Articles | Volume 20, issue 2
https://doi.org/10.5194/os-20-463-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-20-463-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
28 Mar 2024
Research article |
| 28 Mar 2024
| 28 Mar 2024
Tipping of the double-diffusive regime in the southern Adriatic Pit in 2017 in connection with record high-salinity values
Felipe L. L. Amorim
National Institute of Oceanography and Applied Geophysics – OGS, Sgonico, Trieste, 34010, Italy
Julien Le Meur
National Institute of Oceanography and Applied Geophysics – OGS, Sgonico, Trieste, 34010, Italy
Achim Wirth
LEGI, Univ. Grenoble Alpes, CNRS, Grenoble, 38000, France
National Institute of Oceanography and Applied Geophysics – OGS, Sgonico, Trieste, 34010, Italy
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Felipe de Luca Lopes de Amorim, Areti Balkoni, Vera Sidorenko, and Karen Helen Wiltshire
Ocean Sci., 20, 1247–1265, https://doi.org/10.5194/os-20-1247-2024, https://doi.org/10.5194/os-20-1247-2024, 2024
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We studied the increasing or decreasing of chlorophyll a abundance in the German Bight. Chlorophyll a is the pigment present in algae that allows them to capture energy from the sun and indicates both the growth of the algae and the health of the environment. Most of the German Bight has decreasing chlorophyll a concentration in the analysed period. In addition, about 45 % of the changes happening in chlorophyll a were connected with changes in temperature.
Vera Fofonova, Alexey Androsov, Lasse Sander, Ivan Kuznetsov, Felipe Amorim, H. Christian Hass, and Karen H. Wiltshire
Ocean Sci., 15, 1761–1782, https://doi.org/10.5194/os-15-1761-2019, https://doi.org/10.5194/os-15-1761-2019, 2019
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This study is dedicated to tidally induced dynamics in the Sylt-Rømø Bight with a focus on the non-linear component. The tidal residual circulation and asymmetric tidal cycles largely define the circulation pattern, transport and accumulation of sediment, and the distribution of bedforms. The newly obtained high-quality bathymetric data supported the use of high-resolution grids (up to 2 m in the intertidal zone) and elaboration of the details of tidal energy transformation in the domain.
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EGUsphere, https://doi.org/10.5194/egusphere-2024-3391, https://doi.org/10.5194/egusphere-2024-3391, 2025
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We developed a hierarchy of idealized deterministic-stochastic models to simulate the sea surface currents in the Gulf of Trieste. They include tide-and-wind driven sea surface current components, resolving the slowly varying part of the flow and a stochastic signal, representing the fast-varying small-scale dynamics. The comparison with High Frequency Radar observations shows that the non-Gaussian stochastic model captures the essential dynamics and permits to mimic the observed fat-tailed PDF.
Riccardo Martellucci, Michele Giani, Elena Mauri, Laurent Coppola, Melf Paulsen, Marine Fourrier, Sara Pensieri, Vanessa Cardin, Carlotta Dentico, Roberto Bozzano, Carolina Cantoni, Anna Lucchetta, Alfredo Izquierdo, Miguel Bruno, and Ingunn Skjelvan
Earth Syst. Sci. Data, 16, 5333–5356, https://doi.org/10.5194/essd-16-5333-2024, https://doi.org/10.5194/essd-16-5333-2024, 2024
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As part of the ATL2MED demonstration experiment, two autonomous surface vehicles undertook a 9-month mission from the northeastern Atlantic to the Adriatic Sea. Biofouling affected the measurement of variables such as conductivity and dissolved oxygen. COVID-19 limited the availability of discrete samples for validation. We present correction methods for salinity and dissolved oxygen. We use model products to correct salinity and apply the Argo floats in-air correction method for oxygen
Achim Wirth
EGUsphere, https://doi.org/10.5194/egusphere-2024-3307, https://doi.org/10.5194/egusphere-2024-3307, 2024
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The hydrostatic approximation is the basis of most simulations of ocean and climate dynamics. It is here evaluated by using a projection method in the 4D Fourier space. The evaluation is analytic.
