Dissertations / Theses on the topic 'Wind driven ocean circulation'
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1
Davidson, Fraser. "Wind driven circulation in Trinity and Conception Bays /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0020/NQ47495.pdf.
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Duhaut, Thomas H. A. "Wind-driven circulation : impact of a surface velocity dependent wind stress." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101117.
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The use of an ocean surface velocity dependent wind stress is examined in the context of a 3-layer double-gyre quasigeostrophic wind-driven ocean circulation model. The new wind stress formulation results in a large reduction of the power input by the wind into the oceanic circulation. This wind stress is proportional to a quadratic function of Ua--u o, where Ua is the wind at 10m above the ocean surface and uo is the ocean surface current. Because the winds are typically faster than the ocean currents, the impact of the ocean surface velocity on the wind stress itself is relatively small. However, the power input is found to be greatly reduced with the new formulation. This is shown by simple scaling argument and numerical simulations in a square basin. Our results suggest that the wind power input may be as much as 35% smaller than is typically assumed.The ocean current signature is clearly visible in the scatterometer-derived wind stress fields. We argue that because the actual ocean velocity differs from the modeled ocean velocities, care must be taken in directly applying scatterometer-derived wind stress products to the ocean circulation models. This is not to say that the scatterometer-derived wind stress is not useful. Clearly the great spatial and temporal coverage make these data sets invaluable. Our point is that it is better to separate the atmospheric and oceanic contribution to the stresses.
Finally, the new wind stress decreases the sensitivity of the solution to the (poorly known) bottom friction coefficient. The dependence of the circulation strength on different values of bottom friction is examined under the standard and the new wind stress forcing for two topographic configurations. A flat bottom and a meridional ridge case are studied. In the flat bottom case, the new wind stress leads to a significant reduction of the sensitivity to the bottom friction parameter, implying that inertial runaway occurs for smaller values of bottom friction coefficient. The ridge case also gives similar results. In the case of the ridge and the new wind stress formulation, no real inertial runaway regime has been found over the range of parameters explored.
3
Kiss, Andrew Elek. "Dynamics of laboratory models of the wind-driven ocean circulation." View thesis entry in Australian Digital Theses Program, 2000. http://thesis.anu.edu.au/public/adt-ANU20011018.115707/index.html.
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Kiss, Andrew Elek, and Andrew Kiss@anu edu au. "Dynamics of laboratory models of the wind-driven ocean circulation." The Australian National University. Research School of Earth Sciences, 2001. http://thesis.anu.edu.au./public/adt-ANU20011018.115707.
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This thesis presents a numerical exploration of the dynamics governing
rotating flow driven by a surface stress in the " sliced cylinder " model
of Pedlosky & Greenspan (1967) and Beardsley (1969), and its close
relative, the " sliced cone " model introduced by Griffiths & Veronis
(1997). The sliced cylinder model simulates the barotropic wind-driven
circulation in a circular basin with vertical sidewalls, using a depth
gradient to mimic the effects of a gradient in Coriolis parameter. In the
sliced cone the vertical sidewalls are replaced by an azimuthally uniform
slope around the perimeter of the basin to simulate a continental slope.
Since these models can be implemented in the laboratory, their dynamics
can be explored by a complementary interplay of analysis and numerical
and laboratory experiments. ¶
In this thesis a derivation is presented of a generalised
quasigeostrophic formulation which is valid for linear and moderately
nonlinear barotropic flows over large-amplitude topography on an f-plane,
yet retains the simplicity and conservation properties of the standard
quasigeostrophic vorticity equation (which is valid only for small depth
variations). This formulation is implemented in a numerical model based
on a code developed by Page (1982) and Becker & Page (1990). ¶
The accuracy of the formulation and its implementation are confirmed by
detailed comparisons with the laboratory sliced cylinder and sliced cone
results of Griffiths (Griffiths & Kiss, 1999) and Griffiths & Veronis
(1997), respectively. The numerical model is then used to provide insight
into the dynamics responsible for the observed laboratory flows. In the
linear limit the numerical model reveals shortcomings in the sliced cone
analysis by Griffiths & Veronis (1998) in the region where the slope and
interior join, and shows that the potential vorticity is dissipated in an
extended region at the bottom of the slope rather than a localised region
at the east as suggested by Griffiths & Veronis (1997, 1998). Welander's
thermal analogy (Welander, 1968) is used to explain the linear
circulation pattern, and demonstrates that the broadly distributed
potential vorticity dissipation is due to the closure of geostrophic
contours in this geometry. ¶
The numerical results also provide insight into features of the flow at
finite Rossby number. It is demonstrated that separation of the western
boundary current in the sliced cylinder is closely associated with a
" crisis " due to excessive potential vorticity dissipation in the viscous
sublayer, rather than insufficient dissipation in the outer western
boundary current as suggested by Holland & Lin (1975) and Pedlosky
(1987). The stability boundaries in both models are refined using the
numerical results, clarifying in particular the way in which the western
boundary current instability in the sliced cone disappears at large
Rossby and/or Ekman number. A flow regime is also revealed in the sliced
cylinder in which the boundary current separates without reversed flow,
consistent with the potential vorticity " crisis " mechanism. In addition
the location of the stability boundary is determined as a function of the
aspect ratio of the sliced cylinder, which demonstrates that the flow is
stabilised in narrow basins such as those used by Beardsley (1969, 1972,
1973) and Becker & Page (1990) relative to the much wider basin used by
Griffiths & Kiss (1999). ¶
Laboratory studies of the sliced cone by Griffiths & Veronis (1997)
showed that the flow became unstable only under anticyclonic forcing. It
is shown in this thesis that the contrast between flow under cyclonic and
anticyclonic forcing is due to the combined effects of the relative
vorticity and topography in determining the shape of the potential
vorticity contours. The vorticity at the bottom of the sidewall smooths
out the potential vorticity contours under cyclonic forcing, but distorts
them into highly contorted shapes under anticyclonic forcing. In
addition, the flow is dominated by inertial boundary layers under
cyclonic forcing and by standing Rossby waves under anticyclonic forcing
due to the differing flow direction relative to the direction of Rossby
wave phase propagation. The changes to the potential vorticity structure
under strong cyclonic forcing reduce the potential vorticity changes
experienced by fluid columns, and the flow approaches a steady free
inertial circulation. In contrast, the complexity of the flow structure
under anticyclonic forcing results in strong potential vorticity changes
and also leads to barotropic instability under strong forcing. ¶
The numerical results indicate that the instabilities in both models
arise through supercritical Hopf bifurcations. The two types of
instability observed by Griffiths & Veronis (1997) in the sliced cone are
shown to be related to the western boundary current instability and
" interior instability " identified by Meacham & Berloff (1997). The
western boundary current instability is trapped at the western side of
the interior because its northward phase speed exceeds that of the
fastest interior Rossby wave with the same meridional wavenumber, as
discussed by Ierley & Young (1991). ¶
Numerical experiments with different lateral boundary conditions are also
undertaken. These show that the flow in the sliced cylinder is
dramatically altered when the free-slip boundary condition is used
instead of the no-slip condition, as expected from the work of Blandford
(1971). There is no separated jet, because the flow cannot experience a
potential vorticity " crisis " with this boundary condition, so the western
boundary current overshoots and enters the interior from the east. In
contrast, the flow in the sliced cone is identical whether no-slip,
free-slip or super-slip boundary conditions are applied to the horizontal
flow at the top of the sloping sidewall, except in the immediate vicinity
of this region. This insensitivity results from the extremely strong
topographic steering near the edge of the basin due to the vanishing
depth, which demands a balance between wind forcing and Ekman pumping on
the upper slope, regardless of the lateral boundary condition. The
sensitivity to the lateral boundary condition is related to the
importance of lateral friction in the global vorticity balance. The
integrated vorticity must vanish under the no-slip condition, so in the
sliced cylinder the overall vorticity budget is dominated by lateral
viscosity and Ekman friction is negligible. Under the free-slip condition
the Ekman friction assumes a dominant role in the dissipation, leading to
a dramatic change in the flow structure. In contrast, the much larger
depth variation in the sliced cone leads to a global vorticity balance in
which Ekman friction is always dominant, regardless of the boundary
condition.
5
Hines, Adrian. "Models of large-scale wind and buoyancy driven ocean circulation." Thesis, Keele University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389607.
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Wargula, Anna (Anna Elizabeth). "Wave-, wind-, and tide-driven circulation at a well-mixed ocean inlet." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111741.
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Thesis: Ph. D. in Mechanical and Oceanographic Engineering, Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 93-104).
