Circulation Of Warm Water Research Articles

Footprint of sustained poleward warm water flow within East Antarctic submarine canyons

The intrusion of relatively warm water onto the continental shelf is widely recognized as a threat to Antarctic ice shelves and glaciers grounded below sea level, as enhanced ocean heat increases their basal melt. While the circulation of warm water has been documented on the East Antarctic continental shelf, the modes of warm water transport from the deep ocean onto the shelf are still uncertain. This makes predicting the future responses of major East Antarctic marine-grounded glaciers, such as Totten and Ninnis glaciers, particularly challenging. Here, we outline the key role of submarine canyons to convey southward flowing currents that transport warm Circumpolar Deep Water toward the East Antarctic shelf break, thus facilitating warm water intrusion on the continental shelf. Sediment drifts on the eastern flank of the canyons provide evidence for sustained southward-directed flows. These morpho-sedimentary features thus highlight areas potentially prone to enhanced ocean heat transport toward the continental shelf, with repercussions for past, present, and future glacial melting and consequent sea level rise.

On-shelf circulation of warm water toward the Totten Ice Shelf in East Antarctica

The Totten Glacier in East Antarctica, with an ice volume equivalent to >3.5 m of global sea-level rise, is grounded below sea level and, therefore, vulnerable to ocean forcing. Here, we use bathymetric and oceanographic observations from previously unsampled parts of the Totten continental shelf to reveal on-shelf warm water pathways defined by deep topographic features. Access of warm water to the Totten Ice Shelf (TIS) cavity is facilitated by a deep shelf break, a broad and deep depression on the shelf, a cyclonic circulation that carries warm water to the inner shelf, and deep troughs that provide direct access to the TIS cavity. The temperature of the warmest water reaching the TIS cavity varies by ~0.8 °C on an interannual timescale. Numerical simulations constrained by the updated bathymetry demonstrate that the deep troughs play a critical role in regulating ocean heat transport to the TIS cavity and the subsequent basal melt of the ice shelf.

Melting Below the Pine Island Ice Shelf Minds the Gap

New research shows that increased calving from West Antarctica’s Pine Island Ice Shelf will likely drive increased circulation of warm water—and melting—below the ice.

Sea surface temperature variability in the Arctic Ocean and its marginal seas in a changing climate: Patterns and mechanisms

Abstract Understanding temporal variability of sea surface temperature (SST) patterns plays a crucial role in providing insights into the mechanisms causing extreme weather and climate events as well as oceanic and atmospheric teleconnections. This study presents an in-depth analysis of the SST patterns of the Arctic Ocean and its marginal seas on interannual and seasonal timescales from 1982 to 2018. The results reveal potential relationships between SST and climatic variables in order to improve our understanding of underlying physical mechanisms influencing the SST variations in a changing climate. Our findings disclose that the Arctic Ocean shows an overall warming trend, and the Nordic Seas have the highest SST compared to its neighboring seas. The Barents Sea shows spatially varying seasonal trends due to ice cover changes and warm water circulation within the Nordic Seas. Correlation analysis was also performed to facilitate further understanding of climate-induced SST changes. It reveals that climate variables interact differently with the Arctic Ocean SST on a regional scale and vary with different degrees of influence. Notable relationships between SST and climate variables improve understanding of differing trends on spatial and temporal scales. In addition, the wavelet coherence speculates that a significant in-phase relationship exists between SST and Greenland Blocking Index (GBI), which facilitates further studies exploring the complex mechanisms causing teleconnection patterns related to the Arctic Ocean.

