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Articles 1 - 12 of 12
Full-Text Articles in Physical Sciences and Mathematics
Changes In Large-Scale Extreme Precipitation In Over Taiwan And The Northeast United States : Past And Future, Lexi Henny
Legacy Theses & Dissertations (2009 - 2024)
Large-scale extreme precipitation over (1) the mid-Atlantic and Northeast United States and (2) Taiwan is attributed to weather types such as atmospheric river (AR), TC, and extreme integrated vapor transport (IVT). Statistically significant increases in season-total EP day precipitation are seen at many GHCN stations in winter, summer, and fall in the mid-Atlantic and Northeast region, and at certain high-elevation grid points in Taiwan Mei-yu season. During the cold season of winter and spring, the U.S.-based changes come from AR-associated EP days and are associated with strengthened southwesterly winds and IVT either within EP days, in the season mean, or …
It Takes Two To Tango : Understanding The Processes That Lead To Simultaneous Changes In Tropical Cyclone Intensity And Size And Communicating The Associated Hazards To Emergency Managers, Emily A. Paltz
Legacy Theses & Dissertations (2009 - 2024)
The severity of tropical cyclone (TC) hazards is modulated by both TC intensity and size. More intense TCs produce stronger storm surges and increase wind damage. Larger TCs potentially impact more people, increase the duration of TC hazards, produce stronger storm surges and increase the amount of rainfall and flooding. Thus, accurately forecasting both TC intensity and size and effectively communicating those forecasts are critical to properly preparing communities for TC impacts. Forecast accuracy can be improved by enhancing our understanding about the processes that cause changes in TC intensity and size. This research divides the Extended Best Track dataset …
The Sensitivity Of Convection To Boundary Layer Parameterization In Hurricanes Harvey And Irma 2017, Dylan Card
The Sensitivity Of Convection To Boundary Layer Parameterization In Hurricanes Harvey And Irma 2017, Dylan Card
Legacy Theses & Dissertations (2009 - 2024)
Tropical cyclones (TCs) pose a significant threat to life and property, and exhibit many severe weather hazards as they make landfall, such as storm surge, strong winds, flooding rains, and tornadoes. TC convection is associated with nearly all of these hazards, which can extend hundreds of kilometers inland; thus, understanding the characteristics and organization of convective cells is important to mitigating risk. Observational studies have noted that TC convection tends to organize downshear and that rotating thunderstorms tend to occur in the downshear-right quadrant of the TC. Modeling studies have also shown that convective cells tend to form upshear right …
A Revised Technique For Measuring Vertical Velocity Using Dropsondes, Timothy Connor Nelson
A Revised Technique For Measuring Vertical Velocity Using Dropsondes, Timothy Connor Nelson
Legacy Theses & Dissertations (2009 - 2024)
The earliest iterations of dropsondes in the 1960's obtained vertical velocity by measuring the geometric fall speed of the dropsonde and the true airspeed (TAS) of the dropsonde from a pitot-static. The vertical velocity errors from this methodology were claimed to be ±1 m s-1. Subsequent dropsonde iterations used various forms of the drag force equation to obtain vertical velocity. The accuracy of these drag force-based measurements, however, are also quite large at ±1–2 m s-1. In this dissertation, an attempt is made to improve vertical velocity errors by revisiting and revising the pitot-static-derived TAS methodology on the eXpendable Digital …
Influence Of Lightning-Producing Convection On Tropical Cyclone Intensity Change, Stephanie Stevenson
Influence Of Lightning-Producing Convection On Tropical Cyclone Intensity Change, Stephanie Stevenson
Legacy Theses & Dissertations (2009 - 2024)
Lightning observations in tropical cyclones (TCs) over the ocean are a recent advance- ment, and while many studies have noted relationships between lightning and TC intensity change, the relationships are not consistent. This dissertation aims to understand the com- plexities of the relationships between lightning and TC intensity change, and associate the relationships to storm kinematic, thermodynamic, and microphysical processes.
Tropical Cyclone Intensification Under Moderate Vertical Wind Shear, Rosimar Rios-Berrios
Tropical Cyclone Intensification Under Moderate Vertical Wind Shear, Rosimar Rios-Berrios
Legacy Theses & Dissertations (2009 - 2024)
Deep-layer (200–850 hPa) vertical wind shear is generally an inhibiting factor for tropical cyclone intensification. Multiple studies—ranging from case studies to climatological analyses—have consistently shown that the chances of tropical cyclone intensification decrease with increasing vertical wind shear magnitude. However, tropical cyclones can intensify under moderate shear—the range of shear magnitudes that are neither too weak to have negligible influence on intensity nor too strong to completely halt intensification. Intensity, track, and precipitation forecasts of tropical cyclones under moderate shear can be highly uncertain; therefore, explaining how tropical cyclones evolve under seemingly unfavorable conditions is an important step towards improved …
Evaluating Preferred Direction Tropical Cyclone Track Variability In An Operational Global Ensemble Prediction System, Travis Elless
Evaluating Preferred Direction Tropical Cyclone Track Variability In An Operational Global Ensemble Prediction System, Travis Elless
Legacy Theses & Dissertations (2009 - 2024)
Ensemble forecasts of Tropical Storm Debby and Hurricane Sandy (2012) highlight instances where variability in tropical cyclone (TC) position forecasts are stretched along a preferred direction. The goal of this thesis is to analyze this stretching of variability in a global ensemble prediction system, particularly the European Centre for Medium-Range Weather Forecasts (ECMWF), to determine how often and under what conditions does variability stretching occur, and ultimately what feature(s) are responsible for generating this variability.