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Ocean Sci., 20, 1247–1265, https://doi.org/10.5194/os-20-1247-2024, https://doi.org/10.5194/os-20-1247-2024, 2024
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We studied the increasing or decreasing of chlorophyll a abundance in the German Bight. Chlorophyll a is the pigment present in algae that allows them to capture energy from the sun and indicates both the growth of the algae and the health of the environment. Most of the German Bight has decreasing chlorophyll a concentration in the analysed period. In addition, about 45 % of the changes happening in chlorophyll a were connected with changes in temperature.
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Nonlin. Processes Geophys., 30, 515–525, https://doi.org/10.5194/npg-30-515-2023, https://doi.org/10.5194/npg-30-515-2023, 2023
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An increasing amount of data allows us to move from low-order moments of fluctuating observations to their PDFs. We found the analytical fat-tailed PDF form (a combination of Gaussian and two-exponential convolutions) for 2 years of sea surface current increments in the Gulf of Trieste, using superstatistics and the maximum-entropy principle twice: on short and longer timescales. The data from different wind regimes follow the same analytical PDF, pointing towards a universal behaviour.
Nydia Catalina Reyes Suárez, Valentina Tirelli, Laura Ursella, Matjaž Ličer, Massimo Celio, and Vanessa Cardin
Ocean Sci., 18, 1321–1337, https://doi.org/10.5194/os-18-1321-2022, https://doi.org/10.5194/os-18-1321-2022, 2022
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Explaining the dynamics of jellyfish blooms is a challenge for scientists. Biological and meteo-oceanographic data were combined on different timescales to explain the exceptional bloom of the jellyfish Rhizostoma pulmo in the Gulf of Trieste (Adriatic Sea) in April 2021. The bloom was associated with anomalously warm seasonal sea conditions. Then, a strong bora wind event enhanced upwelling and mixing of the water column, causing jellyfish to rise to the surface and accumulate along the coast.
Emma Reyes, Eva Aguiar, Michele Bendoni, Maristella Berta, Carlo Brandini, Alejandro Cáceres-Euse, Fulvio Capodici, Vanessa Cardin, Daniela Cianelli, Giuseppe Ciraolo, Lorenzo Corgnati, Vlado Dadić, Bartolomeo Doronzo, Aldo Drago, Dylan Dumas, Pierpaolo Falco, Maria Fattorini, Maria J. Fernandes, Adam Gauci, Roberto Gómez, Annalisa Griffa, Charles-Antoine Guérin, Ismael Hernández-Carrasco, Jaime Hernández-Lasheras, Matjaž Ličer, Pablo Lorente, Marcello G. Magaldi, Carlo Mantovani, Hrvoje Mihanović, Anne Molcard, Baptiste Mourre, Adèle Révelard, Catalina Reyes-Suárez, Simona Saviano, Roberta Sciascia, Stefano Taddei, Joaquín Tintoré, Yaron Toledo, Marco Uttieri, Ivica Vilibić, Enrico Zambianchi, and Alejandro Orfila
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Pablo Lorente, Eva Aguiar, Michele Bendoni, Maristella Berta, Carlo Brandini, Alejandro Cáceres-Euse, Fulvio Capodici, Daniela Cianelli, Giuseppe Ciraolo, Lorenzo Corgnati, Vlado Dadić, Bartolomeo Doronzo, Aldo Drago, Dylan Dumas, Pierpaolo Falco, Maria Fattorini, Adam Gauci, Roberto Gómez, Annalisa Griffa, Charles-Antoine Guérin, Ismael Hernández-Carrasco, Jaime Hernández-Lasheras, Matjaž Ličer, Marcello G. Magaldi, Carlo Mantovani, Hrvoje Mihanović, Anne Molcard, Baptiste Mourre, Alejandro Orfila, Adèle Révelard, Emma Reyes, Jorge Sánchez, Simona Saviano, Roberta Sciascia, Stefano Taddei, Joaquín Tintoré, Yaron Toledo, Laura Ursella, Marco Uttieri, Ivica Vilibić, Enrico Zambianchi, and Vanessa Cardin
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Achim Wirth and Florian Lemarié
Earth Syst. Dynam., 12, 689–708, https://doi.org/10.5194/esd-12-689-2021, https://doi.org/10.5194/esd-12-689-2021, 2021
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We show that modern concepts of non-equilibrium statistical mechanics can be applied to large-scale environmental fluid dynamics, where fluctuations are not thermal but come from turbulence. The work theorems developed by Jarzynski and Crooks are applied to air–sea interaction. Rather than looking at the average values of thermodynamic variables, their probability density functions are considered, which allows us to replace the inequalities of equilibrium statistical mechanics with equalities.
