The Thermohaline Modes of the Global Ocean Pauthenet, Etienne; Roquet, Fabien; Madec, Gurvan ...
Journal of physical oceanography,
10/2019, Letnik:
49, Številka:
10
Journal Article
Recenzirano
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Abstract
The first 2000 m of the global thermohaline structure of the ocean are statistically decomposed into vertical thermohaline modes, using a multivariate functional principal component analysis ...(FPCA). This method is applied on the Monthly Isopycnal and Mixed-Layer Ocean Climatology (MIMOC). The first three modes account for 92% of the joint temperature and salinity (
T
–
S
) variance, which yields a surprisingly good reduction of dimensionality. The first mode (69% of the variance) is related to the thermocline depth and delineates the subtropical gyres. The second mode (18%) is mostly driven by salinity and mainly displays the asymmetry between the North Pacific and Atlantic basins and the salty circumpolar deep waters in the Southern Ocean. The third mode (5%) identifies the low- and high-salinity intermediate waters, covarying with the freshwater inputs of the upper ocean. The representation of the ocean in the space defined by the first three modes offers a simple visualization of the global thermohaline structure that strikingly emphasizes the role of the Southern Ocean in linking and distributing water masses to the other basins. The vertical thermohaline modes offer a convenient framework for model and observation data comparison. This is illustrated by projecting the repeated Pacific section P16 together with profiles from the Array for Real-Time Geostrophic Oceanography (ARGO) global array of profiling floats on the modes defined with the climatology MIMOC. These thermohaline modes have a potential for water mass identification and robust analysis of heat and salt content.
Deep-sea geofluid systems, such as hydrothermal vents and cold seeps, are key to understanding subseafloor environments of Earth. Fluid chemistry, especially, provides crucial information toward ...elucidating the physical, chemical, and biological processes that occur in these ecosystems. To accurately assess fluid and gas properties of deep-sea geofluids, well-designed pressure-tight fluid samplers are indispensable and as such they are important assets of deep-sea geofluid research. Here, the development of a new flow-through, pressure-tight fluid sampler capable of four independent sampling events (two subsamples for liquid and gas analyses from each) is reported. This new sampler, named WHATS-3, is a new addition to the WHATS-series samplers and a major upgrade from the previous WHATS-2 sampler with improvements in sample number, valve operational time, physical robustness, and ease of maintenance. Routine laboratory-based pressure tests proved that it is suitable for operation up to 35 MPa pressure. Successful field tests of the new sampler were also carried out in five hydrothermal fields, two in Indian Ocean, and three in Okinawa Trough (max. depth 3,300 m). Relations of Mg and major ion species demonstrated bimodal mixing trends between a hydrothermal fluid and seawater, confirming the high quality of fluids sampled. The newly developed WHATS-3 sampler is well-balanced in sampling capability, field usability, and maintenance feasibility, and can serve as one of the best geofluid samplers available at present to conduct efficient research of deep-sea geofluid systems.
•An improved model has been validated for borehole heat exchangers.•Proposed model accounts for transit time effects and short-circuiting heat transfer in U-tube heat exchanger.•Model is validated ...against two multi-flow-rate thermal response tests.•Weighting factor applied to inlet and outlet fluid temperatures estimates mean temperature.
A recently developed vertical borehole ground heat exchanger model that accounts for transit time effects and time-varying short-circuiting heat transfer has been validated against two multi-flow-rate thermal response tests (MFR-TRT). The MFR-TRT, when performed with a wide range of flow rates, results in significant changes in the borehole thermal resistance, the borehole internal thermal resistance, and the short-circuiting heat transfer between the two legs of a single U-tube. The model accounts for short-circuiting by an analytically computed weighting factor that is used to determine the mean fluid temperature. The weighting factor portion of the model can be readily utilized in other ground heat exchanger models that currently rely on a simple mean fluid temperature. Use of the weighting factor is shown to give significantly better estimations of entering and exiting fluid temperature than using the simple mean fluid temperature. The new model is also compared to an alternative approach − using an effective borehole thermal resistance. While both the effective borehole thermal resistance model and the weighting factor give quite good results a few hours after a step change in flow rate, the weighting factor model gives much better results in the first few hours after a step change in flow rate.
Deep-sea research is rarely available to undergraduate students. However, as telepresence technology becomes more available, doors may open for more undergraduates to pursue research that includes ...remote fieldwork. This descriptive case study is an initial investigation into whether such technology might provide a feasible opportunity for undergraduate students to conduct ocean science research remotely, and if so, whether students can move from being spectators to beingactive agents. Specifically, we inquire into the learning of seven students who conducted fieldwork via telepresence, which enabled them to participate in a cruise that used remotely operated vehicles to explore an active underwater volcano and mud volcano cold seeps. This study examines whether the students engaged in authentic research and whether telepresence provided a reasonable experience of fieldwork at sea. Interviews and observation notes suggest that these undergraduates were able to undertake all aspects of research. Students' presentations exhibit a great deal of knowledge about the field sites and show that they contributed findings from their analyses. This study constitutes important initial evidence that telepresence can provide effective approximation of the experience and educational value of fieldwork at sea, and suggests that telepresence is a feasible option for future undergraduate research experiences.