Feasibility of a Miniature Esophageal Heat Exchange Device for Rapid Therapeutic Cooling in Newborns: Preliminary Investigations in a Piglet Model

Therapeutic hypothermia (TH) after neonatal encephalopathy, commonly provided by 72 hours of whole-body cooling using a wrap, limits parents' physical contact with their infants affecting bonding and may not be suitable for encephalopathic preterm infants with fragile skin. Alternative cooling methods are unavailable for this population. We investigated in a neonatal pig model the feasibility of achieving a 3.5°C reduction in rectal temperature (Trectal) similar to clinical TH protocols from 38.5°C (normothermia for pigs) to a target of 35°C ± 0.2°C, using a novel neonatal esophageal heat exchanger (NEHE), compared its efficacy to passive cooling, and investigated its ability to maintain target Trectal. Ventilated and anesthetized Landrace/Large white newborn pigs had the NEHE inserted. Water at adjustable temperatures and rates flowed down a central tube, returning up a surrounding distensible blind ending latex tube in a continuous loop. An initial experiment guided four subsequent cycles of passive cooling (30 minutes), rewarming to 38.5°C, active esophageal cooling to 35°C ± 0.2°C, active maintenance of target Trectal (30 minutes), and rewarming. We compared surface, rectal temperature, and hemodynamic changes among passive, active, and maintenance phases, and esophageal histopathology against control. Compared with passive cooling, esophageal cooling achieved target Trectal significantly earlier (71.3 minutes vs. 17.25 minutes, p = 0.003) with significantly greater rates of reduction in rectal (p = 0.0002) and surface (p = 0.005) temperatures and heart rate (p = 0.04). A water temperature of 39.1°C-40.2°C at a flow of 108-120 mL/min maintained Trectal around 35°C ± 0.2°C. The higher peak heart rate and blood pressure within 8 minutes of the maintenance phase (p = 0.04) subsequently stabilized. Histopathology showed congestion, edema, and neutrophil infiltration with increasing cycles. Esophageal cooling is feasible and effective in achieving rapid cooling in newborns. Subsequent maintenance at this temperature required continued circulation of warm water. Esophageal histopathology needs further evaluation after 72 hours servo-control cooling with a narrower range of water temperatures in a larger group of animals.

Abstract 4945: Evaluating the feasibility and throughput of quintuple modality imaging in a prostate cancer bone metastasis model with PET, SPECT, CT, MRI, and bioluminescence imaging

Abstract Background: Multimodality imaging presents a unique opportunity to image the efficacy of candidate compounds against various models of cancer. The challenge is in integrating the complimentary data that these modalities can provide. The purpose of this study was to evaluate the feasibility of quintuple modality image in order to optimize workflows for maximal efficacy testing of candidate compounds using PET, SPECT, CT, MRI, and Bioluminescence imaging (BLI). Materials and Methods: Male nude mice were injected into the left ventricle with 3x106 PC-3M-luc-C6 cells. BLI was performed to track disease progression and ensure that animals exhibited established metastatic disease prior to initiation of multimodality imaging. Animals were injected with 500µCi Tc99m-MDP and allowed a 1h uptake period prior to imaging. The animals were then placed into an Animal Handling System (AHS, ASI Instruments) that coupled to multiple integrated Positioning Receiver Assemblies (PRA's, ASI Instruments) designed for the PET, SPECT, CT, and MRI scanners, and a 15min, multi-pinhole SPECT scan was acquired. After completion of the SPECT scan, 200µCi of 18F-FDG was administered under anesthesia. MicroCT and MRI anatomical images were acquired during the FDG uptake period. Body temperature was maintained via the integrated warm water circulation in the AHS to ensure adequate FDG uptake and clearance during the procedures. Whole body CT images were acquired at 512 projections, 75kVp, and 220µA. A series of T2-weighted and T1-weighted gadolinium-enhanced images were acquired using a 7T MRI system. At 1h post-FDG administration, a 10min static PET emission scan was acquired and reconstructed using a 3DOSEM/MAP algorithm. Results: Animals were maintained under anesthesia for a total of approximately 2 hours in order to acquire data from all the modalities. Data was able to be co-registered in various forms in order to verify the location and extent of disease, as well as the usefulness of 18F-FDG PET and Tc99m-MDP to serve as biomarker probes for tumor cell metabolism, and osteolytic and osteoblastic activity in bone lesions. Conclusions: Animals tolerated the length of anesthesia well. The feasibility of this imaging was only made possible through the use of the multimodality AHS bed and docking system that permitted reproducible imaging across the different platforms. In order to further optimize workflows, multiple AHS bed systems should be employed so that data can be acquired on the various modalities in parallel, instead of sequentially, thereby greatly increasing animal throughputs. Citation Format: John L. Chunta, Deanne Lister, Chris Bull, Deepa Balagurunathan, Erin Trachet, Chris Chiodo, Scott Wise, Dick Leopold, Patrick McConville. Evaluating the feasibility and throughput of quintuple modality imaging in a prostate cancer bone metastasis model with PET, SPECT, CT, MRI, and bioluminescence imaging. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4945. doi:10.1158/1538-7445.AM2014-4945

