scholarly journals Water Entrainment in Nuclear Detonations: Discovery and Investigation

2018 ◽  
Author(s):  
Adele Myers ◽  
Gregory D. Spriggs
Keyword(s):  
Water Entrainment

Biological Monitoring of Thermal Effects of Cooling Water Discharges from Danish Power Plants

1983 ◽  
Vol 15 (10) ◽  
pp. 89-99
Author(s):  
Bo Møller ◽  
K I Dahl-Madsen
Keyword(s):  
Water Quality ◽  
Biological Monitoring ◽  
Benthic Community ◽  
Power Plants ◽  
Water Discharge ◽  
Cooling Water ◽  
Temperature Fields ◽  
Planning System ◽  
Excess Temperature ◽  
Water Entrainment

In the years from 1970-1982 52 site studies and monitoring studies have been carried out at major existing and planned power plants. The results from the studies have been used in a planning system for water quality. This planning system, which is water quality related, is described in this paper. An important part of the planning system is the description of size and distribution of excess temperature fields and the related biological conditions. In the biological monitoring, emphasis is placed on the benthic community as more vulnerable to the cooling water discharge. The studies have shown that the excess temperature field within the 1-2° isotherm can produce measurable changes in the benthic community. The temperature effect in the pelagic zone is marginal, however, some effects are seen at sites with a deep water intake of nutrient rich water. Entrainment of fish and Zooplankton can be important in bays and estuaries.

Shelf water entrainment by Gulf Stream warm-core rings

1987 ◽  
Vol 92 (C12) ◽  
pp. 13003 ◽  
Author(s):  
Newell Garfield ◽  
David L. Evans
Keyword(s):  
Gulf Stream ◽  
Shelf Water ◽  
Warm Core ◽  
Water Entrainment

scholarly journals On extreme atmospheric and marine nitrogen fluxes and chlorophyll-a levels in the Kattegat Strait

2003 ◽  
Vol 3 (2) ◽  
pp. 1651-1692
Author(s):  
C. B. Hasager ◽  
J. Carstensen ◽  
T. Ellermann ◽  
B. G. Gustafson ◽  
O. Hertel ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Deep Water ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Algal Blooms ◽  
Limiting Factor ◽  
Nitrogen Inputs ◽  
Chlorophyll Level ◽  
Water Entrainment

Abstract. A retrospective analysis is carried out to investigate the importance of the vertical fluxes of nitrogen to the marine sea surface layer in which high chlorophyll a levels may cause blooms of harmful algae and subsequent turn over and oxygen depletion at the bottom of the sea. Typically nitrogen is the limiting factor for phytoplankton in the Kattegat Strait during summer periods (May to August) and the major nitrogen inputs come from the atmosphere and deep-water entrainment. The extreme reoccurence values of nitrogen from atmospheric wet and dry deposition and deep-water flux entrainments are calculated by the periodic maximum method and the results are successfully compared to a map of chlorophyll return periods based on in-situ observations. The one-year return of extreme atmospheric wet deposition is around 70 mg N m−2 day−1 and 30 mg N m−2 day−1 for deep-water entrainment. Atmospheric nitrogen dry deposition is insignificant in the context of algal blooms. At longer time-scales e.g. at 10-year return, the nitrogen deep-water entrainment is larger than the extreme of atmospheric wet deposition. This indicates that the pool of nitrogen released from the sea bottom by deep-water entrainment forced by high winds greatly exceeds the atmospheric pool of nitrogen washed out by precipitation. At the frontal zone of the Kattegat Strait and Skagerrak, the nitrogen deep-water entrainment is very high and this explains the high 10-year return chlorophyll level at 8 mg m−3 in Kattegat. In the southern part, the extreme chlorophyll level is only 4 mg m−3 according to the statistics of a multi-year time-series of water samples. The chlorophyll level varies greatly in time and space as documented by a series of SeaWiFS satellite maps (OC4v4 algorithm) of chlorophyll, ScanFish and buoy observations from an experimental period in Kattegat and it is recommended to sample in-situ chlorophyll observation collocated in time to the satellite overpasses of e.g. SeaWiFS and ENVISAT MERIS to ensure improved mapping of the chlorophyll levels in the Danish waters.

Flow processes and sedimentation in a straight submarine channel on the Qiongdongnan margin, northwestern South China Sea

2020 ◽  
Vol 90 (10) ◽  
pp. 1372-1388
Author(s):  
Chenglin Gong ◽  
Dongwei Li ◽  
Kun Qi ◽  
Hongxiang Xu
Keyword(s):  
Flow Velocity ◽  
Secondary Flow ◽  
Cross Sections ◽  
Vertical Channel ◽  
Mean Value ◽  
Flow Dynamics ◽  
Straight Channel ◽  
Channel Depth ◽  
Water Entrainment ◽  
Stacking Patterns

ABSTRACT Straight channels are ubiquitous in deep-water settings, yet flow dynamics and sedimentation in them are far from being well understood. Stratigraphy and flow dynamics of a middle to late Miocene straight channel in Qiongdongnan Basin were quantified, in terms of angle of channel-complex-growth trajectories (Tc), stratigraphic mobility number (M), Froude number (Fr), layer-averaged flow velocity (U), flow thickness (h), and water entrainment coefficient (Ew). The documented channels are composed of three channel complexes (CC1 to CC3) all of which are all characterized by symmetrical channel cross sections without levees and by organized vertical channel-stacking patterns (represented by high mean value of Tc = 37.4° and low mean value of M = 0.038). Turbidity currents in them were estimated to have U of 1.6 to 2.0 m/s (averaging 1.8 m/s), h of 63 to 89 m (averaging 78), Fr of 0.849 to 0.999 (averaging 0.912), and Ew of 0.0003 to 0.0005. They were, in most case, subcritical over most of the channel length, and had a low degree of water entrainment and low flow height scaled to the channel depth (i.e., 0.786 to 0.81 of the channel depth), most likely inhibiting the gradual loss of sediment to form levees. With reference to modeling results of secondary flow velocity vectors of numerical straight channels with the same sinuosity, two parallel gullies seen on both sides of the interpreted channel beds are interpreted to be induced by high-velocity downward backflows produced by the negative buoyancy. Such symmetrical secondary flow structures most likely promoted symmetrical intrachannel deposition (i.e., less deposition along both channel margins but more deposition near the channel center), and thus forced individual channel complexes to progressively aggrade in a synchronous manner, forming straight-channel complexes with symmetrical channel cross sections and organized vertical channel-stacking patterns.