The effects of waves, wind, and bathymetry on tidal and subtidal hydrodynamics at unstratified, shallow New River Inlet, NC, are evaluated using field observations and numerical simulations. Tidal flows are ebb-dominated (-1.5 to 0.6 m/s, positive is inland) inside the main (2 to 5 m deep) channel on the (1 to 2 m deep) ebb shoal, owing to inflow and outflow asymmetry at the inlet mouth. Ebb-dominance of the flows is reduced during large waves (> 1 m) owing to breaking-induced onshore momentum flux. Shoaling and breaking of large waves cause depression (setdown, offshore of the ebb shoal) and super-elevation (setup, on the shoal and in the inlet) of the mean water levels, resulting in changes to the cross-shoal pressure gradient, which can weaken onshore flows. At a 90-degree bend 800-m inland of the inlet mouth, centrifugal acceleration owing to curvature drives two-layered cross-channel flows (0.1 to 0.2 m/s) with surface flows going away from and bottom flows going toward the bend. The depth-averaged dynamics are tidally asymmetric. Subtidal cross-channel flows are correlated (r² > 0.5) with cross-channel wind speed, suggesting that winds are enhancing and degrading the local-curvature induced two-layer flow, and driving three-layer flow.
by Anna Wargula.
Ph. D. in Mechanical and Oceanographic Engineering
7
Olson, Elise Marie Black. "A coupled atmosphere-ocean model of thermohaline circulation, including wind-driven gyre circulation with an analytical solution." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/114324.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2006.Cataloged from PDF version of thesis. "February 2006."
Includes bibliographical references (page 35).
A parameter representing circulation due to wind forcing is added to the thermohaline circulation model of Marotzke (1996). The model consists of four boxes and is governed by a system of two differential equations governing the temperature and salinity differences between high latitude ocean and low latitude ocean boxes. The modified model is solved numerically for equilibrium solutions, and then solved analytically by the method of Krasovskiy and Stone (1998). At the maximum strength of wind-forced circulation studied, v = 5 x 10-¹¹ s-¹, a stable thermal mode equilibrium temperature difference of 25 K is calculated. Once v reaches a critical value, which is within the range of physically reasonable values, the stable haline mode equlibrium and unstable thermal mode equilibrium are no longer observed. It is concluded that strong wind-forced circulation suppresses the thermal mode equilibrium, but that more research is necessary to determine the degree to which this effect is present in the real world.
by Elise M. Olson.
S.B.
8
Lee, Craig M. "Observations and models of upper ocean response to atmospheric forcing : wind driven flow, surface heating and near-inertial wave interactions with mesoscale currents /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/11039.
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Wu, Zhaohua. "Thermally driven surface winds in the tropics /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/10075.
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Horwitz, Rachel Mandy. "The effect of stratification on wind-driven, cross-shelf circulation and transport on the inner continental shelf." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77779.
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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 209-215).
Observations from a three-year field program on the inner shelf south of Martha's Vineyard, MA and a numerical model are used to describe the effect of stratification on inner shelf circulation, transport, and sediment resuspension height. Thermal stratification above the bottom mixed layer is shown to cap the height to which sediment is resuspended. Stratification increases the transport driven by cross-shelf wind stresses, and this effect is larger in the response to offshore winds than onshore winds. However, a one-dimensional view of the dynamics is not sufficient to explain the relationship between circulation and stratification. An idealized, cross-shelf transect in a numerical model (ROMS) is used to isolate the effects of stratification, wind stress magnitude, surface heat flux, cross-shelf density gradient, and wind direction on the inner shelf response to the cross-shelf component of the wind stress. In well mixed and weakly stratified conditions, the cross-shelf density gradient can be used to predict the transport efficiency of the cross-shelf wind stress. In stratified conditions, the presence of an along-shelf wind stress component makes the inner shelf response to cross-shelf wind stress strongly asymmetric.
by Rachel Mandy Horwitz.
Ph.D.
11
Martinez-Diaz-de-Leon, Asdrubal. "The use of the ERS-2 synthetic aperture radar to study the wind driven ocean circulation in the Gulf of Tehuantepec, Mexico, during Norte events." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246236.
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Nelkien, Haim. "Thermally driven circulation." Woods Hole, Mass. : Woods Hole Oceanographic Institution, 1987. http://hdl.handle.net/1912/3152.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, and (Ph. D.)--Woods Hole Oceanographic Institution, 1987.Cover title. Includes bibliographical references (leaves 181-186).
13
Austin, Jay Alan. "Wind-driven circulation on a shallow, stratified shelf." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/58538.
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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), February 1999.Includes bibliographical references (leaves 235-243).
A detailed examination of the development of a deep convection event observed in the Greenland Sea in 1988-89 is carried out through a combination of modeling, scale estimates, and data analysis. We develop a prognostic one-dimensional mixed layer model which is coupled to a thermodynamic ice model. Our model contains a representation of the lowest order boundary layer dynamics and adjustable coupling strengths between the mixed layer, ice, and atmosphere. We find that the model evolution is not very sensitive to the strength of the coupling between the ice and the mixed layer sufficiently far away from the limits of zero and infinite coupling; we interpret this result in physical terms. Further, we derive an analytical expression which provides a scale estimate of the rate of salinification of the mixed layer during the ice-covered preconditioning period as a function of the rate of ice advection.
by Jay Alan Austin.
Ph.D.
14
Alessandri, Jacopo. "On the wind driven circulation of the Mediterranean Sea." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13937/.
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The Mediterranean circulation appears to be the result of three principal forcing factors: the inflow/outflow at Gibraltar strait, the wind stress applied on the ocean surface and the buoyancy fluxes. In this thesis, the focus is on studying the role of the wind in the ocean circulation. Sub-basin scale gyres are driven in different proportions by winds and heat fluxes (Pinardi and Navarra, 1993; Zavatarelli and Mellor, 1995; Roussenov et al., 1995) and locked or modified by topography. Generally the large scale basin circulation is characterized by cyclonic gyres in the northern regions, and by an anticyclonic gyres and eddy-dominated flow fields in its southern parts, with the exception of the Tyrrhenian and the northern Ionian Sea (Pinardi et al., 2015). The decadal variability of the Mediterranean Sea shows a reversal of the current in the Ionian Sea called Northern Ionian Reversal (NIR; Pinardi et al., 2015) and can be connected to changes in the wind stress. To assess the role of the wind stress in Mediterranean circulation and on the NIR phenomenon, Perpetual Year (PY) experiments are carried out with the NEMO ocean model implemented on the SURF model platform (SURF; Trotta et al., 2015). Sensitivity experiments are performed on the physics of the model and on the wind forcing evaluating the relation between the wind stress and the Mediterranean upper circulation. A diagnostic study of the NIR phenomenon is carried through the NIR index. The NIR index uses the difference of the SSH at two points to evaluate the prevailing circulation in the northern Ionian sea. Positive values of the index are connected to anticyclonic circulation, while negative values are related to cyclonic circulation. SSH field from Reanalysis, model output and SLA Satellite observations are analysed and compared. Studies agree in setting the time of the surface reversal to 1997 and this is confirmed by the change of the NIR index sign, both in Reanalysis and Observations.
15
Zhai, Ping Ph D. Massachusetts Institute of Technology. "Buoyancy-driven circulation in the Red Sea." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95561.
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Thesis: Ph. D., Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 175-180).
This thesis explores the buoyancy-driven circulation in the Red Sea, using a combination of observations, as well as numerical modeling and analytical method. The first part of the thesis investigates the formation mechanism and spreading of Red Sea Overflow Water (RSOW) in the Red Sea. The preconditions required for open-ocean convection, which is suggested to be the formation mechanism of RSOW, are examined. The RSOW is identified and tracked as a layer with minimum potential vorticity and maximum chlorofluorocarbon-12. The pathway of the RSOW is also explored using numerical simulation. If diffusivity is not considered, the production rate of the RSOW is estimated to be 0.63 Sv using Walin's method. By comparing this 0.63 Sv to the actual RSOW transport at the Strait of Bab el Mandeb, it is implied that the vertical diffusivity is about 3.4 x10-5 m 2 s-1. The second part of the thesis studies buoyancy-forced circulation in an idealized Red Sea. Buoyancy-loss driven circulation in marginal seas is usually dominated by cyclonic boundary currents on f-plane, as suggested by previous observations and numerical modeling. This thesis suggests that by including [beta]-effect and buoyancy loss that increases linearly with latitude, the resultant mean Red Sea circulation consists of an anticyclonic gyre in the south and a cyclonic gyre in the north. In mid-basin, the northward surface flow crosses from the western boundary to the eastern boundary. The observational support is also reviewed. The mechanism that controls the crossover of boundary currents is further explored using an ad hoc analytical model based on PV dynamics. This ad hoc analytical model successfully predicts the crossover latitude of boundary currents. It suggests that the competition between advection of planetary vorticity and buoyancy-loss related term determines the crossover latitude. The third part of the thesis investigates three mechanisms that might account for eddy generation in the Red Sea, by conducting a series of numerical experiments. The three mechanisms are: i) baroclinic instability; ii) meridional structure of surface buoyancy losses; iii) cross-basin wind fields.
by Ping Zhai.
Ph. D.
16
Walkington, Ian A. "Wind and bouyancy driven models of sub-tropical ocean gyres." Thesis, Keele University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397658.
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Jackson, Laura Claire. "On the role of topographical torques on the wind-driven circulation." Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408560.
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English, Chad A. "The role of the pressure field in wind driven coastal circulation /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3167853.
