subject:(oceanic current)

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Texas A&M University

1. Xu, Zhao. Oceanic Origins of Southwest Tropical Atlantic Biases.

Degree: PhD, Oceanography, 2013, Texas A&M University

URL: http://hdl.handle.net/1969.1/149583

► The SST bias in the tropical Atlantic exists in the early to latest generation of coupled general circulation models. The maximum bias is not on… (more)

▼ The SST bias in the tropical Atlantic exists in the early to latest generation of coupled general circulation models. The maximum bias is not on the equator but at 16°S, the cause of which has not been thoroughly studied. Newly released CMIP5 models provide a useful tool to investigate the contributions of different physical processes to the SST bias in this area in the coupled system. We tested three existing mechanisms and found that: 1) there is no significant relationship between the SST bias and surface heat flux bias; 2) deficient coastal upwelling is a contributing but not the sole source of the bias; and 3) the SST bias is correlated with temperature biases in the upstream equatorial region. The Angola-Benguela front is displaced southward by more than 10° in latitude in many CIMP5 models. Due to the huge temperature contrasts on two sides of the front, such a frontal displacement generates a very strong SST bias. The correlation between the SST bias and frontal location error in this region is significant at the 99% level, demonstrating that the SST bias in coupled GCMs is attributable to the models’ inability to reproduce a realistic position of the front and the consequent erroneous advection by the southward Angola current. This is due to both errors in the simulated surface wind field and systematic errors in ocean models. Ocean reanalysis datasets and a high-resolution regional model simulation suffer a similar pattern of SST biases. Although they produce a more realistic ocean circulation than coarser resolution simulations and alleviate some of the severe SST bias near the front, a warm bias overlies on a northward current to the south of the front, which actually comes from the north of the front through a subsurface passage. We identify a strong subsurface temperature bias caused by a too-deep and diffused simulated thermocline along the coast of Angola, originating from the equatorial thermocline, advected by the Angola Current and an undercurrent beneath the Benguela current, and then brought to the surface by the coastal upwelling along the Benguela coast, contributing to the warm SST bias south of the front. Advisors/Committee Members: Chang, Ping (advisor), Lin, Xiaopei (advisor), Saravanan, R. (committee member), Hetland, Robert (committee member).

Subjects/Keywords: GCM; Southeast Tropical Atlantic; SST bias; oceanic current

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APA (6^th Edition):

Xu, Z. (2013). Oceanic Origins of Southwest Tropical Atlantic Biases. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/149583

Chicago Manual of Style (16^th Edition):

Xu, Zhao. “Oceanic Origins of Southwest Tropical Atlantic Biases.” 2013. Doctoral Dissertation, Texas A&M University. Accessed January 24, 2021. http://hdl.handle.net/1969.1/149583.

MLA Handbook (7^th Edition):

Xu, Zhao. “Oceanic Origins of Southwest Tropical Atlantic Biases.” 2013. Web. 24 Jan 2021.

Vancouver:

Xu Z. Oceanic Origins of Southwest Tropical Atlantic Biases. [Internet] [Doctoral dissertation]. Texas A&M University; 2013. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/1969.1/149583.

Council of Science Editors:

Xu Z. Oceanic Origins of Southwest Tropical Atlantic Biases. [Doctoral Dissertation]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/149583

2. Poh, Gang Kai. Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics.

Degree: PhD, Atmospheric, Oceanic & Space Science, 2017, University of Michigan

URL: http://hdl.handle.net/2027.42/137093

► Mercury has proven to be a unique natural laboratory for space plasma processes. Mercury’s magnetosphere is formed by the interaction between its intrinsic planetary magnetic… (more)

