AndreaBozzo/ceres-open-data-index huggingface dataset:
Irregular BSR: evidence of an on-going reequilibrium of a gas hydrate system

[Lien vers la fiche source] Gas hydrate (GH) systems constitute methane sinks sensitive to environmental changes such as pressure, temperature or salinity. It remains a matter of debate whether the large GH system of the Black Sea has achieved a steady state since the last glacial maximum (LGM). We report on an irregular free gas distribution occurring in specific sediment layers marking an irregular bottom-simulating reflector (BSR). This anomalous free gas distribution revealed by very high resolution seismic images, acquired by a deep-towed multichannel seismic system, might be an evidence of an on-going migration of the base of the GH stability zone (GHSZ). We show that the reequilibrium is not occurring homogeneously as overpressure from hydrates dissociation slows their decomposition in specific sedimentary layers. The Black Sea example highlights that dissociation and the associated methane released in the water column or even in the atmosphere could be largely delayed by overpressure accumulation.
A global database of vertical profiles derived from Biogeochemical Argo float measurements for biogeochemical and bio-optical applications

[Lien vers la fiche source] The presented database includes 0-1000 m vertical profiles of bio-optical and biogeochemical variables acquired by autonomous profiling Biogeochemical-Argo (BGC-Argo) floats. Data have been collected between October 2012 and January 2016, around local noon, in several oceanic areas encompassing the diversity of ocean’s trophic environments. The database includes profiles of downward irradiance at 3 wavelengths (380, 412 and 490 nm), photosynthetically available radiation, chlorophyll a concentration, fluorescent dissolved organic matter, and particle light backscattering at 700 nm. All variables have been quality controlled following specifically-developed procedures, that aimed to support biogeochemical and bio-optical applications at the global scale. Data corruption by biofouling and any instrumental drift has also been verified. Moreover, to allow users for different biogeochemical applications, vertical profiles of chlorophyll a and particle light backscattering at 700 nm have been presented before and after advanced processing (e.g., non-photochemical quenching correction, identification of spikes). Vertical profiles of temperature and salinity associated to these bio-optical data are also provided although they have been only quality-controlled for sensor issues related to bio-fouling and instrumental drift.
Early diagenesis in sediments of a Mediterranean lagoon (Venice lagoon, Italy) and its relationship to hypoxia

[Lien vers la fiche source] The interaction between sediment biogeochemistry and hypoxia has been largely investigated in ecosystems periodically subjected to the presence of large anoxic zones, and in landlocked stratified environments. Less attention has been provided to shallow water systems in which stratification is absent, and the wind is expected to have a major role in water mixing and reoxygenation. The present work focuses on sediments of a shallow water lagoon, located in a densely populated area subjected to multiple stressors (Venice lagoon, Italy), with the goal of increasing the understanding of the links between diagenetic processes occurring in sediments and the dynamics of dissolved oxygen. Sediment data were collected over three consecutive years, from 2015 to 2017, during the spring-summer season, at a total of 5 different stations, located in different areas of the lagoon. Measured variables included sediment porosity, grain size and solids composition, porewater microprofiles of O2, pH and H2S, porewater profiles, including DIC, Alk, NH4, NO3, dissolved Fe. In addition, long-term water quality monitoring data (years 2005-2017) collected by the Venice Water Authority (Magistrato alle Acque) were analyzed, in order to assess the tendency of the sampled areas to undergo hypoxia. The latter analysis, which was performed at 4 monitoring stations, pointed out that the lagoon waters experience low oxygen concentrations in summer months, with median values below 50% saturation, and that consecutive days with minimum saturation values below 25% (55 mmol/l) can occur, and last one week or more. The inter-annual consistency of data collected by sediment coring was first performed and, subsequently, sampled stations were divided in two categories based on their diagenetic intensity. At intense and moderate diagenesis stations the average DIC flux, estimated trough a simple steady-state model (profile) were respectively of 2.8 and 1.0 mmol m-2 d-1, SO4 fluxes of 1.6 and 0.4 mmol m-2 d-1, while diffusive oxygen uptake fluxes, calculated from the sediment microprofiles data, were of 28.5 and 17.5 mmol m-2 d-1. At the organic-rich stations, dissolved sulfide accumulated in porewaters very near the sediment-water interface, reaching values of 0.7 mM at 10 cm. Considering the typical physico-chemical summer conditions at these stations, we estimated the time required for a complete O2 depletion of the water column by sediment oxygen demand in absence of mixing, which would be comprised between 4 and 14 days, respectively at intense and moderate diagenesis stations. This estimation highlights that changes in regional climate conditions of these systems such as the increase in the frequency of summer heat waves, currently experienced in the Mediterranean region, could extend the duration and increase the severity of hypoxic events. In this respect, an aspect of relevance concerns the consequences that hypoxia can have on water bodies through release of sulfide.
EUREC4A-OA experiment: Air-Sea Flux Mast Data

