To see the other types of publications on this topic, follow the link: Freshwater plumes.
Journal articles on the topic 'Freshwater plumes'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Freshwater plumes.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Osadchiev, Alexander, Igor Medvedev, Sergey Shchuka, Mikhail Kulikov, Eduard Spivak, Maria Pisareva, and Igor Semiletov. "Influence of estuarine tidal mixing on structure and spatial scales of large river plumes." Ocean Science 16, no. 4 (July 3, 2020): 781–98. http://dx.doi.org/10.5194/os-16-781-2020.
Full textAbstract:
Abstract. The Yenisei and Khatanga rivers are among the largest estuarine rivers that inflow to the Arctic Ocean. Discharge of the Yenisei River is 1 order of magnitude larger than that of the Khatanga River. However, spatial scales of buoyant plumes formed by freshwater runoff from the Yenisei and Khatanga gulfs are similar. This feature is caused by different tidal forcing in these estuaries, which have similar sizes, climate conditions, and geomorphology. The Khatanga discharge experiences strong tidal forcing that causes formation of a diluted bottom-advected plume in the Khatanga Gulf. This deep and weakly stratified plume has a small freshwater fraction and therefore occupies a large area on the shelf. The Yenisei Gulf, on the other hand, is a salt-wedge estuary that receives a large freshwater discharge and is less affected by tidal mixing due to low tidal velocities. As a result, the low-salinity and strongly stratified Yenisei plume has a large freshwater fraction and its horizontal size is relatively small. The results show that estuarine tidal mixing determines freshwater fraction in these river plumes, which governs their depth and area after they spread from estuaries to coastal sea. Therefore, the influence of estuarine mixing on spatial scales of a large river plume can be of the same importance as the roles of river discharge rate and wind forcing. In particular, plumes with similar areas can be formed by rivers with significantly different discharge rates, as illustrated by the Yenisei and Khatanga plumes.
2
Kumar, R. K., H. W. Chiang, and F. Kalos. "Entrainment and Mixing in Vertical Buoyant Light-Gas Plumes." Journal of Energy Resources Technology 118, no. 1 (March 1, 1996): 77–81. http://dx.doi.org/10.1115/1.2792697.
Full textAbstract:
A simple model is developed to determine the entrainment coefficient and the spread of a light-gas plume in a quiescent atmosphere. Experiments performed with low-velocity saltwater/freshwater and helium-in-air jets indicate that buoyant gas plumes spread significantly faster than thermal plumes. The calculated effluent concentrations are in excellent agreement with those measured when an entrainment coefficient of 0.15 is used in the plume equations. This is significantly higher than the entrainment coefficients of 0.075 to 0.093 reported for thermal plumes.
3
Liu, Wen-Cheng, Hong-Ming Liu, Chih-Chieh Young, and Wei-Che Huang. "The Influence of Freshwater Discharge and Wind Forcing on the Dispersal of River Plumes Using a Three-Dimensional Circulation Model." Water 14, no. 3 (January 29, 2022): 429. http://dx.doi.org/10.3390/w14030429.
Full textAbstract:
Tidal estuaries provide crucial pathways for contaminant transport. The salinity levels in estuaries and coasts are conserved substances that function as natural tracers to easily understand the offshore transport of substances that are subject to environmental factors. A three-dimensional (3D) circulation and mass transport model were utilized to delineate the salinity plume in a tidal estuary and continental shelf. The numerical modeling results were compared with the tidal amplitudes and phases, velocities, and salinities at different gauging stations in 2017. Quantitatively, the simulation and measurement results are in reasonably good agreement. Furthermore, the validated model was adopted to estimate the recovery times in tidal estuaries that are subjected to extreme freshwater discharges that come from the upstream reaches during typhoon events and to analyze the influences of freshwater discharge and wind stress on the river plume around the continental shelf. The simulated results revealed that the salinity recovery time at the river mouth due to Typhoon Saola in 2012 was less than 8 days. Increased inputs from freshwater discharge resulted in changes in the distances and areas of the river plumes. Linear regression relationships between the plume distance/plume area and the total freshwater discharge inputs were established. Neap and high slack tides were associated with the maximum plume distances and areas. Excluding tidal forcing resulted in larger plume distances and areas compared to the case in which tidal forcing was considered. The southward-favorable and northward-favorable plumes were controlled by northeasterly winds and southwesterly winds, respectively. The relative importance of freshwater discharges and wind forcing was explored. The results indicate that freshwater discharges frequently dominated the river plume, except when strong southwesterly or northeasterly winds prevailed.
4
Kimura, Satoshi, Paul R. Holland, Adrian Jenkins, and Matthew Piggott. "The Effect of Meltwater Plumes on the Melting of a Vertical Glacier Face." Journal of Physical Oceanography 44, no. 12 (November 26, 2014): 3099–117. http://dx.doi.org/10.1175/jpo-d-13-0219.1.
Full textAbstract:
Abstract Freshwater produced by the surface melting of ice sheets is commonly discharged into ocean fjords from the bottom of deep fjord-terminating glaciers. The discharge of the freshwater forms upwelling plumes in front of the glacier calving face. This study simulates the meltwater plumes emanated into an unstratified environment using a nonhydrostatic ocean model with an unstructured mesh and subgrid-scale mixing calibrated by comparison to established plume theory. The presence of an ice face reduces the entrainment of seawater into the meltwater plumes, so the plumes remain attached to the ice front, in contrast to previous simple models. Ice melting increases with height above the discharge, also in contrast to some simple models, and the authors speculate that this “overcutting” may contribute to the tendency of icebergs to topple inwards toward the ice face upon calving. The overall melt rate is found to increase with discharge flux only up to a critical value, which depends on the channel size. The melt rate is not a simple function of the subglacial discharge flux, as assumed by many previous studies. For a given discharge flux, the geometry of the plume source also significantly affects the melting, with higher melt rates obtained for a thinner, wider source. In a wider channel, two plumes are emanated near the source and these plumes eventually coalesce. Such merged meltwater plumes ascend faster and increase the maximum melt rate near the center of the channel. The melt rate per unit discharge decreases as the subglacial system becomes more channelized.
5
De Andrés, Eva, Donald A. Slater, Fiamma Straneo, Jaime Otero, Sarah Das, and Francisco Navarro. "Surface emergence of glacial plumes determined by fjord stratification." Cryosphere 14, no. 6 (June 18, 2020): 1951–69. http://dx.doi.org/10.5194/tc-14-1951-2020.
Full textAbstract:
Abstract. Meltwater and sediment-laden plumes at tidewater glaciers, resulting from the localized subglacial discharge of surface melt, influence submarine melting of the glacier and the delivery of nutrients to the fjord's surface waters. It is usually assumed that increased subglacial discharge will promote the surfacing of these plumes. Here, at a western Greenland tidewater glacier, we investigate the counterintuitive observation of a non-surfacing plume in July 2012 (a year of record surface melting) compared to the surfacing of the plume in July 2013 (an average melt year). We combine oceanographic observations, subglacial discharge estimates and an idealized plume model to explain the observed plumes' behavior and evaluate the relative impact of fjord stratification and subglacial discharge on plume dynamics. We find that increased fjord stratification prevented the plume from surfacing in 2012, show that the fjord was more stratified in 2012 due to increased freshwater content and speculate that this arose from an accumulation of ice sheet surface meltwater in the fjord in this record melt year. By developing theoretical scalings, we show that fjord stratification in general exerts a dominant control on plume vertical extent (and thus surface expression), so that studies using plume surface expression as a means of diagnosing variability in glacial processes should account for possible changes in stratification. We introduce the idea that, despite projections of increased surface melting over Greenland, the appearance of plumes at the fjord surface could in the future become less common if the increased freshwater acts to stratify fjords around the Greenland ice sheet. We discuss the implications of our findings for nutrient fluxes, trapping of atmospheric CO2 and the properties of water exported from Greenland's fjords.
6
Pimenta, Felipe M., A. D. Kirwan, and Pablo Huq. "On the Transport of Buoyant Coastal Plumes." Journal of Physical Oceanography 41, no. 3 (March 1, 2011): 620–40. http://dx.doi.org/10.1175/2010jpo4473.1.
Full textAbstract:
Abstract The role of discharge conditions and shelf geometry on the transport of coastal plumes is studied with a fully nonlinear, primitive equation hydrodynamic model. The physical setting is an estuarine channel with a small discharge Rossby number. By simulating different discharge magnitudes, buoyant plumes are shown to be succinctly described by a simple coastal front model. Three results emerge from the model analysis. First, the plume transport is given by T = γ0(g′ph2/2f ), where γ0 is a parameter dependent on the ratio of the front and the plume widths, g′p is the plume reduced gravity, h is the plume maximum depth, and f is the Coriolis parameter. Second, this model links the plume transport directly to upstream river conditions with T = γQr, where Qr is the river outflow and γ is a parameter that relates to entrainment, the geometry of the plume front and shelf slope, and the fraction of freshwater carried downshelf. Third, these equations reduce to analytic results previously established for special cases, providing useful formulas to estimate the plume transport from hydrographic and river discharge observations.