▼ Mercury has proven to be a unique natural laboratory for space plasma processes. Mercury’s magnetosphere is formed by the interaction between its intrinsic planetary magnetic field and the supersonic solar wind. The structure of Mercury’s magnetosphere is very similar to Earth’s; yet the results from the MESSENGER mission to Mercury have shown that the spatial and temporal scales of magnetospheric processes are very different at Mercury. In this thesis, we analyze in situ observations from the MESSENGER spacecraft to characterize and understand the dynamic physical plasma processes occurring in Mercury’s magnetosphere. We identified and analyzed 345 plasma filaments in Mercury’s northern magnetospheric cusp to determine their physical properties. Cusp plasma filaments are magnetic structures that are identified on the basis of their characteristic 2‒3 seconds long decrease in magnetic field intensity. Our analysis indicates that these cusp filaments are cylindrical flux tubes filled with plasma, which causes a diamagnetic decrease in the magnetic field inside the flux tube. MESSENGER observations of flux transfer events (FTEs) and cusp filament suggests that cusp filaments properties are the low-altitude extension of FTEs formed at Mercury’s dayside magnetopause. We examined 319 central plasma sheet crossings observed by MESSENGER. Using a Harris model, we determined the physical properties of Mercury’s cross-tail current sheet. Analysis of BZ in the current sheet indicated that MESSENGER usually crossed the current sheet sunward of the Near Mercury Neutral Line. Magnetohydrodynamics-based analysis using the MESSENGER magnetic field and plasma measurements suggests that heavy planetary ions and/or ion temperature anisotropy may be important in maintaining radial stress balance within Mercury’s central plasma sheet. We report the observation of significant dawn-dusk variation in Mercury’s cross-tail current sheet with thicker, lower plasma β dawn side current sheets than the dusk side. Using the Harris current sheet model, we determined the peak current sheet current density and reported an asymmetry pattern for peak current density consistent with observed asymmetries in current sheet thickness. We propose that enhancement of heavy ions in the dusk side current sheet, due to centrifugal acceleration and gradient-curvature drift of ions from the cusp and current sheet, provides a partial explanation of the dawn-dusk current sheet asymmetries observed in this study. Furthermore, our results are consistent with earlier studies on reconnection-related structures and phenomenon, which suggest that the asymmetries observed in this study are associated with the asymmetric nature of magnetotail reconnection at Mercury. We also report the possible observation of an Earth-like substorm current wedge in the near-Mercury magnetotail. We calculate the total current in the Hermean substorm current wedge and found that the current close via the conductive planetary core. The current closure mechanism may be similar to the Region… Advisors/Committee Members: Jia, Xianzhe (committee member), Slavin, James Arthur (committee member), Kushner, Mark (committee member), Le, Guan (committee member), Raines, Jim (committee member).

Subjects/Keywords: Mercury's Magnetospheric Cusps; Mercury's Cross-Tail Current Sheet; Atmospheric, Oceanic and Space Sciences; Science

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APA (6^th Edition):

Poh, G. K. (2017). Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/137093

Chicago Manual of Style (16^th Edition):

Poh, Gang Kai. “Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics.” 2017. Doctoral Dissertation, University of Michigan. Accessed January 24, 2021. http://hdl.handle.net/2027.42/137093.

MLA Handbook (7^th Edition):

Poh, Gang Kai. “Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics.” 2017. Web. 24 Jan 2021.

Vancouver:

Poh GK. Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics. [Internet] [Doctoral dissertation]. University of Michigan; 2017. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2027.42/137093.

Council of Science Editors:

Poh GK. Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics. [Doctoral Dissertation]. University of Michigan; 2017. Available from: http://hdl.handle.net/2027.42/137093

3. Haiducek, John. Exploring Magnetotail Structure and Dynamics with Magnetohydrodynamic Simulations.

Degree: PhD, Atmospheric, Oceanic & Space Science, 2018, University of Michigan

URL: http://hdl.handle.net/2027.42/147633

► The magnetotail, the region of stretched magnetic field lines on the night side of the Earth, is important in a number of space weather processes,… (more)

▼ The magnetotail, the region of stretched magnetic field lines on the night side of the Earth, is important in a number of space weather processes, in particular geomagnetic storms and substorms. These processes can cause effects such as geomagnetically induced currents on the ground, spacecraft charging, and communications outages, which cause damage to infrastructure and disruption to human activities. Better understanding of the magnetotail and its properties can help to understand and perhaps predict these phenomena. The vast size of the magnetotail, and combined with a limited number of satellites traversing it, mean that models and simulations play an important role in providing insights into the magnetotail’s structure and its involvement in geospace processes. This dissertation consists of four studies aimed at improving understanding of the magnetotail using MHD simulations performed using the SWMF. The first of these is a validation study which showed that SWMF was able to reproduce important characteristics of the observed distributions of the Kp, Sym-H, and AL indices, as well as cross-polar cap potential. The model’s ability to reproduce these quantities indicates that it accurately represents many aspects of the magnetospheric current system. However, a tendency to under-predict the strength of the most negative diversions of AL was also noted. The second study explores the ion IB, a feature within the ionosphere as a result of pitch angle scattering in the magnetosphere. One of the processes that can cause this is called CSS (current sheet scattering), the strength of which is controlled by the paramter K = Rc/rg, the ratio of the field line radius of curvature to the particle gyroradius. The study estimates K using SWMF and using several empirical models for quiet conditions on 13 February 2009, when CSS was expected to be the operative mechanism for IB formation. After applying correction factors based on in situ satellite observations from the magnetotail, K was shown to be less than 10 in a majority of cases, supporting the hypothesis that the IB’s were formed by CSS. The third study extends the second into storm conditions on 4-6 April, 2010, in which wave-particle interaction as well as CSS is expected to play a role in IB formation. K estimates from SWMF and from empirical models were used to estimate the fraction of IB observations that might have been associated with CSS during this interval. Based on the assumption that the threshold for CSS could fall between K = 8 and K = 12, we found that between 20% and 69% of the IB observations might have been associated with CSS. We also found that K did not vary with local time, suggesting that CSS played a significant role in a majority of the IB’s observed. The fourth study explores the ability of MHD to predict magnetospheric substorms. A new procedure is introduced for combining lists of substorms identified using several different techniques, and this procedure is applied to both MHD output and observational data. It is shown that the… Advisors/Committee Members: Ganjushkina, Natalia (committee member), Gombosi, Tamas I (committee member), Ionides, Edward L (committee member), Welling, Daniel (committee member), Zou, Shasha (committee member).