Evaluation of the Gas Production Potential of Some Particularly Challenging Types of Oceanic Hydrate Deposits

We use the TOUGH+HYDRATE code to assess the production potential of some particularly challenging hydrate deposits, i.e., deposits that are characterized by any combination of the following factors: absence of confining boundaries, high thermodynamic stability, low temperatures, low formation permeability. Using high-resolution grids, we show that a new horizontal well design using thermal stimulation coupled with mild depressurization yields production rates that appear modest and insufficient for commercially viable production levels. The use of parallel horizontal wells (with the lower one providing thermal stimulation through heat addition, direct injection or circulation of warm water, and the upper one producing under a mild depressurization regime) offers tantalizing possibilities, and has the potential of allowing commercial production from a very large number of hydrate deposits that are not currently considered as production candidates if the problem of the corresponding large water production can be solved.

Possibility of gas washout from a gas-hydrate massif by circulation of warm water

A possibility of gas extraction from a gas-hydrate massif by means of warm water circulation through a system of wells is demonstrated. A technological scheme and a theoretical model of this process are proposed.

Quantitative evaluation of Quaternary crustal deformation around the Takayama Basin, central Japan: A paleomagnetic and numerical modeling approach

Neotectonic crustal deformation in central Japan is described quantitatively on the basis of paleomagnetic measurements and numerical modeling. The welded part of the earliest Quaternary Nyukawa Pyroclastic Flow Deposit (NPFD) preserves stable remanent magnetization. Detailed paleo-/rock magnetic experiments reveal that remanence of the NPFD near the Takayama Basin resides in unimodal titanomagnetite and comprises a component of thermoremanent magnetization (TRM) and three components of thermoviscous remanent magnetization (TVRM). Scatter in the untilted declinations of the syn-depositional TRM component represents differential rotation about vertical axes related to Quaternary activity of three faults (Enako, Makigahora and Harayama) associated with the Takayama Basin. The normal and reversed TVRM components, probably acquired by warm water circulation near the active faults during the Jaramillo Subchron, record a complicated rotational sequence since ca. 1 Ma. Dislocation modeling successfully simulates the spatial distribution of rotation and the uplift/subsidence pattern around the Takayama Basin assuming strike–slip motion on the Enako and Makigahora Faults along the basin margin and vertical displacements on the Harayama Fault within the basin. Temporal changes in rotational motions recorded in the TVRMs of near-fault sites can be modeled by considering transition of active segments of the three faults, which is geologically constrained.

Hydrothermal alteration and tectonic evolution of an intermediate‐ to fast‐spreading back‐arc oceanic crust: Late Ordovician Solund‐Stavfjord ophiolite, western Norway

