eastern Mediterranean Transient (EMT), associated with deep water formed in the Aegean sub-basin, could induce a shift in εNd at deep/intermediate depths that could be noticeable in the eastern part of the basin. This underlines that the temporal and geographical variations of εNd could represent an interesting insight of Nd as tracer of the Mediterranean Sea circulation, in particular in the context of palaeo-oceanographic applications.

Collecting training data to map forest management at global scale

2021 ◽  
Author(s):  
Myroslava Lesiv ◽  
Dmitry Schepaschenko ◽  
Martina Dürauer ◽  
Marcel Buchhorn ◽  
Ivelina Georgieva ◽  
...  
Keyword(s):  
Forest Management ◽  
High Resolution ◽  
Remotely Sensed ◽  
Global Scale ◽  
Google Earth ◽  
Training Data ◽  
Tree Cover ◽  
Data Set ◽  
The World ◽  
Very High

&lt;p&gt;Spatially explicit information on forest management at a global scale is critical for understanding the current status of forests for sustainable forest management and restoration. Whereas remotely sensed based datasets, developed by applying ML and AI algorithms, can successfully depict tree cover and other land cover types, it has not yet been used to depict untouched forest and different degrees of forest management. We show for the first time that with sufficient training data derived from very high-resolution imagery a differentiation within the tree cover class of various levels of forest management is possible.&lt;/p&gt;&lt;p&gt;In this session, we would like to present our approach for labeling forest related training data by using Geo-Wiki application (https://www.geo-wiki.org/). Moreover, we would like to share a new open global training data set on forest management we collected from a series of Geo-Wiki campaigns. In February 2019, we organized an expert workshop to (1) discuss the variety of forest management practices that take place in different parts of the world; (2) generalize the definitions for the application at global scale; (3) finalize the Geo-Wiki interface for the crowdsourcing campaigns; and (4) build a data set of control points (or the expert data set), which we used later to monitor the quality of the crowdsourced contributions by the volunteers. We involved forest experts from different regions around the world to explore what types of forest management information could be collected from visual interpretation of very high-resolution images from Google Maps and Microsoft Bing, in combination with Sentinel time series and Normalized Difference Vegetation Index (NDVI) profiles derived from Google Earth Engine (GEE). Based on the results of this analysis, we expanded these campaigns by involving a broader group of participants, mainly people recruited from remote sensing, geography and forest research institutes and universities.&lt;/p&gt;&lt;p&gt;In total, we collected forest data for approximately 230 000 locations globally. These data are of sufficient density and quality and therefore could be used in many ML and AI applications for forests at regional and local scale.&amp;#160; We also provide an example of ML application, a remotely sensed based global forest management map at a 100 m resolution (PROBA-V) for the year 2015. It includes such classes as intact forests, forests with signs of human impact, including clear cuts and logging, replanted forest, woody plantations with a rotation period up to 15 years, oil palms and agroforestry. The results of independent statistical validation show that the map&amp;#8217;s overall accuracy is 81%.&lt;/p&gt;

scholarly journals Short-scale temporal variability of physical, biological and biogeochemical processes in the NW Mediterranean Sea: an introduction

2009 ◽  
Vol 6 (3) ◽  
pp. 453-461 ◽  
Author(s):  
V. Andersen ◽  
M. Goutx ◽  
L. Prieur ◽  
J. R. Dolan
Keyword(s):  
Mediterranean Sea ◽  
Temporal Variability ◽  
Time Course ◽  
Special Section ◽  
Zooplankton Community ◽  
Western Mediterranean ◽  
Trophic Levels ◽  
Data Set ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

Abstract. In the framework of the PROOF-PECHE project (http://www.obs-vlfr.fr/proof/vt/op/ec/peche/pec.htm) a multi-disciplinary team performed experiments and collected samples during the DYNAPROC 2 cruise aboard the RV Thalassa from September to October in 2004. The cruise provided data on the functioning of the pelagic food web by sampling over a month long period in the NW Mediterranean Sea at a fixed station subject to weak horizontal advection currents during a period of hydrological stability. This paper describes the background of the cruise and provides an overview of the results derived from the campaign which constitute the special section. The major objective of the cruise was to assess the relative importance and variability of the pathways of carbon in the open ocean. Intensive sampling through 4 periods of 5 days each was accomplished at a site near the DYFAMED time-series site. The site was near stable in terms of hydrodynamics as there was some evidence of an intrusion of low-salinity coastal water. The cruise yielded a comprehensive data set acquired by sampling over a vertical spatial dimension (0–1000 m) and at high frequencies (ranging from every 3, 6, 12 and/or 24 h), unique for the summer to autumn transition in the North Western Mediterranean. Parameters investigated included the biochemical composition of dissolved organic matter (lipids), and the structure of bacterial communities, phytoplankton and zooplankton community compositions and abundances, as well as zooplankton metabolism, and particulate organic carbon fluxes. Nearly all the parameters described in this section, as well as reports appearing elsewhere, showed time-course variabilities of similar magnitude to those known from a previous study of the spring-summer seasonal transition, a period of marked hydrological change, at the same study site. Remarkably, the least variable characteristic of the system appeared to be the identities of the dominant taxa across several trophic levels (copepods, phytoplankton, ciliates, and bacteria) throughout the study period despite large shifts in stock sizes and fluxes. Thus, the studies of DYNAPROC 2 documented considerable temporal variability of stocks and rates in a system which was, from a hydrological and taxonomic point of view, relatively stable.

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