Dagmar Hainbucher, Marta Álvarez, Blanca Astray Uceda, Giancarlo Bachi, Vanessa Cardin, Paolo Celentano, Spyros Chaikalis, Maria del Mar Chaves Montero, Giuseppe Civitarese, Noelia M. Fajar, Francois Fripiat, Lennart Gerke, Alexandra Gogou, Elisa F. Guallart, Birte Gülk, Abed El Rahman Hassoun, Nico Lange, Andrea Rochner, Chiara Santinelli, Tobias Steinhoff, Toste Tanhua, Lidia Urbini, Dimitrios Velaoras, Fabian Wolf, and Andreas Welsch
Earth Syst. Sci. Data, 12, 2747–2763, https://doi.org/10.5194/essd-12-2747-2020, https://doi.org/10.5194/essd-12-2747-2020, 2020
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We report on data from an oceanographic cruise in the Mediterranean Sea (MSM72, March 2018). The main objective of the cruise was to contribute to the understanding of long-term changes and trends in physical and biogeochemical parameters, such as the anthropogenic carbon uptake, and further assess the hydrographical situation after the Eastern and Western Mediterranean Transients. Multidisciplinary measurements were conducted on a predominantly
zonal section throughout the Mediterranean Sea.
Achim Wirth
Ocean Sci. Discuss., https://doi.org/10.5194/os-2019-128, https://doi.org/10.5194/os-2019-128, 2020
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The input of mechanical power to the ocean due to the surface wind-stress is considered using data from satellites observations. Its dependence on the coarse-graining scale of the atmospheric and oceanic velocity in space and time is determined. The power input is found to increase monotonically with shorter coarse-graining in time. Results show that including the dynamics at scales below a few degrees reduces considerably the power input by air-sea interaction.
Vera Fofonova, Alexey Androsov, Lasse Sander, Ivan Kuznetsov, Felipe Amorim, H. Christian Hass, and Karen H. Wiltshire
Ocean Sci., 15, 1761–1782, https://doi.org/10.5194/os-15-1761-2019, https://doi.org/10.5194/os-15-1761-2019, 2019
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This study is dedicated to tidally induced dynamics in the Sylt-Rømø Bight with a focus on the non-linear component. The tidal residual circulation and asymmetric tidal cycles largely define the circulation pattern, transport and accumulation of sediment, and the distribution of bedforms. The newly obtained high-quality bathymetric data supported the use of high-resolution grids (up to 2 m in the intertidal zone) and elaboration of the details of tidal energy transformation in the domain.
Achim Wirth
Nonlin. Processes Geophys., 26, 457–477, https://doi.org/10.5194/npg-26-457-2019, https://doi.org/10.5194/npg-26-457-2019, 2019
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The conspicuous feature of the atmosphere–ocean system is the large difference in the masses of the two media. In this respect there is a strong analogy to Brownian motion, with light and fast molecules colliding with heavy and slow Brownian particles. I apply the tools of non-equilibrium statistical mechanics for studying Brownian motion to air–sea interaction.
Achim Wirth
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2018-300, https://doi.org/10.5194/gmd-2018-300, 2019
Revised manuscript not accepted
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The dynamics of three local linear models of air-sea-interaction commonly employed in climate or ocean simulations is compared. The models differ by whether or not the ocean velocity is included in the shear calculation applied to the ocean and the atmosphere. Analytic calculations for the models with deterministic and random forcing (white and colored) are presented.The fluctuation-dissipation-relation, the fluctuation-dissipation-theorem and the fluctuation-theorem is discussed.
