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Full-Text Articles in Meteorology
A Comparison Of The Upscale Influence Of Various Planetary Boundary Layer Turbulence Parameterizations On The Evolution Of Extratropical Cyclones, Matthew Vaughan
A Comparison Of The Upscale Influence Of Various Planetary Boundary Layer Turbulence Parameterizations On The Evolution Of Extratropical Cyclones, Matthew Vaughan
Legacy Theses & Dissertations (2009 - 2024)
Subgrid-scale turbulence in numerical weather prediction models is typically handled by a PBL parameterization. These schemes attempt to represent turbulent mixing processes occurring below the resolvable scale of the model grid in the vertical direction, and they act upon temperature, moisture, and momentum within the boundary layer. This dissertation utilizes idealized and full-physics numerical model simulations to understand how variations in turbulent mixing parameterizations may influence sensible weather forecasts of baroclinic cyclones across a variety of spatial and temporal scales. Furthermore, a primary pathway through which PBL turbulence projects upscale during baroclinic cyclone events is identified using a combination of …
Influence Of Upper-Tropospheric Troughs On Tropical Cyclone Intensity Change And Structure : Observational, Reanalysis, And Idealized Numerical Modeling Perspectives, Casey Peirano
Legacy Theses & Dissertations (2009 - 2024)
The interaction between tropical cyclones (TCs) and upper-tropospheric troughs is a
The Upper-Level Turbulence, Static Stability And Tropopause Structure Of Tropical Cyclones, Patrick Duran
The Upper-Level Turbulence, Static Stability And Tropopause Structure Of Tropical Cyclones, Patrick Duran
Legacy Theses & Dissertations (2009 - 2024)
Upper-tropospheric thermodynamic processes can play an important role in tropical cyclone (TC) structure and evolution. Despite its importance, until recently few in-situ observations were available in the upper levels of TCs. Two recent field campaigns -- the National Aeronautics and Space Administration (NASA) Hurricane and Severe Storm Sentinel (HS3) and the Office of Naval Research Tropical Cyclone Intensity (TCI) experiment -- provided a wealth of high-altitude observations within TCs. These observations revealed that the upper-level static stability and tropopause structure of TCs can change dramatically with both space and time.
Predictability Of African Easterly Waves In An Operational Ensemble Prediction System, Travis J. Elless
Predictability Of African Easterly Waves In An Operational Ensemble Prediction System, Travis J. Elless
Legacy Theses & Dissertations (2009 - 2024)
African easterly waves (AEWs) are the primary synoptic-scale weather feature found in sub-Saharan Africa during boreal summer. Many studies have used observations and idealized models to highlight processes associated with the movement and growth of AEWs, yet there have been few studies documenting the performance of operational ensemble prediction systems (EPSs) for these phenomena. Here, the predictability of AEWs in ECMWF EPS forecasts is assessed during two periods of enhanced AEW activity (July--September 2007--2009 and 2011--2013). Specifically, AEW predictability is analyzed through three main areas of focus: 1) verifying AEW position and intensity forecasts, and assessing their relation to convective …
Tropical Cyclone Rapid Intensification In Environments Of Upper-Tropospheric Troughs : Environmental Influences And Convective Characteristics, Michael Fischer
Tropical Cyclone Rapid Intensification In Environments Of Upper-Tropospheric Troughs : Environmental Influences And Convective Characteristics, Michael Fischer
Legacy Theses & Dissertations (2009 - 2024)
Intensity forecasts for tropical cyclones that undergo a period of rapid intensification are particularly susceptible to large errors. For those storms that interact with an upper-tropospheric trough, tropical cyclone intensity forecasts are complicated, as upper-tropospheric troughs can provide unique intensification mechanisms, but are often associated with unfavorable environmental conditions. Although tropical cyclones in environments with nearby upper-tropospheric troughs are associated with lesser intensification rates than tropical cyclones in environments devoid of upper-tropospheric troughs, some tropical cyclone--trough interactions are associated with a period of rapid intensification. This dissertation utilizes reanalysis output, satellite observations, and ensemble modeling simulations to understand whether rapid …
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 …
Turbulence In The Upper Levels Of Tropical Cyclones, Michaela Leigh Rosenmayer
Turbulence In The Upper Levels Of Tropical Cyclones, Michaela Leigh Rosenmayer
Legacy Theses & Dissertations (2009 - 2024)
Turbulence in the cirrus canopy of tropical cyclones (TCs) can give an indication about the physical processes that occur in this expansive cloud deck. The low stability and/or large shear that likely coincides with turbulent layers can be produced by radiative forcing, convective forcing, and sublimation of frozen precipitation from the cirrus canopy. As a result, turbulence in the cirrus canopy can give an indication about the impact of various physical processes in tropical cyclones.
Evolution Of African Easterly Waves And Their Relationship To Tropical Cyclogenesis, Alan Brammer
Evolution Of African Easterly Waves And Their Relationship To Tropical Cyclogenesis, Alan Brammer
Legacy Theses & Dissertations (2009 - 2024)
The research in this thesis explores the relationship between African easterly waves (AEWs) and tropical cyclogenesis over the eastern Atlantic. This research utilises 33 years of reanalysis and satellite data to investigate the interaction between AEW troughs, the surrounding environment and the embedded vortex.
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.
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).