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Articles 181 - 201 of 201
Full-Text Articles in Physical Sciences and Mathematics
Rainfall And Streamflow Variability In Ghana, Michael Mawutor Tanu
Rainfall And Streamflow Variability In Ghana, Michael Mawutor Tanu
Legacy Theses & Dissertations (2009 - 2024)
The objective of this research is to investigate the variability of rainfall and streamflow over Ghana. Analyses of rainfall shows larger daily variability and maxima amounts in the southern coastal belt than in either the middle or northern parts of the country. The high variability in rainfall at the coast is associated with sea surface temperatures (SSTs) changes over the Guinea coast. This is related to the evolution of the cold tongue over the Atlantic during the rainfall season. The results indicate that the extreme rainfall events occur as single events, but there are occasions when they occur sequentially, and …
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).
A Preliminary Climatology Of Tropical Moisture Exports In The Southern Hemisphere, Alicia M. Bentley, Lance F. Bosart, Jason M. Cordeira
A Preliminary Climatology Of Tropical Moisture Exports In The Southern Hemisphere, Alicia M. Bentley, Lance F. Bosart, Jason M. Cordeira
Atmospheric & Environmental Sciences
Heavy precipitation events in the midlatitudes can be supported by the poleward transport of tropical air masses within the warm sector of extratropical cyclones. Previous studies have established a climatology of the four preferred pathways of tropical moisture export (TME) events into the midlatitudes over the Northern Hemisphere (NH). The present study constructs a similar climatology of TME timing and frequency over the Southern Hemisphere (SH), highlighting three preferential regions for tropicalmidlatitude interaction. These regions correspond to the locations of the: (i) South Pacific convergence zone (Pacific Ocean pathway, PO), (ii) South Atlantic convergence zone (South American pathway, SA), and …
Searching For Melting-Induced Cold-Pool Circulations In An Oklahoma Winter Storm, Gabriel Susca-Lopata
Searching For Melting-Induced Cold-Pool Circulations In An Oklahoma Winter Storm, Gabriel Susca-Lopata
Atmospheric & Environmental Sciences
This paper investigates the thermodynamic and dynamic impacts of melting precipitation through a case study of an Oklahoma winter storm. On 28 January 2005 a rain and snow event affected the state of Oklahoma. A combination of radiosonde data, wind profiler data, radar imagery and Oklahoma Mesonet surface data show that latent cooling from melting caused the surface temperatures to fall in western Oklahoma while evaporation caused surface cooling in central and eastern Oklahoma. The wind and surface pressure fields in western Oklahoma are analyzed along with radar data from Frederick Air Force Base, and some limited evidence for melting-driven …
Analysis Of Banding In 26-27 December 2010 East Coast Blizzard, Sara Ganetis
Analysis Of Banding In 26-27 December 2010 East Coast Blizzard, Sara Ganetis
Atmospheric & Environmental Sciences
Blizzard conditions occurred in the New York City metropolitan area and portions of adjacent southern New England on 26-27 December 2010 in conjunction with a strong coastal cyclone. Parts of New Jersey received over 80 cm of snow while Long Island and coastal Connecticut observed wind gusts of over 30 ms-1. The heaviest snow was concentrated along a north-south oriented mesoscale snowband that extended from coastal New Jersey northward through the New York City metropolitan area. This mesoscale snowband, which remained quasi-stationary for approximately 12 h, was associated with strong low and mid-level frontogenetical forcing. In addition to the primary …
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 Influence Of The Great Lakes On Mcs Formation And Development In The Warm Season, Alan Frederick Srock
The Influence Of The Great Lakes On Mcs Formation And Development In The Warm Season, Alan Frederick Srock
Legacy Theses & Dissertations (2009 - 2024)
This study focuses on how near-surface thermal boundaries that form near the Great Lakes during the warm season can contribute to the formation of mesoscale convective systems (MCSs). Differential heating across land-water interfaces can create a cold dome of air over the lake; convection may develop when the relatively-cold dome of air becomes deep enough to enable air parcels that intersect these boundaries to reach their level of free convection. A radar-based climatology of MCS events surrounding the Great Lakes for 2002-2005 showed that MCSs frequently form in the vicinity of the Great Lakes. Composites of MCS events over the …