D. Hainbucher, V. Cardin, G. Siena, U. Hübner, M. Moritz, U. Drübbisch, and F. Basan
Earth Syst. Sci. Data, 7, 231–237, https://doi.org/10.5194/essd-7-231-2015, https://doi.org/10.5194/essd-7-231-2015, 2015
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We report on data from an oceanographic cruise in the Mediterranean in April 2014. Data were taken on a west-east section starting at the Strait of Gibraltar and ending south-east of Crete, as well on sections in the Ionian and Adriatic Sea. The measurements include salinity, temperature, oxygen and currents. We study the mesoscale eddy field and support long-term investigations of the hydrography in the Mediterranean Sea.
C. Q. C. Akuetevi and A. Wirth
Ocean Sci., 11, 471–481, https://doi.org/10.5194/os-11-471-2015, https://doi.org/10.5194/os-11-471-2015, 2015
V. Cardin, G. Civitarese, D. Hainbucher, M. Bensi, and A. Rubino
Ocean Sci., 11, 53–66, https://doi.org/10.5194/os-11-53-2015, https://doi.org/10.5194/os-11-53-2015, 2015
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The results of this study reveal that the thermohaline properties in the study area in 2011 lie between the thermohaline characteristics of the EMT and those of the pre-EMT phase, indicating a possible slow return towards the latter. It highlights the relationship between the hydrological property distribution of the upper layer in the Levantine basin and the alternate circulation regimes in the Ionian, which modulates the salinity distribution in the Eastern Mediterranean Sea.
D. Hainbucher, A. Rubino, V. Cardin, T. Tanhua, K. Schroeder, and M. Bensi
Ocean Sci., 10, 669–682, https://doi.org/10.5194/os-10-669-2014, https://doi.org/10.5194/os-10-669-2014, 2014
M. Gačić, G. Civitarese, V. Kovačević, L. Ursella, M. Bensi, M. Menna, V. Cardin, P.-M. Poulain, S. Cosoli, G. Notarstefano, and C. Pizzi
Ocean Sci., 10, 513–522, https://doi.org/10.5194/os-10-513-2014, https://doi.org/10.5194/os-10-513-2014, 2014
P. Malanotte-Rizzoli, V. Artale, G. L. Borzelli-Eusebi, S. Brenner, A. Crise, M. Gacic, N. Kress, S. Marullo, M. Ribera d'Alcalà, S. Sofianos, T. Tanhua, A. Theocharis, M. Alvarez, Y. Ashkenazy, A. Bergamasco, V. Cardin, S. Carniel, G. Civitarese, F. D'Ortenzio, J. Font, E. Garcia-Ladona, J. M. Garcia-Lafuente, A. Gogou, M. Gregoire, D. Hainbucher, H. Kontoyannis, V. Kovacevic, E. Kraskapoulou, G. Kroskos, A. Incarbona, M. G. Mazzocchi, M. Orlic, E. Ozsoy, A. Pascual, P.-M. Poulain, W. Roether, A. Rubino, K. Schroeder, J. Siokou-Frangou, E. Souvermezoglou, M. Sprovieri, J. Tintoré, and G. Triantafyllou
Ocean Sci., 10, 281–322, https://doi.org/10.5194/os-10-281-2014, https://doi.org/10.5194/os-10-281-2014, 2014
C. Q. C. Akuetevi and A. Wirth
Ocean Sci. Discuss., https://doi.org/10.5194/osd-11-753-2014, https://doi.org/10.5194/osd-11-753-2014, 2014
Revised manuscript not accepted
T. Tanhua, D. Hainbucher, K. Schroeder, V. Cardin, M. Álvarez, and G. Civitarese
Ocean Sci., 9, 789–803, https://doi.org/10.5194/os-9-789-2013, https://doi.org/10.5194/os-9-789-2013, 2013
T. Tanhua, D. Hainbucher, V. Cardin, M. Álvarez, G. Civitarese, A. P. McNichol, and R. M. Key
Earth Syst. Sci. Data, 5, 289–294, https://doi.org/10.5194/essd-5-289-2013, https://doi.org/10.5194/essd-5-289-2013, 2013
A. Wirth
Nonlin. Processes Geophys., 20, 25–34, https://doi.org/10.5194/npg-20-25-2013, https://doi.org/10.5194/npg-20-25-2013, 2013
Related subject area
Approach: In situ Observations | Properties and processes: Mesoscale to submesoscale dynamics
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Subsurface manifestation of Marine Heatwaves in the South West Indian Ocean
The Polar Front in the northwestern Barents Sea: structure, variability and mixing
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Ria Oelerich, Birte Gülk, Julia Dräger-Dietel, and Alexa Griesel
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Yan Barabinot, Sabrina Speich, Xavier Carton, Pierre L'Hégaret, Corentin Subirade, Rémi Laxenaire, and Johannes Karstensen