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Primeau, François W. (François William) 1966. "Multiple equilibria and low-frequency variability of wind-driven ocean models." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/58512.
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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1998.Includes bibliographical references (leaves 156-158).
by François W. Primeau.
Ph.D.
20
Loveday, Benjamin. "Modelling wind-driven inter-ocean exchange in the greater Agulhas with the regional ocean modelling system." Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/8805.
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Includes bibliographical references.Two Regional Ocean Modelling System configurations, AGIO and ARC112, are developed to investigate (1) the structure of the Agulhas leakage, (2) the dynamical link between the leakage and the Agulhas Current, and (3) the sensitivity of this link to changes in the regional wind field. Both configurations span the Indian Ocean and South East Atlantic Ocean (29° W - 115° E, 48.25° S - 7.5° N) at 1/4° resolution. ARC112 includes a two-way, AGRIF nested, 1/12° child domain, encapsulating the Agulhas retroflection (0° E - 40° E, 45.5° S - 29.5° S). Model evaluation shows that the basin-scale circulation patterns of the South Indian Ocean are appropriately captured. Western boundary transports match those derived from in situ hydrography, though source region fluxes exceed those observed. Both configurations exhibit inertially governed retroflections and produce Agulhas rings with eddy kinetic energy patterns consistent with those derived from altimetry. Improved topography in ARC112 yields a retroflection position and leakage value closer to observations. Dominant regional water masses are captured, but discrepancies in their distributions remain, especially in highly turbulent areas. The interannual variability of upper ocean heat content is well captured, and Indian Ocean dipole modes are appropriately expressed. Leakage is shown to be confined to the top 1500 m. Flux estimates, derived using complementary Eulerian passive tracer and Lagrangian virtual float techniques, converge where retroflection position is more accurate. Eddy flux, isolated using an Okubo-Weiss parameterisation, contributes only 1/3 to the total flux at the GoodHope line, with a 2:1 anticyclone to cyclone ratio. The remaining intra-ring flux occurs due to mixing between rings in the Cape Basin thermocline, which contains up to 50% Indian Ocean waters. Using a hybrid-criteria eddy-tracking scheme, ARC112i is shown to represent all three recently identified eddy paths, producing an accurate number of rings and cyclones with trajectories and radii that mirror observations, despite higher simulated speeds. A multi-decadal strengthening of the eddy component of Agulhas leakage is ascribed to increases in anti-cyclone speed and cyclone size. Linear changes in trade wind intensity, imposed through a series of idealised wind stress anomalies, concomitantly modulate Agulhas Current transport. The leakage flux response to changing western boundary current inertia is minimal, decreasing with higher resolution. Large changes in eddy kinetic energy are associated with small leakage anomalies, suggesting that the former is a poor leakage proxy. Initially, the leakage responds linearly to increasing westerly wind intensity, but increased mixing between the Agulhas Return Current and Antarctic Circumpolar Current reduces inter-basin flux as the latter adjusts. Consequently, it is suggested that Agulhas Current and leakage magnitude may, to a degree, vary independently, and that multi-decadal trends in the region may be a function of the wind forcing used. Equatorward shifts in the zero line of wind-stress curl drive a small leakage increase, counter to proposed palaeoceanographic mechanism where leakage is implied to reduce under these conditions.
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Weddle, Charles A. OCEAN CURRENTS PACIFIC OCEAN OCEAN MODELS WIND STRESS STRESSES MATHEMATICAL MODELS WIND SENSITIVITY DEPTH CIRCULATION TROPICAL CYCLONES LONGITUDE INSTABILITY CYCLONES AIR WATER INTERACTIONS MIXED LAYER(MARINE) IMAGES METEOROLOGICAL SATELLITES THESES EQUATORIAL REGIONS TEMPERATURE. "The effect of westerly wind bursts on a tropical ocean general circulation model /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA276423.
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Thesis (M.S. in Meteorology and M.S. in Physical Oceanography) Naval Postgraduate School, December 1993.Thesis advisor(s): Murphree, James Thomas ; Garwood, Roland W. "December 1993." Bibliography: p. 115-118. Also available online.
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Weddle, Charles A., and CURRENTS PACIFIC OCEAN OCEAN MODELS WIND STRESS STRESSES MATHEMATICAL MODELS WIND SENSITIVITY DEPTH CIRCULATION TROPICAL CYCLONES LONGITUDE INSTABILITY CYCLONES AIR WATER INTERACTIONS MIXED LAYER(MARINE) IMAGES ME OCEAN. "The effect of westerly wind bursts on a tropical ocean general circulation model." Thesis, Monterey, California. Naval Postgraduate School, 1993. http://hdl.handle.net/10945/26516.
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A primitive equation general circulation model with imbedded mixed layer physics has been used to investigate the response of the equatorial Pacific ocean to daily varying winds and westerly wind bursts. The major issue addressed by this study is the impact of daily varying winds, including westerly wind bursts, in the modeling of the tropical Pacific ocean and El Nino. In the developmental phase, the sensitivity of the model to the integration time step and the domain size were investigated. The results of this work were used to determine the optimal time step and model domain size for the main experimental model runs. In the experimental phase, the model was spun-up using time averaged wind stresses. The model ocean was then exposed to two years of realistic daily varying wind stresses covering the period of 1991 and 1992. The model developed an El Nino like response that corresponded in several respects with observed features of the 1991-92 El Nino. The model also developed tropical instability waves in the eastern Pacific similar to those observed in situ and in satellite SST images. The model's responses to the tropical cyclones that occurred during 1991-92 were also consistent in several ways with observations
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Da, Silva Meyre Pereira. "On the role of wind driven ocean dynamics in tropical Atlantic variability." Texas A&M University, 2003. http://hdl.handle.net/1969.1/3867.
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The response of the tropical Atlantic Ocean to wind stress forcing on
seasonal and interannual time scales is examined using an ocean data
assimilation product from the Geophysical Fluid Dynamics Laboratory (GFDL),
and an ocean general circulation model which incorporates a three dimensional
flux correction technique to correct biases of the mean state of the ocean.
On a seasonal time scale, we investigated the impact of the annual
migration of the ITCZ on the exchange pathways of the northern tropical Atlantic.
The results indicate that seasonal variation of the zonal slope of the thermal
ridge along the boundary between the north equatorial countercurrent and north
equatorial current in response to changes in the ITCZ controls, to a large extent,
the amount of water participating in the equatorial circulation. These changes
can be explained in terms of a simple dynamical model where local Ekman
pumping dominates thermocline variation in the western part of the basin, and
Rossby wave adjustment comes into play in the eastern basin.
On an interannual time scale, we examined the upper heat budget of the
equatorial Atlantic in order to identify the key mechanisms by which wind-driven
ocean dynamics control SST variability during the onset and peak phases of the
Atlantic zonal mode. It is found that, in contrast with Pacific ENSO, both
Bjerknes and Ekman feedbacks act together to force the zonal mode, although
their relative importance and dominance depend on season and location.
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Kuo, Yu-Heng. "Errors caused by incompatible wind and buoyancy forcing in the ocean general circulation models." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23658.
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Approved for public release; distribution is unlimitedThe Geophysical Fluid Dynamics Laboratory Modular Ocean Model (GFDL MOM) is used to investigate the model difference between compatible and incompatible surface wind and buoyancy forcing. The atmosphere is a physical system in which surface wind and temperature fields are related, however in most ocean numerical models, the wind stress and buoyancy forcing are usually specified separately, i.e., no constraint between the surface wind stress and surface air temperature is considered. In reality, only one of these two fields can be prescribed in the atmosphere-driven ocean models. When the surface wind field is prescribed, the surface air temperature should be derived, and vice versa. If the two related fields are treated as totally independent in forcing the ocean models the results will be distorted. Since the model solutions depend upon the atmospheric forcing, it is important that we study the compatibility between the wind and buoyancy forcings and the effect which incompatibility might have on the ocean numerical models. This study shows that the surface wind and buoyancy forcing widely used in ocean numerical models are incompatible. Such an incompatibility results in 21 % error in the total northward transport of heat, 16% error in the total northward transport of salt, 25% error in v velocity, and 16% error in w velocity.
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Song, Qingtao. "Surface wind response to oceanic fronts /." View online ; access limited to URI, 2006. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3225330.
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Yu, Xuri. "Dynamics of seasonal and interannual variability in the equatorial Pacific." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11065.
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Seymour, Sian. "Impact of Wind Driven Variability on Sea Surface Temperature and Ocean Colour in False Bay." Master's thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/31235.