Subjects/Keywords: magnetotail; current sheet scattering; magnetohydrodynamics; magnetosphere; model validation; Atmospheric, Oceanic and Space Sciences; Science

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APA (6^th Edition):

Haiducek, J. (2018). Exploring Magnetotail Structure and Dynamics with Magnetohydrodynamic Simulations. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/147633

Chicago Manual of Style (16^th Edition):

Haiducek, John. “Exploring Magnetotail Structure and Dynamics with Magnetohydrodynamic Simulations.” 2018. Doctoral Dissertation, University of Michigan. Accessed January 24, 2021. http://hdl.handle.net/2027.42/147633.

MLA Handbook (7^th Edition):

Haiducek, John. “Exploring Magnetotail Structure and Dynamics with Magnetohydrodynamic Simulations.” 2018. Web. 24 Jan 2021.

Vancouver:

Haiducek J. Exploring Magnetotail Structure and Dynamics with Magnetohydrodynamic Simulations. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2027.42/147633.

Council of Science Editors:

Haiducek J. Exploring Magnetotail Structure and Dynamics with Magnetohydrodynamic Simulations. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/147633

4. Malarky, Lacey. Faunal Composition and Distribution of Pelagic Larval and Juvenile Flatfishes (Teleostei: Pleuronectiformes) in the Northern Gulf of Mexico: Connectivity Between Coastal and Oceanic Epipelagic Ecosystems.

Degree: 2015, Nova Southeastern University

URL: http://nsuworks.nova.edu/occ_stuetd/397

► Pleuronectiformes (flatfishes) occur throughout the global oceans, and have high ecological and commercial importance in some areas. Though much is known regarding life history, abundance,… (more)

▼ Pleuronectiformes (flatfishes) occur throughout the global oceans, and have high ecological and commercial importance in some areas. Though much is known regarding life history, abundance, and distribution for the benthic adult stage of flatfish species, much less is known about the pelagic larval phases of flatfishes in the open ocean. Taxonomic uncertainty and limited sampling in the oceanic Gulf of Mexico contribute to data gaps with respect to the distribution of early life history stage of flatfishes in this region. Knowledge of the faunal composition, abundance and distribution of larval flatfishes, such as members of Bothus, which have extended pelagic phases, is important for modeling their population dynamics as well as for understanding the importance of connectivity between neritic and oceanic ecosystems in their life histories. Pleuronectiform specimens utilized in this study were collected in the northern offshore Gulf of Mexico during several cruises conducted throughout 2010-2011 as part of the NOAA Natural Resource Damage Assessment (NRDA) after the Deepwater Horizon Oil Spill (DWHOS). The Offshore Nekton Sampling and Analysis program (ONSAP) was established to determine composition, abundance and distribution of deep-water invertebrates and fishes in Gulf of Mexico waters that were potentially affected by the DWHOS. Results of the first large-scale discrete-depth distributional analysis of fishes in this region revealed that flatfishes were an intrinsic component of the oceanic ichthyofauna of these waters. A total of 2365 flatfish specimens were collected in offshore waters, representing four families and 11 of the 18 genera that occur in the Gulf of Mexico. Species composition was dominated by members of the genus Bothus, which had a high frequency of occurrence in the epipelagic zone throughout the year. Citharichthys spilopterus and Trichopsetta ventralis were the second- and third-most abundant and frequently occurring taxa, respectively. Detailed spatial analyses of taxa in the epipelagic zone revealed that larvae of Citharichthys spilopterus were only collected in winter and occurred most frequently near the continental shelf break, while early life stages of Bothus spp. were more abundant at the northern convergence flow of a large anticyclonic Loop Current eddy during spring and summer.