7
Hudson, B., I. Overeem, D. McGrath, J. P. M. Syvitski, A. Mikkelsen, and B. Hasholt. "MODIS observed increase in duration and spatial extent of sediment plumes in Greenland fjords." Cryosphere 8, no. 4 (July 4, 2014): 1161–76. http://dx.doi.org/10.5194/tc-8-1161-2014.
Full textAbstract:
Abstract. The freshwater flux from the Greenland Ice Sheet (GrIS) to the North Atlantic Ocean carries extensive but poorly documented volumes of sediment. We develop a suspended sediment concentration (SSC) retrieval algorithm using a large Greenland specific in situ data set. This algorithm is applied to all cloud-free NASA Moderate Resolution Imaging Spectrometer (MODIS) Terra images from 2000 to 2012 to monitor SSC dynamics at six river plumes in three fjords in southwest Greenland. Melt-season mean plume SSC increased at all but one site, although these trends were primarily not statistically significant. Zones of sediment concentration > 50 mg L−1 expanded in three river plumes, with potential consequences for biological productivity. The high SSC cores of sediment plumes ( > 250 mg L−1 expanded in one-third of study locations. At a regional scale, higher volumes of runoff were associated with higher melt-season mean plume SSC values, but this relationship did not hold for individual rivers. High spatial variability between proximal plumes highlights the complex processes operating in Greenland's glacio–fluvial–fjord systems.
8
Marta-Almeida, Martinho, Anna Dalbosco, David Franco, and Manuel Ruiz-Villarreal. "Dynamics of river plumes in the South Brazilian Bight and South Brazil." Ocean Dynamics 71, no. 1 (November 11, 2020): 59–80. http://dx.doi.org/10.1007/s10236-020-01397-x.
Full textAbstract:
AbstractThe plumes from the rivers of the South Brazilian Bight (SBB) and South Brazil (SB) were studied using a realistic model configuration. River plume variability on continental shelves is driven by the input of river runoff into the shelf, by wind variability, and also by ambient currents and its seasonal variability, especially the Brazil Current, which are realistically modelled in this study. It is presented a simulation of 4 years using a nested configuration, which allows resolving the region around Florianópolis with very high resolution (∼150 m). The dispersion of river plumes was assessed not only with the hydrodynamical model results but also by using passive tracers whose dynamics was analyzed seasonally. Several dyes were released together with the river discharges. This approach allowed calculating the depths of the riverine freshwater, and the resulting regions affected by the plumes. Northward intrusions of waters from the southern region, under the potential influence of the distant La Plata river plume, were evaluated with a Lagrangian approach. The local river plumes are confined to the inner shelf, except south of 30°S where discharges from Lagoa dos Patos disperse over the shelf in the spring and summer. The Brazil Current flowing southward over the slope prevents the river plumes from interaction with oceanic mesoscale dynamics. The river plumes are, thus, mainly controlled by the wind forcing. The plumes from SBB are able to disperse until SB following the southward wind regime typical of the summer. And both the SB and La Plata river plumes are also able to reach SBB, forced by the northward wind typical of the winter season, until the latitude of 25.5°S. A low salinity belt (below 35) is present along the coastal region of SB and SBB year-round, supported by contributions from both the large and small rivers. The interaction between the different plumes influences the dispersion patterns, shielding the Florianṕolis coastal region from plumes of distant rivers, and dispersing the plume of SBB rivers away from Santa Catarina Island as it disperses southward during the summer months.
9
Rodrigues, Raphael Paiva, Bastiaan Adriaan Knoppers, Weber Friederichs Landim de Souza, and Elisamara Sabadini Santos. "Suspended matter and nutrient gradients of a small-scale river plume in Sepetiba Bay, SE-Brazil." Brazilian Archives of Biology and Technology 52, no. 2 (April 2009): 503–12. http://dx.doi.org/10.1590/s1516-89132009000200030.
Full textAbstract:
Coastal river plumes represent one of the final stages of material transport across the land-sea interface. Most studies, however have focused on the behavior of medium to large sized river plumes of coastal-shelf waters, whereas small sized river plumes acting within estuaries have been neglected. This study addressed the behavior of suspended particulate matter (SPM), dissolved inorganic nutrients (DIN, DIP and DSi) and Chlorophyll a (Chl. a) of a small sized river plume derived from the closely lain São Francisco and Guandú river channels, set in the Sepetiba Bay estuary, SE-Brazil. Two surface water sampling campaigns were conducted, one in January 2003 (humid summer conditions) and the other in June 2003 (dry winter conditions). On both occasions, the plumes dispersed in a SE direction towards the inner portion of the bay. The "wet" event plume was more turbid, nutrient rich and dispersed beyond nearshore waters, whereas the "dry" event plume proliferated as a narrow, less turbid and more nutrient poor film alongshore. Both exhibited a marked degree of patchiness, induced by the differential input of materials from the river sources and resuspension processes from the shallow nearshore bottom. The São Francisco river channel was the main source of freshwater, SPM and nutrients, except for ammonia (NH4+-N) derived from domestic effluents of the Guandú river. The mesohaline portion of the estuarine mixing zone of the plumes behaved as a slight source for SPM, DSi and DIP, due to bottom resuspension processes. N:P molar ratios ranged between 80:1 and 20:1 along the estuarine gradient, being higher in the summer than in the winter event, indicating that DIP was the potential nutrient limiting primary production. Chl. a concentrations increased at the outer premises of the plume, suggesting that the short residence times and turbidity of the plume waters, hampered primary production nearshore, particularly during the summer occasion. The small sized plume lacked the spatial decoupling between the estuarine mixing and turbidity zones, generally observed in larger sized coastal-shelf plumes.
10
Matano, Ricardo P., and Elbio D. Palma. "The Spindown of Bottom-Trapped Plumes." Journal of Physical Oceanography 40, no. 7 (July 1, 2010): 1651–58. http://dx.doi.org/10.1175/2010jpo4352.1.
Full textAbstract:
Abstract This note considers the decay of a bottom-trapped freshwater plume after the causative freshwater inflow has ceased. It is shown that shortly after the low-density inflow stops, the barotropic pressure field that it created radiates away and the ocean circulation becomes controlled by baroclinic pressure gradients generated by the remnants of the inflow. This produces a reversal of the circulation in the region downstream of the inflow, after which the entire plume starts to move in the upstream direction. The decay of the plume is henceforth controlled by upstream oceanic flow and dilution through cross-isopycnal mixing.
11
Baddour, R. E. "Computer simulation of ice control with thermal-bubble plumes — line source configuration." Canadian Journal of Civil Engineering 17, no. 4 (August 1, 1990): 509–13. http://dx.doi.org/10.1139/l90-058.
Full textAbstract:
Thermal-bubble plumes in a freshwater environment are studied to determine their ice control capabilities. A computer model is developed to optimize the operation of thermal-bubble installations when designed to control ice. Steady-state and transient simulations of ice control are presented. It is conceivable to fully computerize the operation of thermal-bubble installations by combining data acquisition, data analysis, computer simulation, and control automation. Key words: ice control, ice management, thermal-bubble plume, computer simulation.
12
Cenedese, Claudia, and V. Marco Gatto. "Impact of Two Plumes’ Interaction on Submarine Melting of Tidewater Glaciers: A Laboratory Study." Journal of Physical Oceanography 46, no. 1 (January 2016): 361–67. http://dx.doi.org/10.1175/jpo-d-15-0171.1.
Full textAbstract:
AbstractIdealized laboratory experiments investigate the glacier–ocean boundary dynamics near a vertical glacier in a two-layer stratified fluid. Discharge of meltwater runoff at the base of the glacier (subglacial discharge) enhances submarine melting. In the laboratory, the effect of multiple sources of subglacial discharge is simulated by introducing freshwater at freezing temperature from two point sources at the base of an ice block representing the glacier. The buoyant plumes of cold meltwater and subglacial discharge water entrain warm ambient water, rise vertically, and interact within a layer of depth H2 if the distance between the sources x0 is smaller than H2α/0.35, where α is the entrainment constant. The plume water detaches from the glacier face at the interface between the two layers and/or at the free surface, as confirmed by previous numerical studies and field observations. A plume model is used to explain the observed nonmonotonic dependence of submarine melting on the sources’ separation. The distance between the two sources influences the entrainment of warm water in the plumes and consequently the amount of submarine melting and the final location of the meltwater within the water column. Two interacting plumes located very close together are observed to melt approximately half as much as two independent plumes. The inclusion, or parameterization, of the dynamics regulating multiple plumes’ interaction is therefore necessary for a correct estimate of submarine melting. Hence, the distribution and number of sources of subglacial discharge may play an important role in glacial melt rates and fjord stratification and circulation.
