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Dissertations / Theses on the topic 'Tropical Cyclones'
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1
Budzko, David C. "North Pacific tropical cyclones and teleconnections." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://handle.dtic.mil/100.2/ADA432435.
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Spollen, Rachael A. "Meteorological and model traits knowledge bases for North Indian Ocean tropical cyclones." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FSpollen.pdf.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2002.Thesis advisor(s): Russell L. Elsberry, Patrick A. Harr, Mark A. Boothe. Includes bibliographical references (p. 119-120). Also available online.
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Fu, Bing. "An observational analysis of tropical cyclogenesis in the Western North Pacific." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7030.
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Petty, Kevin R. "The effects of synoptic factors on the intensities of tropical cyclones over the eastern North Pacific Ocean." The Ohio State University, 1997. http://catalog.hathitrust.org/api/volumes/oclc/39803779.html.
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Ford, Debra M. "Forecasting tropical cyclone recurvature using an empirical othogonal [sic] function representation of vorticity fields." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA238489.
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Thesis (M.S. in Meteorology and Oceanography)--Naval Postgraduate School, September 1990.Thesis Advisor(s): Elsberry, Russell L. ; Harr, Patrick A. "September 1990." Description based on title screen as viewed on December 16, 2009. DTIC Identifier(s): EOF (empirical orthogonal functions). Author(s) subject terms: Tropical cyclones, recurvature, empirical orthogonal functions. Includes bibliographical references (p. 73-74). Also available in print.
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Dorics, Theodore G. "An assessment of NOGAPS performance in the prediction of tropical Atlantic circulation formation." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FDorics.pdf.
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Wang, Lei. "Study of tropical cyclogenesis over the South China Sea /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MATH%202008%20WANG.
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Fritz, Angela Marcelun. "North Atlantic tropical cyclones a kinetic energy perspective /." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29781.
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Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2010.Committee Chair: Curry, Judith A.; Committee Member: Black, Robert X.; Committee Member: Deng, Yi. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Blackerby, Jason S. "Accuracy of Western North Pacific tropical cyclone intensity guidance /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FBlackberry.pdf.
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Tao, Cheng. "Climatology of overshootings in tropical cyclones and their roles in tropical cyclone intensity changes using TRMM data." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2457.
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The climatology of overshooting convection in tropical cyclones (TCs) is examined using Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR). The percentage of TC convective systems with overshooting convection is highest over the North Indian Ocean basin, while the northwest Pacific basin contains the highest population of both TC convective systems and convection with overshooting tops. Convective systems in the inner core region are more capable of penetrating 14 km and the associated overshooting convection are featured with much stronger overshooting properties compared with those in the inner rainband and outer rainband regions. In the inner core region of TCs, convection associated with precipitating systems of higher intensity and intensification rates has a larger probability of containing overshooting tops.
To identify the relative importance of shallow/moderate versus deep/very deep convection in the rapid intensification (RI) of TCs, four types of precipitation-convection are defined based on the 20 dBZ radar echo height (Z20dBZ). Distributions of four types of precipitation-convection, and their contributions to total volumetric rain and total latent heating are quantified. It is shown that RI is closely associated with increased and widespread shallow precipitation around the storm center, while moderately deep and very deep convection (or overshooting convection) does not increase until in the middle of RI. This is further confirmed by the study of rainfall and convection evolution with respect to the timeline of RI events. Statistically, the onset of RI follows a significant increase in the areal coverage of rainfall, shallow precipitation, and cyan of 37 GHz color composites upshear-left, which in turn could be used as potential parameters to forecast RI. Very deep convection is most frequent 12-24 hours before RI onset and concentrates upshear-left, but it quickly decreases in the following 24 hours. The percent occurrence of very deep convection is less than 1% for RI storms. The tilt of vortex is large prior to, and near the RI onset, but rapidly decreases in the middle of RI, suggesting that the vertical alignment is a result instead of a trigger of RI.
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黃詩偉 and Sze-wai Wong. "Patterns and behaviors of global tropical cyclones." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/192994.
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This study examines the global tropical cyclones (TC) patterns and distributions from 2001-2010. The objective of the study was to find out the possible relationship between the TC activities between different oceans. The TC track record was obtained from the Hurricane Data Centre at Unisys Weather webpage and it has been plotted and transferred to a spread sheet format. By combining the data with the oceanic maps from General Bathymetric Chart of the Oceans (GEBCO) digital Atlas, we could conclude the trend and distributions of the TC in each year. Various data were also collected from the National Oceanic and Atmospheric Administration (NOAA), Climate Prediction Center and Bureau of Meteorology (BOM) so as to further explain the TC relationships in different regions. It is concluded that the TC distributions has no significant relationship between oceans in the same hemisphere but it shows certain pattern throughout the ten years record.published_or_final_version
Applied Geosciences
Master
Master of Science
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Malvig, Steven C. "Analysis of a non-developing tropical circulation system during the Tropical Cyclone Structure (TCS08) field experiment." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Dec/09Dec%5FMalvig.pdf.
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Thesis (M.S. in Meteorology and Oceanography)--Naval Postgraduate School, December 2009.Thesis Advisor: Harr, Patrick. Second Reader: Elsberry, Russell. "December 2009." Description based on title screen as viewed on January 27, 2010. Author(s) subject terms: Electra Doppler Radar (ELDORA), Tropical Cyclone Structure (TCS08), TCS08, tropical cyclone formation, Tropical Circulation System (TCS), TCS025. Includes bibliographical references (p. 75-76). Also available in print.
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Mundhenk, Bryan D. "A statistical-dynamical approach to intraseasonal prediction of tropical cyclogenesis in the western North Pacific." Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/March/09Mar%5FMundhenk.pdf.
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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2009.Thesis Advisor(s): Murphree, Tom; Meyer, David W. "March 2009." Description based on title screen as viewed on April 23, 2009. Author(s) subject terms: Tropical Cyclones, Western North Pacific, Tropical Cyclogenesis, Intraseasonal Forecasting, Smart Climatology, Tropical Climatology, Long-Range Forecast, Long-Range Weather Support, Tropical Genesis Parameters, NCEP Climate Forecast System. Includes bibliographical references (p. 103-106). Also available in print.
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Fenlason, Joel W. "Accuracy of tropical cyclone induced winds using TYDET at Kadena AB." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Mar%5FFenlason.pdf.
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Klein, Peter M. "Extratropical transition of Western North Pacific tropical cyclones." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA341420.
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Thesis (M.S. in Meteorology and Physical Oceanography) Naval Postgraduate School, September 1997."September 1997." Thesis advisor(s): Russell L. Elsberry, Patrick A. Harr. Includes bibliographical references (p. 87-88). Also available online.
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Gilford, Daniel Michael. "The tropopause region thermal structure and tropical cyclones." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115639.
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Thesis: Ph. D. in Atmospheric Science, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 187-207).