[Lien vers la fiche source] As part of the EUREC4A-OA project (H. Bellenger, S. Speich, LMD), which is the French oceanographic component of the larger EUREC4A field experiments, the “flux mast” national instrument was installed on the Reseach Vessel R/V Atalante from Genavir. The flux mast holds instruments that measure atmospheric turbulence and meteorological variables. The collected data are used to estimate the turbulent fluxes of momentum and heat at the air-sea interface. Specifically, the flux mast instruments measure air pressure, air temperature, humidity, air refraction index, H2O, the three components of the wind vector, and the upward and downward solar and infrared radiation fluxes. The fluxes calculated are the latent and sensible heat fluxes, and the friction velocity.
Distribution of Scleractinia (Madrepora oculata and Lophelia pertusa) reported between 1995 and 2013 in the French Mediterranean Sea

[Lien vers la fiche source] In the Mediterranean deep-sea two scleractinian species, Lophelia pertusa (= Desmophyllum pertusum) and Madrepora oculata, make up the dominant structure-forming corals. The Lacaze-Duthiers canyon is the only French Mediterranean canyon where the two species L. pertusa and M. oculata have been observed living together in large quantities, the situation generally described for the biocoenosis of cold-water corals (CWC). In this canyon large colonies (more than 40 cm) of both species of scleractinians were observed at depths ranging from 246 m to 541 m at the head of the canyon and its western flank. The second canyon is the Cassidaigne canyon, where M. oculata seems to be the only structure-forming scleractinian there. The largest concentration of M. oculata colonies was observed on the west flank of the canyon along a crest at depths ranging from 200 to 210 m. Mature M. oculata colonies attained heights up to 40 cm. M. oculata were observed in three other canyons: Bourcart, Sicié and Var. In the Bourcart canyon, M. oculata was observed on a shelf of hard substratum at 331 m depth. Several single branches protruded from a slab. In the Sicié canyon a 15-cm colony of M. oculata was observed at 255 m depth, while in the Var canyon, three young branches 2 cm long were seen growing at 350 m depth on a wall of hard rock.
MOOSE T00_27 (EGO milou glider) deployment (Mediterranean Sea - Western basin)

[Lien vers la fiche source] The proposed research is based on the monitoring of the long term evolution of the North Western Mediterranean Sea with glider repeat-sections carried out in the framework of the ALLENVI/INSU/ SOERE MOOSE (http://moose-network.fr), INSU/MISTRALS (http://www.mistrals-home.org), and EU FP7 PERSEUS (http://www.perseus-net.eu). The objective is to monitor the oceanographic variability (physical and biogeochemical) of the north western Mediterranean Sea, over a continuum of spatial and temporal scales. Two cross-basin repeat-sections with a repeat rate of about 10-20 days allow to monitor the main circulation features (Northern Current, North Balearic Front, Western Corsica Current) on a regular basis, as well as major processes such as winter intermediate and deep water formations and vernal blooms. The gliders regularly visit MOOSE moorings for cross-calibration purposes and to explore the variability around these moorings. i) T00 is a repeat-section between Nice and Calvi passing by the MOOSE mooring DYFAMED located in the central Ligurian Sea ii) T02 is a repeat-section between Marseille and Menorca passing by the MOOSE mooring LION located in the center of the deep convection area The following parameters are provided : - Practical salinity - Sea temperature in-situ ITS-90 scale - Electrical conductivity - Sea water pressure, equals 0 at sea-level
Interfaces and Ocean Heat Flux derived from SIMBA_2015a and SIMBA_2015f data during N-ICE campaign in winter 2015.