A nonlinear model of flow in meandering submarine and subaerial channels

1999 ◽  
Vol 400 ◽  
pp. 295-331 ◽  
Author(s):  
JASIM IMRAN ◽  
GARY PARKER ◽  
CARLOS PIRMEZ
Keyword(s):  
Sediment Concentration ◽  
Turbidity Current ◽  
Specific Data ◽  
North West ◽  
Coriolis Effects ◽  
The North ◽  
Density Flow ◽  
Meander Bends ◽  
Water Entrainment

A generalized model of flow in meandering subaqueous and subaerial channels is developed. The conservation equations of mass and momentum are depth/layer integrated, normalized, and represented as deviations from a straight base state. This allows the determination of integrable forms which can be solved at both linear and nonlinear levels. The effects of various flow and geometric parameters on the flow dynamics are studied. Although the model is not limited to any specific planform, this study focuses on sine-generated curves. In analysing the flow patterns, the turbidity current of the subaqueous case is simplified to a conservative density flow with water entrainment from above neglected. The subaqueous model thus formally corresponds to a subcritical or only mildly supercritical mud-rich turbidity current. By extension, however the analysis can be applied to a depositional or erosional current carrying sand that is changing only slowly in the streamwise direction. By bringing the subaqueous and subaerial cases into a common form, flow behaviour in the two environments can be compared under similar geometric and boundary conditions. A major difference between the two cases is the degree of superelevation of channel flow around bends, which is modest in the subaerial case but substantial in the subaqueous case. Another difference concerns Coriolis effects: some of the largest subaqueous meandering systems are so large that Coriolis effects can become important. The model is applied to meander bends on the youngest channel in the mid-fan region of the Amazon Fan and a mildly sinuous bend of the North-West Atlantic Mid-Ocean Channel. In the absence of specific data on the turbid flows that created the channel, the model can be used to make inferences about the flow, and in particular the range of values of flow velocity and sediment concentration that would allow the growth and downfan migration of meander bends.

Effect of bed roughness on velocity profile and water entrainment in a sedimentary density current

2018 ◽  
Vol 45 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Seyed Mahmood Kashefipour ◽  
Mehdi Daryaee ◽  
Mehdi Ghomeshi
Keyword(s):  
Velocity Profile ◽  
Richardson Number ◽  
Density Current ◽  
Wall Region ◽  
Density Currents ◽  
Relative Roughness ◽  
Bed Roughness ◽  
Water Entrainment ◽  
Relationship Of ◽  
The Relationship

In this study, the effect of bed roughness on velocity profile and water entrainment in a sedimentary density current for Richardson numbers of 1.2–7 (subcritical flow conditions) was investigated. Experiments were carried out in a tilting flume with four different bed slopes, four roughness heights, and two fluid densities of sedimentary density currents. The results showed that bed roughness significantly affects the general shapes of velocity profiles, especially in the wall region. Two empirical equations were developed as the functions of the relative roughness for the wall and jet regions of velocity profile using the measured velocities of density currents. Water entrainment was also affected by bed roughness and an empirical equation was developed describing the relationship of this phenomenon with the Richardson number and relative roughness. Sensitivity analysis of this equation by using elasticity coefficient method showed that the effectiveness of the Richardson number is 3.9 times more than the effect of relative roughness on water entrainment.

scholarly journals Covariability of Near-Surface Wind Speed Statistics and Mesoscale Sea Surface Temperature Fluctuations

2018 ◽  
Vol 48 (3) ◽  
pp. 465-478 ◽  
Author(s):  
Johannes Gemmrich ◽  
Adam Monahan
Keyword(s):  
Wind Speed ◽  
Cold Water ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Western Boundary ◽  
Near Surface ◽  
Water Entrainment ◽  
Speed Fluctuations ◽  
Coupling Processes

AbstractThe atmospheric (ABL) and ocean (OBL) boundary layers are intimately linked via mechanical and thermal coupling processes. In many regions over the world’s oceans, this results in a strong covariability between anomalies in wind speed and SST. At oceanic mesoscale, this coupling can be driven either from the atmosphere or the ocean. Gridded SST and wind speed data at 0.25° resolution show that over the western North Atlantic, the ABL mainly responds to the OBL, whereas in the eastern North Pacific and in the Southern Ocean, the OBL largely responds to wind speed anomalies. This general behavior is also verified by in situ buoy observations in the Atlantic and Pacific. A stochastic, nondimensional, 1D coupled air–sea boundary layer model is utilized to assess the relative importance of the coupling processes. For regions of little intrinsic SST fluctuations (i.e., most regions of the world’s oceans away from strong temperature fronts), the inclusion of cold water entrainment at the thermocline is crucial. In regions with strong frontal activities (e.g., the western boundary regions), the coupling is dominated by the SST fluctuations, and the frontal variability needs to be included in models. Generally, atmospheric and ocean-driven coupling lead to an opposite relationship between SST and wind speed fluctuations. This effect can be especially important for higher wind speed quantiles.

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