Subjects/Keywords: Early life stages; Offshore; Oceanic Gulf of Mexico; Loop Current; Marine Biology; Oceanography and Atmospheric Sciences and Meteorology

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APA (6^th Edition):

Malarky, L. (2015). Faunal Composition and Distribution of Pelagic Larval and Juvenile Flatfishes (Teleostei: Pleuronectiformes) in the Northern Gulf of Mexico: Connectivity Between Coastal and Oceanic Epipelagic Ecosystems. (Thesis). Nova Southeastern University. Retrieved from http://nsuworks.nova.edu/occ_stuetd/397

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Malarky, Lacey. “Faunal Composition and Distribution of Pelagic Larval and Juvenile Flatfishes (Teleostei: Pleuronectiformes) in the Northern Gulf of Mexico: Connectivity Between Coastal and Oceanic Epipelagic Ecosystems.” 2015. Thesis, Nova Southeastern University. Accessed January 24, 2021. http://nsuworks.nova.edu/occ_stuetd/397.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Vancouver:

Malarky L. Faunal Composition and Distribution of Pelagic Larval and Juvenile Flatfishes (Teleostei: Pleuronectiformes) in the Northern Gulf of Mexico: Connectivity Between Coastal and Oceanic Epipelagic Ecosystems. [Internet] [Thesis]. Nova Southeastern University; 2015. [cited 2021 Jan 24]. Available from: http://nsuworks.nova.edu/occ_stuetd/397.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Malarky L. Faunal Composition and Distribution of Pelagic Larval and Juvenile Flatfishes (Teleostei: Pleuronectiformes) in the Northern Gulf of Mexico: Connectivity Between Coastal and Oceanic Epipelagic Ecosystems. [Thesis]. Nova Southeastern University; 2015. Available from: http://nsuworks.nova.edu/occ_stuetd/397

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Washington

5. Stone, Hally. Transport effects on coastal productivity and harmful algal blooms.

Degree: PhD, 2020, University of Washington

URL: http://hdl.handle.net/1773/46534

► This dissertation examines the effect of transport on coastal productivity and harmful algal blooms in coastal upwelling systems in three parts, using the Pacific Northwest… (more)

▼ This dissertation examines the effect of transport on coastal productivity and harmful algal blooms in coastal upwelling systems in three parts, using the Pacific Northwest coastal ocean (also referred to as the Northern California Current System) and the greater California Current System (CCS) as a case study. These three studies utilize a combination of observations and model output. Chapter 2 investigates the effects of upwelling variability and large-scale advection on slope and shelf water properties in the Northern CCS using both Eulerian and Lagrangian analyses in a 7-year ROMS hindcast model. Results suggest that variability in the depth of the California Undercurrent as well as in alongshore local and remote wind stress are responsible for about 50% of shelf bottom water variability, and that the shelf and slope experience similar large-scale alongcoast advection patterns. These results were then combined with observations of dissolved oxygen and dissolved inorganic carbon concentrations to approximate the relative effects of variability in upwelling and in large-scale advection on shelf and slope water properties. Next, in Chapter 3, we examine the relationship between phytoplankton productivity, wind patterns, and retention in the Northern and Central CCS using chlorophyll concentration and wind stress derived from satellite observations, as well as particle tracking experiments conducted in the same ROMS model. Results from this analysis suggest that while there is a dome-shaped relationship between mean chlorophyll concentration and wind stress for the whole system, the Central and Northern CCS have significantly different relationships. However, results from the particle tracking experiments suggest that the effect of wind intermittency on retention is minimal in the Northern CCS on a 1˚ latitude-wide scale. Lastly, we present a revised hypothesis to describe the relationship between chlorophyll concentration and wind stress in the CCS that includes the influence of non-upwelling-derived nutrients in the Northern CCS. Finally, in Chapter 4 we use similar particle tracking experiments combined with observations of Pseudo-nitzschia cells at Pacific Northwest coastal beaches and meridional wind stress to test whether the model reproduces the observed beaching patterns of Pseudo-nitzschia cells. With the goal of improving how the model is used to forecast beaching events, we test a suite of beaching criteria as well as two resolutions of the model. Results suggest that allowing for multiple coastal proximity events as well as using the loosest beaching criteria resulted in the most successfully simulated HAB events in the medium-resolution version of the model, and that the high-resolution version of the model performed best overall. All together, these three studies help elucidate the numerous effects that transport, both positive and negative, can have on the biology of the coastal ocean. Advisors/Committee Members: Banas, Neil S (advisor), MacCready, Parker (advisor).

Subjects/Keywords: California Current System; coastal upwelling dynamics; harmful algal blooms; phytoplankton productivity; regional oceanic modeling system; wind; Physical oceanography; Biological oceanography; Oceanography

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APA (6^th Edition):

Stone, H. (2020). Transport effects on coastal productivity and harmful algal blooms. (Doctoral Dissertation). University of Washington. Retrieved from http://hdl.handle.net/1773/46534

Chicago Manual of Style (16^th Edition):

Stone, Hally. “Transport effects on coastal productivity and harmful algal blooms.” 2020. Doctoral Dissertation, University of Washington. Accessed January 24, 2021. http://hdl.handle.net/1773/46534.