13
Swieca, K., S. Sponaugle, C. Briseño-Avena, MS Schmid, RD Brodeur, and RK Cowen. "Changing with the tides: fine-scale larval fish prey availability and predation pressure near a tidally modulated river plume." Marine Ecology Progress Series 650 (September 17, 2020): 217–38. http://dx.doi.org/10.3354/meps13367.
Full textAbstract:
Tidally controlled river plumes form distinct frontal boundaries that can alter the spatial distributions of larval fishes and their planktonic prey and predators. Variable in nature, they may expose larval fishes to different trophic environments over small spatio-temporal scales, with unknown consequences for survival and recruitment. In the northern California Current, the Columbia River Plume is strongly influenced by twice-daily freshwater injections that create a highly dynamic coastal environment. Using the In situ Ichthyoplankton Imaging System, we examined changes in the fine-scale horizontal and vertical distributions of larval fishes, their prey, and their predators over space and time (ebb/flood tide). In total, 6095 fish larvae and ~1.5 million prey/predator zooplankton were imaged and measured. Plume regions provided substantially higher concentrations of prey and enhanced spatial overlap between larval fishes and their prey relative to oceanic waters. The functionality of river plumes as a refuge from predators was less clear. Predator concentrations were also higher in plume regions, but overlap with larval fishes was taxon-specific and varied with the tide. Notably, regions of high zooplankton concentrations did not necessarily confer high spatial overlap on small scales (meters vertical, kms horizontal) relevant to trophic interactions. Surface salinity and chlorophyll a were the most important factors influencing the spatial overlap of zooplankton with larval fishes. In the vicinity of river plumes, larval fishes experience a diversity of unique prey and predator fields over short spatio-temporal scales, which likely contribute to variable growth and mortality patterns at much finer scales than previously thought.
14
Matano, Ricardo P., and Elbio D. Palma. "The Upstream Spreading of Bottom-Trapped Plumes." Journal of Physical Oceanography 40, no. 7 (July 1, 2010): 1631–50. http://dx.doi.org/10.1175/2010jpo4351.1.
Full textAbstract:
Abstract It is well known that numerical simulations of freshwater discharges produce plumes that spread in the direction opposite to that of the propagation of coastally trapped waves (the upstream direction). The lack of a theory explaining these motions in unforced environments deemed the numerical results suspect. Thus, it became a common practice in numerical studies to add a downstream mean flow to arrest the development of the upstream perturbation. This approach is generally unjustified, and it remains a matter of interest to determine if the upstream displacement produced by models is a geophysical phenomenon or a consequence of erroneous assumptions in the model setup. In this article, the results of highly idealized numerical experiments are used to investigate these matters. It is shown that this phenomenon is associated with the geostrophic adjustment of the discharge and that upstream motion is endemic to the baroclinic structure of bottom-trapped plumes. It is also shown that downstream displacements are generated by the cross-shelf barotropic pressure gradient generated by the propagation of coastally trapped waves. Sensitivity experiments indicate that the speed of upstream propagation and the density structure of the plume are affected by bottom friction, the slope of the bottom, and the magnitude of the density anomaly. Bottom friction in particular slows down the progression of the plume and changes its density structure, producing a more homogeneous downstream region and a more stratified upstream region.
15
Liao, Xiaomei, Yan Du, Tianyu Wang, Shuibo Hu, Haigang Zhan, Huizeng Liu, and Guofeng Wu. "High-Frequency Variations in Pearl River Plume Observed by Soil Moisture Active Passive Sea Surface Salinity." Remote Sensing 12, no. 3 (February 8, 2020): 563. http://dx.doi.org/10.3390/rs12030563.
Full textAbstract:
River plumes play an important role in the cross-margin transport of phytoplankton and nutrients, which have profound impacts on coastal ecosystems. Using recently available Soil Moisture Active Passive (SMAP) sea surface salinity (SSS) data and high-resolution ocean color products, this study investigated summertime high-frequency variations in the Pearl River plume of China and its biological response. The SMAP SSS captures the intraseasonal oscillations in the offshore transport of the Pearl River plume well, which has distinct 30–60 day variations from mid-May to late September. The offshore transport of freshwater varies concurrently with southwesterly wind anomalies and is roughly in phase with the Madden–Julian Oscillation (MJO) index in phases 1–5, thus implying that the MJO exerts a significant influence. During MJO phases 1–2, the southwest wind anomalies in the northeastern South China Sea (SCS) enhanced cross-shore Ekman transport, while the northeast wind anomalies during MJO phases 3–5 favored the subsequent southwestward transport of the plume. The high chlorophyll-a concentration coincided well with the low-salinity water variations, emphasizing the important role of the offshore transport of the Pearl River plume in sustaining biological production over the oligotrophic northern SCS. The strong offshore transport of the plume in June 2015 clearly revealed that the proximity of a cyclonic eddy plays a role in the plume’s dispersal pathway. In addition, heavy rainfall related to the landfall of tropical cyclones in the Pearl River Estuary region contributed to the episodic offshore transport of the plume.
16
Liste, Maria, Manel Grifoll, Ingrid Keupers, Jaak Monbaliu, and Manuel Espino. "INCORPORATION OF CONTINENTAL AND URBAN RUN-OFF INTO A COASTAL CIRCULATION MODEL: APPLICATION TO THE CATALAN COAST." Coastal Engineering Proceedings 1, no. 33 (December 14, 2012): 40. http://dx.doi.org/10.9753/icce.v33.currents.40.
Full textAbstract:
A 3D hydrodynamical model has been set up to incorporate the continental and urban run-off into the Catalan Coastal waters. Particular attention was paid to introducing correctly the freshwater plumes and attention was also paid to determinate the influence of the land discharge profile with regard to the distributed continental run-off. The model domain includes a small part of the Catalan Coast where the combination of local land topography with torrential rainfall caused considerable local runoff on a short period of time with a large impact on the receiving coastal waters.
The Regional Ocean Modeling System (ROMS) simulations were used to examine the dispersal to a freshwater delivery from two relevant event; a low river discharge typical of mean conditions during April 2011 and a high discharge representative of the storm event during March 2011 are considered. We have observed the plume responses to an abrupt change in river discharge. During the mean conditions, low salinity water is concentrated around the rivers mouth while during the flood event, the plume spread offshore in the direction of river water outflow and turned downstream close to the coast. The differences between a simulation including the river outflow as a land forcing and a simulation including river and urban runoff as a land forcing suggested that the urban runoff plays an important role in the spreading and shape of the river plume.
17
Chen, Shih-Nan. "Enhancement of Alongshore Freshwater Transport in Surface-Advected River Plumes by Tides." Journal of Physical Oceanography 44, no. 11 (November 1, 2014): 2951–71. http://dx.doi.org/10.1175/jpo-d-14-0008.1.
Full textAbstract:
Abstract A recent numerical study by Isobe showed that imposing alongshore tidal forcing on buoyant coastal discharge enhances the net freshwater transport in the coastal currents. The mechanisms for this transport enhancement are studied using a three-dimensional, primitive equation ocean model [Regional Ocean Modeling System (ROMS)]. Lagrangian drifters are used to trace the freshwater transport paths. It is found that the river plume bulge circulation largely follows the rigid-body motion (i.e., constant vorticity). The buoyant fluid near the bulge’s outer edge is thinner and faster, behaving as a baroclinic jet. The bulge currents then split after impinging on the coast. The outer fluid feeds the downshelf-flowing coastal currents, while the inner fluid recirculates to form the bulge. The coastal current transport estimated from the present and prior studies corresponds well to a baroclinic jet theory, with the incident angle of bulge currents at the coast being a key parameter. Without tides, the bulge is approximately circular. The incident angle measured with respect to the cross-shore axis is small. With tides, the convergence of tidal momentum fluxes near the upshelf plume front leads to a positive pressure anomaly, which acts to compress the bulge shoreward. As a result, the incident angle increases, which in turn enhances the downshelf momentum input, thus increasing the freshwater transport in the coastal currents. Finally, the parameter space for coastal current transport in the presence of tidal forcing is explored with a conceptual model. A few observational examples are given.
18
Ffield, Amy. "Amazon and Orinoco River Plumes and NBC Rings: Bystanders or Participants in Hurricane Events?" Journal of Climate 20, no. 2 (January 15, 2007): 316–33. http://dx.doi.org/10.1175/jcli3985.1.