EGUsphere, https://doi.org/10.5194/egusphere-2025-586, https://doi.org/10.5194/egusphere-2025-586, 2025
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Mesoscale eddies are rotating oceanic currents key to ocean variability. Off Brazil’s northeast coast, the North Brazil Current generates in average 4.5 eddies per year, which drift towards the West Indies, transporting waters from the southern hemisphere. Using data collected at sea by the EUREC4A-OA cruise, this study reveals that deep eddies transport five times more water than surface ones, reshaping our understanding of the regional water transport.
Gillian Mary Damerell, Anthony Bosse, and Ilker Fer
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The Lofoten Vortex is an unusual feature in the ocean: a permanent eddy which doesn’t dissipate as most eddies do. We have long thought that other eddies must merge into the Vortex in order to maintain its heat content and energetics, but such mergers are very difficult to observe due to their transient, unpredictable nature. For the first time, we have observed a merger using an ocean glider and high resolution satellite data and can document how the merger affects the properties of the Vortex.
Yan Barabinot, Sabrina Speich, and Xavier Carton
Ocean Sci., 21, 151–179, https://doi.org/10.5194/os-21-151-2025, https://doi.org/10.5194/os-21-151-2025, 2025
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Mesoscale eddies are ubiquitous rotating currents in the ocean. Some eddies, called "materially coherent", are able to transport a different water mass from the surrounding water. By analyzing 3D eddy structures sampled during oceanographic cruises, we found that eddies can be nonmaterially coherent, accounting only for their surface properties, but materially coherent considering their properties at depth. Future studies cannot rely solely on satellite data to evaluate heat and salt transport.
Yosef Ashkenazy, Hezi Gildor, and Aviv Solodoch
EGUsphere, https://doi.org/10.5194/egusphere-2025-53, https://doi.org/10.5194/egusphere-2025-53, 2025
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We studied ocean currents in the Eastern Mediterranean near Israel's coast (2016–2024) across depths up to 1.3 km. The Generalized Gamma distribution best matched current speed data. The speed increments time series fit a stretched exponential distribution better than a normal distribution. Comparisons with high-resolution and regional general circulation models showed discrepancies, highlighting the need to refine the models for better extreme current speed event predictions.
Kjersti Kalhagen, Ragnheid Skogseth, Till M. Baumann, Eva Falck, and Ilker Fer
Ocean Sci., 20, 981–1001, https://doi.org/10.5194/os-20-981-2024, https://doi.org/10.5194/os-20-981-2024, 2024
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Atlantic water (AW) is a key driver of change in the Barents Sea. We studied an emerging pathway through the Svalbard Archipelago that allows AW to enter the Barents Sea. We found that the Atlantic sector near the study site has warmed over the past 2 decades; that Atlantic-origin waters intermittently enter the Barents Sea through the aforementioned pathway; and that heat transport is driven by tides, wind events, and variations in the upstream current system.
Clea Baker Welch, Neil Malan, Daneeja Mawren, Tamaryn Morris, Janet Sprintall, and Juliet Clair Hermes
EGUsphere, https://doi.org/10.5194/egusphere-2024-2210, https://doi.org/10.5194/egusphere-2024-2210, 2024
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Marine heatwaves (MHWs) are prolonged periods of extreme ocean temperatures with significant impacts on marine ecosystems. Much research has focused on surface MHWs, but less is known about their subsurface extent. This study uses satellite and in situ data to investigate MHWs in the Southwest Indian Ocean (SWIO). We find that MHWs in the SWIO are typically moderate in severity, closely linked to mesoscale eddies, and that strong temperature anomalies extend below surface-identified MHWs.