MLA Handbook (7^th Edition):

Stone, Hally. “Transport effects on coastal productivity and harmful algal blooms.” 2020. Web. 24 Jan 2021.

Vancouver:

Stone H. Transport effects on coastal productivity and harmful algal blooms. [Internet] [Doctoral dissertation]. University of Washington; 2020. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/1773/46534.

Council of Science Editors:

Stone H. Transport effects on coastal productivity and harmful algal blooms. [Doctoral Dissertation]. University of Washington; 2020. Available from: http://hdl.handle.net/1773/46534

Indian Institute of Science

6. Rath, Subham. Dynamics of Summer Monsoon Current around Sri Lanka.

Degree: MSc Engg, Faculty of Engineering, 2018, Indian Institute of Science

URL: http://etd.iisc.ac.in/handle/2005/3573

► Summer monsoon current (SMC) in the north Indian Ocean (NIO) is an open ocean current that flows eastward and enter into Bay of Bengal (BoB)… (more)

▼ Summer monsoon current (SMC) in the north Indian Ocean (NIO) is an open ocean current that flows eastward and enter into Bay of Bengal (BoB) during southwest monsoon (June–September). South of Sri Lanka, the SMC turns north-eastward instead of following eastward course and feeds into the BoB. Understanding the dynamics of SMC is crucial to understanding the interaction between Arabian sea (AS) and BoB. In the year 2009, the current moved north-eastward, meandered and then finally terminated into the southeast BoB. The northward bend of the current southeast of Sri Lanka has been attributed to the interaction of the eastward SMC with Rossby waves radiated from eastern boundary. An anticyclonic vortex formed right of the north-eastward meandering current which was associated with significantly high speeds. Reasons behind the unusually high speeds of SMC in this region remain unknown. Processes involved in the interaction of eddies with eastward SMC, the meandering of the current and its ultimate termination in southeast BoB are also not understood. Our study investigates the evolution, intensfication and meandering of SMC around Sri Lanka using an Indian Ocean general circulation model (MOM4p1) simulation for the year 2009. The model simulation, when compared with observational data OSCAR, showed good agreement. The study also explores the role of local and remote forcing in modulating the dynamics of SMC in the region. An eddy kinetic energy budget analysis for the region was performed which indicates the region to be a zone of significant eddy activity. Both barotropic, baroclinic instabilities were found to be the dominant mechanisms behind the generation of eddies. Based on eddy energetic analysis, the evolution of SMC was classified into stages i ii of onset, intensification, anticyclonic bend, anticyclonic vortices formation and meandering. Effect of eddies on mean flow were studied with the help of a transformed Eulerian mean (TEM) approach under quasi-geostrophic approximation. Eddy potential vorticity fluxes appearing in the TEM momentum equation and eddy enstrophy decay, divergence of eddy enstrophy advection from eddy enstrophy equation, helped to un-derstand when, where and how the eddies tended to drive the mean flow. Rossby waves and other westward propagating eddies arriving from the east, energise the SMC in June and induce an acceleration tendency on the mean flow through regions associated with upgradient eddy potential vorticity flux. In addition to the eddies, local winds also play a crucial role in driving the mean flow. Wind power, surface mean ocean kinetic energy and available potential energy (APE) were computed, integrated over the region of interest and compared to each other. The effect of local winds appear to be predominant in driving the mean flows as it not only increases the surface mean kinetic energy of the SMC but also raises the isopycnals and builds up large amount of APE in the ocean. Baroclinic instability takes place in late July and early August associated with the… Advisors/Committee Members: Vinayachandran, P N (advisor).

Subjects/Keywords: Monsoon Currents; Winds; Sea Level Anomalies; Eddy Kinetic Energy; Summer Monsoon Current - North Indian Ocean; Summer Monsoon Current - Sri Lanka; Transformed Eulerian Mean (TEM); Atmospheric and Oceanic Sciences

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APA (6^th Edition):

Rath, S. (2018). Dynamics of Summer Monsoon Current around Sri Lanka. (Thesis). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/3573

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Rath, Subham. “Dynamics of Summer Monsoon Current around Sri Lanka.” 2018. Thesis, Indian Institute of Science. Accessed January 24, 2021. http://etd.iisc.ac.in/handle/2005/3573.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Rath, Subham. “Dynamics of Summer Monsoon Current around Sri Lanka.” 2018. Web. 24 Jan 2021.

Vancouver:

Rath S. Dynamics of Summer Monsoon Current around Sri Lanka. [Internet] [Thesis]. Indian Institute of Science; 2018. [cited 2021 Jan 24]. Available from: http://etd.iisc.ac.in/handle/2005/3573.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Rath S. Dynamics of Summer Monsoon Current around Sri Lanka. [Thesis]. Indian Institute of Science; 2018. Available from: http://etd.iisc.ac.in/handle/2005/3573

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

7. Assassi, Charefeddine. Variabilité interannuelle et analyse de la turbulence géostrophique dans le golfe de Gascogne à partir de simulations : lnterannual variability and analysis of geostroph¡c turbulence in the Bay of Biscay from simulations.