Full textAbstract:
Abstract The Amazon and Orinoco River plumes and North Brazil Current (NBC) rings are investigated during the 1 June through 30 November Atlantic hurricane season to identify their impact on upper-ocean temperatures in the region and to draw attention to their potential role in hurricane maintenance and intensification. The analysis uses ocean temperature and salinity stratification data, infrared and microwave satellite-derived sea surface temperature (SST) data, and Atlantic tropical storm and hurricane tracks data. The Amazon–Orinoco River plume spreads into the western equatorial Atlantic Ocean forming an extensive (0°–20°N, 78°–33°W) 10–60-m-thick buoyant surface layer associated with the warmest surface temperatures (up to +3°C) in the region due to the freshwater barrier layer effect. At times the warm Amazon–Orinoco River plume is bisected by cool-surface NBC rings. For the 1960 to 2000 time period, 68% of all category 5 hurricanes passed directly over the historical region of the plume, revealing that most of the most destructive hurricanes may be influenced by ocean–atmosphere interaction with the warm plume just prior to reaching the Caribbean. Statistical analyses of tropical Atlantic SSTs and tropical cyclone wind speeds reveal a significant and unique relationship between warm (cool) SSTs in the Amazon–Orinoco River plume and stronger (weaker) tropical cyclone wind speeds between 35° and 55°W. This implies that warmer (cooler) plume SSTs due to increased (decreased) river discharge may directly contribute to a more (less) vigorous hurricane season.
19
Chérubin, L. M., and P. L. Richardson. "Caribbean current variability and the influence of the Amazon and Orinoco freshwater plumes." Deep Sea Research Part I: Oceanographic Research Papers 54, no. 9 (September 2007): 1451–73. http://dx.doi.org/10.1016/j.dsr.2007.04.021.
Full text
20
Ostrander, Chris E., Margaret A. McManus, Eric H. DeCarlo, and Fred T. Mackenzie. "Temporal and Spatial Variability of Freshwater Plumes in a Semienclosed Estuarine–Bay System." Estuaries and Coasts 31, no. 1 (December 12, 2007): 192–203. http://dx.doi.org/10.1007/s12237-007-9001-z.
Full text
21
Axler, KE, S. Sponaugle, F. Hernandez, C. Culpepper, and RK Cowen. "Consequences of plume encounter on larval fish growth and condition in the Gulf of Mexico." Marine Ecology Progress Series 650 (September 17, 2020): 63–80. http://dx.doi.org/10.3354/meps13396.
Full textAbstract:
Freshwater input into nearshore continental shelf waters from coastal river-estuarine plumes can greatly alter the physical and trophic environments experienced by fish larvae. However, the biological consequences of plume encounter on larval fish survival remain equivocal, largely due to the extreme variability of these systems but also because traditional sampling techniques alone are too coarse to effectively characterize the dynamic biophysical environment at spatiotemporal scales relevant to individual larvae. Using a multidimensional approach, we simultaneously collected in situ imagery and net samples of larval fishes and zooplankton from the Mobile Bay plume (Alabama, USA) and ambient continental shelf waters during a high discharge event (8-11 April 2016). We measured the effects of plume encounter on growth and condition of larval striped anchovy Anchoa hepsetus and sand seatrout Cynoscion arenarius, 2 prominent nearshore species in the northern Gulf of Mexico. Size-frequency distributions of both species indicated that larger individuals were present in shelf waters but absent from plume waters. Otolith microstructure analysis revealed that recent growth of both focal species was significantly lower for plume-collected larvae during the last few days prior to capture. Furthermore, plume larvae were in poorer morphometric condition (skinnier at length) than their shelf counterparts, despite the fact that there were higher concentrations of zooplankton prey in plume water masses. Taken together, these results suggest that elevated prey concentrations do not necessarily translate to higher growth and condition. High turbulence and turbidity within the plume may physically inhibit the prey capture ability and feeding success of fish larvae.
22
Zavialov, P. O., O. О. Moller Jr., and X. H. Wang. "Relations between marine plastic litter and river plumes: First results of PLUMPLAS project." Journal of Oceanological Research 48, no. 4 (December 18, 2020): 32–44. http://dx.doi.org/10.29006/1564-2291.jor-2020.48(4).2.
Full textAbstract:
We report here first and preliminary results of the PLUMPLAS Project – an ongoing international joint research effort between Federal University of Rio Grande (Brazil), Xiamen University (China), and P.P. Shirshov Institute of Oceanology (Russia) developed within science and technology cooperation initiative (STI) between BRICS countries. The studies are focused on specific model regions representing different conditions of river discharges and anthropogenic loads, namely, the areas adjacent to the Kerch Strait in the Black Sea (Russia); the region of the Patos Lagoon mouth in the South Atlantic (Brazil); and Jiulong river estuary in Xiamen (China). The working hypothesis being tested is as follows: the floating plastic litter in the coastal ocean is mainly concentrated in the river plumes associated with continental freshwater discharges, and its dynamics is largely controlled by the dynamics of the plumes. The preliminary results of in situ observations and modeling accomplished to date seem to be in line with this hypothesis.
23
Saldías, Gonzalo S., P. Ted Strub, and R. Kipp Shearman. "Spatio-temporal variability and ENSO modulation of turbid freshwater plumes along the Oregon coast." Estuarine, Coastal and Shelf Science 243 (September 2020): 106880. http://dx.doi.org/10.1016/j.ecss.2020.106880.
Full text
24
Schlacher, Thomas A., Anna J. Skillington, Rod M. Connolly, Wayne Robinson, and Troy F. Gaston. "Coupling between Marine Plankton and Freshwater Flow in the Plumes off a Small Estuary." International Review of Hydrobiology 93, no. 6 (December 2008): 641–58. http://dx.doi.org/10.1002/iroh.200711050.
Full text
25
Prend, Channing J., Hyodae Seo, Robert A. Weller, and John T. Farrar. "Impact of freshwater plumes on intraseasonal upper ocean variability in the Bay of Bengal." Deep Sea Research Part II: Topical Studies in Oceanography 161 (March 2019): 63–71. http://dx.doi.org/10.1016/j.dsr2.2018.09.007.
Full text
26
Sotillo, Marcos G., Francisco Campuzano, Karen Guihou, Pablo Lorente, Estrella Olmedo, Ania Matulka, Flavio Santos, María Aránzazu Amo-Baladrón, and Antonio Novellino. "River Freshwater Contribution in Operational Ocean Models along the European Atlantic Façade: Impact of a New River Discharge Forcing Data on the CMEMS IBI Regional Model Solution." Journal of Marine Science and Engineering 9, no. 4 (April 9, 2021): 401. http://dx.doi.org/10.3390/jmse9040401.
Full textAbstract:
River freshwater contribution in the European Atlantic margin and its influence on the sea salinity field are analyzed. The impacts of using a new river discharge database as part of the freshwater forcing in a regional ocean model are assessed. Ocean model scenarios, based on the CMEMS (Copernicus Marine Environment Monitoring Service) operational IBI-MFC (Iberia Biscay Ireland Monitoring Forecasting Centre) model set-up, are run to test different (observed, modeled and climatological) river and coastal freshwater forcing configurations throughout 2018. The modelled salinity fields are validated, using as a reference all known available in-situ observational data sources. The IBI model application is proven to adequately simulate the regional salinity, and the scenarios showcase the effects of varying imposed river outflows. Some model improvement is achieved using the new forcing (i.e., better capture of salinity variability and more realistic simulation of baroclinic frontal structures linked to coastal and river freshwater buoyancy plumes). Major impacts are identified in areas with bigger river discharges (i.e., the French shelf or the northwestern Iberian coast). Instead, the Portuguese shelf or the Gulf of Cadiz are less impacted by changes in the imposed river inflows, and other dynamical factors in these areas play a major role in the configuration of the regional salinity.
27
Kasper, Jeremy L., and Thomas J. Weingartner. "The Spreading of a Buoyant Plume Beneath a Landfast Ice Cover." Journal of Physical Oceanography 45, no. 2 (February 2015): 478–94. http://dx.doi.org/10.1175/jpo-d-14-0101.1.
