Rapid coastal deoxygenation due to ocean circulation shift in the NW Atlantic.

Global observations show that the ocean lost approximately 2% of its oxygen inventory over the last five decades 1-3, with important implications for marine ecosystems 4, 5. The rate of change varies with northwest Atlantic coastal waters showing a long-term drop 6, 7 that vastly outpaces the global and North Atlantic basin mean deoxygenation rates 5, 8. However, past work has been unable to resolve mechanisms of large-scale climate forcing from local processes. Here, we use hydrographic evidence to show a Labrador Current retreat is playing a key role in the deoxygenation on the northwest Atlantic shelf. A high-resolution global coupled climate-biogeochemistry model 9 reproduces the observed decline of saturation oxygen concentrations in the region, driven by a retreat of the equatorward-flowing Labrador Current and an associated shift toward more oxygen-poor subtropical waters on the shelf. The dynamical changes underlying the shift in shelf water properties are correlated with a slowdown in the simulated Atlantic Meridional Overturning Circulation 10. Our results provide strong evidence that a major, centennial-scale change of the Labrador Current is underway, and highlight the potential for ocean dynamics to impact coastal deoxygenation over the coming century

An Analysis on Bumpei Usui\u27s Rooftop Party in Relation to John Sloan, Prohibition, and Immigration

This study investigates the advection of positive-salinity anomalies by the Equatorial Undercurrent (EUC) and their potential importance in inducing vertical convective mixing. For this purpose we use hydrographic and velocity observations taken in April 2010 along the western Atlantic equatorial ocean (32 to 43°W). The high-salinity EUC core is a few tens of metres thick and occupies the base of the surface mixed layer and the upper portion of the surface thermocline. It leads to high positive values of the vertical salinity gradient, which in many instances cause statically unstable conditions in otherwise well-stratified regions. The unstable regions result in vertical convection, hence favouring the occurrence of step-like features. We propose that this combination of horizontal advection and vertical-instability leads to a sequence of downward-convective events. As a result the EUC salinity is diffused down to a potential density of 26.43, or about 200 m deep. This mechanism is responsible for water-mass and salt downwelling in the equatorial Atlantic Ocean, with a potentially large influence on the tropical and subtropical cells

Assessing the role of high-frequency winds and sea ice loss on arctic phytoplankton blooms in an ice-ocean-biogeochemical model

Identificadors digitals: Digital object identifier for the 'European Research Council' (http://dx.doi.org/10.13039/501100000781) and Digital object identifier for 'Horizon 2020' (http://dx.doi.org/10.13039/501100007601)Unidad de excelencia María de Maeztu MdM-2015-0552The long-term trend of increasing phytoplankton net primary production (NPP) in the Arctic correlates with increasing light penetration due to sea ice loss. However, recent studies suggest that enhanced stormy wind mixing may also play a significant role enhancing NPP. Here, we isolate the role of sea ice and stormy winds (hereafter high-frequency winds) using an eddy-permitting ice-ocean-biogeochemical model configured for the North Atlantic and the Arctic. In the model, the presence of high-frequency winds stimulates nutrient upwelling by producing an earlier and longer autumn-winter mixing period with deeper mixing layer. The early onset of autumn mixing results in nutrients being brought-up to near-surface waters before the light becomes the dominant limiting factor, which leads to the autumn bloom. The enhanced mixing results in higher nutrient concentrations in spring and thus a large spring bloom. The model also shows significant iron limitation in the Labrador Sea, which is intensified by high-frequency winds. The effect of sea ice loss on NPP was found to be regionally dependent on the presence of high-frequency winds. This numerical study suggests high-frequency winds play significant role increasing NPP in the Arctic and sub-Arctic by alleviating phytoplankton nutrient limitation and that the isolated effect of sea ice loss on light plays a comparatively minor role

ALBOREX: an intensive multi-platform and multidisciplinary experiment in the Alboran Sea. Marine Environmental Monitoring, Modelling And Prediction

Trabajo presentado en el International Liège Colloquium on Ocean Dynamics, celebrado en Liege, Bélgica, del 23 al 27 de mayo de 2015Peer Reviewe

A multiplatform experiment to unravel meso- and submesoscale processes in an intense front (AlborEx).