Degree: Docteur es, Océanographie physique, 2015, Brest

URL: http://www.theses.fr/2015BRES0102

►

Le golfe de Gascogne (GdG), un milieu riche en processus physiques a été étudié à partir de simulations numériques. L’étude est construite autour d'échelles allant… (more)

▼

Le golfe de Gascogne (GdG), un milieu riche en processus physiques a été étudié à partir de simulations numériques. L’étude est construite autour d'échelles allant du GdG à la sous méso-échelle. Dans la première partie, nous avons examiné la variabilité interannuelle de la température et de la salinité de surface sur une période de 53 ans : nous avons pu décrire deux tendances en lien avec I'Atlantique Nord-Est. Le refroidissement et la dessalure jusqu'en 1976 seraient liés à la grande anomalie de salinité, le réchauffement et la salinification actuels liés à I'augmentation de CO2 atmosphérique. Le GdG se caractérise par un courant de pente, lberian Poleward Current (lPC) : sa variabilité serait liée au vent du Sud-Ouest qui renforce l'lPC par un courant géostrophique dans le Bassin lbérique. L’un des résultats intéressant trouvé dans les simulations et confìrmé par les observations est l'apparition des anomalies froides liées à des upwellings en alternance avec des anomalies chaudes "La Navidad". Ces upwellings seraient liés au vent de Nord dans le Bassin lbérique mais au courant d'Ouest le long des côtes Nord espagnoles. Dans une deuxième partie, nous nous sommes attachés à la méso et sous méso-échelle à travers la détection des tourbillons et la variabilité des spectres d'énergie. Un indice basé sur le rapport entre I'anomalie de densité de surface et I'anomalie de niveau de la mer permet de détecter les tourbillons de subsurface et de les distinguer des tourbillons de surface. Une application de cet indice à partir des données satellites confirme le potentiel de détection des Slope Water Oceanic eDDIES (tourbillons de subsurface caractéristiques du GdG). La description de l'énergie cinétique turbulente (EKE) dans le GdG montre une variabilité spatiale avec un maximum le long de la côte Nord espagnole liée à I'lPC. Les pentes des spectres (k-4.2 pour la SSH, en k-2.4 pour la SST et en k-2.4 pour l'énergie cinétique) sont différents des observations satellites, mais comparables avec les précédentes études. Ces pentes de spectres ont également une variabilité saisonnière avec un maximum en hiver et un minimum en été, liée au cycle saisonnier de I'EKE.

The Bay of Biscay (BoB), an environment rich in physical processes has been studied from numerical simulations. Thestudy is built around scales from the size of BoB until sub mesoscale.ln the first part, we examined the interannual variability of the sea surface temperature and saliniÇ over a period of 53years: we were able to describe two trends related to the North-East Atlantic. Cooling and freshening until 1976 thatcould be related to the Great Salinity Anomaly and current salinification related to the atmospheric increase of CO2.The Bay of Biscay is characterized by a slope current, the lberian Poleward Current (lPC): its variability is linked to theSouth West wind strengthens the IPC by a geostrophic current in the lberian Basin. One of the interesting results foundin simulations and confirmed by observations is the appearance of cold anomalies related to…

Advisors/Committee Members: Morel, Yves (thesis director), Vandermeirsch, Frédéric (thesis director).

Subjects/Keywords: Golfe de Gascogne; Simulations numériques; Température; Salinité; Iberian Poleward Current; Navidad; Upwelling; Slope Water Oceanic eDDlES; Tourbillons de subsurface; Turbulence géostrophique; Énergie cinétique turbulente; Spectre d'énergie; Bay of Biscay; Numerical simulation; Temperature; Salinity; Iberian poleward Current; Navidad; Upwelling; Slope Water Oceanic Eddies; Subsurface vortices; Geostrophic turbulence; Turbulent kinetic energy; Energy spectrum; 551.462

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APA (6^th Edition):

Assassi, C. (2015). Variabilité interannuelle et analyse de la turbulence géostrophique dans le golfe de Gascogne à partir de simulations : lnterannual variability and analysis of geostroph¡c turbulence in the Bay of Biscay from simulations. (Doctoral Dissertation). Brest. Retrieved from http://www.theses.fr/2015BRES0102

Chicago Manual of Style (16^th Edition):

Assassi, Charefeddine. “Variabilité interannuelle et analyse de la turbulence géostrophique dans le golfe de Gascogne à partir de simulations : lnterannual variability and analysis of geostroph¡c turbulence in the Bay of Biscay from simulations.” 2015. Doctoral Dissertation, Brest. Accessed January 24, 2021. http://www.theses.fr/2015BRES0102.