This thesis is an exploration of two seemingly unrelated questions: First, how do water vapor and ozone variations radiatively influence the thermal structure of the tropopause region? Second, what sets the thermodynamic limits of tropical cyclone intensity across the seasonal cycle? The link between these subjects is tropical cyclone outflow, which often reaches into the tropopause region, allowing the thermal structure there to impact tropical cyclone potential intensity. A radiative transfer model is employed to calculate the radiative effects of the 2000 and 2011 tropopause region abrupt drops -- events in which temperatures, water vapor, and ozone plunge suddenly to anomalously low levels. Results show that radiative effects partially offset in the region above the tropopause, but nonlocally combine to cool the layers below the tropopause. Persistently low water vapor concentrations associated with the abrupt drops spread to extratropical latitudes, and produce a total negative radiative forcing that offsets <12% of the carbon dioxide forcing over 1990-2013. Next, the importance of local and nonlocal radiative heating/cooling for tropopause region temperature seasonal cycles is examined. The radiative effects of water vapor seasonality are weak and local to the tropopause, whereas ozone radiatively amplifies temperature seasonality in the tropopause region by 30%, in part because stratospheric ozone seasonality nonlocally affects the tropopause region thermal structure. To determine how the tropopause region thermal structure affects thermodynamic limits on tropical cyclone intensity, this study presents the first comprehensive seasonal cycle climatology of potential intensity. Perennially warm sea surface temperatures in the Western Pacific result in outflow altitudes that are near the tropical tropopause region throughout the seasonal cycle, whereas the seasonalities of other ocean basins are less influenced by the tropopause region. Probing the potential intensity environmental drivers reveals that the seasonality of near-tropopause temperatures in the Western Pacific damps potential intensity seasonal variability by <30%. Incorporating a best track tropical cyclone archive shows that this result is relevant for real-world tropical cyclones: the tropopause region thermal structure permits intense Western Pacific tropical cyclones in every month of the year, which may have critical consequences for coastal societies.
by Daniel Michael Gilford.
Ph. D. in Atmospheric Science
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Miltenberger, Alexander Reid. "The effects of ocean eddies on tropical cyclones." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78538.
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Thesis (S.M.)--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), 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 40-41).
The purpose of this study is to understand the interactions of tropical cyclones with ocean eddies. In particular we examine the influence of a cold-core eddy on the cold wake formed during the passage of Typhoon Fanapi (2010). The three-dimensional version of the numerical Price-Weller-Pinkel (PWP) vertical mixing model has previously been used to simulate and study the cold wakes of Atlantic hurricanes. The model has not been used in comparison with observations of typhoons in the Western Pacific Ocean. In 2010 several typhoons were studied during the Impact of Typhoons on the Ocean in the Pacific (ITOP) field campaign and Fanapi was particularly well observed. We use these observations and the 3DPWP to understand the ocean cold wake generated by Fanapi. The cold wake of Fanapi was advected by a cyclonic eddy that was south of the typhoon track. The 3DPWP model outputs with and without an eddy are compared with observations made during the field campaign. These observations are compared to model outputs with eddies in a series of positions right and left of the storm track in order to study effects of mesoscale eddies on ocean vertical mixing in the cold wake of typhoons.
by Alexander Reid Miltenberger.
S.M.
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Bister, Marja Helena. "Development of tropical cyclones from mesoscale convective systems." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/57851.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996.Includes bibliographical references (p. 109-112).
by Marja Helena Bister.
Ph.D.
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Yang, He. "Numerical modelling studies on asymmetries in tropical cyclones." Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.646002.
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Hurricanes are the most destructive of all weather systems. Conditions necessary for their formation are well known, but not those sufficient to guarantee their occurrence. A thorough understanding of their structure, the physical and dynamical processes which operate within them, and their interactions with the large-scale environmental flow are necessary if accurate forecasts are to be made of their development and tracks. In the present study, both 2-D (axisymmetric) and 3-D (asymmetric), two-layer (plus the boundary layer) numerical models have been developed. The 2 -D model is used to investigate the essential characteristics of the symmetric flow component of tropical cyclones. The heating rate, which is computed at the mid-level in the model, is related to the vortexflow itself. It consists of three parts: moisture convergence over the whole column, Ekman pumping and surface evaporation. The moisture convergence is found to be crucial in providing latent heating released by condensation of water vapour sufficient to compensate adiabatic ascent cooling. The Ekman pumping plays an important role as a 'contractor', i.e. to cause the maximum winds to concentrate towards the centre, and consequent intensification of the modelled vortex. The surface evaporation, although relatively S11UJU, spreads over a larger area than the other two. It is found to beessentialformaintenance of the mature stage.
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Wang, Shuai. "The low-level wind structure of tropical cyclones." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/44564.
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The main effects of tropical cyclones include high winds, extensive storm surges, and widespread flooding. These main effects are all closely related to the low-level wind structure, the height of which is about 2 km from the underlying surface. A physically based analytic model (λ model) is presented to describe the low-level wind structure of tropical cyclones in terms of one intensity measure, one size measure, and the storm meridional position. The λ model provides an accurate fit of the near-surface azimuthal wind field simulated with an idealized full-physics numerical model. This numerical model is further applied to investigate the tropical cyclone low-level wind structure evolution during the mature stage with observations. Three basic features at the mature stage are observed: the outward expansion of eyewall, the reduction of intensity and the increase of tangential wind in the outer spiral bands. Model simulations show that the outer circulation expansion is accompanied by the outward migration of diabatic heating at mid-level in the eyewall. The outward movement of eyewall is caused by the opposing angular momentum transports. Consequently, the intensity decays due to the angular momentum conservation and cyclostrophic adjustment, which is captured in a new analytic pressure-wind relationship derived from the λ model. To investigate the relationship between the tropical cyclone damage and low-level wind structure, the λ model is used to reconstruct the historical wind structure of hurricanes that allows us, for the first time, to calculate the correlation of damage with the integrated wind profile of all hurricanes at landfall since 1988. We find that those metrics, which include the horizontal wind structure, rather than just maximum intensity, are better correlated with the hurricane cost. The vertical wind shear over the main development region of hurricanes plays a more dominant role than the sea surface temperature in controlling these metrics and therefore also ultimately the cost of hurricanes.
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Foster, Ian J. "The development of tropical cyclones in Northwest Australia." Thesis, Foster, Ian J. (1986) The development of tropical cyclones in Northwest Australia. PhD thesis, Murdoch University, 1986. https://researchrepository.murdoch.edu.au/id/eprint/51651/.
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Case studies of developing and nondeveloping tropical depressions in the northwest Australian region during the 1979/80 and 1980/81 seasons have been constructed using conventional and satellite observations. Overland and near coastal depressions were selected because of their forecasting importance. The daily evolution of synoptic situations associated with the two types of depression were described without the loss of individuality inherent in the compositing approach. The correlation of cyclogenesis with surges in the low level westerly and easterly wind regimes was investigated via longitude-time sections along 10°S and 25°S.