Full textAbstract:
AbstractIdealized numerical simulations using the Regional Ocean Modeling System demonstrate the effects of an immobile landfast ice cover that is frictionally coupled to an underice buoyant plume established by river discharge. The discharge rapidly increases and decreases over a 30-day period and has a maximum of 6000 m3 s−1. This study examined the response to a landfast ice cover of 26-km width and one that encompasses the entire shelf width. The model setting mimics spring conditions on the Alaskan Beaufort Sea (ABS) shelf. In comparison with the ice-free case subject to the same discharge scenario, underice plumes are broader and deeper, and the downwave freshwater flux is substantially decreased and delayed. Multiple anticyclonic bulges form in the ice-free case, but only a single, large bulge forms when ice is present. These differences are because of the frictional coupling between the ice and plume, which results in an Ekman-like underice boundary layer, a subsurface velocity maximum, and frictional shears that enhance vertical mixing and entrainment. For a partially ice-covered shelf, the plume spreads across the ice edge to form a swift, buoyant, ice-edge jet, whose width accords with the scale of Yankovsky and Chapman for a surface-advected plume. For a fully ice-covered shelf, the buoyant water spreads 60 km offshore over a 30-day period. For a steady discharge of 6000 m3 s−1 and a completely ice-covered shelf, the plume spreads offshore at a rate of ~1.5 km day−1 and extends ~95 km offshore after 60 days.
28
Vargas, Cristian A., Diego A. Narváez, Andrea Piñones, Sergio A. Navarrete, and Nelson A. Lagos. "River plume dynamic influences transport of barnacle larvae in the inner shelf off central Chile." Journal of the Marine Biological Association of the United Kingdom 86, no. 5 (August 25, 2006): 1057–65. http://dx.doi.org/10.1017/s0025315406014032.
Full textAbstract:
Off central Chile, around 33.5°S, the freshwater discharge of the River Maipo generates a small- to intermediate-size plume, which moves up to the north driven by the daily sea breeze and with localized effects on a costal zone of about 10–15 km. The influence of this river plume motion on abundance patterns of larval barnacles was studied in a ∼12 km long transect, including 2–3 stations inside the river plume, one station on the visible turbidity front, and two stations outside the plume. Shipboard campaigns were conducted in January (summer), August (winter), and October 2003 (spring). On each occasion, conductivity–temperature–depth casts, bottom track acoustic Doppler current profiler current measurements, size-fractioned chlorophyll concentration, and stratified plankton sampling were conducted. A significantly higher abundance of barnacle nauplii was found at the river plume front than at the plume or outside the plume. Abundance was highest in the upper 10 m of the water column, where most nauplius larvae were found. The river plume appeared as a surface layer of less saline water moving north of the river mouth, with a buoyant frontal structure progressing at speeds of 5 to 20 cm s−1. Although no peak in chlorophyll was observed at the buoyant front, the highest concentration of effective prey size for feeding nauplii (chlorophyl-a <5 and 5–20 μm) was generally associated with less saline plume waters. Thus, the accumulation of barnacle larvae at the front may facilitate foraging, potentially increasing larval growth and energy reserves. Our results suggest that the spatial structure and temporal dynamics of river plumes should be considered by benthic ecologists as transport mechanisms that potentially affect larval delivery and settlement of barnacles on rocky shores.
29
Flores, Raúl P., Carlos Lara, Gonzalo S. Saldías, Sebastián I. Vásquez, and Alonso Roco. "Spatio-temporal variability of turbid freshwater plumes in the Inner Sea of Chiloé, northern Patagonia." Journal of Marine Systems 228 (April 2022): 103709. http://dx.doi.org/10.1016/j.jmarsys.2022.103709.
Full text
30
Hernandez, O., J. Jouanno, and F. Durand. "Do the Amazon and Orinoco freshwater plumes really matter for hurricane‐induced ocean surface cooling?" Journal of Geophysical Research: Oceans 121, no. 4 (April 2016): 2119–41. http://dx.doi.org/10.1002/2015jc011021.
Full text
31
DiNapoli, Robert J., Carl P. Lipo, Timothy S. de Smet, and Terry L. Hunt. "Thermal Imaging Shows Submarine Groundwater Discharge Plumes Associated with Ancient Settlements on Rapa Nui (Easter Island, Chile)." Remote Sensing 13, no. 13 (June 28, 2021): 2531. http://dx.doi.org/10.3390/rs13132531.
Full textAbstract:
Submarine groundwater discharge (SGD) is an important component of many coastal environments and hydrologic processes, providing sources of nutrients to marine ecosystems, and potentially, an important source of fresh water for human populations. Here, we use a combination of unpiloted aerial systems (UAS) thermal infrared (TIR) imaging and salinity measurements to characterize SGD on the remote East Polynesian island of Rapa Nui (Easter Island, Chile). Previous research has shown that coastal freshwater seeps are abundant on Rapa Nui and strongly associated with the locations of ancient settlement sites. We currently lack, however, information on the differential magnitude or quality of these sources of fresh water. Our UAS-based TIR results from four locations on Rapa Nui suggest that locations of variably-sized SGD plumes are associated with many ancient settlement sites on the island and that these water sources are resilient to drought events. These findings support previous work indicating that ancient Rapa Nui communities responded to the inherent and climate-induced hydrological challenges of the island by focusing on these abundant and resilient freshwater sources. Our results highlight the efficacy of using UAS-based TIR for detecting relatively small SGD locations and provide key insights on the potential uses of these water sources for past and current Rapa Nui communities.
32
Rashid, Mehboob Ur, Waqas Ahmad, Muhammad Jawad Zeb, Naghmah Haider, Asad Khan, and Sajjad Khan. "Determination of Underground Structure and Migration of Hot Plumes Contaminating Fresh Water Using Vertical Electrical Survey (VES) and Magnetic Survey, A Case Study of Tattapani Thermal Spring, Azad Kashmir." International Journal of Economic and Environmental Geology 10, no. 1 (May 24, 2019): 84–92. http://dx.doi.org/10.46660/ijeeg.vol10.iss1.2019.222.
Full textAbstract:
A geophysical survey was carried out at Tattapani thermal spring Azad Kashmir to delineate structure,thickness, depth, lithology and migration of hot plumes contaminating fresh water. The study area was investigated byVertical Electrical Sounding (VES) using schlumberger array at 21 locations arranged in ten profiles to a maximumdepth of 500 m and 200 magnetic observations. The extension and tectonic setup of thermal spring was mapped bygeoelectrical litho sections, subsurface geological sections (20m, 20-100m and 100-500m) pseudo section, apparentresistivity map, geoelectrical parameters, statistical distribution of apparent resistivity, total magnetic intensity andanomaly map. The data show that Tattapani hot spring is concentrated along the fault line delineated by geoelectricallitho sections and magnetic section with value of -120 nT to -300 nT, total field intensity of 50000-50450 nT andconfirm by macro anisotropy (1.0 to 2.7). The geoelectrical lithological section portrays that study area compriseslithological fabric of dolomite (≥400 ohm.m), sandstone (150-200 ohm.m), clay (80-150 ohm.m), Shaley clay (50-80)and shale (≤ 50). The Thermal Plumes (10-70 ohm.m) were pictured by resistivity section and pseudo section ataverage depth of 30-60 m and showing migration of hot plumes in the North-Eastern direction contaminating freshwater (100-200 ohm.m). The longitudinal conductance (0.95-15 mhos), transverse resistance (20-300 ohm.m2) are seenhaving maximum value in the North-Eastern and North-Western side of the study area. The study also shows that freshground water is mostly concentrated in sandstone (150-200 ohm.m), dolomite (≥400 ohm.m) and lies above the thermalplumes and thus highly prone to contamination due to upwelling of thermal water.
33
Rashid, Mehboob Ur, Waqas Ahmad, Muhammad Jawad Zeb, Naghmah Haider, Asad Khan, and Sajjad Khan. "Determination of Underground Structure and Migration of Hot Plumes Contaminating Fresh Water Using Vertical Electrical Survey (VES) and Magnetic Survey, A Case Study of Tattapani Thermal Spring, Azad Kashmir." International Journal of Economic and Environmental Geology 10, no. 1 (May 24, 2019): 84–92. http://dx.doi.org/10.46660/ojs.v10i1.222.
Full textAbstract:
A geophysical survey was carried out at Tattapani thermal spring Azad Kashmir to delineate structure,thickness, depth, lithology and migration of hot plumes contaminating fresh water. The study area was investigated byVertical Electrical Sounding (VES) using schlumberger array at 21 locations arranged in ten profiles to a maximumdepth of 500 m and 200 magnetic observations. The extension and tectonic setup of thermal spring was mapped bygeoelectrical litho sections, subsurface geological sections (20m, 20-100m and 100-500m) pseudo section, apparentresistivity map, geoelectrical parameters, statistical distribution of apparent resistivity, total magnetic intensity andanomaly map. The data show that Tattapani hot spring is concentrated along the fault line delineated by geoelectricallitho sections and magnetic section with value of -120 nT to -300 nT, total field intensity of 50000-50450 nT andconfirm by macro anisotropy (1.0 to 2.7). The geoelectrical lithological section portrays that study area compriseslithological fabric of dolomite (≥400 ohm.m), sandstone (150-200 ohm.m), clay (80-150 ohm.m), Shaley clay (50-80)and shale (≤ 50). The Thermal Plumes (10-70 ohm.m) were pictured by resistivity section and pseudo section ataverage depth of 30-60 m and showing migration of hot plumes in the North-Eastern direction contaminating freshwater (100-200 ohm.m). The longitudinal conductance (0.95-15 mhos), transverse resistance (20-300 ohm.m2) are seenhaving maximum value in the North-Eastern and North-Western side of the study area. The study also shows that freshground water is mostly concentrated in sandstone (150-200 ohm.m), dolomite (≥400 ohm.m) and lies above the thermalplumes and thus highly prone to contamination due to upwelling of thermal water.