MLA Handbook (7^th Edition):

Vancouver:

Assassi C. Variabilité interannuelle et analyse de la turbulence géostrophique dans le golfe de Gascogne à partir de simulations : lnterannual variability and analysis of geostroph¡c turbulence in the Bay of Biscay from simulations. [Internet] [Doctoral dissertation]. Brest; 2015. [cited 2021 Jan 24]. Available from: http://www.theses.fr/2015BRES0102.

Council of Science Editors:

Assassi C. Variabilité interannuelle et analyse de la turbulence géostrophique dans le golfe de Gascogne à partir de simulations : lnterannual variability and analysis of geostroph¡c turbulence in the Bay of Biscay from simulations. [Doctoral Dissertation]. Brest; 2015. Available from: http://www.theses.fr/2015BRES0102

University of Miami

8. Jaimes, Benjamin. On the Response to Tropical Cyclones in Mesoscale Oceanic Eddies.

Degree: PhD, Meteorology and Physical Oceanography (Marine), 2009, University of Miami

URL: https://scholarlyrepository.miami.edu/oa_dissertations/342

► Tropical cyclones (TCs) often change intensity as they move over mesoscale oceanic features, as a function of the oceanic mixed layer (OML) thermal response… (more)

▼ Tropical cyclones (TCs) often change intensity as they move over mesoscale oceanic features, as a function of the oceanic mixed layer (OML) thermal response (cooling) to the storm's wind stress. For example, observational evidence indicates that TCs in the Gulf of Mexico rapidly weaken over cyclonic cold core eddies (CCEs) where the cooling response is enhanced, and they rapidly intensify over anticyclonic warm features such as the Loop Current (LC) and Warm Core Eddies (WCEs) where OML cooling is reduced. Understanding this contrasting thermal response has important implications for oceanic feedback to TCs' intensity in forecasting models. Based on numerical experimentation and data acquired during hurricanes Katrina and Rita, this dissertation delineates the contrasting velocity and thermal response to TCs in mesoscale oceanic eddies. Observational evidence and model results indicate that, during the forced stage, the wind-driven horizontal current divergence under the storm's eye is affected by the underlying geostrophic circulation. Upwelling (downwelling) regimes develop when the wind stress vector is with (against) the geostrophic OML velocity vector. During the relaxation stage, background geostrophic circulations modulate vertical dispersion of OML near-inertial energy. The near-inertial velocity response is subsequently shifted toward more sub-inertial frequencies inside WCEs, where rapid vertical dispersion prevents accumulation of kinetic energy in the OML that reduces vertical shears and layer cooling. By contrast, near-inertial oscillations are vertically trapped in OMLs inside CCEs that increases vertical shears and entrainment. Estimates of downward vertical radiation of near-inertial wave energies were significantly stronger in the LC bulge (12.1X10 super -2 W m super -2) compared to that in CCEs (1.8X10 super -2 W m super -2). The rotational and translation properties of the geostrophic eddies have an important impact on the internal wave wake produced by TCs. More near-inertial kinetic energy is horizontally trapped in more rapidly rotating eddies. This response enhances vertical shear development and mixing. Moreover, the upper ocean temperature anomaly and near-inertial oscillations induced by TCs are transported by the westward-propagating geostrophic eddies. From a broader perspective, coupled models must capture oceanic features to reproduce the differentiated TC-induced OML cooling to improve intensity forecasting. Advisors/Committee Members: Lynn K. Shay, George H. Halliwell, William E. Johns, Kevin D. Leaman, Mark D. Powell.

Subjects/Keywords: Cold Core Eddy; Warm Core Eddy; Loop Current; Upwelling; Cold Wake; Oceanic Mixed Layer; Near-inertial Oscillations; Gulf Of Mexico; Air-sea Interaction; Tropical Cyclones; Hurricane Katrina; Hurricane Rita; Mesoscale Oceanic Eddies

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Jaimes, B. (2009). On the Response to Tropical Cyclones in Mesoscale Oceanic Eddies. (Doctoral Dissertation). University of Miami. Retrieved from https://scholarlyrepository.miami.edu/oa_dissertations/342

Chicago Manual of Style (16^th Edition):

Jaimes, Benjamin. “On the Response to Tropical Cyclones in Mesoscale Oceanic Eddies.” 2009. Doctoral Dissertation, University of Miami. Accessed January 24, 2021. https://scholarlyrepository.miami.edu/oa_dissertations/342.

MLA Handbook (7^th Edition):

Jaimes, Benjamin. “On the Response to Tropical Cyclones in Mesoscale Oceanic Eddies.” 2009. Web. 24 Jan 2021.