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False Bay is the largest true bay in South Africa and is an important area for conservation, the local fishing industry and marine based recreational activities. A large amount of studies, both recent and historical, have been carried out on the biology of the bay, but studies on the physics of the bay are very few in comparison. In this study high resolution satellite imagery is used to investigate wind variability and its impact on sea surface temperature (SST) and chlorophyll concentration (Chl-a) variability within False Bay and the Cape Peninsula region. High resolution (1 km) coastal winds derived from the Sentinel-1 satellite Synthetic Aperture Radar (SAR) show that winds are strongly influenced by topography under the predominantly south-easterly wind regime. The Hottentots Holland mountain range and Cape Peninsula mountain range create wind shadows as well as areas of increased wind speed within False Bay and west of the Cape Peninsula. Our observations also show that global atmospheric models, such as ECMWF, are not able to capture the spatial variability in the wind fields driven by the orography. Analyses of the SST and ocean colour imagery show that wind shadows are generally associated with warmer surface waters and higher Chl-a. In contrast, regions of enhanced wind speeds show colder surface waters and decreased chlorophyll concentration. Our results suggest that spatial variation in the horizontal wind fields have direct and significant impact on the water properties within False Bay. This study highlights the need for high resolution wind observations and simulations to force regional oceanic models of False Bay and the Cape Peninsula region.
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Jung, Kyung Tae. "On three-dimensional hydrodynamic numerical modelling of wind induced flows in stably stratified waters : a Galerkin-finite difference approach." Title page, contents and summary only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phj95.pdf.
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Taylor, Stephen V. "Northerly surface wind events over the eastern North Pacific Ocean spatial distribution, seasonality, atmospheric circulation, and forcing /." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3237552.
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Thesis (Ph. D.)--University of California, San Diego, 2006.Title from first page of PDF file (viewed December 12, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 126-133).
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Fox-Kemper, Baylor 1973. "Eddies and friction : removal of vorticity from the wind-driven gyre." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/39405.
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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences and the Woods Hole Oceanographic Institution), 2003.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 299-310).
Inertial terms dominate the single-gyre ocean model and prevent western-intensification when the viscosity is small. This occurs long before the oceanically-appropriate parameter range. It is demonstrated here that the circulation is controlled if a mechanism for ultimate removal of vorticity exists, even if it is active only in a narrow region near the boundary. Vorticity removal is modeled here as a viscosity enhanced very near the solid boundaries to roughly parameterize missing boundary physics like topographic interaction and three dimensional turbulence over the shelf. This boundary-enhanced viscosity allows western-intensified mean flows even when the inertial boundary width is much wider than the frictional region because eddies flux vorticity from within the interior streamlines to the frictional region for removal. Using boundary-enhanced viscosity, western-intensified calculations are possible with lower interior viscosity than in previous studies. Interesting behaviors result: a boundary-layer balance novel to the model, calculations with promise for eddy param- eterization, eddy-driven gyres rotating opposite the wind, and temporal complexity including basin resonances.
(cont.) I also demonstrate that multiple-gyre calculations have weaker mean circulation than single-gyres with the same viscosity and subtropical forcing. Despite traditional understanding, almost no inter-gyre flux occurs if no-slip boundary conditions are used. The inter-gyre eddy flux is in control only with exactly symmetric gyres and free slip boundaries. Even without the inter-gyre flux, the multiple-gyre circulation is weak because of sinuous instabilities on the jet which are not present in the single-gyre model. These modes efficiently flux vorticity to the boundary and reduce the circulation without an inter-gyre flux, postponing inertial domination to much smaller viscosities.
by Baylor Fix-Kemper.
Ph.D.
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Chen, Shih-Nan. "Density- and wind-driven lateral circulation and the associated transport of sediments in idealized partially mixed estuaries." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8514.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Zhang, Yu Ph D. Massachusetts Institute of Technology. "Slope/shelf circulation and cross-slope/shelf transport out of a bay driven by eddies from the open ocean." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55165.
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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 219-222).
Interaction between the Antarctic Circumpolar Current and the continental slope/shelf in the Marguerite Bay and west Antarctic Peninsula is examined as interaction between a wind-driven channel flow and a zonally uniform slope with a bay-shaped shelf to the south. Two control mechanisms, eddy advection and propagation of topographic waves, are identified in barotropic vortex-escarpment interactions. The two mechanisms advect the potential vorticity (PV) perturbations in opposite directions in anticyclone-induced interactions but in the same direction in cyclone-induced interactions, resulting in dramatic differences in the two kinds of interactions. The topographic waves become more nonlinear near the western(eastern if in the Northern Hemisphere) boundary of the bay, where strong cross-escarpment motion occurs. In the interaction between a surface anticyclone and a slope penetrating into the upper layer in a two-layer isopycnal model, the eddy advection decays on length scales on the order of the internal deformation radius, so shoreward over a slope that is wider than the deformation radius, the wave mechanism becomes noticeably significant. It acts to spread the cross-isobath transport in a much wider range while the transport directly driven by the anticyclone is concentrated in space. A two-layer wind-driven channel flow is constructed to the north of the slope in the Southern Hemisphere, spontaneously generating eddies through baroclinic instability. A PV front forms in the first layer shoreward of the base of the topography due to the lower-layer eddy-slope interactions.
(cont.) Perturbed by the jet in the center of the channel, the front interacts with the slope/shelf persistently yet episodically, driving a clockwise mean circulation within the bay as well as crossisobath transport. Both the transports across the slope edge and out of the bay are comparable with the maximum Ekman transport in the channel, indicative of the significance of the examined mechanism. The wave-boundary interaction identified in the barotropic model is found essential for the out-of-bay transport and responsible for the heterogeneity of the transport within the bay. Much more water is transported out of the bay from the west than from the east, and the southeastern area is the most isolated region. These results suggest that strong out-of-bay transport may be found near the western boundary of the Marguerite Bay while the southeastern region is a retention area where high population of Antarctic krill may be found.
by Yu Zhang.
Ph.D.
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Foster, Erich Leigh. "Finite Elements for the Quasi-Geostrophic Equations of the Ocean." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19362.
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The quasi-geostrophic equations (QGE) are usually discretized in space by the finite difference method. The finite element (FE) method, however, offers several advantages over the finite difference method, such as the easy treatment of complex boundaries and a natural treatment of boundary conditions [Myers1995]. Despite these advantages, there are relatively few papers that consider the FE method applied to the QGE.Most FE discretizations of the QGE have been developed for the streamfunction-vorticity formulation. The reason is simple: The streamfunction-vorticity formulation yields a second order \\emph{partial differential equation (PDE)}, whereas the streamfunction formulation yields a fourth order PDE. Thus, although the streamfunction-vorticity formulation has two variables ($q$ and $\\psi$) and the streamfunction formulation has just one ($\\psi$), the former is the preferred formulation used in practical computations, since its conforming FE discretization requires low-order ($C^0$) elements, whereas the latter requires a high-order ($C^1$) FE discretization.
We present a conforming FE discretization of the QGE based on the Argyris element and we present a two-level FE discretization of the Stationary QGE (SQGE) based on the same conforming FE discretization using the Argyris element. We also, for the first time, develop optimal error estimates for the FE discretization QGE. Numerical tests for the FE discretization and the two-level FE discretization of the QGE are presented and theoretical error estimates are verified. By benchmarking the numerical results against those in the published literature, we conclude that our FE discretization is accurate. �Furthermore, the numerical results have the same convergence rates as those predicted by the theoretical error estimates.
Ph. D.
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Prokhorov, Boris E. [Verfasser], and Matthias [Akademischer Betreuer] Holschneider. "High-latitude coupling processes between thermospheric circulation and solar wind driven magnetospheric currents and plasma convection / Boris E. Prokhorov ; Betreuer: Matthias Holschneider." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218400560/34.
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Keenlyside, Noel S. 1974. "Improved modelling of zonal currents and SST in the tropical Pacific." Monash University, Dept. of Mathematics and Statistics, 2001. http://arrow.monash.edu.au/hdl/1959.1/9072.
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Blayo, Éric. "Développement d'un modèle quasi-géostrophique de circulation océanique : application à l'océan atlantique nord." Université Joseph Fourier (Grenoble ; 1971-2015), 1992. http://www.theses.fr/1992GRE10193.
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Un modele quasi-geostrophique multicouche d'ocean, developpe anterieurement pour des etudes de processus sur la circulation oceanique, dans des domaines de forme rectangulaire, est adapte pour etre applique a des bassins oceaniques reels et simuler les circulations dans ces bassins. La forme irreguliere des cotes est prise en compte grace a l'utilisation d'une methode de capacite (hockney, 1970). Le long des frontieres ouvertes, une condition de radiation est implementee afin de pouvoir laisser entrer et sortir le fluide. Basee sur la formulation de raymond et kuo (1984), cette condition comporte de plus un terme de rappel vers des donnees climatologiques moyennes. Ce modele est ensuite applique a l'ocean atlantique nord. Une premiere configuration de calcul couvre la partie ouest du bassin, de la cote americaine a 55 w. De nombreux aspects du comportement des circulations simulees sont compares favorablement avec des donnees d'observation. De plus, des etudes concernant le role du vent, de la topographie et la sensibilite du modele a la condition a la cote sont presentees. Une deuxieme configuration du modele englobe tout l'atlantique nord de 20n a 50n. Pour cette seconde application, on presente une experience preliminaire dans laquelle on assimile des mesures altimetriques satellitaires geosat dans le modele. A l'issue de ce travail, un certain nombre de directions de recherche complementaires sont suggerees: introduction de la variabilite temporelle du vent et augmentation de la resolution horizontale et verticale du modele, optimisation de la technique d'assimilation de donnees, utilisation des donnees recentes ers-1 et topex-poseidon, application du modele a l'ocean atlantique sud
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Nwaodua, Emmanuel C. "Last Deglacial Arctic to Pacific Transgressions via the Bering Strait: Implications for Climate, Meltwater Source, Ecosystems and Southern Ocean Wind Strength." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1385374398.