© The Authors, 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Pascual, A., Ruiz, S., Olita, A., Troupin, C., Claret, M., Casas, B., Mourre, B., Poulain, P. M., Tovar-Sanchez, A., Capet, A., Mason, E., Allen, J. T., Mahadevan, A., & Tintore, J. A multiplatform experiment to unravel meso- and submesoscale processes in an intense front (AlborEx). Frontiers in Marine Science, 4(39), (2017), doi:10.3389/fmars.2017.00039.The challenges associated with meso- and submesoscale variability (between 1 and 100 km) require high-resolution observations and integrated approaches. Here we describe a major oceanographic experiment designed to capture the intense but transient vertical motions in an area characterized by strong fronts. Finescale processes were studied in the eastern Alboran Sea (Western Mediterranean) about 400 km east of the Strait of Gibraltar, a relatively sparsely sampled area. In-situ systems were coordinated with satellite data and numerical simulations to provide a full description of the physical and biogeochemical variability. Hydrographic data confirmed the presence of an intense salinity front formed by the confluence of Atlantic Waters, entering from Gibraltar, with the local Mediterranean waters. The drifters coherently followed the northeastern limb of an anticyclonic gyre. Near real time data from acoustic current meter data profiler showed consistent patterns with currents of up to 1 m/s in the southern part of the sampled domain. High-resolution glider data revealed submesoscale structures with tongues of chlorophyll-a and oxygen associated with the frontal zone. Numerical results show large vertical excursions of tracers that could explain the subducted tongues and filaments captured by ocean gliders. A unique aspect of AlborEx is the combination of high-resolution synoptic measurements of vessel-based measurements, autonomous sampling, remote sensing and modeling, enabling the evaluation of the underlying mechanisms responsible for the observed distributions and biogeochemical patchiness. The main findings point to the importance of fine-scale processes enhancing the vertical exchanges between the upper ocean and the ocean interior.The AlborEx experiment was conducted in the framework of PERSEUS EU-funded project (Grant agreement no: 287600). The experiment was led by the Spanish National Research Council (CSIC) institution with strong involvement and cooperation from other national and international partners: Balearic Islands Coastal Observing and Forecasting System (SOCIB, Spain); Consiglio Nazionale delle Ricerche (CNR, Italy), McGill University (Canada); Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italy) and Woods Hole Oceanographic Institution (WHOI, USA). Glider operations were partially funded by JERICO FP7 project. AP acknowledges support from the Spanish National Research Program (E-MOTION/CTM2012-31014 and PRE-SWOT/CTM2016-78607-P). SR and AP are also supported by the Copernicus Marine Environment Monitoring Service (CMEMS) MedSUB project. EM is supported by a post-doctoral grant from the Conselleria d'Educació, Cultura i Universitats del Govern de les Illes Balears (Mallorca, Spain) and the European Social Fund. AC is a FNRS researcher under the FNRS BENTHOX project (Convention T.1009.15). The altimeter products were produced by Ssalto/Duacs and distributed by CMEMS. The profiling floats and some drifters were contributed by the Argo-Italy program. The authors are in debt with A. Massanet, F. Margirier, M. Palmer, C. Castilla, P. Balaguer and for their efficient work and implication during the AlborEx cruise. We also thank M. Menna, G. Notarstefano and A. Bussani for their help with the drifter and float data processing and the production of some figures. This article was initiated during a research visit of the first two authors to Woods Hole Oceanographic Institution

Roles of the ocean mesoscale in the horizontal supply of mass, heat, carbon and nutrients to the Northern Hemisphere subtropical gyres

Horizontal transport at the boundaries of the subtropical gyres plays a crucial role in providing the nutrients that fuel gyre primary productivity, the heat that helps restratify the surface mixed layer, and the dissolved inorganic carbon (DIC) that influences air‐sea carbon exchange. Mesoscale eddies may be an important component of these horizontal transports; however, previous studies have not quantified the horizontal tracer transport due to eddies across the subtropical gyre boundaries. Here we assess the physical mechanisms that control the horizontal transport of mass, heat, nutrients and carbon across the North Pacific and North Atlantic subtropical gyre boundaries using the eddy‐rich ocean component of a climate model (GFDL's CM2.6) coupled to a simple biogeochemical model (mini‐BLING). Our results suggest that horizontal transport across the gyre boundaries supplies a substantial amount of mass and tracers to the ventilated layer of both Northern Hemisphere subtropical gyres, with the Kuroshio and Gulf Stream acting as main exchange gateways. Mass, heat, and DIC supply is principally driven by the time‐mean circulation, whereas nutrient transport differs markedly from the other tracers, as nutrients are mainly supplied to both subtropical gyres by down‐gradient eddy mixing across gyre boundaries. A budget analysis further reveals that the horizontal nutrient transport, combining the roles of both mean and eddy components, is responsible for more than three quarters of the total nutrient supply into the subtropical gyres, surpassing a recent estimate based on a coarse resolution model and thus further highlighting the importance of horizontal nutrient transport

