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Articles 31 - 46 of 46
Full-Text Articles in Atmospheric Sciences
The Intensification Of Sheared Tropical Cyclones, Leon Nguyen
The Intensification Of Sheared Tropical Cyclones, Leon Nguyen
Legacy Theses & Dissertations (2009 - 2024)
Environmental vertical wind shear has been shown to have a generally detrimental impact on tropical cyclone (TC) intensity change. However, many cases of rapidly intensifying (RI) sheared TCs have been observed, and TCs in moderate (5-10 m s-1) shear often have the largest intensity forecast errors. Thus, advancing the understanding of TC-shear interactions is vital to improving TC intensity forecasts, which have not seen much improvement over the past few decades. This dissertation employs both observational and high-resolution numerical modeling approaches to investigate how some TCs are able to resist shear and intensify.
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.
Global View Of The Role Of The Itcz/Monsoon Trough In Tropical Cyclogenesis, Steven Fuhrman
Global View Of The Role Of The Itcz/Monsoon Trough In Tropical Cyclogenesis, Steven Fuhrman
Legacy Theses & Dissertations (2009 - 2024)
ABSTRACT
Northeast Cool-Season Cyclones Associated With Significant Upper-Level Easterly Wind Anomalies, Adrian Mitchell
Northeast Cool-Season Cyclones Associated With Significant Upper-Level Easterly Wind Anomalies, Adrian Mitchell
Legacy Theses & Dissertations (2009 - 2024)
A subset of Northeast U.S. cool-season cyclones is associated with upper-level easterly flow and, occasionally, well-defined easterly jet streaks. These events occur approximately once per year and may be associated with retrograding surface cyclones and precipitation caused by northerly warm-air advection, leading to forecast challenges. The deepest extratropical cyclone that affected the Northeast U.S. during the 2009-2010 cool-season was associated with an upper-level easterly jet streak, and produced a record snowfall total of 85 cm in Burlington, Vermont. Orographic precipitation enhancement in this case resulted from an interaction of the low-level flow with the complex topography of northern Vermont. This …
A Climatology Of Central American Gyres, Philippe Pierre Papin
A Climatology Of Central American Gyres, Philippe Pierre Papin
Legacy Theses & Dissertations (2009 - 2024)
Central American gyres (CAGs) are large, low-level, cyclonic circulations that are observed over Central America during the tropical cyclone (TC) season. CAGs often occur in conjunction with TCs, and can result in torrential rainfall over portions of Central America, the Caribbean Islands, and eastern United States. The lack of prior research on CAGs, their apparent links to TC activity, and their association with high- impact weather motivates this study.
Upper-Tropospheric Precursors Associated With Subtropical Cyclone Formation In The North Atlantic Basin, Alicia Marie Bentley
Upper-Tropospheric Precursors Associated With Subtropical Cyclone Formation In The North Atlantic Basin, Alicia Marie Bentley
Legacy Theses & Dissertations (2009 - 2024)
Oceanic cyclones exhibiting properties of both tropical and extratropical systems have been categorized as subtropical cyclones (STCs) since the early 1950s. The opportunity to investigate the roles of baroclinic and diabatic processes during the evolution of STCs from a potential vorticity (PV) perspective motivates this study. This study investigates the roles of baroclinic and diabatic processes during the evolution of STCs by calculating three PV metrics from the National Centers for Environmental Prediction Climate Forecast System Reanalysis 0.5° gridded dataset. The three PV metrics quantify the relative contributions of lower-tropospheric baroclinic processes, midtropospheric diabatic heating, and upper-tropospheric dynamical processes during …
An Analysis Of Arctic Climate, The Intense Arctic Cyclone Of Early August 2012, And Middle To High Latitude Snowcover, Adam H. Turchioe
An Analysis Of Arctic Climate, The Intense Arctic Cyclone Of Early August 2012, And Middle To High Latitude Snowcover, Adam H. Turchioe
Legacy Theses & Dissertations (2009 - 2024)
On 03 August 2012, a cyclone formed over Central Siberia and progressed northeastwards. By 0000 UTC 05 August, the cyclone reached the Arctic Ocean with a mean sea-level pressure (MSLP) of 984 hPa. Once over the Arctic Ocean, the cyclone rapidly intensified and reached a minimum pressure of 966 hPa on 06 August near 83°N and 170°W. The cyclone slowly weakened, and on 0000 UTC 10 August once again had a minimum MSLP of 984 hPa. The motivation for this presentation is driven by the likelihood that this cyclone is one of the most intense storm systems to ever impact …
Observed Versus Gcm-Generated Local Tropical Cyclone Frequency: Comparisons Using A Spatial Lattice, Sarah Strazzo, Daniel J. Halperin, James Elsner, Tim Larow, Ming Zhao
Observed Versus Gcm-Generated Local Tropical Cyclone Frequency: Comparisons Using A Spatial Lattice, Sarah Strazzo, Daniel J. Halperin, James Elsner, Tim Larow, Ming Zhao
Publications
Of broad scientific and public interest is the reliability of global climate models (GCMs) to simulate future regional and local tropical cyclone (TC) occurrences. Atmospheric GCMs are now able to generate vortices resembling actual TCs, but questions remain about their fidelity to observed TCs. Here the authors demonstrate a spatial lattice approach for comparing actual with simulated TC occurrences regionally using observed TCs from the International Best Track Archive for Climate Stewardship (IBTrACS) dataset and GCM-generated TCs from the Geophysical Fluid Dynamics Laboratory (GFDL) High Resolution Atmospheric Model (HiRAM) and Florida State University (FSU) Center for Ocean–Atmospheric Prediction Studies (COAPS) …
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).