34
Jenkins, Adrian. "Convection-Driven Melting near the Grounding Lines of Ice Shelves and Tidewater Glaciers." Journal of Physical Oceanography 41, no. 12 (December 1, 2011): 2279–94. http://dx.doi.org/10.1175/jpo-d-11-03.1.
Full textAbstract:
Abstract Subglacial meltwater draining along the bed of fast-flowing, marine-terminating glaciers emerges at the grounding line, where the ice either goes afloat to form an ice shelf or terminates in a calving face. The input of freshwater to the ocean provides a source of buoyancy and drives convective motion alongside the ice–ocean interface. This process is modeled using the theory of buoyant plumes that has previously been applied to the study of the larger-scale circulation beneath ice shelves. The plume grows through entrainment of ocean waters, and the heat brought into the plume as a result drives melting at the ice–ocean interface. The equations are nondimensionalized by using scales appropriate for the region where the subglacial drainage, rather than the subsequent addition of meltwater, supplies the majority of the buoyancy forcing. It is found that the melt rate within this region can be approximated reasonably well by a function that is linear in ocean temperature, has a cube root dependence on the flux of subglacial meltwater, and has a complex dependency on the slope of the ice–ocean interface. The model is used to investigate variability in melting induced by changes in both ocean temperature and subglacial discharge for a number of realistic examples of ice shelves and tidewater glaciers. The results show how warming ocean waters and increasing subglacial drainage both generate increases in melting near the grounding line.
35
Nishizawa, Bungo, Naoya Kanna, Yoshiyuki Abe, Yoshihiko Ohashi, Daiki Sakakibara, Izumi Asaji, Shin Sugiyama, Atsushi Yamaguchi, and Yutaka Watanuki. "Contrasting assemblages of seabirds in the subglacial meltwater plume and oceanic water of Bowdoin Fjord, northwestern Greenland." ICES Journal of Marine Science 77, no. 2 (December 14, 2019): 711–20. http://dx.doi.org/10.1093/icesjms/fsz213.
Full textAbstract:
Abstract In Greenland, tidewater glaciers discharge turbid subglacial freshwater into fjords, forming plumes near the calving fronts, and these areas serve as an important foraging habitat for seabirds. To investigate the effect of subglacial discharge on the foraging assemblages of surface feeders and divers in a glacial fjord, we conducted boat-based seabird surveys, near-surface zooplankton samplings, and hydrographic measurements at Bowdoin Fjord, northwestern Greenland in July. Foraging surface feeders (black-legged kittiwake Rissa tridactyla, glaucous gull Larus hyperboreus, and northern fulmar Fulmarus glacialis) aggregated within a plume-affected area in front of Bowdoin Glacier. This area was characterized by highly turbid subglacial meltwater and abundant large-sized zooplankton including Calanus hyperboreus, chaetognaths, and ctenophores near the surface. Surface feeders fed on these aggregated prey presumably transported to the surface by strong upwelling of subglacial meltwater. In contrast, divers (little auk Alle alle, thick-billed murre Uria lomvia, and black guillemot Cepphus grylle) foraged outside the fjord, where turbidity was low and jellyfish and Calanus copepods dominated under the influence of Atlantic water. Our study indicates spatial segregation between surface feeders and divers in a glacial fjord; surface feeders are not hindered by turbidity if taking prey at the surface, whereas divers need clear water.
36
Osadchiev, Alexander. "A method for quantifying freshwater discharge rates from satellite observations and Lagrangian numerical modeling of river plumes." Environmental Research Letters 10, no. 8 (August 1, 2015): 085009. http://dx.doi.org/10.1088/1748-9326/10/8/085009.
Full text
37
Reichert, Julie M., Brian J. Fryer, Kevin L. Pangle, Timothy B. Johnson, Jeff T. Tyson, Alison B. Drelich, and Stuart A. Ludsin. "River-plume use during the pelagic larval stage benefits recruitment of a lentic fish." Canadian Journal of Fisheries and Aquatic Sciences 67, no. 6 (June 2010): 987–1004. http://dx.doi.org/10.1139/f10-036.
Full textAbstract:
Similar to coastal marine systems, Lake Erie exhibits open-water river plumes that differ physicochemically and biologically from surrounding waters. To explore their importance to yellow perch ( Perca flavescens ) recruitment in western Lake Erie, we tested two related hypotheses: (i) contributions of larvae to the juvenile stage (when recruitment is set) would be greater from nutrient-rich Maumee River plume (MRP) waters than from less-productive non-MRP waters; and (ii) warmer temperatures and higher zooplankton (prey) production in the MRP (versus non-MRP waters) would underlie this expected recruitment difference through “bottom-up” effects on larval growth. Peak larval yellow perch density was 10-fold and 5-fold less in the MRP than in non-MRP waters during 2006 and 2007, respectively. However, otolith microchemical analyses demonstrated that disproportionately more juvenile recruits emanated from the MRP than from non-MRP waters during both years. Although temperature and zooplankton production were higher in the MRP than in non-MRP waters during both years, observed recruitment differences were not definitively linked to bottom-up effects. Top-down effects also appeared important, as high turbidity in the MRP may offer a survival advantage by reducing predation mortality on larvae. Our research highlights the need to better understand biophysical coupling in freshwater systems and demonstrates how stochastic tributary inputs can influence fish recruitment.
38
Umbert, Marta, Carolina Gabarro, Estrella Olmedo, Rafael Gonçalves-Araujo, Sebastien Guimbard, and Justino Martinez. "Using Remotely Sensed Sea Surface Salinity and Colored Detrital Matter to Characterize Freshened Surface Layers in the Kara and Laptev Seas during the Ice-Free Season." Remote Sensing 13, no. 19 (September 24, 2021): 3828. http://dx.doi.org/10.3390/rs13193828.
Full textAbstract:
The overall volume of freshwater entering the Arctic Ocean has been growing as glaciers melt and river runoff increases. Since 1980, a 20% increase in river runoff has been observed in the Arctic system. As the discharges of the Ob, Yenisei, and Lena rivers are an important source of freshwater in the Kara and Laptev Seas, an increase in river discharge might have a significant impact on the upper ocean circulation. The fresh river water mixes with ocean water and forms a large freshened surface layer (FSL), which carries high loads of dissolved organic matter and suspended matter into the Arctic Ocean. Optically active material (e.g., phytoplankton and detrital matter) are spread out into plumes, which are evident in satellite data. Russian river signatures in the Kara and Laptev Seas are also evident in recent SMOS Sea Surface Salinity (SSS) Arctic products. In this study, we compare the new Arctic+ SSS products, produced at the Barcelona Expert Center, with the Ocean Color absorption coefficient of colored detrital matter (CDM) in the Kara and Laptev Seas for the period 2011–2019. The SSS and CDM are found to be strongly negatively correlated in the regions of freshwater influence, with regression coefficients between −0.72 and −0.91 in the studied period. Exploiting this linear correlation, we estimate the SSS back to 1998 using two techniques: one assuming that the relationship between the CDM and SSS varies regionally in the river-influenced areas, and another assuming that it does not. We use the 22-year time-series of reconstructed SSS to estimate the interannual variability of the extension of the FSL in the Kara and Laptev Seas as well as their freshwater content. For the Kara and Laptev Seas, we use 32 and 28 psu as reference salinities, and 26 and 24 psu isohalines as FSL boundaries, respectively. The average FSL extension in the Kara Sea is 2089–2611 km2, with a typical freshwater content of 11.84–14.02 km3. The Laptev Sea has a slightly higher mean FSL extension of 2320–2686 km2 and a freshwater content of 10.15–12.44 km3. The yearly mean freshwater content and extension of the FSL, computed from SMOS SSS and Optical data, is (as expected) found to co-vary with in situ measurements of river discharge from the Arctic Great Rivers Observatory database, demonstrating the potential of SMOS SSS to better monitor the river discharge changes in Eurasia and to understand the Arctic freshwater system during the ice-free season.
39
Cenedese, Claudia, and V. Marco Gatto. "Impact of a Localized Source of Subglacial Discharge on the Heat Flux and Submarine Melting of a Tidewater Glacier: A Laboratory Study." Journal of Physical Oceanography 46, no. 10 (October 2016): 3155–63. http://dx.doi.org/10.1175/jpo-d-16-0123.1.