Abstract The Solund‐Stavfjord ophiolite complex (SSOC) in western Norway represents a remnant of the Late Ordovician oceanic lithosphere, which developed in an intermediate‐ to fast‐spreading Caledonian back‐arc basin. The internal architecture and magmatic features of its crustal component suggest that the SSOC has a complex, multistage sea floor spreading history in a supra‐subduction zone environment. The youngest crustal section associated with the propagating rift tectonics consists of a relatively complete ophiolite pseudostratigraphy, including basaltic volcanic rocks, a transition zone between the sheeted dyke complex and the extrusive sequence, sheeted dykes, and high‐level isotropic gabbros. Large‐scale variations in major and trace element distributions indicate significant remobilization far beyond that which would result from magmatic processes, as a result of the hydrothermal alteration of crustal rocks. Whereas K2O is strongly enriched in volcanic rocks of the extrusive sequence, Cu and Zn show the largest enrichment in the dyke complex near the dyke–volcanic transition zone or within this transition zone. The δ18O values of the whole‐rock samples show a general depletion structurally downwards in the ophiolite, with the largest and smallest variations observed in volcanic rocks and the transition zone, respectively. δ18O values of epidote–quartz mineral pairs indicate 260–290°C for volcanic rocks, 420°C for the transition zone, 280–345°C for the sheeted dyke complex and 290–475°C for the gabbros. The 87Sr/86Sr isotope ratios show the widest range and highest values in the extrusive rocks (0.70316–0.70495), and generally the lowest values and the narrowest range in the sheeted dyke complex (0.70338–0.70377). The minimum water/rock ratios calculated show the largest variations in volcanic rocks and gabbros (approximately 0–14), and generally the lowest values and range in the sheeted dyke complex (approximately 1–3). The δD values of epidote (−1 to −12‰), together with the δ18O calculated for Ordovician seawater, are similar to those of present‐day seawater. Volcanic rocks experienced both cold and warm water circulation, resulting in the observed K2O‐enrichment and the largest scatter in the δ18O values. As a result of metal leaching in the hot reaction zone above a magma chamber, Zn is strongly depleted in the gabbros but enriched in the sheeted dyke complex because of precipitation from upwelling of discharged hydrothermal fluids. The present study demonstrates that the near intact effect of ocean floor hydrothermal activity is preserved in the upper part of the SSOC crust, despite the influence of regional lower greenschist facies metamorphism.

The relationship between the thermohaline circulation and climate variability

The long-term integration with the Global Ocean-Atmosphere-Land System model of the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics(IAP), Chinese Academy of Sciences has been used in the investigations on the relationship between the thermohaline circulation and climate variability. The results show that the strength of the North Atlantic Thermohaline circulation (THC) is negatively correlated with the North Atlantic Oscillation (NAO). Based on this kind of relationship, and also the instrument- measured climate record such as air pressure and sea surface temperature, the activity of the thermohaline circulation during the 20th century has been evaluated. The inferred variations of the strength of the THC is that, during two multi-decadal periods of 1867 1903 and 1934 1972, the THC is estimated to have been running stronger, whereas during the two periods of 1904 1933 and 1973 1994, it appears to have been weaker. The climate system of the Earth can be broken down into a number of components: the ocean, the atmosphere, the lithosphere, the cryosphere, and the biosphere. The ultimate forcing mechanism of oceanic and atmospheric motions is the pole-to-equator gradient of radiative heating of the planet. There exists surplus of heat in the equatorial region and deficit of heat in the polar region. In order to keep the thermal balance of the Earth, the excessive heat collected in the equatorial regions must be transported to the polar regions. The transport is taken up by the meridional circulation branch of the climate system, which is mainly made up of the atmospheric components of the famous Hadley cell, the Ferrel cell, and the polar cell, and also its ocean component of the Atlantic thermohaline circulation. About 90% of the water in the world ocean are involved in the thermohalien circulation, which is located beneath the wind driven surface currents and at great depths. The power for this slower, deeper circulation comes from the action of gravity on adjacent water masses of different densities. Since density is largely a function of temperature and salinity, the circulation due to density difference is called thermohaline circulation. The contemporary thermohaline circulation is characterized as the Atlantic Great Ocean Conveyor Belt. Intense radiative cooling of the polar ocean surface during the winter causes the formation or extension of sea ice. Cooling and brine rejection (i.e. salt ejection during ice formation) produces an unstable density gradient in the upper ocean allowing the cool and saline dense water to mix down convectively. Just as the tropical ascent is the rising part of the atmospheric direct circulation (i.e. warm air rising), the sinking motion of the ocean is the thermally direct part of the ocean circulation (i.e. cold water sinking). The thermodynamically direct circulation converts potential energy into kinetic energy. These processes lead to the formation of the deep ocean water, which spreads out away from the poles until it slowly ascends toward the equator. At last, the water moves back to the poles from the equator in the form of shallow warm water circulation (1,2) .