A major finding is that enhanced low level winds can occur during the lifetime of nondeveloping disturbances, they are not exclusively associated with cyclogenesis. Rather, the emphasis is on the three dimensional structure of the atmosphere around a cloud cluster and how that structure was maintained or altered through time. The requirement for flow out to 10 degrees radius and below 500 mb is for a sustained cyclonic organization of the winds rather than their magnitudes to exceed a critical value. In contrast, winds above 250 mb within 5 degrees radius must remain at less than 15 m/s. There was less dependence on the horizontal organization of the large scale upper flow. Intensification could occur under a light easterly flow as well as under a vigorous upper anticyclone. The most common cause for the failure of the nondevelopers was the strong upper easterlies and attendant large vertical wind shear.
The importance of both upper and lower level regimes of the Southern Hemisphere subtropical ridge also became apparent. This ranged from the effect of dry air advection on near coastal convection to the inhibitory effect of strong upper easterlies. The ridge could also affect cyclogenesis through its influence on the on or offshore movement of tropical depressions. Upper troughs played an indirect role in cyclogenesis through their interaction with the upper ridge rather than by providing outflow channels to the westerlies.
This study suggests that it is the large scale flows. primarily in the Southern Hemisphere, that ultimately control tropical cyclogenesis. Accurate forecasting of genesis cannot be achieved without greater understanding of the influence of large scale mid-latitude events on the environment of tropical depressions.
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Zuki, Zabani Md. "The interannual variability of tropical cyclones in the southern South China Sea /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426118.
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Hoarau, Thomas. "Couplage aérosols-microphysique pour la simulation des cyclones tropicaux : Cas du cyclone Dumile (2013)." Thesis, La Réunion, 2018. http://www.theses.fr/2018LARE0012/document.
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La prévision de l'intensité des cyclones tropicaux est aujourd'hui un enjeu scientifique majeur. Parmi de nombreux facteurs multi-échelle, l'impact de la microphysique nuageuse et des aérosols sur les variations d'intensité a été récemment mis en évidence. Cette problématique a motivé l'évaluation du schéma microphysique à 2-moments LIMA en milieu tropical et le développement d'un couplage avec le schéma d'aérosols ORILAM au sein du modèle atmosphérique Meso-NH. L'intérêt de ce développement numérique est d'inclure l'émission des aérosols marins en fonction des vents cycloniques et des paramètres océaniques. L'application de ce couplage aérosols-microphysique à la simulation du cyclone tropical Dumile (2013) montre que le modèle couplé tend à améliorer la représentation de l'intensité, la trajectoire, la structure microphysique du cyclone tropical et les précipitations associées, en comparaison avec les observations. La production secondaire des cristaux de glace est également un thème de recherche actif en microphysique nuageuse. Ainsi, une paramétrisation du processus de rupture collisionnelle de la glace a été implémentée dans le schéma microphysique LIMA. L'impact de ce processus a été testé sur le développement d'un orage des moyennes latitudes et sur le cyclone tropical Dumile. Les deux cas d'étude ont des réponses similaires vis-à-vis de ce processus : une augmentation de la concentration et de la masse des cristaux de glace et une diminution des cumuls de précipitations. La poursuite de ces travaux pourrait permettre de déterminer si ce processus de formation secondaire peut améliorer la modélisation de la couverture cirriforme des cyclones tropicauxIntensity forecast of tropical cyclones is a major scientific issue. Among many factors, the impact of cloud microphysics and aerosols on intensity variations has been recently underlined. This issue motivated the evaluation of the 2-moment microphysical scheme LIMA in a tropical context and the development of a coupling with the aerosol scheme ORILAM into the atmospheric model Meso-NH. The interest of this numerical development is to represent the emission of sea salt aerosols depending on cyclonic winds and oceanic parameters. The application of this aerosols-microphysics coupling to the simulation of tropical cyclone Dumile (2013) shows that the coupled model tends to improve the representation of the intensity, the track, the microphysical structure of the tropical cyclone and the associated precipitation, when comparing with observations. The secondary production of ice crystals is also an active research topic in cloud microphysics. A parameterization of the collisional ice break-up process is thus implemented into the microphysical scheme LIMA. The impact of this process has been analyzed on a mid-latitude storm and on tropical cyclone Dumile. Both case studies display similar results regarding this process: an increase of ice crystals concentration and mass, and a decrease of precipitation. The continuation of this work could allow to determine if this process of secondary formation could improve the cirrus modelling in tropical cyclones
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Bower, Caroline A. "Prediction of tropical cyclone formation in the western North Pacific using the Navy global model." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FBower.pdf.
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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2004.Thesis advisor(s): Patrick A. Harr, Russell L. Elsberry. Includes bibliographical references (p. 117-118). Also available online.
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Suzuki-Parker, Asuka. "An assessment of uncertainties and limitations in simulating tropical cyclone climatology and future changes." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41062.
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The recent elevated North Atlantic hurricane activity has generated considerable interests in the interaction between tropical cyclones (TCs) and climate change. The possible connection between TCs and the changing climate has been indicated by observational studies based on historical TC records; they indicate emerging trends in TC frequency and intensity in some TC basins, but the detection of trends has been hotly debated due to TC track data issues. Dynamical climate modeling has also been applied to the problem, but brings its own set of limitations owing to limited model resolution and uncertainties.
The final goal of this study is to project the future changes of North Atlantic TC behavior with global warming for the next 50 years using the Nested Regional Climate Model (NRCM). Throughout the course of reaching this goal, various uncertainties and limitations in simulating TCs by the NRCM are identified and explored.
First we examine the TC tracking algorithm to detect and track simulated TCs from model output. The criteria and thresholds used in the tracking algorithm control the simulated TC climatology, making it difficult to objectively assess the model's ability in simulating TC climatology. Existing tracking algorithms used by previous studies are surveyed and it is found that the criteria and thresholds are very diverse. Sensitivity of varying criteria and thresholds in TC tracking algorithm to simulated TC climatology is very high, especially with the intensity and duration thresholds. It is found that the commonly used criteria may not be strict enough to filter out intense extratropical systems and hybrid systems. We propose that a better distinction between TCs and other low-pressure systems can be achieved by adding the Cyclone Phase technique.
Two sets of NRCM simulations are presented in this dissertation: One in the hindcasting mode, and the other with forcing from the Community Climate System Model (CCSM) to project into the future with global warming. Both of these simulations are assessed using the tracking algorithm with cyclone phase technique.
The NRCM is run in a hindcasting mode for the global tropics in order to assess its ability to simulate the current observed TC climatology. It is found that the NRCM is capable of capturing the general spatial and temporal distributions of TCs, but tends to overproduce TCs particularly in the Northwest Pacific. The overpredction of TCs is associated with the overall convective tendency in the model added with an outstanding theory of wave energy accumulation leading to TC genesis. On the other hand, TC frequency in the tropical North Atlantic is under predicted due to the lack of moist African Easterly Waves. The importance of high-resolution is shown with the additional simulation with two-way nesting.