Full textAbstract:
AbstractIdealized laboratory experiments have been conducted in a two-layer stratified fluid to investigate the leading-order dynamics that control submarine melting and meltwater export near a vertical ice–ocean interface as a function of subglacial discharge. In summer, the discharge of surface runoff at the base of a glacier (subglacial discharge) generates strong buoyant plumes that rise along the glacier front entraining ambient water along the way. The entrainment enhances the heat transport toward the glacier front and hence the submarine melt rate increases with the subglacial discharge rate. In the laboratory, the effect of subglacial discharge is simulated by introducing freshwater at freezing temperature from a point source at the base of an ice block representing the glacier. The circulation pattern observed both with and without subglacial discharge resembles those observed in previous observational and numerical studies. Buoyant plumes rise vertically until they find either their neutrally buoyant level or the free surface. Hence, the meltwater can deposit within the interior of the water column and not entirely at the free surface, as confirmed by field observations. The heat budget in the tank, calculated following a new framework, gives estimates of submarine melt rate that increase with the subglacial discharge and are in agreement with the directly measured submarine melting. This laboratory study provides the first direct measurements of submarine melt rates for different subglacial discharges, and the results are consistent with the predictions of previous theoretical and numerical studies.
40
Gancheva, Irina, Elisaveta Peneva, and Violeta Slabakova. "Detecting the Surface Signature of Riverine and Effluent Plumes along the Bulgarian Black Sea Coast Using Satellite Data." Remote Sensing 13, no. 20 (October 13, 2021): 4094. http://dx.doi.org/10.3390/rs13204094.
Full textAbstract:
The clear and reliable detection of effluent plumes using satellite data is especially challenging. The surface signature of such events is of a small scale; it shows a complex interaction with the local environment and depends greatly on the effluent and marine water constitution. In the context of remote sensing techniques for detecting treated wastewater discharges, we study the surface signature of small river plumes, as they share specific characteristics, such as higher turbidity levels and increased nutrient concentration, and are fresh compared to the salty marine water. The Bulgarian Black Sea zone proves to be a challenging study area, with its optically complex waters and positive freshwater balance. Additionally, the Bulgarian Black Sea coast is a known tourist destination with an increased seasonal load; thus, the problem of the identification of wastewater discharges is a topical issue. In this study, we analyze the absorption components of the Inherent Optical Properties (IOPs) for 84 study points that are located at outfall discharging areas, river estuaries and at different distances from the shoreline, reaching the open sea area at a bottom depth of more than 2000 m. The calculations of IOPs take into account all available Sentinel 2 cloudless acquisitions for three years from 2017 until 2019 and are performed using the Case-2 Regional CoastColour (C2RCC) processor, implemented in the Sentinel Application Platform (SNAP). The predominant absorber for each study area and its temporal variation is determined, deriving the specific characteristics of the different areas and tracking their seasonal and annual course. Optical data from the Galata AERONET-OC site are used for validating the absorption coefficient of phytoplankton pigment. A conclusion regarding the possibility of distinguishing riverine, marine and coastal water is derived. The study provides a sound basis for estimating the advantages and drawbacks of optical satellite data for tracking the extent of effluent and fluvial plumes with unknown concentrations of optically significant seawater constituents.
41
Carneiro, Marcos Tavares, Myriam Bandeira Vianna Cortes, and Julio Cesar Wasserman. "Critical evaluation of the factors affecting Escherichia coli environmental decay for outfall plume models." Ambiente e Agua - An Interdisciplinary Journal of Applied Science 13, no. 4 (July 3, 2018): 1. http://dx.doi.org/10.4136/ambi-agua.2106.
Full textAbstract:
The Escherichia coli T90 parameter is widely employed in outfall plume hydrodynamic models. Although there is a great deal of academic literature estimating T90, no standard methodology has been validated so far. Estimation of die-off rates should consider many other biological, chemical and physical processes. Over the last three decades, while a great deal of new knowledge about microbial biology and ecology has become available, it has not been fully incorporated into the overall research. Consequently, hydrodynamic models of sewage plumes lack consistency with environmental dynamics and frequently do not fully reproduce processes. This article scrutinized the relevant works that could improve T90 assessment using the most robust and realistic approaches. The most important related literature since the 1990s was considered, together with earlier relevant works. The research focused on techniques and methodologies, especially their ecologic and cellular biology aspects. A brief discussion of the methods applied to evaluate the T90 of bacteria examined aspects like representativeness of incubation, incubation scale, measurement procedures and models’ representations of bacterial decay. The factors affecting population decay, such as solar radiation, salinity and interaction with solids, were considered in the light of the very large literature registry. Finally, biological aspects affecting decay, like predation and genetic resistance, were also analyzed. The resulting updated understanding of T90 may contribute to better managerial procedures that could improve water quality in freshwater and coastal systems, and consequently improve human health outcomes.
42
Su, Zhan, Andrew P. Ingersoll, and Feng He. "On the Abruptness of Bølling–Allerød Warming." Journal of Climate 29, no. 13 (June 21, 2016): 4965–75. http://dx.doi.org/10.1175/jcli-d-15-0675.1.
Full textAbstract:
Abstract Previous observations and simulations suggest that an approximate 3°–5°C warming occurred at intermediate depths in the North Atlantic over several millennia during Heinrich stadial 1 (HS1), which induces warm salty water (WSW) lying beneath surface cold freshwater. This arrangement eventually generates ocean convective available potential energy (OCAPE), the maximum potential energy releasable by adiabatic vertical parcel rearrangements in an ocean column. The authors find that basin-scale OCAPE starts to appear in the North Atlantic (~67.5°–73.5°N) and builds up over decades at the end of HS1 with a magnitude of about 0.05 J kg−1. OCAPE provides a key kinetic energy source for thermobaric cabbeling convection (TCC). Using a high-resolution TCC-resolved regional model, it is found that this decadal-scale accumulation of OCAPE ultimately overshoots its intrinsic threshold and is released abruptly (~1 month) into kinetic energy of TCC, with further intensification from cabbeling. TCC has convective plumes with approximately 0.2–1-km horizontal scales and large vertical displacements (~1 km), which make TCC difficult to be resolved or parameterized by current general circulation models. The simulation herein indicates that these local TCC events are spread quickly throughout the OCAPE-contained basin by internal wave perturbations. Their convective plumes have large vertical velocities (~8–15 cm s−1) and bring the WSW to the surface, causing an approximate 2°C sea surface warming for the whole basin (~700 km) within a month. This exposes a huge heat reservoir to the atmosphere, which helps to explain the abrupt Bølling–Allerød warming.
43
Brandon, Mark, Richard Hodgkins, Helgi Björnsson, and Jón Ólafsson. "Multiple melt plumes observed at the Breiðamerkurjökull ice face in the upper waters of Jökulsárlón lagoon, Iceland." Annals of Glaciology 58, no. 74 (April 2017): 131–43. http://dx.doi.org/10.1017/aog.2017.10.
Full textAbstract:
ABSTRACT Breiðamerkurjökull flows from the Vatnajökull ice cap and calves into the Jökulsárlón proglacial lagoon. The lagoon is connected to the North Atlantic Ocean through a 6 m deep narrow channel. Four hydrographic surveys in spring 2012, and a 2011 4-month long temperature and salinity time series of lagoon inflow show that the lake has significantly changed since 1976. Warm saline ocean water enters each tidal cycle and descends below the maximum sampled depths. The lagoon has a surface layer of ice melt, freshwater and Atlantic derived water. Beneath 10 m depth an advective/diffusive balance is responsible for determining the temperature and salinity of the lagoon waters down to ~90 m. To maintain the observed hydrographic structure, we calculate an upwelling of deep water of ~0.2 m d−1. A survey within 30 m of Breiðamerkurjökull showed that the warmest and most saline waters sampled within the lagoon below 10 m depth were adjacent to the glacier face, along with multiple interleaved warm and cold layers. A heat and salt balance model shows that submarine melting along the ice face generates multiple meltwater plumes that are mixed and diluted within 200 m of the ice face.
44
Athanasiadou, Laoura, Emmanouil Psomiadis, and Georgios Stamatis. "Thermal Remote Sensing for Water Outflows Detection and Determination of the Role of Lineaments in Underground Hydrodynamics of Evia Island, Central Greece." Bulletin of the Geological Society of Greece 56, no. 1 (April 16, 2020): 100. http://dx.doi.org/10.12681/bgsg.20948.