A novel method for supervisory control of multilink manipulators mounted on underwater vehicles is considered. This method is designed to significantly increase the level of automation of ...manipulative operations, by the building of motion trajectories for a manipulator working tool along the surfaces of work objects on the basis of target indications given by the operator. This is achieved as follows: The operator targets the camera (with changeable spatial orientation of optical axis) mounted on the vehicle at the work object, and uses it to set one or more working point on the selected object. The geometric shape of the object in the work area is determined using clouds of points obtained from the technical vision system. Depending on the manipulative task set, the spatial motion trajectories and the orientation of the manipulator working tool are automatically set using the spatial coordinates of these points lying on the work object surfaces. The designed method was implemented in the C++ programming language. A graphical interface has also been created that provides rapid testing of the accuracy of overlaying the planned trajectories on the mathematically described surface of a work object. Supervisory control of an underwater manipulator was successfully simulated in the V-REP environment.
Polish Geography of Industry in Sea Research Czapliński, Paweł
Prace Komisji Geografii Przemysłu Polskiego Towarzystwa Geograficznego,
01/2018, Letnik:
32, Številka:
4
Journal Article
Recenzirano
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Industry, still one of the most significant sectors of the economy, is undergoing permanent quantitative and qualitative changes. Therefore it should be the subject of not only business analyses, but ...also research which more broadly explain our reality in the environmental, social and economic dimensions, noting the more and more complex relations between the elements, sets and even entire systems functioning in various spatial arrangements. The research on the changes in industry structures implemented by Polish researchers representing various fields of science has been an essential element of the cognitive process for many years. Among them are also geographers for whom the spatial aspects (the characteristics and issues) of industrial activity seem particularly significant. However, the issues handled by them mostly regard land areas. Therefore, there is also a strong need for wide-range theoretical and applicable research on the identification of sea and coastal areas functioning on the basis of diversified industrial structures, using the previous academic achievements, including the achievements of the Polish economic sea geography.
The synthesis of the BONUS+ research is introduced. The HELCOM Baltic Sea Action Plan is examined as a case to illustrate the potentials and challenges in building the science–policymaking interface ...on a macroregional level. The projects address environmental challenges in the Baltic Sea as defined by the Baltic Sea Action Plan, or consider the environmental governance and decision making within the Baltic Sea context in general. Eutrophication, biodiversity, hazardous substances, maritime activities, and the environment governance are addressed, as are crosscutting issues, such as the impact of climate change, maritime spatial planning and impacts of future development on ecosystem services. The projects contributed to relevant policy developments: 37 consultations carried out at EU level, 49 modifications to policy documents and action plans, 153 suggestions for the efficacy of pertinent public policies and governance, and in 570 occasions, scientists working in BONUS+ projects served as members or observers in scientific and stakeholder committees.
Identifying efficient solutions to protect coastal regions from marine pollution requires expertise from a range of specialties and strategic approaches. This book gathers information on the impact ...of oil spills at a coastal level from different experts' points of view, identifying synergies between domains such as mathematics, numerical modeling, mechanics, biology, economics and law. The collaborative research presented here is based on the 4th International Workshop on Anti-Pollution and Marine Coastal Water Pollution, held in La Rochelle, France at the Engineering School EIGSI, in April 2012. The areas addressed include: materials and structures (fluid-structure and capture interaction, cable and membrane equations, optimization); coastal hydrodynamics (computational fluid dynamics, numerical analysis of shallow water equations, analytical and numerical derivatives); biological impacts (biology, multivariate analysis, indicators); and economics and law (compensation costs, insurance coverage, coastal vulnerability).
The paleomagnetic records and mineral-magnetic properties of unconsolidated core sediment from the east Mariana Basin of the western Pacific have been analyzed to trace the time-dependent variations ...in sedimentary environments. Progressive alternating field demagnetization effectively extracts a stable remanent magnetization showing both normal and reverse polarities. Comparison of successive polarity changes, recorded in the sediment core, with reference magnetic polarity time-scale, reveals that the recovered sediment column was deposited since the late Pliocene. From the sediment age model, calculated sedimentation rate during the late Pliocene was 9.8 times higher than that during the Pleistocene. Considering the oceanic environments and geologic setting in the study area, the anomalous high sediment flux during the late Pliocene was probably caused by enhanced current flows, such as North Equatorial Current, associated with atmospheric circulation as well as by debris flows from adjacent sea mounts. In addition, the systematic variation of mineral-magnetic properties indicates periodical fluxes of coarse and magnetically stable particles, on the fine-grained dominant sedimentary environments. Such influxes, however, would not be related to syn-volcanic activities, because the summits of seamounts were totally blanketed by biogenic Pliocene-Pleistocene sediments. It is, hence, reasonable to interpret that paleomagnetic and mineral-magnetic data probably reflect drastic paleoenvironmental changes at the boundary between the Pliocene and Pleistocene, where strong current and atmospheric circulations decreased.
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