The plate tectonic impact on climatic change with particular relevance to Mesoamerica

The oceanic circulation and associated climatic zonations some 120 Ma can be taken as more geologically ‘normal’ than the last few million years. It was dominated by a strong circum-Equatorial current accompanied by warm water circulation well into Polar areas. This resulted in a marked increase in salinity between 10 and 25 °N/S, with consequential strong ocean stratificación and circulación mostly in the upper one kilometre. This pattern was likely to be associated with a simple Two Hadley-Cell atmospheric circulación. Orbitally forced periodical variacións in solar insolación gave eustatic sea-level changes of less than 10 m amplitude. During the last 50 Ma, the relative posicións of the MesoAmerican continental plates have not changed greatly and hence plate mocións have had little or no effect on the Atlantic deep-ocean haline circulación. Secondary plate tectonic processes — topographic change, volcanism and seismic activity — were more important and had marked local effects on the climate which could be mistaken for global changes. The Chihuahua area of Mexico provides the optimum site for identifying Recent global climatic changes.

Study on the heat transfer aspect of thermal burns caused by mats with warm water circulation.

In order to prevent an anesthetized patient's body temperature from decreasing in the operating room, a mat with warm water circulation is often used. However, burn injuries sometimes occur on a patient's body in spite of the correct use of the mat. The cause of this injury has not yet been clarified. In this study, heat transfer between the bio1ogical tissue and the mat was calculated numerically under the condition of heat transfer by blood flow. The effects of the thickness of biological tissue, water temperature, heat transfer coefficient of the water flow in the mat, metabolic heat production rate, and blood perfusion rate distribution on heat transfer in biological tissues were clarified. From the standpoint of these effects, the conditions of occurrence of burn injury were examined. Results indicated that the model in this study was capable of simulating the mechanism by which burn injuries in the operating room are caused.

Resultados científicos do cruzeiro do Baependi e do Vega à Ilha da Trindade: oceanografia física - contribuição para o conhecimento das características físicas e químicas das águas

In May 1950 a trip was undertaken by the ships Baependi and Vega to the Trindade Island - 20o30'S and 29o20'W - Approximately 1200 km off the coast of Espirito Santo State. This scientific expedition was realized by the iniciative of the Minister J. A. Lins de Barros. In this expedition the supervisor of the oceanographic works was Prof. W. Besnard, the director of the Sao Paulo Oceanographic Institute. He brougth home 42 samples of water for study, collected upon the insular terrace of the island, referring to the 15 established stations - see table I - with depths varying between 0 m and 115 m. The physical and chemical properties of them are to be seen on table II. The results obtained were compared with those of the German Expedition to the South Atlantic, 1925/27 (Meteor), observed at the stations 157-158-159-163 of profile VI and 168-169-170 of profile VII. The mean results obtaneid by the boats Baependi and Vega are represented on table IV. We constructed vertical sections - I to VI - of each group of Stations, showing the slope of the insular shelves and, in a general manner, the distribution of salinity. We made also longitudinal section - E, M, I - involving the island and corresponding, respectively, to the groups of stations, the farthest, nearest and intermediary ones. As the number of samples received is reduced and consequently the data obtained are few, no conclusions could be deduced. We made only a commentary supposing that the predominating waters surrounding the island are the same as those coming from the mentioned stations on Profile VI, marked by the Meteor. No indication authorizes the supposition that waters of the Brazil Current or those of Profile VII of the Meteor reach the Trindade Island. On the contrary, its waters must be warm and salted to which Albert Defant (Die Troposphaere, Wiss. Erg. D. Atl. Exp. Meteor Band VI, 1 Tel Lief. 3, Berlin, 1936) has referred, as the island is located very near to the limits of the perspective diagram of warm water circulation pointed out. (Kieler Meeresforschungen, Inst. Meereskunde, Universit. Kiel, Band VII, Heft 1, S 24, 1950).