The NRCM is then forced by the CCSM to project the future changes in North Atlantic TCs. An El Nino-like SST bias in the CCSM induced a high vertical wind shear in tropical North Atlantic, preventing TCs from forming in this region. A simple bias correction method is applied to remove this bias. The model projected an increase both in TC frequency and intensity owing to enhanced TC genesis in the main development region, where the model projects an increased favorability of large-scale environment for TC genesis. However, the model is not capable of explicitly simulating intense (Category 3-5) storms due to the limited model resolution. To extrapolate the prediction to intense storms, we propose a hybrid approach that combines the model results and a statistical modeling using extreme value theory. Specifically, the current observed TC intensity is statistically modeled with the General Pareto distribution, and the simulated intensity changes from the NRCM are applied to the statistical model to project the changes in intense storms. The results suggest that the occurrence of Category 5 storms may be increased by approximately 50% by 2055.
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Springer, Cory A. "Short term teleconnections associated with western Pacific tropical cyclones." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA284032.
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Moon, Yumin. "Dynamical Impacts of Rotating Convective Asymmetries on Tropical Cyclones." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_theses/126.
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Although a tropical cyclone may conceptually be regarded as an axisymmetric vortex, there is substantial evidence that asymmetric dynamics play an important role. In this thesis, dynamical impacts of rotating convective asymmetries are examined in this thesis. Two types of rotating convective asymmetries are considered: rotating eyewall convective maximum which is located in the core region of the storm and spiral bands which are located outside the core. Both of them can be characterized as rotating asymmetric convective heat sources, and they are superimposed on a balanced, axisymmetric vortex to approximate the effect of rotating eyewall convective maximum and spiral bands on tropical cyclone by using a simple nonhydrostatic three-dimensional, but linear model that is based on vortex anelastic equations. The evolution of rotating convective asymmetric heat sources on a balanced, axisymmetric vortex, which is modeled after tropical cyclones, is investigated to examine angular momentum transport by gravity waves that radiate away from the core region. Results show that gravity waves can transport angular momentum away from a tropical cyclone, but a very small amount, which is several orders of magnitude smaller than the estimate by recent studies. The significantly large difference may largely be due to the difference between two-dimensional and three-dimensional adjustment processes. Assuming that the effects of spiral bands on tropical cyclone wind field are caused by the response to diabatic heating in their convection, rotating asymmetric heat sources are constructed to reflect observations of spiral bands. These heat sources are rotated around a realistic but idealized balanced axisymmetric vortex. Simulation results show that the response of tropical cyclone wind field to idealized spiral band heat sources can successfully capture a number of observed well-known features of spiral band circulation, such as overturning secondary circulation, descending mid-level inflow, and cyclonic tangential acceleration. Comparison to full-physics numerical simulations confirms the validity of this method which provides a simple dynamical framework to better understand the impact of spiral bands in tropical cyclone.
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Desflots, Melicie. "Environmental and Internal Controls of Tropical Cyclones Intensity Change." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/120.
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Tropical cyclone (TC) intensity change is governed by internal dynamics (e.g. eyewall contraction, eyewall replacement cycles, interactions of the inner-core with the rainbands) and environmental conditions (e.g. vertical wind shear, moisture distribution, and surface properties). This study aims to gain a better understanding of the physical mechanisms responsible for TC intensity changes with a particular focus to those related to the vertical wind shear and surface properties by using high resolution, full physics numerical simulations. First, the effects of the vertical wind shear on a rapidly intensifying storm and its subsequent weakening are examined. Second, a fully coupled atmosphere-wave-ocean model with a sea spray parameterization is used to study the impact of sea spray on the hurricane boundary layer. The coupled model consists of three components: the high resolution, non-hydrostatic, fifth generation Pennsylvania State University-NCAR mesoscale model (MM5), the NOAA/NCEPWAVEWATCH III (WW3) ocean surface wave model, and theWHOI threedimensional upper ocean circulation model (3DPWP). Sea spray parameterizations were developed at NOAA/ESRL and modified by the author to be introduced in uncoupled and coupled simulations. The model simulations are conducted in both uncoupled and coupled modes to isolate various physical processes influencing TC intensity. The very high-resolutionMM5 simulation of Hurricane Lili (at 0.5 km grid resolution) showed a rapid intensification associated with a contracting eyewall. Changes in both the magnitude and the direction of the vertical wind shear associated with an approaching upper-tropospheric trough were responsible for the weakening of the storm before landfall. Hurricane Lili weakened in a 5-10 m/s vertical wind shear environment. The simulated storm experienced wind shear direction normal to the storm motion, which produced a strong wavenumber one rainfall asymmetry in the downshear-left quadrant of the storm. The rainfall asymmetry was confirmed by various observations from the TRMM satellite and the WSR-88D ground radar in the coastal region. The increasing vertical wind shear induced a vertical tilt of the vortex with a time lag of about 5-6 hours after the wavenumber one rainfall asymmetry was first observed in the model simulation. Other key factors controlling intensity and intensity change in tropical cyclones are the air-sea fluxes. Accurate measurement and parameterization of air-sea fluxes under hurricane conditions are challenging. Although recent studies have shown that the momentum exchange coefficient levels off at high wind speed, little is known about the high wind behavior of the exchange coefficient for enthalpy flux. One of the largest uncertainties is the potential impact of sea spray. The current sea spray parameterizations are closely tied to wind speed and tend to overestimate the mediated heat fluxes by sea spray in the hurricane boundary layer. The sea spray generation depends not only on the wind speed but also on the variable wave state. A new spray parameterization based on the surface wave energy dissipation is introduced in the coupled model. In the coupled simulations, the wave energy dissipation is used to quantify the amount of wave breaking related to the generation of sea spray. The spray parameterization coupled to the waves may be an improvement compared to sea spray parameterizations that depends on wind speed only.
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Young, Jeremy. "Teleconnective Influences on the Strength of Post-tropical Cyclones." TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1219.
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Over the 1951-2009 time period, 47% of all tropical systems in the Atlantic Basin transitioned to post-tropical storms. These storms are capable of producing hurricaneforce winds, torrential, flooding rains and storm surge that floods coastal areas. This study adds to previous climatological work by completing a case-study of Hurricane Ike (2008) and examining how teleconnections such as the El Niño Southern Oscillation (ENSO), the Madden-Julian Oscillation (MJO), the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO) contribute to the strength of a transitioning post-tropical storm. T-tests performed show strong statistical relationships between an increase (decrease) in post-tropical storm frequency and warm PDO – La Niña (cold PDO – La Niña), cold PDO – ENSO neutral (warm PDO – ENSO neutral), and warm (cold) AMO conditions. Moreover, nearly significant results were found for the same increase (decrease) and La Niña seasons since (pre) 1980 and for cold (warm) PDO conditions. Modeling the MJO suggests that increased (decreased) relative humidity associated with the wet (dry) phase could increase (decrease) precipitation output from the storm and decrease (increase) forward speed of the storm, decreasing (increasing) wind speeds observed at the surface.
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Kowch, Roman S. "Diurnal analysis of intensity trends in Atlantic tropical cyclones." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84725.