Vancouver:

Jaimes B. On the Response to Tropical Cyclones in Mesoscale Oceanic Eddies. [Internet] [Doctoral dissertation]. University of Miami; 2009. [cited 2021 Jan 24]. Available from: https://scholarlyrepository.miami.edu/oa_dissertations/342.

Council of Science Editors:

Jaimes B. On the Response to Tropical Cyclones in Mesoscale Oceanic Eddies. [Doctoral Dissertation]. University of Miami; 2009. Available from: https://scholarlyrepository.miami.edu/oa_dissertations/342

9. Dong, Chuanfei. Space Weather at Mars: 3-D Studies Using One-way Coupling Between the Multi-fluid MHD, M-GITM and M-AMPS Models.

Degree: PhD, Atmospheric, Oceanic and Space Sciences, 2015, University of Michigan

URL: http://hdl.handle.net/2027.42/116686

► This dissertation presents numerical simulation results of the solar wind interaction with the Martian upper atmosphere by using three comprehensive 3-D models: the Mars Global… (more)

▼ This dissertation presents numerical simulation results of the solar wind interaction with the Martian upper atmosphere by using three comprehensive 3-D models: the Mars Global Ionosphere Thermosphere Model (M-GITM), the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M-AMPS), and the BATS-R-US Mars multi-fluid MHD (MF-MHD) model. The coupled framework has the potential to provide improved predictions for ion escape rates for comparison with future data to be returned by the MAVEN mission (2014 – 2016) and thereby improve our understanding of present day escape processes. Estimates of ion escape rates over Mars history must start from properly validated models that can be extrapolated into the past. This thesis aims to build a model library for the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, which will thus enhance the science return from the MAVEN mission. In this thesis, we aim to address the following four main scientific questions by adopting the one-way coupled framework developed here: (1) What are the Martian ion escape rates at the current epoch and ancient times? (2) What controls the ion escape processes at the current epoch? How are the ion escape variations connected to the solar cycle, crustal field orientation and seasonal variations? (3) How do the variable 3-D cold neutral thermosphere and hot oxygen corona affect the solar wind-Mars interaction? (4) How does the Martian atmosphere respond to extreme variations (e.g., ICMEs) in the solar wind and its interplanetary environment? These questions are closely related to the primary scientific goals of NASA's MAVEN mission and European Space Agency's Mars Express (MEX) mission. We reasonably answer all these four questions at the end of this thesis by employing the one-way coupled framework and comparing the simulation results with both MEX and MAVEN observational data. Advisors/Committee Members: Bougher, Stephen (committee member), Powell, Ken (committee member), Ma, Ying-Juan (committee member), Liemohn, Michael Warren (committee member), Toth, Gabor (committee member).

Subjects/Keywords: What are the Martian ion escape rates at the current epoch and ancient times?; What controls the ion escape processes at the current epoch?; How do the variable 3-D cold neutral thermosphere and hot oxygen corona affect the solar wind-Mars interaction?; How does the Martian atmosphere respond to extreme variations (e.g., ICMEs) in the solar wind and its interplanetary environment?; Atmospheric, Oceanic and Space Sciences; Science

…interaction with Mars upper atmosphere during current and ancient times: Results from the one-way… …Ion escape at the current epoch 3.3.2 Ion escape over Mars history . . 3.3.3 Discussion… …Martian ion escape rates at the current epoch and ancient times? (2) What controls the… …ion escape processes at the current epoch? How are the ion escape variations connected to… …represent the current state-of-the-art; the models are not currently capable of simulating…

11 more images…

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Dong, C. (2015). Space Weather at Mars: 3-D Studies Using One-way Coupling Between the Multi-fluid MHD, M-GITM and M-AMPS Models. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/116686

Chicago Manual of Style (16^th Edition):

Dong, Chuanfei. “Space Weather at Mars: 3-D Studies Using One-way Coupling Between the Multi-fluid MHD, M-GITM and M-AMPS Models.” 2015. Doctoral Dissertation, University of Michigan. Accessed January 24, 2021. http://hdl.handle.net/2027.42/116686.

MLA Handbook (7^th Edition):

Dong, Chuanfei. “Space Weather at Mars: 3-D Studies Using One-way Coupling Between the Multi-fluid MHD, M-GITM and M-AMPS Models.” 2015. Web. 24 Jan 2021.

Vancouver:

Dong C. Space Weather at Mars: 3-D Studies Using One-way Coupling Between the Multi-fluid MHD, M-GITM and M-AMPS Models. [Internet] [Doctoral dissertation]. University of Michigan; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2027.42/116686.

Council of Science Editors:

Dong C. Space Weather at Mars: 3-D Studies Using One-way Coupling Between the Multi-fluid MHD, M-GITM and M-AMPS Models. [Doctoral Dissertation]. University of Michigan; 2015. Available from: http://hdl.handle.net/2027.42/116686

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Open Access Theses and Dissertations