Full textAbstract:
The coastal karst system of Evia Island is developed due to the extended presence of carbonate formations, discharges into the sea either at the coastal zone or via submarine springs, having a direct relation to the tectonic system of the area. Thermal infrared remote sensing has been proved its capability in monitoring thermal differentiations of coastal water plumes. This work aims to locate the freshwater outflows through remote sensing and specific with the use of Landsat’s 8 thermal images and to reveal how the lineaments of the area control this karstification process. L8 contains two thermal bands (Band 10, high gain and Band 11, low gain) with resolution 30m which record the scattering of infrared radiation from the sea surface. Spectral Band 10 was selected due to the high gain characteristics which provide more suitable radiometric resolution (sensitivity). Finally, combing thermal images with geological maps, sea surface temperature (SST) maps have been created.
45
Carter, B. R., J. R. Toggweiler, R. M. Key, and J. L. Sarmiento. "Processes determining the marine alkalinity and carbonate saturation distributions." Biogeosciences Discussions 11, no. 7 (July 21, 2014): 11139–78. http://dx.doi.org/10.5194/bgd-11-11139-2014.
Full textAbstract:
Abstract. We introduce a composite tracer, Alk*, that has a global distribution primarily determined by CaCO3 precipitation and dissolution. Alk* also highlights riverine alkalinity plumes that are due to dissolved calcium carbonate from land. We estimate the Arctic receives approximately twice the riverine alkalinity per unit area as the Atlantic, and 8 times that of the other oceans. Riverine inputs broadly elevate Alk* in the Arctic surface and particularly near river mouths. Strong net carbonate precipitation lowers basin mean Indian and Atlantic Alk*, while upwelling of dissolved CaCO3 rich deep waters elevates Northern Pacific and Southern Ocean Alk*. We use the Alk* distribution to estimate the carbonate saturation variability resulting from CaCO3 cycling and other processes. We show regional variations in surface carbonate saturation are due to temperature changes driving CO2 fluxes and, to a lesser extent, freshwater cycling. Calcium carbonate cycling plays a tertiary role. Monitoring the Alk* distribution would allow us to isolate the impact of acidification on biological calcification and remineralization.
46
Rowling, Kevin R. "Comment on 'Spawning dynamics of the eastern gemfish (Rexea solandri) in relation to regional oceanography'." Marine and Freshwater Research 52, no. 4 (2001): 623. http://dx.doi.org/10.1071/mf01041.
Full textAbstract:
A comment on ‘Spawning dynamics of the eastern gemfish (Rexea solandri) in relation to regional oceanography in south-eastern Australia’ by J. D. Prince and D. A. Griffin, Marine and Freshwater Research 52, 611–22. Temporal trends through the winter seasons in commercial landings of eastern gemfish (Rexea solandri) during the years 1977–79, 1982–85, 1986–87 and 1989–92 were reasonably stable for given latitudes, despite variable oceanographic influences, as depicted by 250 m isotherm data. This suggests that the overall pattern of occurrence of pre-spawning aggregations of eastern gemfish in these periods was determined by a combination of time of the season and latitude, rather than by oceanographic factors. Between 1986 and 1996, only four instances were identified where gemfish catches contained >10%of ‘running ripe’ females, and the variety of oceanographic conditions under which these catches were made provides little support for the hypothesis that eastern gemfish spawn into subsurface plumes of upwelled sub-Antarctic water.
47
Sorensen, Peter W., and Keith A. Hobson. "Stable Isotope Analysis of Amphidromous Hawaiian Gobies Suggests Their Larvae Spend a Substantial Period of Time in Freshwater River Plumes." Environmental Biology of Fishes 74, no. 1 (September 2005): 31–42. http://dx.doi.org/10.1007/s10641-005-3212-6.
Full text
48
Pereira, Humberto, Magda C. Sousa, Luís R. Vieira, Fernando Morgado, and João M. Dias. "Modelling Salt Intrusion and Estuarine Plumes under Climate Change Scenarios in Two Transitional Ecosystems from the NW Atlantic Coast." Journal of Marine Science and Engineering 10, no. 2 (February 14, 2022): 262. http://dx.doi.org/10.3390/jmse10020262.
Full textAbstract:
The Minho and Lima estuaries, separated by approximately 20 km, are two important transitional systems from the NW Atlantic Portuguese coast. Considering their contrasting characteristics, the present work aims to investigate climate change impacts in salt intrusion and estuarine plumes interaction, through an integrated hydrological characterization. The three-dimensional numerical model Delft3D was implemented to explore the hydrological response of these two systems taking into account their interaction. The model was applied to investigate two different climate change scenarios (RCP 4.5 and RCP 8.5), where physical variables such as sea level and river outflow were varied following summer and winter conditions. The numerical results revealed typically estuarine hydrological patterns, although some different features were found for each estuary. The head and mouth of the estuaries may be the zones most affected by climate change. In the first zone, the salinity may increase in the future in response to freshwater reduction from the Minho and Lima rivers. Considering the cumulative impact of the sea level rise, the saline intrusion may increase in the future: in the Minho estuary it reaches 14 km for the Present scenario during the dry season, penetrating further under climate change conditions (15 km for the RCP 4.5 scenario, and 17 km for the RCP 8.5 scenario); in the Lima estuary, the salt propagates further inland, reaching 17 km for the Present scenario, 18 km for the RCP 4.5 scenario, and a maximum of 20 km for the RCP 8.5 scenario. In all scenarios, during winter conditions, the estuarine plumes are larger and wider, being predicted that in the future they will reduce their dimensions during the winter period, and remain unchanged during summertime. Concisely, this modelling study provided more expertise about the physical patterns of these two estuaries and their interaction, as well as to anticipate the climate change impacts in their dynamics.
49
Cook, Samuel J., Poul Christoffersen, Joe Todd, Donald Slater, and Nolwenn Chauché. "Coupled modelling of subglacial hydrology and calving-front melting at Store Glacier, West Greenland." Cryosphere 14, no. 3 (March 11, 2020): 905–24. http://dx.doi.org/10.5194/tc-14-905-2020.
Full textAbstract:
Abstract. We investigate the subglacial hydrology of Store Glacier in West Greenland, using the open-source, full-Stokes model Elmer/Ice in a novel 3D application that includes a distributed water sheet, as well as discrete channelised drainage, and a 1D model to simulate submarine plumes at the calving front. At first, we produce a baseline winter scenario with no surface meltwater. We then investigate the hydrological system during summer, focussing specifically on 2012 and 2017, which provide examples of high and low surface-meltwater inputs, respectively. We show that the common assumption of zero winter freshwater flux is invalid, and we find channels over 1 m2 in area occurring up to 5 km inland in winter. We also find that the production of water from friction and geothermal heat is sufficiently high to drive year-round plume activity, with ice-front melting averaging 0.15 m d−1. When the model is forced with seasonally averaged surface melt from summer, we show a hydrological system with significant distributed sheet activity extending 65 and 45 km inland in 2012 and 2017, respectively; while channels with a cross-sectional area higher than 1 m2 form as far as 55 and 30 km inland. Using daily values for the surface melt as forcing, we find only a weak relationship between the input of surface meltwater and the intensity of plume melting at the calving front, whereas there is a strong correlation between surface-meltwater peaks and basal water pressures. The former shows that storage of water on multiple timescales within the subglacial drainage system plays an important role in modulating subglacial discharge. The latter shows that high melt inputs can drive high basal water pressures even when the channelised network grows larger. This has implications for the future velocity and mass loss of Store Glacier, and the consequent sea-level rise, in a warming world.
50
Howley, C., M. Devlin, and M. Burford. "Assessment of water quality from the Normanby River catchment to coastal flood plumes on the northern Great Barrier Reef, Australia." Marine and Freshwater Research 69, no. 6 (2018): 859. http://dx.doi.org/10.1071/mf17009.
Full textAbstract:
Understanding the flux and fate of nutrients and sediments from rivers is of global importance because of the effects of these materials on coastal ecosystems. The present study followed three flood events from upper tributaries of the Normanby River to Princess Charlotte Bay in the northern Great Barrier Reef (GBR) lagoon, Australia. During each event, nutrients and suspended sediment concentrations were measured along a freshwater to marine transect. The upper catchment provided the majority of suspended sediments and nutrients supplied to the river system, although concentrations of most materials decreased by 52–85% between the upper catchment and estuary. As an exception, ammonium concentrations doubled within the estuary, indicating that undisturbed coastal ecosystems can provide a significant source of dissolved inorganic nitrogen to tropical river flood plumes. The dissolved nutrients in floodwaters stimulated phytoplankton blooms that inundated seagrass meadows and coral reefs. Northern GBR marine ecosystems are increasingly threatened by climate change and catchment development. The results of this study show that increased anthropogenic loads of nutrients and sediments from the upper Normanby catchment have the potential to affect the condition of marine ecosystems at Princess Charlotte Bay.