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Siefridt, Laure. "VValidation des données de vent ERS-1 et des flux de surface du CEPMMT dans le contexte de la modélisation des circulations océaniques à l'échelle d'un bassin." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10242.
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Une validation d'ensembles de donnees relatives a la surface de l'ocean est proposee dans le contexte de la modelisation numerique realiste des circulations oceaniques. Les flux de surface (chaleur et quantite de mouvement) produits au centre europeen pour les previsions meteorologiques a moyen terme (cepmmt) sont d'abord etudies. A cette occasion, une banque de donnees des variables atmospheriques de surface du cepmmt de 1986 a 1992 est mise a la disposition de la communaute scientifique. Une validation climatologique de ces analyses, produites a l'origine dans un objectif de previsions a moyen terme (10 jours), est primordiale et s'accompagne de l'etude de la variabilite interannuelle du signal. Enfin, une parametrisation du forcage thermique des modeles d'oceans est proposee ; elle permet le reequilibrage du modele avec une atmosphere en etat stationnaire prescrit, qui est representee par les variables climatologiques du cepmmt. Dans une seconde partie, les vents diffusiometriques satellitaires ers-1 sont analyses par une procedure variationnelle. Le but est de produire, sur une periode de quelques jours et a l'echelle d'un bassin, des champs de vent complets sur une grille reguliere, qui possedent les caracteristiques des mesures initiales ainsi que des proprietes physiques definies, tout en s'affranchissant de l'echantillonnage sequentiel satellitaire. La procedure est mise au point par comparaison a des mesures in-situ, et l'on verifie par une etude spectrale que les echelles pertinentes au forcage des oceans sont conservees. Les cartes de vent a 3 et 5 jours ainsi produites representent la premiere vision du vent a ces echelles et ouvrent des perspectives nouvelles pour la modelisation oceanique
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He, Yanping. "Representations of boundary layer cloudiness and surface wind probability distributions in subtropical marine stratus and stratocumulus regions." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22585.
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Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2007.Committee Chair: Dr. Robert E. Dickinson; Committee Member: Dr. Irina Sokolik; Committee Member: Dr. Judth Curry; Committee Member: Dr. Peter Webster; Committee Member: Dr. Rong Fu.
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Kounta, Diop Lala. "Le rôle de la dynamique océanique et atmosphérique en Atlantique Nord sur le fonctionnement de l'upwelling ouest-africain." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS649.pdf.
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Cette thèse avait pour objectif de mieux comprendre le rôle de la dynamique océanique et atmosphérique régionale sur le fonctionnement de l’upwelling ouest africain. La première partie est consacrée à l’étude du cycle saisonnier, de la dynamique et de l’origine des masses d’eau du courant de bord qui alimente l’upwelling ouest africain. Ce courant est situé sur la pente continentale et est dénommé WABC (pour West African poleward Boundary Current en anglais). Son lien avec la circulation à l’échelle de l’Atlantique Tropical Nord Est (ATNE) est aussi étudié. Les résultats obtenus sont principalement basés sur des sorties de simulations numériques avec une configuration régionale du modèle NEMO (TROP025). Le WABC est constitué d’un sous courant dirigé vers le pôle (communément appelé Poleward Under Current (PUC) en anglais) et d’un courant de surface également dirigé vers le pôle et fréquemment appelé courant de Mauritanie (Mauritania Current en anglais ; MC). Le WABC est présent quasiment toute l’année. Il est visible en surface (en l’absence du jet d’upwelling côtier) et s’étend jusqu’à ~ 250 m de profondeur ou en gamme de densité. Son transport méridien vers le nord est la conséquence des gradients de pression baroclines mis en place par le vent et aussi d’un rotationnel de vent positif le long des côtes ouest africaines. L’étude du cycle saisonnier a permis de montrer que le WABC présente deux pics de transport dans l’année : un premier en Avril-Mai et un second en Octobre- Novembre. Ce cycle semi-annuel du WABC résulte de l’activité des ondes côtières générées par les fluctuations du forçage par le vent. Le premier pic est causé par une relaxation des vents locaux (dans la zone côtière ouest africaine). Pour le second pic automnal la zone de forçage est distante et principalement située dans le golfe de Guinée. La quantité d’eau transportée par le WABC est estimée à 1 Sv en moyenne annuelle. Du fait de la variation du paramètre de Coriolis avec la latitude (effet β), les ondes côtières associées à la variation du WABC donnent naissance à des ondes de Rossby se propageant vers l’ouest. Les caractéristiques de ces ondes qui changent suivant la latitude, sont mises en évidence dans la thèse. L’étude de l’origine des masses d’eau du WABC a permis de clarifier le lien entre le WABC et la circulation dans l’ATNE. En effet, les masses d’eau transportées par le WABC sont amenées par le sous courant nord équatorial et sont principalement situées dans la thermocline (100-240 m). Elles subissent de fortes recirculations et une advection moyenne faible (~1 cm/s) dans la "shadow zone" avant d’être amenées par le WABC. Cette étude nous a aussi permis de montrer que la circulation au nord du dôme de Guinée (notamment la recirculation vers l’ouest associée à la présence du dôme de Guinée) tend à être surestimée lorsque les vitesses sont calculées à partir de l’équation du vent thermique avec des niveaux de références peu profonds. En effet, la prise en compte des gradients thermohalins profonds est importante et tend à renforcer l’advection vers le nord-est dans l’ATNE. La dernière partie de la thèse a concerné l’étude des modes de variabilité atmosphérique grandes échelles qui modulent, aux échelles de temps synoptiques, l’intensité des vents d’upwelling le long des côtes sénégalaises. Les analyses menées sur des données de réanalyses (Era-Interim) montrent que les fluctuations du vent, à ces échelles de temps et dans cette zone, sont principalement liées à l’intensité et la position de l’anticyclone des Açores, de l’anticyclone Saharo-Libyen et de la dépression Saharo-sahélienne. La variabilité du régime de vent à Dakar en lien avec ENSO s’explique notamment par la manière dont ces centres d’action sont affectés par ce mode de variabilité climatiqueThe southern end of the Canary current system comprises of an original upwelling center that has so far received little attention. This Ph.D. Thesis focuses on the dynamical functioning of the Southern Senegal-Gambia Upwelling Center (SSUC). We are interested in the upwelling circulation and thermohaline structure on the shelf between the coastline and 100-200 km offshore. Our focus is on the upwelling period (November to May). The main originality of the SSUC compared to other upwelling centers stems from its conti-nental shelf that is broad and shallow (20–30 m over tens of kilometers). The normal state of the system comprises the classical upwelling front but also a well-defined inner-shelf front that separates cold upwelled waters from nearshore warmer waters. We investigate its dynamical functioning using analysed satellite images, in situ data and state-of-the- art 3D numerical simulations. Through a fine-scale analysis of the physical conditions of the SSUC, this work poses the basis of an integrated approach to the Senegalese marine environment functioning. A first part of results is based on the careful examinations and analysis of over 1500 satellite images of sea surface temperature scenes contextualized with respect to wind conditions. Analysis confirm the regularity and stability of the SSUC dynamical functioning (as manifested by the recurrence and persistence of particular SST patterns). The analyses also reveal subtle aspects of its upwelling structure : shelf break cooling of surface waters consistent with internal tide breaking/mixing ; complex interplay between local upwelling and the Mauritanian current off the Cape Verde headland ; complexity of the inner-shelf/mid shelf frontal transition. The amplitude of the diurnal cycle suggests that large uncertainties exist in the SSUC heat budget. The studies limitations underscore the need for continuous in situ measurement in the SSUC, particularly of winds. The dynamical functioning of SSUC is also investigated by means of numerical simulations, using the hydrodynamical Regional Ocean Modeling System ROMS (∆x ≈ 2 km). Different simulations have been carried with varying forcings (climatological or synoptic wind ; fine-scale adjustments of heat flux in coastal area ; presence or absence of tides). Numerical solutions show a good agreement with available satellite and in situ observations. These solutions clarify the dynamical functioning of the system especially in terms of circulation, location of cold water upwelling but also fate of upwelled water through a Lagrangian analysis. We show in particular that the northern part of the SSUC is the main upwelling area. Waters that upwelled in this area predominantly come from the southern of the SSUC, through advection by the Mauritanian current. Lagrangian analysis also revealed the dynamics associated with the coastal area of nursery and nuance the conceptual retention scheme previously admitted. The sensitivity of the dynamics of SSUC to atmospheric forcings is modest with nevertheless some modulations of the cross-shore exchanges that may be important to the ecosystem
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Schimmelpfennig, Sebastian. "Lake Tegel: hydrodynamics, pharmaceutical micro-pollutants and management strategies." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17392.