Fiber-Optic Observations of Internal Waves and Tides

13 pages, 5 figures, supporting information https://doi.org/10.1029/2023JC019980.-- Data Availability Statement: All 4.5 days of DAS data from the Strait of Gibraltar necessary to reproduce Figure 2 and the 3 days of DAS data from Gran Canaria necessary to reproduce Figures 3 and 4 are available through the CaltechDATA repository (Williams et al., 2023). Figures were produced using GMT6 (Wessel et al., 2019)Although typically used to measure dynamic strain from seismic and acoustic waves, Rayleigh-based distributed acoustic sensing (DAS) is also sensitive to temperature, offering longer range and higher sensitivity to small temperature perturbations than conventional Raman-based distributed temperature sensing. Here, we demonstrate that ocean-bottom DAS can be employed to study internal wave and tide dynamics in the bottom boundary layer, a region of enhanced ocean mixing but scarce observations. First, we show temperature transients up to about 4 K from a power cable in the Strait of Gibraltar south of Spain, associated with passing trains of internal solitary waves in water depth <200 m. Second, we show the propagation of thermal fronts associated with the nonlinear internal tide on the near-critical slope of the island of Gran Canaria, off the coast of West Africa, with perturbations up to about 2 K at 1-km depth and 0.2 K at 2.5-km depth. With spatial averaging, we also recover a signal proportional to the barotropic tidal pressure, including the lunar fortnightly variation. In addition to applications in observational physical oceanography, our results suggest that contemporary chirped-pulse DAS possesses sufficient long-period sensitivity for seafloor geodesy and tsunami monitoring if ocean temperature variations can be separated.Funding for this project was provided through the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S), the Spanish MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR Program under projects PSI ref. PLEC2021-007875 and TREMORS ref. CPP2021-008869, the Spanish MCIN/AEI/10.13039/501100011033 and FEDER Program under projects PID2021-128000OB-C21 and PID2021-128000OB-C22, and the European Innovation Council under Grant SAFE: ref. 101098992. E. F. W. was supported by a National Science Foundation Graduate Research Fellowship. M.C. was funded by the European Union (HORIZON-MSCA-2021-PF MOORING, grant agreement no. 101064423). M. R. F.-R. and H. F. M. acknowledge support from the MCIN/AEI/10.13039/501100011033 and European Union NextGenerationEU/PRTR under Grants RYC2021-032167-I and RYC2021-035009-I, respectively. J. C. acknowledges support from the National Science Foundation (Grant OCE-2023161). K. B. W. acknowledges funding provided by the National Science Foundation (Grants OCE-2045399 and OCE-185076) and the U.S. Office of Naval Research (Grant N00014-18-1-2803). Z. Z. acknowledges support from the Moore Foundation and NSF under CAREER Award 1848166Peer reviewe

Developmental and Tumor Angiogenesis Requires the Mitochondria-Shaping Protein Opa1

While endothelial cell (EC) function is influenced by mitochondrial metabolism, the role of mitochondrial dynamics in angiogenesis, the formation of new blood vessels from existing vasculature, is unknown. Here we show that the inner mitochondrial membrane mitochondrial fusion protein optic atrophy 1 (OPA1) is required for angiogenesis. In response to angiogenic stimuli, OPA1 levels rapidly increase to limit nuclear factor kappa-light-chain-enhancer of activated B cell (NFκB) signaling, ultimately allowing angiogenic genes expression and angiogenesis. Endothelial Opa1 is indeed required in an NFκB-dependent pathway essential for developmental and tumor angiogenesis, impacting tumor growth and metastatization. A first-in-class small molecule-specific OPA1 inhibitor confirms that EC Opa1 can be pharmacologically targeted to curtail tumor growth. Our data identify Opa1 as a crucial component of physiological and tumor angiogenesis