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Thesis (S.M. in Atmospheric Science)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 79-84).
I postulate that a diurnal cycle may exist in observational variables related to tropical cyclone (TC) intensity. Prior studies document a significant diurnal signal in moist convection across tropical regions. Since convection becomes more pronounced in intense TCs, daily solar insolation possibly affects observed TC intensities. What remains unclear is if the diurnal signals in physical influences, or factors that modulate TC intensity over hourly timescales, are also prominent in observed TC intensity fields. We apply various analytical techniques to two TC datasets and uncover a slight, yet detectable, diurnal trend in some calculated intensity fields. We first calculate 6-h maximum sustained surface wind (MSSW) tendencies using Atlantic TC best-track data from the National Oceanic and Atmospheric Administration (NOAA) National Hurricane Center (NHC) over years 1967-2011. In addition, we separate land tracks from warm-water tracks to analyze diurnal departures from the background states of these physical situations. We obtain a mid to late morning maximum in rapid intensification (RI) events over warm water. No discernible trend exists for land-filling TCs, even after using the decay model of Kaplan and DeMaria (1995) to find diurnal departures from mean decay rates. We also calculate theoretical TC indices using Atlantic TC dropsonde data from NOAA NHC over years 2002-2005 and 2011-2012. The indices, which measure physical influences on TC intensity, shift significantly during morning hours. This trend includes higher potential intensity (PI) and lower ventilation during late morning. The diurnal signal in RI frequency and intensity indices follows prior statistics and two physical mechanisms. The signal's greater PI coincides with more frequent occurrences of RI events, as confirmed statistically for Atlantic TCs by Kaplan and DeMaria (2003). Data noise likely obscures a possible diurnal signal in the negative MSSW tendencies analyzed in our study. Large-scale mechanisms that support our observed diurnal signal include enhanced radiatively driven low-level convergence and mid-level moisture during morning hours.
by Roman S. Kowch.
S.M.in Atmospheric Science
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Belanger, James Ian. "Predictability and prediction of tropical cyclones on daily to interannual time scales." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44877.
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The spatial and temporal complexity of tropical cyclones (TCs) raises a number of scientific questions regarding their genesis, movement, intensification, and variability. In this dissertation, the principal goal is to determine the current state of predictability for each of these processes. To quantify the current extent of tropical cyclone predictability, we assess probabilistic forecasts from the most advanced global numerical weather prediction system to date, the ECMWF Variable Resolution Ensemble Prediction System (VarEPS). Using a new false alarm clustering technique to maximize the utility of the VarEPS, the ensemble system is shown to provide well-calibrated probabilistic forecasts for TC genesis through a lead-time of one week, and pregenesis track forecasts with similar skill compared to the VarEPS's postgenesis track forecasts. To quantify the predictability of TCs on intraseasonal time scales, forecasts from the ECMWF Monthly Forecast System (ECMFS) are examined for the North Atlantic Ocean. From this assessment, dynamically based forecasts from the ECMFS provide forecast skill exceeding climatology out to weeks three and four for portions of the southern Gulf of Mexico, western Caribbean and the Main Development Region. Forecast skill in these regions is traced to the model's ability to capture correctly the variability in deep-layer vertical wind shear, the relative frequency of easterly waves moving through these regions, and the intraseasonal modulation of the Madden-Julian Oscillation.
On interannual time scales, the predictability of TCs is examined by considering their relationship with tropical Atlantic easterly waves. First, a set of easterly wave climatologies for the CFS-R, ERA-Interim, ERA-40, and NCEP/NCAR Reanalysis are developed using a new easterly wave-tracking algorithm. From the reanalysis-derived climatologies, a moderately positive and statistically significant relationship is seen with tropical Atlantic TCs. In relation to large-scale climate modes, the Atlantic Multidecadal Oscillation (AMO) and Atlantic Meridional Mode (AMM) exhibit the strongest positive covariability with Atlantic easterly wave frequency. Besides changes in the number of easterly waves, the intensification efficiency of easterly waves has also been evaluated. These findings offer a plausible physical explanation for the recent increase in the number of NATL TCs, as it has been concomitant with an increasing trend in both the number of tropical Atlantic easterly waves and intensification efficiency.
The last component of this dissertation examines how the historical variability in U.S. landfalling TCs has impacted the annual TC tornado record. To reconcile the inhomogeneous, historical tornado record, two statistical tornado models, developed from a set of a priori predictors for TC tornado formation, are used to reconstruct the TC tornado climatology. While the synthetic TC tornado record reflects decadal scale variations in association with the AMO, a comparison of the current warm phase of the AMO with the previous warm phase period shows that the median number of tornadoes per Gulf TC landfall has significantly increased. This change likely reflects the increase in median TC size (by 35%) of Gulf landfalling TCs along with an increased frequency of large TCs at landfall.
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Zagrodnik, Joseph P. "Comparison and Validation of Tropical Rainfall Measuring Mission (TRMM) Rainfall Algorithms in Tropical Cyclones." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/903.
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Tropical Rainfall Measuring Mission (TRMM) rainfall retrieval algorithms are evaluated in tropical cyclones (TCs). Differences between the Precipitation Radar (PR) and TRMM Microwave Imager (TMI) retrievals are found to be related to the storm region (inner core vs. rainbands) and the convective nature of the precipitation as measured by radar reflectivity and ice scattering signature. In landfalling TCs, the algorithms perform differently depending on whether the rainfall is located over ocean, land, or coastal surfaces. Various statistical techniques are applied to quantify these differences and identify the discrepancies in rainfall detection and intensity. Ground validation is accomplished by comparing the landfalling storms over the Southeast US to the NEXRAD Multisensor Precipitation Estimates (MPE) Stage-IV product. Numerous recommendations are given to algorithm users and developers for applying and interpreting these algorithms in areas of heavy and widespread tropical rainfall such as tropical cyclones.
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Cheung, Kin-wai. "Understanding and forecasting interannual variability of tropical cyclone activity in the Western North Pacific Ocean /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2036488X.
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Reynes, Anthony. "Environmental steering flow analysis for central north Pacific tropical cyclones based on NCEP/NCAR reanalysis data." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7009.
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Ntafis, Stavros. "Contribution de la convection profonde à l’intensification des cyclones méditerranéens Remote sensing of deep convestion within a tropical-like cyclone over the Mediterranean Sea Insights into the convective evolution of Mediterranean tropical‐like cyclones." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX106.