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Ziele dieser Dissertation sind die Aufklärung der Strömungsverhältnisse und Untersuchungen zum Verhalten von Arzneimittelrückständen im Tegeler See, die Entwicklung eines Simulationsmodells für Szenarioberechnungen sowie die Ableitung neuer Bewirtschaftungskonzepte unter Zuhilfenahme der gewonnenen Erkenntnisse und Modellergebnisse. Das zweidimensionale Strömungsmodell 2D-POM kann die Mischungsverhältnisse der beiden Zuflüsse zum Tegeler See, insbesondere den Einstrom der Oberhavel, ausreichend genau abbilden. Der Oberhaveleinstrom ist sowohl windinduziert als auch vom Abfluss der Oberhavel abhängig. Der Wind wirkt je nach Windrichtung verstärkend oder abschwächend auf den Oberhaveleinstrom. Der Tegeler See weist im Vergleich zu anderen Oberflächengewässern, die als Trinkwasserressource dienen, die höchsten bisher berichteten Gehalte an Arzneimittelrückständen auf. Die räumliche Verteilung von Carbamazepin (CBZ) und Sulfamethoxazol (SMX) wird hauptsächlich durch die Verdünnung mit Oberhavelwasser bestimmt. Nur ein geringer Teil des CBZ (40%) wird im Tegeler See eliminiert. Für SMX konnte keine Elimination festgestellt werden. Im Gegensatz dazu wird Diclofenac (DCF) im Oberflächenwasser photolytisch abgebaut (50% in den Wintermonaten, mehr als 95% im Sommer). Die Konzentrationen von DCF im Tegeler See zeigen deshalb eine hohe saisonale Variabilität. Durch Simulation von sieben Bewirtschaftungsszenarien wurde untersucht, ob mithilfe der existierenden Seeleitung und Phosphateliminierungsanlage die Konzentrationen der Arzneimittelrückstände im Tegeler See verringert werden können, ohne die erfolgreiche Seerestaurierung zu gefährden. In keinem Szenario konnten die Gehalte an Arzneimittelrückständen und Phosphor gleichzeitig auf einem akzeptablen Niveau gehalten werden. Aus diesem Grund sind ergänzende Maßnahmen notwendig, z.B. eine zusätzliche Spurenstoffentfernung im Zulauf des Sees oder eine weitere Phosphorreduzierung in der Oberhavel.This cumulative thesis aims at (i) understanding the hydrodynamic characteristics of Lake Tegel, (ii) examining the occurrence and fate of pharmaceutical micro-pollutants in the lake, (iii) developing a modeling tool for scenario prediction, and (iv) utilizing the above findings and applying the above modeling tool to create new management strategies for Lake Tegel. The free-surface two-dimensional circulation model 2D-POM serves as an adequate tool for representing the intrusion of River Havel and the mixing intensity of both inflows, as validated by measured data. The calculations indicated that the intrusion of River Havel into Lake Tegel fluctuates with river discharge and wind, both of which can amplify or neutralize the other. Compared to other surface waters also used as drinking water resources, Lake Tegel seams to feature the highest ever reported pharmaceutical concentrations worldwide. The spatial distribution of carbamazepine (CBZ) and sulfamethoxazole (SMX) in the lake was shown to be primarily affected by dilution with water from River Havel rather than by degradation within the lake. By contrast, concentrations of diclofenac (DCL) are affected by both dilution and photodegradation. DCF showed the strongest elimination of all three pharmaceuticals and revealed significant seasonality with 50% elimination in winter and more than 95% in summer. Elimination of CBZ was 40%, while SMX did not degrade at determinable rates. Seven different management scenarios were tested to answer the question of whether the existing lake pipeline could be used to reduce the amount of pharmaceuticals in Lake Tegel without deteriorating the current phosphorus level. No scenario provided a strategy optimal for both pharmaceuticals and phosphorus. Consequently, additional efforts need to be made, such as supplementary pharmaceutical treatment of the inflow originating from the wastewater treatment plant, or phosphorus reduction in the River Havel catchment.
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Mazoyer, Camille. "Modélisation des flux et du transport de polluants en rade de Toulon." Electronic Thesis or Diss., Toulon, 2019. http://www.theses.fr/2019TOUL0005.
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Cette thèse s'est intéressée aux processus hydrodynamiques dans une baie semi-fermée telle que la Rade d Toulon et leurs importances pour la dispersion de contaminants dissous. Pour cette étude, une configuration à très haute résolution (100 m de résolution spatiale) nommée TBAY100, basée sur le modèle de circulation océanique MITgcm a été mise en place. Un emboîtement multi-modèle a été effectué pour arriver à une telle résolution, en partant d'une configuration NEMO-GLAZUR64 à 1.3 km de la Méditerranée Nord-Occidentale puis NEMO-NIDOR à 400 m du littoral Varois pour forcer correctement les frontières de TBAY100. Dans un premier temps, une analyse mathématique a permis de quantifier les échanges d'énergie pour un système simplifié pour ensuite étendre cette réflexion à la Rade de Toulon et mieux comprendre les échanges aux frontières ouvertes du domaine. Cette configuration a été ensuite validée avec diverses observations dont des données d'ADCP et des trajectoires de flotteurs qéolocalisables dérivants. Des schémas de circulation typiques dépendant des conditions hydrodynamiques et météorologiques ont été dégagés. Dans un deuxième temps, nos recherches se sont portées sur les processus de distribution de polluants en s'appuyant sur des prélèvements chimiques, principalement le cuivre relargué par les peintures-antifouling. Les hypothèses de contamination (sources et taux) ont fait l'objet d'un travail collaboratif avec une équipe de chimie. Le transport des contaminants a été analysé à l'aide de traceurs passifs implémentés dans TBAY100 et a abouti à 4 schémas de dispersion de polluants indiquant un export soit vers le Courant Nord, soit vers le Parc National Marin de Port-Cros, ainsi qu'une rétention des polluants dans la Grande Rade de Toulon. Cette maquette pourra avoir d'autres applications sociétales importantes puisqu'elle peut servir d'outil de prédiction de courants et de dispersion de contaminant dans la Rade de ToulonThis doctoral research aim was to study hydrodynamic processes in a semi-enclosed bay such as the Toulon bay and their importance for the dispersion of dissolved contaminants. For this study, a YfilY high resolution (100 m spatial resolution) configuration named TBAY100, based on the MITgcm ocean circulation model, was implemented. A multi-model nesting was carried out ta work at such a resolution, starting from a 1.3 km NEMO-GLAZUR64 configuration of the North-Western Mediterranean then a 400 m NEMO-NIDOR configuration of the Var coastline ta correctly force the TBAY100 boundaries. Firstly, a mathematical analysis aimed to guantify energy exchanges for a simplified system then this analysis has been extended ta the Toulon bay to better understand the exchanges at the domain open boundaries. This configuration was then validated with various observations inoludin ADCP data and driftin eolocalisable
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Paskin, Liad. "On the interaction of fast traveling Ocean Waves and the Atmospheric Boundary Layer : A Mechanistic Approach combining Field Measurements and High-fidelity Simulations." Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0012.
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Dans les zones côtières, l’industrie de l’énergie éolienne migre vers l’environnement marin, où de vastes espaces sont encore disponibles avec des conditions de vent plus fort et mieux contrôlé. L’environnement marin impose de nouveaux défis à une industrie éolienne pourtant bien établie. Il est impératif de prédire et de décrire avec précision la ressource éolienne en mer afin de concevoir des solutions techniques rentables. L’écoulement concerné est caractérisé par une couche limite atmosphérique (CLA), turbulente, où la dynamique de l’océan modifie considérablement l’écoulement atmosphérique par une capacité thermique plus élevée, et par des interactions vent-vagues complexes, importantes dans des situations assez courantes. Cette thèse passe en revue et étend les connaissances actuelles concernant les interactions vent-vagues dans la partie inférieure de la CLA Marine (CLAM), où elles peuvent être importantespour la caractérisation de la ressource éolienne. La CLAM est étudiée par des expériences physiques et numériques, afin de révéler le rôle des mouvements Induits par les Vagues (IV) transférés de la mer vers l’atmosphère. Grâce à l’utilisation d’expériences physiques et numériques complémentaires, de nouvelles perspectives sur les processus d’interaction vent-vague sont obtenuesIn coastal areas, the wind energy industry migrates to the offshore environment, where huge spaces are still available in stronger and better behaved wind conditions. The offshore environment imposes new challenges to a well established wind energy industry. It is imperative to accurately predict and describe the offshore wind resource in order to design cost efficient solutions. The concerned flow is characterized by a turbulent Atmospheric Boundary Layer (ABL) where the ocean’s dynamics significantly alter the atmospheric flow through higher heat capacity and complex wind-wave interactions important in fairly common situations.So this Thesis reviews and extends the current knowledge regarding Wind-Wave interactions in the lower part of the Marine ABL (MABL), where they are possibly significant in the characterization of the wind resource. The MABL is investigated through physical and numerical experiments, to reveal the role of Wave Induced (WI) motions transferred from the sea into the atmosphere. Thanks to the use of complementary physical and numerical experiments, new insights on the wind-wave interaction processes are obtained
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Cambra, Rémi. "Etude des flux turbulents à l'interface air-mer à partir de données de la plateforme OCARINA." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLV024/document.