An Analysis Of The Formation And Evolution Of The 1989 Western North Pacific Subtropical Gyre, Brian Andrew Crandall
An Analysis Of The Formation And Evolution Of The 1989 Western North Pacific Subtropical Gyre, Brian Andrew Crandall
Legacy Theses & Dissertations (2009 - 2024)
This thesis conducts an observational study of a large cyclonic gyre that developed in the Western North Pacific (WNP) in late July 1989. For a period of six days, azimuthally-averaged winds at 850 hPa remained cyclonic out from the center of circulation to the 2000 km radius, with azimuthally-averaged tangential wind speeds at or greater than 10 m s-1. The gyre exhibited an asymmetric convection pattern, with the center, north and west flanks devoid of large convective areas, but the southern and eastern flanks maintained large-scale convective regions, extending as much as 4000 km in longitude.
Convectively-Coupled Kelvin Waves Over The Tropical Atlantic And African Regions And Their Influence On Atlantic Tropical Cyclogenesis, Michael John Ventrice
Convectively-Coupled Kelvin Waves Over The Tropical Atlantic And African Regions And Their Influence On Atlantic Tropical Cyclogenesis, Michael John Ventrice
Legacy Theses & Dissertations (2009 - 2024)
High-amplitude convectively coupled atmospheric Kelvin waves (CCKWs) are explored over the tropical Atlantic during the boreal summer. Atlantic tropical cyclogenesis is found to be more frequent during the passage of the convectively active phase of the CCKW, and most frequent two days after its passage. CCKWs impact convection within the mean latitude of the inter-tropical convergence zone over the northern tropical Atlantic. In addition to convection, CCKWs also impact the large scale environment that favors Atlantic tropical cyclogenesis (i.e., deep vertical wind shear, moisture, and low-level relative vorticity).
Easterly Waves And Tropical Cyclogenesis In The Caribbean, Kay Louise Shelton
Easterly Waves And Tropical Cyclogenesis In The Caribbean, Kay Louise Shelton
Legacy Theses & Dissertations (2009 - 2024)
This thesis is concerned with the evolution of easterly waves in the Atlantic and Caribbean and their relationship to tropical cyclogenesis. Motivation for this study is the apparent "genesis hole" in the eastern Caribbean and the lack of knowledge regarding the evolution of the transient disturbances passing through this region. The environment of the Caribbean is reviewed revealing large vertical wind shear and dry mid-levels as the key factors determining the presence of the genesis hole.
The Downstream Extratropical Flow Response To Recurving Western North Pacific Tropical Cyclones, Heather M. Archambault
The Downstream Extratropical Flow Response To Recurving Western North Pacific Tropical Cyclones, Heather M. Archambault
Legacy Theses & Dissertations (2009 - 2024)
The factors that govern the downstream flow response to recurving western North Pacific (WNP) tropical cyclones (TCs) are investigated from climatological, composite analysis, case study, and predictability perspectives. A 1979–2009 climatology of WNP TC recurvature indicates that TC recurvature is followed by a four-day period of above-normal North Pacific meridional flow. The relationship between TC recurvature and above-normal North Pacific meridional flow is found to be stronger in late summer through mid-fall than in early summer and early winter, and stronger for TCs that interact strongly with the jet stream than for TCs that interact weakly with the jet stream. …
Role Of Equatorial Waves In Tropical Cyclogenesis, Carl J. Schreck, Iii
Role Of Equatorial Waves In Tropical Cyclogenesis, Carl J. Schreck, Iii
Legacy Theses & Dissertations (2009 - 2024)
Tropical cyclones typically form within preexisting wavelike disturbances that couple with convection. Using Tropical Rainfall Measuring Mission (TRMM) multisatellite rainfall estimates, this study determines the relative number of tropical cyclones that can be attributed to various wave types, including the Madden-Julian oscillation (MJO), Kelvin waves, equatorial Rossby (ER) waves, mixed Rossby-gravity (MRG) waves, and tropical depression (TD)-type disturbances. Tropical cyclogenesis is attributed to an equatorial wave's convection when the filtered rainfall anomaly exceeds a threshold value at the genesis location.