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Le rôle de la convection profonde dans l’intensification des cyclones subtropicaux méditerranéen est examiné dans le cadre de cette thèse. Alors que la plupart des cyclones méditerranéens présentent un cycle de vie barocline typique, où la cyclogenèse est principalement déclenchée par les perturbations situées dans la haute troposphère, le rôle de la convection profonde sur le développement des cyclones été jeu abordé jusqu’ici. Afin d'étudier la contribution de celle-ci sur l'intensification de neuf médicanes entre 2005 et 2018, l'accent a été mis sur le bassin méditerranéen central et oriental moins étudié, que ceux de la Méditerranée occidentale.Dans une première partie, la relation entre la convection profonde et la formation et l'intensification des cyclones est étudiée à l'aide de techniques de télédétection par une approche multi-satellites en utilisant des observations dans l’infrarouge et les micro-onde. Des observations provenant des radiomètres micro-ondes AMSU-B et MHS volant à bord de plusieurs satellites opérationnels (NOAA16 à NOAA19; MetOpA / B), ainsi que l'imageur visible et infrarouge SEVIRI installé à bord des satellites géostationnaires Meteosat-8 à 11 ont été utilisées. Les canaux humidité sondant autour de 183 GHz des capteurs AMSU / MHS et les canaux infrarouges de SEVIRI ont été utilisés pour détecter la convection profonde durant le cycle de vie des médicanes. De plus, le cisaillement vertical du vent et l'inclinaison du vortex ont été calculés en utilisant les réanalyses ERA5 afin d’étudier l'évolution de la structure du cyclone. Les résultats fournissent des informations inédites sur les relations entre la convection profonde et l'évolution des cyclones : ainsi il est montré que seule une fraction des cyclones étudiés subissent une activité convective intense près de leurs centres et qu’une convection profonde persistante dans les secteurs où le cisaillement est positif mène à des périodes d'intensification. L'activité convective des secteurs où le cisaillement est négatif n'est pas liée à des périodes d'intensification, tandis que les structures de courte durée de type ouragans se développent uniquement pendant l'activité convective symétrique ce qui peut conduire à une intensification des cyclones dans certains cas. En raison de ces comportements variés, les neuf médicanes étudiés ont été groupés en trois familles en fonction des caractéristiques de leur cycle de vie.Dans un deuxième temps, pour aborder l'impact de la thermodynamique à fine échelle en lien avec la convection profonde et expliquer l'activité convective observée, une modélisation atmosphérique a été effectuée. Pour cela on a utilisé le modèle de recherche et de prévisions météorologiques WRF à une résolution spatiale fine (3 km). Les simulations numériques ont été forcées par les réanalyses ERA5. Pour tenir compte des effets de la libération de chaleur latente pendant la convection profonde, des traceurs de vorticité potentielle (PV). De plus, une version modifiée de l'équation de tendance de pression a été utilisée pour post-traiter les résultats numériques afin d'étudier la dynamique atmosphérique liée à six médicanes. Les résultats ont montré que les changements d'intensité des cyclones n'étaient que partiellement expliqués par l'activité de la convection profonde, les facteurs principaux étant les champs de PV diabatique de basse couche induits et le chauffage diabatique. L'environnement barocline dans lequel ces cyclones se sont développés présentait finalement très peu de similitudes avec les cyclones tropicaux. Les résultats numériques appuient en partie notre hypothèse issue du travail mené sur les observations selon laquelle les médicanes feraient bien partie de la famille des cyclones méditerranéens, mais qu’ils possèdent également certaines caractéristiques particulières, à savoir la contribution des processus diabatiques et barocliniques lors de leur développement et au stade matureThe role of deep convection in the intensification of Mediterranean tropical-like cyclones is examined in this thesis. While most of the Mediterranean cyclones present a common baroclinic life cycle where cyclogenesis is mainly triggered by upper tropospheric systems, the role of deep convection on cyclones development has only been addressed by few studies in the recent past. In order to investigate the contribution of deep convection in the intensification of 9 Mediterranean tropical-like cyclones between 2005 and 2018, the emphasis has been put on the Central and Eastern Mediterranean basin where these cyclones have received less attention than those in the Western Mediterranean.In a first part, the relation of deep convection with cyclones formation and intensification is investigated using remote sensing techniques, through a multi-satellite approach, with observations in the infrared and microwave spectrum. Observations derived from the Advanced Microwave Sounding Unit (AMSU-B) and the Microwave Humidity Sounder (MHS) on several operational satellites (NOAA16 through NOAA19); MetOpA/B, as well as the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the geostationary satellites Meteosat-8 to 11 have been used. The humidity sounding channels around 183 GHz from the AMSU/MHS sensors and a method of infrared channel differencing from SEVIRI were used to detect deep convection during the Mediterranean tropical-like cyclones. Moreover, vertical wind shear and vortex tilt were calculated by ERA5 reanalysis data to study the cyclone structure evolution. Results provide new insights about the relations between deep convection and cyclone evolution, with only a fraction of the studied cyclones experiencing intense convective activity close to their centres and persistent deep convection in the upshear quadrants leads to intensification periods. Convective activity solely in the downshear quadrants is not linked to intensification periods, while short-lived hurricane-like structures develop only during symmetric convective activity, leading to cyclone intensification in some of the cases. For this reason, the Mediterranean tropical-like cyclones have been divided into 3 groups based on distinct differences during their lifetime.As a second step, to address the impact of fine-scale thermodynamics related to deep convection and explain the observed convective activity, atmospheric modeling is employed, using the Weather Research and Forecast model (WRF) with a fine spatial resolution (3 km). The numerical simulations are forced by ERA5 reanalysis data with a high temporal resolution. To account for the effects of latent heat release during deep convection, online potential vorticity (PV) tracers are used at every model time step. In addition, a modified version of the classical pressure tendency equation (PTE) is used to post-process the numerical results to study the atmospheric dynamics related to 6 Mediterranean tropical-like cyclones. Results show that cyclone intensity changes are only partly explained by deep convection activity, with an emphasis given on the diabatically-induced low-level PV fields and diabatic heating. The baroclinic environment into which these cyclones develop has very few similarities with tropical cyclones. The numerical findings partially support our hypothesis in the observational study that the Mediterranean tropical-like cyclones may be part of a continuous spectrum of Mediterranean cyclones, but they are also distinct differences among them, namely the contribution of diabatic and baroclinic processes at their developing and mature stages
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Kastelein, Bryce. "VULNERABILITY TO TROPICAL CYCLONE RELATED MORTALITIES ON HISPANIOLA." Kent State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1416264208.
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Miller, Henry A. "The contribution of symmetrization to the intensification of Tropical Cyclones." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA401557.
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Thesis (M.S. in Meteorology and Physical Oceanography) Naval Postgraduate School, Dec. 2001.Thesis advisor, Roger T. Williams. "December 2001." Includes bibliographical references (p. 74-79). Also available in print.
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Onderlinde, Matthew. "Developing a parameter for forecasting tornadoes in landfalling tropical cyclones." Tallahassee, Florida : Florida State University, 2010. http://etd.lib.fsu.edu/theses/available/etd-12182009-181446/.
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Thesis (M.S.)--Florida State University, 2010.Advisor: Henry E. Fuelberg, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed on July 14, 2010). Document formatted into pages; contains viii, 39 pages. Includes bibliographical references.
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Jaimes, Benjamin. "On the Response to Tropical Cyclones in Mesoscale Oceanic Eddies." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/342.
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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.
