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  • 1
    Publication Date: 2024-02-27
    Description: In Summer 2015 (4-31 August), CNR-ISMAR carried out an oceanographic field-study in the Western Mediterranean Sea, on board of R/V MINERVA UNO. Sampling stations consisted in 7 transects, that spanned from Sicily Channel to Ligurian sea, Catalan sea, and Balearic Basin, dividing the area in sub-basins. 92 stations were visited totally. The dataset includes 550 discrete data of carbonate chemistry (pH-total scale and Total Alkalinity), concentrations of dissolved oxygen, and basic hydrological data (temperature, salinity and density). Methods: At each station, pressure (dbar), temperature (°C), and conductivity(mS/cm) were measured with a CTD SBE 911 plus General Oceanics Rosette System, equipped with 24 12-litres Niskin Bottles. Salinity (S, psu) and depth (m) were calculated by Sea-Bird Scientific routines. Seawater samples (n = 550) for the determination of biogeochemical parameters were collected from the Niskin bottles. Samples for dissolved oxygen (DO) were drawn in 60-mL BOD bottles and treated with Winkler reagents immediately after collection. For the determination of pH on the total hydrogen ion scale at 25 °C (pHT25), the samples were drawn after DO samples into 10 cm long cylindrical glass cells and analyzed spectrophotometrically. For the determination of total alkalinity (TA; μmol kg-1), the samples were collected in 300 ml borosilicate bottles, poisoned with mercuric chloride, tightly closed and stored in the dark at a temperature similar to the in situ one (4-25 °C). DO samples were analyzed by the Winkler method (Grasshoff et al., 1999) using an automated Metrohm 798 MPT Titrino potentiometric titration system (CV = 0.17 % at 210 µmol L-1). pHT25 was measured on board, within 24 h after the sampling, using the spectrophotometric method with m-cresol purple as indicator (Clayton and Byrne, 1993). The precision was ±0.002 units (n = 3), accuracy and stability of the method were checked daily with reference seawater certified for TA and TCO2 (n = 34, CRM batch 146 provided by Prof A. G. Dickson, Scripps, 210 California). TA was determined by potentiometric titration in an open cell with a difference derivative readout (Hernandez-Ayon et al., 1999). The average precision was ±2.0 μmol kg-1 (n = 86 duplicate samples) and the accuracy was checked daily by the titration of certified reference seawater (n = 59, CRM batch 146)
    Keywords: 108; 109; 110; 111; 213; 215; 217; 218; 219; 225; 227; 231; 261; 291; 405; 406; 433; 434; 438; 451; 460; 462; 51; 900; 901; 903; 906; 907; 908; 910; 911; 912; 913; Alkalinity, total; B1; B2; B3; B4; B5; B6; B7; B8; Balearic Basin; CORS-MOOR; CTD, Sea-Bird SBE 911plus; CTD/Rosette; CTD-RO; D1; D2; D3; D5; D7; DATE/TIME; DEPTH, water; Elevation of event; Event label; Latitude of event; Longitude of event; M9; MINERVA UNO; OC2015; OC2015_108; OC2015_109; OC2015_110; OC2015_111; OC2015_213; OC2015_215; OC2015_217; OC2015_218; OC2015_219; OC2015_225; OC2015_227; OC2015_231; OC2015_261; OC2015_291; OC2015_405; OC2015_406; OC2015_433; OC2015_434; OC2015_438; OC2015_451; OC2015_460; OC2015_462; OC2015_51; OC2015_900; OC2015_901; OC2015_903; OC2015_906; OC2015_907; OC2015_908; OC2015_910; OC2015_911; OC2015_912; OC2015_913; OC2015_B1; OC2015_B2; OC2015_B3; OC2015_B4; OC2015_B5; OC2015_B6; OC2015_B7; OC2015_B8; OC2015_CORS-MOOR; OC2015_D1; OC2015_D2; OC2015_D3; OC2015_D5; OC2015_D7; OC2015_M9; OC2015_S10; OC2015_S12; OC2015_S14; OC2015_S16; OC2015_S18; OC2015_S19; OC2015_S2; OC2015_S20; OC2015_S4; OC2015_S6; OC2015_S8; Ocean acidification; OCEAN-CERTAIN; Ocean Food-web Patrol – Climate Effects: Reducing Targeted Uncertainties with an Interactive Network; Oxygen; pH; Pressure, water; S10; S12; S14; S16; S18; S19; S2; S20; S4; S6; S8; Salinity; Sicily Channel; Spectrophotometry; Temperature, water; Titration, Winkler; Titration potentiometric; Total alkalinity; Western Mediterranean; Winkler oxygen
    Type: Dataset
    Format: text/tab-separated-values, 2921 data points
    Location Call Number Limitation Availability
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  • 2
    Publication Date: 2022-02-11
    Description: Thermohaline staircases are a well-known peculiar feature of the Tyrrhenian Sea. Generated by extensive double diffusion processes fueled by lateral intrusions, they are considered to be the most stable of all the staircases that have been detected in the world ocean, seeing their persistence of more than 40 years in the literature. Double diffusion leads to efficient vertical mixing, potentially playing a significant role in guiding the diapycnal mixing. The present study investigates this process of mixing in the case of the Tyrrhenian staircases by calculating the heat and salt fluxes in their gradient zones (interfaces) and the resulting net fluxes in adjacent layers using hydrological profiles collected from 2003 to 2016 at a station in the heart of the basin interior. The staircases favor downward fluxes of heat and salt, and the results of the calculations show that these are greater where temperature and salinity gradients are also high. This condition is more frequently encountered at thin and sharp interfaces, which sometimes appear as substructures of the thicker interfaces of the staircases. These substructures are hot spots where vertical fluxes are further accentuated. Due to the increasing salt and heat content of the Levantine Intermediate Water (LIW) during the observation period, a rise in the values of the fluxes was noted in the portion of the water column below it down to about 1800 m. The data furthermore show that internal gravity waves can modulate the structure of the staircases and very likely contribute to the mixing, too, but the sampling frequency of the time series is too large to permit a proper assessment of these processes. It is shown that, at least during the period of observation, the fluxes due to salt fingers do not reach the bottom layer but remain within the staircases.
    Description: Published
    Description: 672437
    Description: 4A. Oceanografia e clima
    Description: JCR Journal
    Keywords: Tyrrhenian Sea ; thermohaline staircases ; salt fingers ; diapycnal mixing ; heat and salt fluxes ; 03.03. Physical
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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