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Les échanges de chaleur et de quantité de mouvement à l'interface-océan atmosphère jouent un rôle majeur dans la formation et la dynamique des masses d'air et d'eau. Malgré des décennies de recherche, nous avons encore besoin d'améliorer nos connaissances sur ces échanges, et plus spécifiquement nos connaissances sur les flux turbulents, qui sont des variables clés dans les modèles météorologiques et de climat. Dans ces modèles, les processus turbulents sont des processus sous-maille, non-résolus explicitement, ainsi les flux turbulents doivent être modélisés, au travers de paramétrisations, qui sont pour la plupart réalisées à partir de la théorie des similitudes de Monin-Obukhov [1954]. Cependant, d'une part, l'utilisation d'un modèle implique que les coefficients doivent être ajustés. D'autre part, le modèle lui-même peut demander des améliorations. Malheureusement, l'obtention d'estimations de flux avec une bonne précision est un gros défi, à cause des effets intrusifs de la plate-forme sur la mesure, de la précision limité des instruments et des capacités d'échantillonnages propres de chaque instrument.Notre étude porte sur l'estimation des flux turbulents en mer à partir de mesures réalisées avec la nouvelle plate-forme OCARINA (trimaran autonome) lors des campagnes STRASSE 2012 et AMOP 2014. Nous analysons les caractéristiques de la turbulence dans la couche limite de surface, nous estimons les flux turbulents par différentes méthodes, et nous comparons les valeurs des flux en fonction des conditions environnementales, en prenant en compte l'état de merExchanges of heat and momentum at the air-sea interface play a major role in the formation and the dynamics of water and air masses. In spite of decades of research, we still need to improve our knowledge of these exchanges, and more specifically our knowledge of turbulent fluxes, which are key variables in meteorological and climate models. In these models, sub-grid turbulent processes, thus turbulent fluxes also have to be modeled, which is mostly done with the Monin-Obukhov (1954, MOS hereafter) similarity theory. However, on the one hand, the use of a model implies that coefficients have to be adjusted. On the other hand, the model itself may require improvements. Unfortunately, obtaining flux estimates that have a good accuracy is a challenging effort, because of the intrusive effect of the platform, the limited accuracy the instruments, and because the instruments have their own sampling volume.Our study focuses on the estimation of turbulent fluxes at sea from measurements made with the new OCARINA platform (autonomous trimaran) during two campaigns : STRASSE 2012 and AMOP 2014. We analyze the characteristics of turbulence in the surface boundary layer, we estimate the turbulent fluxes by different methods, and compare the values of fluxes depending on environmental conditions, taking into account the sea state
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Amorim, Fabiola Negreiros de. "A Dinâmica Sazonal da Plataforma Continental Leste Brasileira entre 10ºS e 16ºS." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/21/21132/tde-19042012-111805/.
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A circulação sazonal da Plataforma Continental Leste Brasileira (PCLB) entre 10oS e 16oS é investigada com base em um inédito conjunto de dados in situ e em modelagem hidrodinâmica. Os dados observados possibilitaram a compreensão da dinâmica da circulação em partes específicas da região de estudo e a sua interação com os diversos mecanismos forçantes, ilustrando a forte influência da circulação atmosférica e oceânica de meso/larga escalas, de processos transientes e da topografia local, na circulação regional, apresentando cenários distintos entre as estações do ano. Os resultados da modelagem hidrodinâmica não só complementaram os estudos observacionais, como também permitiram uma maior compreensão da variabilidade sazonal e espaço-temporal da circulação na PCLB, assim como a sua interação com os diversos mecanismos forçantes, para uma região mais ampla (10oS-16oS). A PCLB é fortemente afetada pela sazonalidade de larga escala do regime dos ventos alísios e da latitude da Zona de Convergência Intertropical (ZCIT). Seguindo esta dinâmica, durante as estações de primavera/verão, as correntes na Plataforma Continental (PC) ao sul de 12oS ficam sujeitas a ventos preferenciais de E-NE e, no oceano, a bifurcação da Corrente Sul Equatorial (bSEC) atinge a sua posição mais ao norte (~13oS em novembro). Nas regiões da quebra da PC e do talude continental, as correntes são também influenciadas pelas Correntes de Contorno Oeste (CCO). No domínio norte (10oS), a circulação na PC interna é para sul, seguindo o campo de ventos preferencial, enquanto a circulação na PC média e na quebra da PC é mais influenciada pelas correntes na região do talude continental, que são claramente dominadas pela dinâmica da Corrente Norte do Brasil/Sub-Corrente Norte do Brasil (CNB/SCNB). No domínio central (14oS), embora a circulação seja de certa forma similar à observada para o domínio norte, a circulação no talude continental apresenta uma maior variabilidade como resposta à presença dos fluxos contrários da Corrente do Brasil (CB) e da SCNB. A circulação no domínio sul (16oS) possui uma clara divisão ao longo da PC/talude continental, apresentando um intenso e organizado fluxo direcionado para sul na PC interna e média, como resposta à forçante remota do vento, e uma circulação polarizada na direção perpendicular à costa nas regiões da quebra da PC/talude continental, sugerindo uma associação com a CCO e com a topografia local do Banco Royal Charlotte. Durante as estações de outono/inverno, seguindo o regime sazonal dos ventos alísios e da latitude da ZCIT, a PC ao norte de ~20oS fica sujeita a ventos preferenciais de E-SE e as correntes sofrem uma reversão do fluxo médio, e a bCSE atinge seu limite sul (~17oS em julho). A circulação na PC interna e média no domínio norte durante estas estações, apresenta um fraco fluxo para norte com uma alta variabilidade. Enquanto na PC interna esta variabilidade está relacionada à entrada mais frequente de frentes frias, na PC média está relacionada com a circulação na região do talude continental. A circulação nesta região possui uma alta correlação com aquela na região da quebra da PC e ambas apresentam um fluxo médio para norte mais intenso e menos variável, que pode estar relacionado com o fluxo da CNB/SCNB, que ocupa toda a região do talude continental durante estas estações do ano. O fluxo médio para norte no domínio central, apresenta uma fraca intensidade e alta variabilidade nas regiões da PC interna e média e na quebra da PC, que pode estar relacionada com o aumento da frequência de sistemas frontais, ao fato desta região ser influenciada pela bifurcação do fluxo médio em superfície e, para a região da quebra da PC, à variabilidade da SCNB, que apresenta maiores episódios em que ocupa esta região. A CNB/SCNB exerce uma clara influência na circulação da região do talude continental. A circulação no domínio sul é principalmente gerada pelo vento remoto nas regiões da PC interna e média, enquanto nas regiões da quebra da PC e talude continental apresenta uma significativa influência da CCO.The seasonal circulation of the Eastern Brazilian Shelf (EBS) between 10oS and 16oS is investigated based on original in situ data sets and hydrodynamic modeling. The observational data provided an understanding of the circulation dynamics within specific parts of the the study region and its interaction with the various forcing mechanisms, illustrating the strong influence of the large/meso scales atmospheric and oceanic circulation, transient processes and local topography on the regional circulation, presenting very distinct scenarios between seasons. The hydrodynamic modeling results not only complemented the observational studies but also allowed for a broader understanding of the seasonality and time-space variability of the EBS circulation, as well as its interaction with the various forcing mechanisms, in a wider region (10oS-16oS). The EBS is highly affected by large-scale seasonality in the trade wind regime and the latitude of the Intertropical Convergence Zone (ITCZ). Following this dynamics, during the spring/summer seasons, the currents within the continental shelf south of 12oS are influenced by preferential E-NE winds and, in the ocean, the bifurcation of the South Equatorial Current (bSEC) reaches its northernmost position (~13oS in November). At the shelf break and slope region, the currents are also influenced by the Western Boundary Currents (WBC). At the northern domain (10oS) the inner shelf circulation is to the south following the preferential winds, while the circulation at the mid shelf and shelf break is more influence by the currents at the slope, which are clearly dominated by the North Brazil Current/North Brazil Undercurrent (NBC/NBUC) dynamics. At the central region (14oS), although the circulation is somehow similar to that observed for the northern domain, the slope circulation presents a greater variability in response to the presence of the opposing Brazil Current (BC) and NBUC flow. At the southern domain (16oS) the circulation has a clear division along the continental shelf/slope regions, presenting an intense and organized southward flow at the inner and mid shelves, as a response to the remote wind forcing, and a polarized cross-shelf circulation at the shelf break/slope region, suggesting an association with the WBC and the local topography of the Royal Charlotte Bank. During the autumn/winter seasons, following the seasonal regime of the trade winds and the latitude of the ITCZ, the continental shelf north of ~20oS are influenced by preferential E-SE winds and the currents experience a reversal of the mean flow, and the bSEC reaches its southernmost position (~17oS in July). The circulation during these seasons at the northern domain inner and mid shelves presents a weak northward flow with a strong variability. While at the inner shelf this variability is related to the more frequent cold front passages at the mid shelf it is related to the slope region circulation. The circulation at this region has a high correlation with the circulation at the shelf break and both present a less variable and more intense northward net flow which could be related to the NBC/NBUC flow, that occupies the entire slope region during these seasons. The northward net flow at the central domain presents a weak intensity and high variability at the inner/mid shelves and shelf break regions, which could be related to the increase in the cold fronts frequency, to the fact that this region is under the influence of the bifurcation of the surface net flow and, for the shelf break region, to the NBUC variability which presents more episodes that occupies this region. At the slope region the NBC/NBUC exerts a clear influence in the circulation. The circulation at the southern domain is mainly driven by the remote wind forcing at the inner and mid shelves, while at the shelf break/slope regions presents a significant WBC influence.