[Lien vers la fiche source] We defined the interfaces between the air/snow, snow/ice, and ice/ocean and calculated the ocean heat flux for two SIMBA recordings (SIMBA2015a and SIMBA_2015f) of repeated temperature profiles at 6h interval and 2cm vertical resolution, during N-ICE 2015 experiment floe1. - The snow/ice interface is derived from the sharp contrast in the diffusivity proxy values between both media. The snow/ice interface does not change except for slush formation associated with flooding events. - The air/snow interface is calculated using simultaneous information from the vertical gradient of the temperature and the standard deviation over 24, 48, and 72 h period. Snow accumulation of more than 10 centimeters happened at different time for the 2 SIMBA. - The ice/ocean interface is estimated from temperature profiles alone since the winter sea-ice remains colder than the ocean. The ocean just below the ice is at or just above the freezing temperature (estimated from a near surface conductivity-temperature-depth (CTD) sensor see Koenig et al. [2016]). The method detects (1) the first sensor, downward of the snow/ice interface, with a temperature above the ocean freezing temperature and (2) the last sensor in the ice with a temperature below the mean ocean temperature by at least twice the ocean temperature standard deviation in that profile. The ice/ocean interface is then defined as half way between the last sensor in the ice and the first sensor in the ocean. Note it take 3-4 days for the deployment hole to refreeze. Then the ice thickness remains constant up to 20 February when floe1 breaks. Simba_2015f stops working and SIMBA_2015a features basal melt events corresponding to temperature changes in the ocean. The consistency of the 3 interfaces estimate is validated with the thermal diffusivity proxy and the vertical and temporal derivatives of temperature. - The ocean heat flux is derived from the latent heat flux which is directly proportional to the change in time of the ice/ocean interface depth and the conductive heat flux in the lower portion of the ice estimated 6 cm above the ice/ocean interface. The ocean heat flux values for SIMBA_2015a and SIMBA2015f range from -50 to 350 W/m2, and -50 to 150 W/m2 respectively, while the basal melt events associated with ocean temperature increase stand out in SIMBA_2015a. The SIMBA data are available through the Norwegian Polar Institute’s data center (https://data.npolar.no/dataset/6ed9a8ca-95b0-43be-bedf-8176bf56da80) and the method of interface detection is thoroughly described in Provost et al. (2017). Note that all time series have been smoothed with a 36-h running mean. Provost, C., N. Sennechael, J. Miguet, P. Itkin, A. Rosel, Z. Koenig, N. Villacieros-Robineau, and M. A. Granskog (2017), Observations of flooding and snow-ice formation in a thinner Arctic sea-ice regime during the N-ICE2015 campaign: Influence of basal ice melt and storms, J. Geophys. Res. Oceans, 122, 7115–7134, doi:10.1002/2016JC012011.
Biogeochemical data at a Mediterranean mussel farm, Northern Adriatic Sea

[Lien vers la fiche source] The database presents the field data used within the study carried out in the north-western Adriatic Sea (Brigolin et al., 2018, Biogeosciences https://doi.org/10.5194/bg-2017-206). A longline mussel farm was taken as a local source of perturbation to the natural Particulate Organic Carbon (POC) downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment traps data, and its effects on sediment bioirrigation capacity and OM degradation pathways were investigated constraining an early diagenesis model by using original data collected in sediment porewaters. The measurements were performed at stations located inside and outside the area affected by mussel farm deposition.
2000-2015 climatology of the Subtropical Mode Waters and Permanent Pycnocline properties in the World Ocean

[Lien vers la fiche source] This dataset contains OAC-P results from application to Argo data in the World Ocean : - the 2000-2015 climatology of OAC-P results mapped onto a 0.5x0.5 grid with mapping error estimates; - the 2000-2015 probability density function of the permanent pycnocline potential density referenced to the sea surface vs Brunt-Väisälä frequency squared.OAC-P is an "Objective Algorithm for the Characterization of the permanent Pycnocline" developed to characterize subtropical gyre stratification features with both observed and modeled potential density profiles. OAC-P estimates the following properties: - for the permanent pycnocline: depth, upper and lower thicknesses, Brunt-Väisälä frequency squared, potential density, temperature and salinity; - for the surface mode water overlying the permanent pycnocline: depth, Brunt-Väisälä frequency squared, potential density, temperature and salinity. Argo data were download from Coriolis Argo GDAC on February, 8th 2016. Only Argo data with QC=1, 2, 5 or 8 were used.
Ocean Salinity Stratification (OSS)