Multiscale Analyses Of Inland Tropical Cylcone--Midlatitude Jet Interactions : Camille (1969) And Danny (1997), Matthew S. Potter
Multiscale Analyses Of Inland Tropical Cylcone--Midlatitude Jet Interactions : Camille (1969) And Danny (1997), Matthew S. Potter
Legacy Theses & Dissertations (2009 - 2024)
TC Camille (1969) and TC Danny (1997) both interacted with the equatorward entrance region of an upper-tropospheric jet as they traversed the Appalachian Mountains; however, their societal impacts differed. During the 12-h period starting 0000 UTC 20 August 1969, 690 mm of rain fell over Massies Mill, Virginia, as TC Camille traversed the central Appalachian Mountains. On 24 July 1997, TC Danny underwent inland reintensification while moving across the Carolinas. TC Danny's minimum central mean sea level pressure decreased from 1012 hPa to 1000 hPa and its maximum sustained wind speed increased from 20 kt to 40 kt during the …
Large-Scale Influences On The Pre-Genesis Of Tropical Cyclone Karl (2010), Kyle S. Griffin
Large-Scale Influences On The Pre-Genesis Of Tropical Cyclone Karl (2010), Kyle S. Griffin
Legacy Theses & Dissertations (2009 - 2024)
The genesis of Tropical Cyclone (TC) Karl (2010) in September 2010 provided a unique opportunity to examine the continuing problem of understanding tropical cyclogenesis. The precursor disturbance to Karl originated from a cluster of showers east of the Windward Islands and was well sampled by ongoing field campaigns, particularly the PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT), as the targeted disturbance progressed westward. While traditional genesis theories focusing on moisture and mass fields (e.g. top-down showerhead method) can explain the initial spin-up of the disturbance several days prior to its official genesis, additional perspectives are examined in concert with …
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. …
Tropical Cyclogenesis Associated With Extratropical Precursors In The North Atlantic Basin, Thomas J. Galarneau
Tropical Cyclogenesis Associated With Extratropical Precursors In The North Atlantic Basin, Thomas J. Galarneau
Legacy Theses & Dissertations (2009 - 2024)
This thesis investigates genesis pathways of tropical cyclones (TCs) over the North Atlantic basin during 2004-2008 with a focus on TCs that form in conjunction with extratropical precursor disturbances. These genesis pathways are nonbaroclinic, low-level baroclinic, trough-induced, transient-trough interaction, weak tropical transition (TT), and strong TT. The transient-trough interaction, trough-induced, weak TT, and strong TT genesis pathways all occur in conjunction with extratropical precursor disturbances. This thesis will assess the physical and dynamical mechanisms relevant to TC genesis among these genesis pathways via composite and case study analyses.
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.
Improved Associated Conditions In Rapid Intensifications Of Tropical Cyclones, Ruixin Yang, J. Tang, Menas Kafatos
Improved Associated Conditions In Rapid Intensifications Of Tropical Cyclones, Ruixin Yang, J. Tang, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
Rapid intensification (RI) of tropical cyclones (TC) is a major error source in TC intensity forecasting. In order to improve the estimates of RI probability, association rules are used to facilitate the process of mining for candidate sets of conditions. Compared to the relation analysis method, the technique of association rules can simply explore associations among multiple conditions. Our mining results identified a reduced predictor set with fewer factors identified in previous studies but improved RI probabilities. That is, the RI probability with three conditions satisfied: low vertical shear, high humidity, and the TC being in an intensification phase is …