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Al-Breiki, Mohamed Ahmed Mohamed Naser. "Digital signal processing extra-tropical cyclones warning system using WiMAX." Thesis, University of Hertfordshire, 2013. http://hdl.handle.net/2299/10628.
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This research project proposed a unique solution to make use of these base stations to keep all subscribers alerted with warning of possible disaster should that be required. As the current, network does not provide a provision for such a noble approach, a new network model has been developed and simulated to interface a sensor (weather station, WeS), with WiMAX weather station. The weather station is based on DSP processor to receive a digitised sensor values, process these values, analyse them and if they fall within the alert zones, packet them according to WiMAX protocol and send them to subscribers. The developed standard bypasses any commercial network to offer free transmission to subscribers. This setup is also able to extract information on weather condition or react on uncertainty, i.e. disaster scenarios. Natural disasters, such as torrent, tornado/ hurricane, volcano eruption, earthquake, Tsunamis or landslide are increasing. Unfortunately they bring with them human tragedies, environment catastrophes, villages, cities and counties are subject to endless devastation during and after the destructive forces. Water, electricity and gas supply are most disrupted and difficult to restore in short time. However, communication is another item that can be affected adversely but WLAN with specific considerations, should be excluded from the effect. This project presents a solution, albeit minor relative to the maximum effect of the disaster, but will keep the telecommunication/communication in operation. Our novel technique, a “Clone Wireless Wide Area Network (CloneWAN)” is a clone wireless network to the wired Network. In the event of natural calamities, it gives continuity of network operation. It is based on WiMAX. The realization of CloneWAN has been formed and simulated to set the national network of the UAE at its correct form. CloneWAN model has been simulated with Opnet platform. All results revealed that the model is complete. The interface to Alerting System is discussed. Results show that the dynamic behavior of the parameters delay and Throughput of CloneWAN model is stable over various and different load scenarios. WiMAX is a de-facto standard in the current and future network requirement standards. Its main component is the Base Station which is normally stationed in the air, high enough to couple signals from other base stations. It is purpose is merely focused on networking signals for commercial purposes. The suggested hardware interface for the Weather Station is based on DSP SHARC processor. The model has been written in C and simulated under Opnet package. A number of scenarios have been set to represent different disasters worldwide. All results are listed and discussed later in the thesis.
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Madison, Emily Victoria. "Sensitivity analysis of surface wind field reconstructions in tropical cyclones." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52306.
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Accurate forecasts of tropical cyclone surface wind fields are essential for decisions involving evacuation preparation and damage potential. Towards addressing these actions, a comparison of the CFAN tropical cyclone surface wind field model with the H*Wind wind field reanalyzes is done to assess the accuracy of the CFAN algorithm and to determine potential limitations of its use. 16 tropical cyclones were assessed through correlation coefficient, mean bias, and root mean square error. The resolution of initial conditions to be ingested into the model was also analyzed, along with storm type and whether or not wind shear was a limiting factor. Results suggest that the CFAN wind model accurately predicts the H*Wind analyses in most regions of the TC. The center of circulation has the highest error due to the CFAN wind model treating the center of circulation as a point rather than having finite lateral extent. Results from the sensitivity analysis based on input resolution show that the minimum input resolution for the CFAN wind model to produce fine spatial resolutions with high fidelity is 0.25°. It is shown that the reproductions of weaker tropical cyclones have lower accuracy due to wind field asymmetries within these systems, while stronger TCs are better reproduced, as these systems are usually better organized. Finally, through the wind shear analysis, it is shown that the accuracy of reconstruction is not dependent on the magnitude of vertical wind shear.
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Gray, Suzanne Louise. "Intensification and eye dynamics of tropical cyclones and polar lows." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336671.
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Parker, Bhawoodien Abbasmia. "Composite structure of tropical cyclones in the SW Indian Ocean." Master's thesis, University of Cape Town, 1994. http://hdl.handle.net/11427/19524.
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This work examines SW Indian Ocean tropical cyclone (TC) structure as a function of movement using ECMWF gridded data. Analyses of the mean summer climate for the period 1987 1992 shown that conditions conducive to the development ofTCs are present between the latitudes 5° and 15°S. Six westward moving TCs are selected to form the westward moving composite TC and four are used in the recurving TC composite from 3-days before the maximum surface intensity to 1 day after. The westward moving composite was found to have a steady TC signature. Comparisons were made with TC Firinga which passed near Mauritius on 29 January 1989. The recurving TC composite was found to exhibit rapid growth with sharp parameters tendencies. Interaction with a sub tropical trough is seen in both TC composites. Upper level westerly winds create effective uplift which strengthens the recurving TC on the poleward side. Spectral analysis of a rainfall index compiled from Mauritius data demonstrates spectral peaks at the seasonal and intra-seasonal scale. Three peaks were identified. one within the 40-60 day Madden Julian Oscillation. one at 23 days and one with a 16 day oscillation. The 23 day oscillation was found to have a highest spectral power. The results of TC and rainfall analyses offer useful insights to the climate and weather of the SW Indian Ocean.
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Wan, Mohammad Syarifah Kamariah. "Effects of cyclones on tropical rain forest structure and dynamics." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/29651/.
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Spatial patterns of forest trees, stand level effects of cyclones, and factors affecting mortality and growth of individual trees were investigated in 20 experimental plots (0.5 ha) in North Queensland tropical rain forests, Australia. Cyclone disturbance has been recorded in individual plots for 20 times since establishment in 1971. Spatial point patterns of trees were mapped, and pair correlation and mark correlation function were used to investigate relationships between the trees. Effects of cyclones on stand level properties of the forests (total basal area, stem densities, stem size inequality, species diversity, recruitment, mortality) were estimated using generalised additive modelling. Factors affecting individual tree mortality and growth were analysed in generalised mixed effects modelling. The spatial pattern analysis showed minor changes of tree density and tree death in the forest spatial patterns following cyclones. The models revealed that the forest properties were changed significantly. Cyclones decreasing total basal area and increased tree mortality rates and number of abundant species. Higher mortality rates are likely influenced by individual tree characteristics of low wood density, negative growth rates and belonging to particular sets of families. Factors that increase growth rates are include higher crowding effects of tree density, cyclone occurrence, crowding effects by smaller trees, and trees of some families. Slower growth rates are likely influenced by higher wood density, higher surrounding basal area of competing trees and in certain families. From this research, evidence has found for cyclones to be a factor increasing stand level mortality rates but not individual tree mortality. The dynamics from individual trees in mortality and growth, forest spatial patterns and stand level properties has characterised the tropical rain forests of North Queensland in facing frequent cyclone disturbances.
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Halterman, R. Ryan. "Observation and tracking of tropical cyclones using resolution enhanced scatterometry /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1667.pdf.
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Halterman, Richard Ryan. "Observation and Tracking of Tropical Cyclones Using Resolution Enhanced Scatterometry." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1062.