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Nguyen, Dac Da. "Variabilité interannuelle de l'upwelling du sud Vietnam : contributions du forçage atmosphérique, océanique, hydrologique et de la variabilité intrinsèque océanique." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30081/document.
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L'upwelling du Sud Vietnam (SVU) joue un rôle clef dans la dynamique océanique et la productivité biologique en Mer de Chine du Sud. Cette thèse vise à quantifier la variabilité interannuelle du SVU et identifier les facteurs et mécanismes en jeu. Pour cela, un jeu de simulations numériques pluri-annuelles à haute résolution a été utilisé. Le réalisme du modèle a été évalué et optimisé par comparaison aux observations in-situ et satellites. Les résultats montrent que la grande variabilité du SVU est fortement pilotée par le rotationnel du vent estival, et liée à l'oscillation ENSO via son impact sur le vent. Cependant, cette influence du vent est significativement modulée par la variabilité intrinsèque océanique liée aux interactions entre la vorticité associée aux tourbillons océaniques et le vent, et dans une moindre mesure par la circulation océanique de grande échelle et les fleuves. Ces conclusions sont robustes aux choix effectués pour corriger la dérive de surface du modèleThe summer South Vietnam Upwelling (SVU) is a major component of the South China Sea circulation that also influences the ecosystems. The objectives of this thesis are first to quantitatively assess the interannual variability of the SVU in terms of intensity and spatial extent, second to quantify the respective contributions from different factors (atmospheric, river and oceanic forcings; ocean intrinsic variability OIV; El-Niño Southern Oscillation ENSO) to the SVU interannual variability, and third to identify and examine the underlying physical mechanisms. To fulfill these goals we use a set of sensitivity eddy-resolving simulations of the SCS circulation performed with the ROMS_AGRIF ocean regional model at 1/12° resolution for the period 1991-2004. The ability of the model to realistically represent the water masses and dynamics of the circulation in the SCS and SVU regions was first evaluated by comparison with available satellite and in-situ observations. We then defined a group of sea-surface-temperature upwelling indices to quantify in detail the interannual variability of the SVU in terms of intensity, spatial distribution and duration. Our results reveal that strong SVU years are offshore-dominant with upwelling centers located in the area within 11-12oN and 110-112oE, whereas weak SVU years are coastal-dominant with upwelling centers located near the coast and over a larger latitude range (10-14oN). The first factor that triggers the strength and extent of the SVU is the summer wind curl associated with the summer monsoon. However, its effect is modulated by several factors including first the OIV, whose contribution reaches 50% of the total SVU variability, but also the river discharge and the remote ocean circulation. The coastal upwelling variability is strongly related to the variability of the eastward jet that develops from the coast. The offshore upwelling variability is impacted by the spatio-temporal interactions of the ocean cyclonic eddies with the wind stress curl, which are responsible for the impact of the OIV. The ocean and river forcing also modulate the SVU variability due to their contribution to the eddy field variability. ENSO has a strong influence on the SVU, mainly due to its direct influence on the summer wind. Those results regarding the interannual variability of the SVU are robust to the choice of the surface bias correction method used in the model. We finally present in Appendix-A2 preliminary results about the impacts of tides
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Basile, Isabelle. "Origine des aérosols volcaniques et continentaux de la carotte de glace de Vostok (Antarctique)." Phd thesis, Grenoble 1, 1997. http://tel.archives-ouvertes.fr/tel-00756041.
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Déposés en Antarctique de l'Est au cours des 4 derniers cycles climatiques, les aérosols volcaniques (5-50 )um) et continentaux (2-3 )um) de la carotte de Vostok constituent des traceurs de circulations atmosphériques passées. Pour reconstruire leurs trajectoires troposphériques, il est nécessaire d'identifier les sources (volcans ou régions désertiques) à l'origine des émissions des cendres et des poussières continentales. Pour cela, on compare les caractéristiques géochimiques des aérosols avec les caractéristiques des sources potentielles répertoriées. Ces analyses reposent sur les concentrations en éléments majeurs (obtenues par microsonde électronique), en éléments traces (ICPMS), et sur les compositions isotopiques en Strontium et Néodyme (TIMS). Nous avons dû adapter ces méthodes analytiques à la petite taille des aérosols et à leur très faible quantité. Les caractéristiques géochimiques des volcans sources potentiels (latitude>30oS, activité<-500 ka) sont basées sur une synthèse bibliographique. On montre que les cendres des horizons volcaniques analysés proviennent essentiellement de l'arc volcanique des îles Sandwichs (situé dans l'Atlantique Sud, à 5000 km), mais aussi d'Antarctique de l'Ouest et d'Amérique du Sud. De plus, certains horizons peuvent être utilisés comme marqueurs stratigraphiques pour dater (e.g. 141 ka) et corréler les carottes. Les caractéristiques isotopiques (Sr et Nd) des régions désertiques d'Afrique du Sud, d'Australie, du Sud de l'Amérique du Sud, d'Antarctique et de Nouvelle Zélande sont mesurées sur des échantillons prélevés in situ. On remarque qu'il est nécessaire d'utiliser, pour la comparaison avec les aérosols, la fraction granulométrique inférieure à 5 um. Il est ainsi montré que les poussières continentales déposées à Vostok au cours des 4 derniers cycles climatiques proviennent de la Patagonie en période interglaciaire (flux -1,5 mg/m2/an) comme en période glaciaire (flux -20 mg/m2/an). Une partie de cette augmentation de flux peut être expliquée par la présence de vastes épandages de particules détritiques fluvio-glaciaires qui recouvrent, en période glaciaire, la Patagonie et le plateau continental argentin émergé. L'ensemble des sources des aérosols volcaniques et continentaux est donc localisé, quelle que soit la période climatique, dans une région située du côté Atlantique de l'Antarctique, aux moyennes et hautes latitudes. Le transport des particules semble quant à lui être assuré par un courant d'ouest circumpolaire convergent versl'Antarctique. Ce travail montre donc que, à partir des aérosols volcaniques et continentaux, on peut obtenir des paléo-informations dynamiques qui, au travers des corrélations, des datations, ou des modèles de circulation atmosphérique globaux, seront utiles aux reconstitutions des climats du passé.
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Bigorre, Sebastien Dewar William K. "Topographic effects on wind driven oceanic circulation." Diss., 2005. http://etd.lib.fsu.edu/theses/available/etd-07052005-163825.
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Thesis (Ph. D.)--Florida State University, 2005.Advisor: Dr. William K. Dewar, Florida State University, College of Arts and Sciences, Dept. of Oceanography. Title and description from dissertation home page (viewed Sept. 23, 2005). Document formatted into pages; contains ix, 100 pages. Includes bibliographical references.
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Kiss, Andrew Elek. "Dynamics of laboratory models of the wind-driven ocean circulation." Phd thesis, 2000. http://hdl.handle.net/1885/47497.
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This thesis presents a numerical exploration of the dynamics governing rotating flow driven by a surface stress in the " sliced cylinder " model of Pedlosky & Greenspan (1967) and Beardsley (1969), and its close relative, the " sliced cone " model introduced by Griffiths & Veronis (1997). The sliced cylinder model simulates the barotropic wind-driven circulation in a circular basin with vertical sidewalls, using a depth gradient to mimic the effects of a gradient in Coriolis parameter. In the sliced cone the vertical sidewalls are replaced by an azimuthally uniform slope around the perimeter of the basin to simulate a continental slope. Since these models can be implemented in the laboratory, their dynamics can be explored by a complementary interplay of analysis and numerical and laboratory experiments. ¶ In this thesis a derivation is presented of a generalised quasigeostrophic formulation which is valid for linear and moderately nonlinear barotropic flows over large-amplitude topography on an f-plane, yet retains the simplicity and conservation properties of the standard quasigeostrophic vorticity equation (which is valid only for small depth variations). This formulation is implemented in a numerical model based on a code developed by Page (1982) and Becker & Page (1990). ¶ ...
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Furnans, Jordan Ernest. "Drifter modeling and error assessment in wind driven currents." Thesis, 2005. http://hdl.handle.net/2152/2422.
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