Eivind H. Kolås, Ilker Fer, and Till M. Baumann
Ocean Sci., 20, 895–916, https://doi.org/10.5194/os-20-895-2024, https://doi.org/10.5194/os-20-895-2024, 2024
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In the northwestern Barents Sea, we study the Barents Sea Polar Front formed by Atlantic Water meeting Polar Water. Analyses of ship and glider data from October 2020 to February 2021 show a density front with warm, salty water intruding under cold, fresh water. Short-term variability is linked to tidal currents and mesoscale eddies, influencing front position, density slopes and water mass transformation. Despite seasonal changes in the upper layers, the front remains stable below 100 m depth.
Ryan P. North, Julia Dräger-Dietel, and Alexa Griesel
Ocean Sci., 20, 103–121, https://doi.org/10.5194/os-20-103-2024, https://doi.org/10.5194/os-20-103-2024, 2024
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The Benguela upwelling region off the coast of Namibia supplies cold water from the deep ocean that is transported offshore in finger-like structures called filaments. We investigate one major filament using measurements from a ship that crossed it multiple times and with mutiple buoys that follow the ocean currents. We find that the motions associated with the filament enhance the kinetic energy at small scales and provide a pathway for mixing of water and turbulent dissipation of energy.
Pierre-Marie Poulain, Luca Centurioni, Carlo Brandini, Stefano Taddei, Maristella Berta, and Milena Menna
Ocean Sci., 19, 1617–1631, https://doi.org/10.5194/os-19-1617-2023, https://doi.org/10.5194/os-19-1617-2023, 2023
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Drifters and a profiling float were deployed in the coastal waters of the southeastern Ligurian Sea to characterize the near-surface circulation at a scale of ~10 km. The drifters were trapped in an offshore-flowing filament and a cyclonic eddy that developed at the southwestern extremity of the filament. Drifter velocities are used to estimate differential kinematic properties and relative dispersion statistics of the surface currents.
Ria Oelerich, Karen J. Heywood, Gillian M. Damerell, Marcel du Plessis, Louise C. Biddle, and Sebastiaan Swart
Ocean Sci., 19, 1465–1482, https://doi.org/10.5194/os-19-1465-2023, https://doi.org/10.5194/os-19-1465-2023, 2023
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At the southern boundary of the Antarctic Circumpolar Current, relatively warm waters encounter the colder waters surrounding Antarctica. Observations from underwater vehicles and altimetry show that medium-sized cold-core eddies influence the southern boundary's barrier properties by strengthening the slopes of constant density lines across it and amplifying its associated jet. As a result, the ability of exchanging properties, such as heat, across the southern boundary is reduced.
Arthur Coquereau and Nicholas P. Foukal
Ocean Sci., 19, 1393–1411, https://doi.org/10.5194/os-19-1393-2023, https://doi.org/10.5194/os-19-1393-2023, 2023
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Understanding meltwater circulation around Greenland is crucial as it could influence climate variability but difficult as data are scarce. Here, we use 34 surface drifters to evaluate satellite-derived surface currents and show that satellite data recover the general structure of the flow and can recreate the pathways of particles around the southern tip of Greenland. This result permits a wide range of work to proceed looking at long-term changes in the circulation of the region since 1993.
Cited articles
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Short summary
Analysis of a high-frequency time series of thermohaline data measured at the EMSO-E2M3A regional facility in the southern Adriatic Pit (SAP) reveals a significant change in the double-diffusive regime in 2017 associated with the intrusion of extremely salty waters into the area, suggesting salt fingering as the dominant regime. The strong heat loss at the surface during this winter allowed deep convection to transport this high-salinity water from the intermediate to deep layers of the pit.
Analysis of a high-frequency time series of thermohaline data measured at the EMSO-E2M3A...