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The QuikSCAT scatterometer provides global daily coverage of oceanic near-surface vector winds. Recently, algorithms have been developed to enhance the spatial resolution of QuikSCAT winds from 25~km to 2.5~km posting. These ultra-high resolution winds are used, in comparison with standard L2B data product winds, to observe and track tropical cyclones. Resolution enhanced winds are found to provide additional storm structure such as inner core size and structure and the presence of multiple eyewalls compared with standard resolution winds. The 2.5~km winds are also able to observe storms nearer to the shore than 25~km winds. An analysis of circulation center locatability with each resolution wind field is performed. Center fixes with enhanced resolution winds are nearer the National Hurricane Center best-track positions than are standard resolution center fixes. A data and image set of every tropical cyclone worldwide observed by Seawinds on QuikSCAT or SeaWinds on ADEOS II from 1999 through 2005 is generated and made available to the scientific community at http://scp.byu.edu.
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Kelley, Owen A. "The association of tall eyewall convection with tropical cyclone intensification." Fairfax, VA : George Mason University, 2008. http://hdl.handle.net/1920/3073.
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Thesis (Ph.D.)--George Mason University, 2008.Vita: p. 320. Thesis director: Michael Summers. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computational Sciences and Informatics. Title from PDF t.p. (viewed July 3, 2008). Includes bibliographical references (p. 291-319). Also issued in print.
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Oliva, François. "Multi-Scale, Multi-Proxy Investigation of Late Holocene Tropical Cyclone Activity in the Western North Atlantic Basin." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36679.
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Paleotempestology, the study of past tropical cyclones (TCs) using geological proxy techniques, is a growing discipline that utilizes data from a broad range of sources. Most paleotempestological studies have been conducted using “established proxies”, such as grain-size analysis, loss-on-ignition, and micropaleontological indicators. More recently researchers have been applying more advanced geochemical analyses, such as X-ray fluorescence (XRF) core scanning and stable isotopic geochemistry to generate new paleotempestological records. This is presented as a four article-type thesis that investigates how changing climate conditions have impacted the frequency and paths of tropical cyclones in the western North Atlantic basin on different spatial and temporal scales.
The first article (Chapter 2; Oliva et al., 2017, Prog Phys Geog) provides an in-depth and up-to-date literature review of the current state of paleotempestological studies in the western North Atlantic basin. The assumptions, strengths and limitations of paleotempestological studies are discussed. Moreover, this article discusses innovative venues for paleotempestological research that will lead to a better understanding of TC dynamics under future climate change scenarios.
The second article (Chapter 3; Oliva et al., submitted, The Holocene) presents the development of the first database summarizing the most up-to-date paleotempestological proxy data available for TC reconstructions for the western North Atlantic basin. Subsets of this new database are then used to reconstruct TC variability in the western North Atlantic basin. Using our new developed subsets, we investigate a key hypothesis, the Bermuda High Hypothesis that has been proposed to have influenced TC paths over centennial to millennial timescales. Results show an oscillation in the distribution of TC landfalls along the North American coast, suggesting a centennial oscillation in the mean summer position of the high pressure system. We suggest that a more serious, millennial scale shift in the Bermuda High to a northeastern (NE position) may have occurred at ~3000 and ~1000 cal yr BP.
The third article (Chapter 4; Oliva et al., under review, Marine Geology) presents a local multi-proxy reconstruction of TC activity during the past 800 years from Robinson Lake, Chezzetcook Inlet in Nova Scotia, Canada. Here, we are testing the more recent use of the XRF scanning approach to paleotempestology at a local scale. Two sediment cores were extracted from Robinson Lake that were dated by 210Pb and 14C, analyzed for organic matter content, benthic foraminifera and thecamoebians, sediment grain size, and a range of elements and elemental ratios determined by XRF core scanning. Results show two periods of low TC activity based on multiple proxies including XRF technology: one from ~1150 to 1475 CE (800 – 475 cal yr BP) and the other from 1670 CE (280 cal yr BP) to the present, with the intervening period from ~1475 to 1670 CE (475 – 280 cal yr BP) as a time of more frequent and possibly higher magnitude TC activity.
The fourth article (Chapter 5. Oliva et al., in preparation, Canadian Journal of Earth Sciences) explores the potential use of stable oxygen isotopes in tree ring α-cellulose to reconstruct past local TC activity surrounding areas of known TC strikes. Cores of 12 Picea mariana trees were extracted adjacent to Robinson Lake, Chezzetcook Inlet, Nova Scotia in order to test more contemporary and historically documented records of TC activity in this region as per Chapter 4. TCs precipitate 18O-depleted rain, leaving a unique signature in the source water that trees use to form cellulose. Using an autoregressive integrated moving average (ARIMA AR-1) model to detrend the data, local and regional time series were reconstructed. Local reconstructions led to most (> 95%) hurricanes and all major hurricane (± 1 year) being recorded in the isotope record, whereas the regional reconstruction shows no major hurricane, only a few hurricanes (< 40%) and one signal with a higher error (> 1 year).
This thesis contributes to advancing our knowledge in paleotempestology of the western North Atlantic basin by: 1) bringing an up-to-date current status on paleotempestology, 2) the development and ongoing use of a new paleotempestology database for the western North Atlantic basin publicly available, 3) a local scale study using new XRF core elemental technology and 4) the exploratory use of tree-ring α-cellulose oxygen isotopic analysis based on contemporary and historical documents at local sites.
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Long, Dana Marie. "Excitation of Low-Level Energy Wave Accumulations and Tropical Cyclone Formation." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7282.
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A spectral shallow water model is used at the 850 mb level to investigate the effects of cyclonic vorticity on heating in the lower troposphere and how this in turn causes an increase in cyclonic vorticity generation, creating a nonlinear vorticity feedback mechanism.
The model is initialized with NCEP-NCAR reanalysis data from the period 1990-2003 and then used to simulate a heating forcing function centered in east Africa. The model is simulated using a Gaussian damped basic state, a zonally symmetric basic state, and a zero basic state. The heating forcing function is applied to these different basic states with a scaled mass sink to simulate heating in the atmosphere. The heating forcing function creates a vorticity feedback mechanism that increases cyclonic vorticity.
The analysis of these different basic states shows that the Gaussian damped basic state reduces the amplitude of the observational fields at the poles, increases the observational fields in the tropical region and increases the stability of the model at shallow depths. The zero basic state does have a significant effect on cyclonic vorticity generation, but does not improve the capability of the wave to propagate westward into the Atlantic Ocean. The zonally symmetric basic state succeeds in increasing the amount of cyclonic vorticity generated. The zonally symmetric basic state, once the vorticity non-feedback region is extended, is also very effective at increasing the amount of cyclonic vorticity generated and increasing the propagation of this wave westward into the Atlantic Ocean. The analysis suggests that the vorticity feedback mechanism created by the heating forcing function is affected by cyclonic vorticity when a zero and zonally symmetric basic state are used.
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Rossouw, Cobus. "The probability of occurrence and the intensity of tropical cyclones along the Southern African East Coast /." Thesis, Link to the online version, 1999. http://hdl.handle.net/10019.1/3633.
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