[Lien vers la fiche source] This dataset is composed by the climatological seasonal field of the Ocean Salinity Stratification as defined from the Brunt-Vaisala frequency limited to the upper 300 m depth. The details are given in Maes, C., and T. J. O’Kane (2014), Seasonal variations of the upper ocean salinity stratification in the Tropics, J. Geophys. Res. Oceans, 119, 1706–1722, doi:10.1002/2013JC009366.
A global bio-optical database derived from Biogeochemical Argo float measurements within the layer of interest for field and remote ocean color applications

[Lien vers la fiche source] The database here presented includes quality-controlled bio-optical and biogeochemical variables derived from autonomous profiling Biogeochemical Argo float measurements, and supports field and remote ocean color applications. Data represent the first optical depth (i.e., the layer of interest for satellite remote sensing) and have been collected between October 2012 and January 2016, around local noon, in several oceanic areas encompassing the diversity of ocean’s trophic environments. In addition to the first optical depth (as derived from the in situ measured depth of the euphotic layer), the presented database is compiled with data of diffuse light attenuation coefficients of photosynthetically available radiation and downward irradiance at 3 wavelengths (380, 412 and 490 nm), chlorophyll a concentration, fluorescent dissolved organic matter, and particle light backscattering at 700 nm. Associated errors to each variable are also reported.
Marine Strategy Framework Directive: Coriolis data centre contribution to French observations

[Lien vers la fiche source] This dataset is an aggregation of all availale in situ data from Coriolis and Copernicus in situ data centres, observed in the French DCSMM area. It contains 5167 NetCDF CF files from 1903 to 2017. Each file contains the observations of a specific platform (e.g. vessel, mooring site, sea level station). Observed parameters are temperature, salinity, pressure, oxygen, nitrate, chlorophyll (and other bio-geo-chemicals), current, wave, sea level, river flow.
MOOSE T02_01 (EGO eudoxus glider) deployment (Mediterranean Sea - Western basin)

[Lien vers la fiche source] The proposed research is based on the monitoring of the long term evolution of the North Western Mediterranean Sea with glider repeat-sections carried out in the framework of the ALLENVI/INSU/ SOERE MOOSE (http://moose-network.fr), INSU/MISTRALS (http://www.mistrals-home.org), and EU FP7 PERSEUS (http://www.perseus-net.eu). The objective is to monitor the oceanographic variability (physical and biogeochemical) of the north western Mediterranean Sea, over a continuum of spatial and temporal scales. Two cross-basin repeat-sections with a repeat rate of about 10-20 days allow to monitor the main circulation features (Northern Current, North Balearic Front, Western Corsica Current) on a regular basis, as well as major processes such as winter intermediate and deep water formations and vernal blooms. The gliders regularly visit MOOSE moorings for cross-calibration purposes and to explore the variability around these moorings. i) T00 is a repeat-section between Nice and Calvi passing by the MOOSE mooring DYFAMED located in the central Ligurian Sea ii) T02 is a repeat-section between Marseille and Menorca passing by the MOOSE mooring LION located in the center of the deep convection area The following parameters are provided : - Chlorophyll-A signal from fluorescence sensor - Particle backscattering at 532 nanometers - Concentration of coloured dissolved organic matter in sea water
Data from marine sediment core MOZ4-CS09

[Lien vers la fiche source] A 27-meter core collected on the seafloor (1909 meters depth) near Juan de Nova island preserves a high-resolution record of carbonate export to the deep sea over the past 1 Myr. Core chronology was established using calcareous nannofossil biostratigraphy and benthic foraminiferal δ18O, which was correlated with variations in the aragonite content within seafloor muds. Throughout the core, preserved highstand intervals (MIS 1, 5, 7, 9, 11, 13, 15, 23 and 25) are marked by an increase in the aragonite content within the sediment. Aragonite is likely sourced from the nearby Juan de Nova carbonate platform ~10 km to the south, and is interpreted to result from flooding of the platform top. Platform inundation allows carbonate muds to be winnowed from their original shallow-water environment of deposition, suspended in the water column, and redeposited into the proximal slopes and basin. Sharp increases in aragonite content at the beginning of each highstand interval can be used to estimate the approximate sea level range when platform flooding occurred; results show that the depth of the platform top has likely changed little over the past 1 Myr due to balanced aggradation and subsidence. Previously hypothesized large-scale aragonite dissolution cycles are evidenced by a disproportionally low aragonite response during MIS 11. This study provides a new, exceptionally long record of highstand shedding, expanding the known occurrences of the process to the southern Indian Ocean and supporting its importance as a globally significant depositional mechanism that impacts deep-sea stratigraphic records.
MOOSE T02_05 (EGO eudoxus glider) deployment (Mediterranean Sea - Western basin)

[Lien vers la fiche source] The observations of eudoxus glider on perseust02_05 deployment (Mediterranean Sea - Western basin) are distributed in 4 files: - EGO NetCDF time-series (data, metadata, derived sea water current) - NetCDF profiles extracted from the above time-series - Raw data - JSON metadata used by the decoder The following parameters are provided : - sea water pressure - Sea water temperature - Sea water conductivity - Sea water salinity
High-resolution observations of a dual-core anticyclonic eddy in the Algerian Basin (PROTEVS-MED 2016)

[Lien vers la fiche source] Mesoscale dynamics in the Mediterranean Sea have been investigated for years and anticyclonic eddies are regularly observed features in the Algerian Basin. In early spring 2016, a field experiment during the ProtevsMed 2016 cruise thoroughly investigated this specific eddy, when it was located near the North Balearic Front, taking high-resolution (Seasoar) hydrological transects, several CTD casts and LADCP measurements. In addition, four drifting buoys were released in the eddy core. These in situ measurements revealed that the vertical structure of this anticyclone was made of two water lenses of very different origins (Atlantic Water above and Western Intermediate Water below) spinning together. In the vicinity of the North Balearic Front, which may act as a dynamical barrier for structures, the eddy interacted with a subsurface anticyclonic eddy made of modal water, which fostered cross-front exchanges generating filaments by stirring. The high-resolution sampling revealed fine scales structures both adjacent to the eddy and within its core. The eddy has been targeted from 21 March to 1 April 2016 taking advantage of a meteorological window. It has been sampled with: - a towed undulating vehicle, the SeaSoar designed and built by Chelsea Instruments; it gets mounted on its sides two Sea-bird SBE-9 (SBE 3 temperature and SBE 4 conductivity sensors) and a Wetlabs Fluorometer of type ChloroA WetStar - CTD casts performed with a Sea-bird SBE-9 (SBE 3 temperature and SBE 4 conductivity sensor) and an RDI 150 kHz current profiler mounted in a general oceanics 12-place rosette, with12l Niskin bottles - drifters with holey-sock positioned at 50 m deep below the expected Ekman layer thickness (remaining in the eddy until mid May).
ELISA (1997-1998) mesoscale survey in the Algerian sub-basin (Western Mediterranean): hydrological data set of the cruise ELISA-3 (spring 1998)

[Lien vers la fiche source] The Eddies and Leddies Interdisciplinary Study in the Algerian sub-basin (ELISA) experiment (1997–1998) was a multidisciplinary and multiplatform experiment designed to study the anticyclonic Algerian Eddies (AEs) generated by the instability of the Algerian Current, and their influence on the general circulation and biological phenomena. The data collected confirmed for instance the eastward path of LIW along the Algerian slope, and showed that these anticyclones correspond to the richer areas in spring. Following the daily analysis of satellite thermal images to track the AEs, the sampling scheme was adapted in real time, using transects with CTD casts every ~10km. So that the data are strongly "biased" toward describing (moving) eddies at high resolution: they are likely to be unadequate for a few purposes. The ELISA hydrological data sets have been obtained during the four cruises ELISA-1 to 4, from summer 1997 to summer 1998. This data set includes the ELISA-3 cruise (spring 1998) with 52 CTD profiles plus associated water bottles samples. Data sets are delivered in both netcdf and ODV formats.
COSTOF, technical data from SeaMoN West, node of the EMSO-Azores observatory, 2010-2011

[Lien vers la fiche source] This dataset contains technical parameters (Voltage in V, current in mA, energy in Ah, internal pressure in mbar, water leak detection) acquired between October 2010 and December 2010 (n=332) by the COSTOF (COmmunication and STOrage Front-end), which is the Electronic core of SeaMoN West, the bottom station of EMSO-Azores dedicated to geophysical observations (data acquired every 6 hours).