Review Of The Simulation Of The Precis Regional Climate Model Over Tropical South America Using Gcm And Reanalysis Lateral Boundary Conditions, Dana Mcglone
Legacy Theses & Dissertations (2009 - 2024)
High-resolution regional climate models (RCM) run over a limited domain are increasingly used to simulate seasonal to interannual climate variability over South America and to assess the spatiotemporal impact of future climate change under a variety of emission scenarios. Global climate models (GCM) are often too coarse to resolve local circulations and the topography of the Andes, leading to problems with simulation of temperature and precipitation patterns throughout the domain. A RCM model can also better represent the climate at a regional scale; however, they are subject to errors introduced by the driving global models. For this study, the Hadley …
Northeast United States Heat Waves : A Statistical Analysis And Synoptic Climatology, Scott Cooper Runyon
Northeast United States Heat Waves : A Statistical Analysis And Synoptic Climatology, Scott Cooper Runyon
Legacy Theses & Dissertations (2009 - 2024)
The results of a statistical analysis of anomalously hot day and heat wave frequency in the United States (U.S.) are presented, along with a synoptic climatology of northeast U.S. heat waves (NHWs) for 1948-2001. This study used daily high temperatures retrieved from the National Climatic Data Center (NCDC) Daily Surface Dataset for 54 stations binned into the nine standard NCDC climate regions. Anomalously hot days were defined as when the daily high temperature exceeded the climatological 97.5-percentile temperature. Heat waves were defined as at least three consecutive anomalously hot days, whereas regional heat waves (e.g., NHWs) were defined as simultaneous …
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-Extratropical Interactions And Arctic-Extratropical Interactions Conducive To Intraseasonal Variability Of The North Pacific Jet Stream, Jason Michael Cordeira
Tropical-Extratropical Interactions And Arctic-Extratropical Interactions Conducive To Intraseasonal Variability Of The North Pacific Jet Stream, Jason Michael Cordeira
Legacy Theses & Dissertations (2009 - 2024)
The autumnal spin up of the Northern Hemisphere (NH) general circulation is characterized by intraseasonal variability in the structure of the North Pacific jet stream (NPJ). The variability in the structure of the NPJ is often associated with large-scale flow reconfigurations over the North Pacific and North America and changes in the NH zonal available potential energy (AZ). This dissertation investigates variability in the structure of the NPJ and the NH AZ in conjunction with tropical-extratropical interactions (TEIs) and arctic-extratropical interactions (AEIs). The former are investigated in association with the El Niño-Southern Oscillation, the Madden-Julian Oscillation, and western North Pacific …
Significance Of Hno3 Acid Photolysis On Surfaces In Tropospheric Chemistry, Honglian Gao
Significance Of Hno3 Acid Photolysis On Surfaces In Tropospheric Chemistry, Honglian Gao
Legacy Theses & Dissertations (2009 - 2024)
The reactive nitrogen trace gases (NOy) including nitrogen oxides (NOx) and their secondary products are known to cause ground-level ozone pollution, photochemical smog, acid deposition, and overall air quality degradation. NOx was believed to be permanently removed from the atmospheric by HNO3 formation and deposition. However, our laboratory experimental results show that HNO3 can be remobilized back to photochemically labile HONO and NOx (re-NOx-ification). We have verified and quantified HONO and NOx production from the photolysis of HNO3 on various surfaces, including Pyrex, leaves of plants, and other environmentally relevant …
Origin And Maintenance Of The Stable Boundary Layer In A Patchy Landscape, Luiz Eduardo Medeiros
Origin And Maintenance Of The Stable Boundary Layer In A Patchy Landscape, Luiz Eduardo Medeiros
Legacy Theses & Dissertations (2009 - 2024)
Field observations made in Hudson Valley region, NY during the Hudson Valley Ambient Meteorology Study (HVAMS) are analyzed to examine how terrain and land cover influence nocturnal mixing in real-world landscapes. Important terrain features such as local topographic concavity and site sheltering are shown to exhibit systematic influence on turbulent intermittency and on the consequent nocturnal heat and momentum fluxes. Very local obstacles have their most important effects on mixing during strong winds (> 5m/s). Local terrain concavity was found to be the more important factor influencing surface fluxes than sheltering for all classes of winds.
Persistence And Dissipation Of Lake Michigan-Crossing Mesoscale Convective Systems, Nicholas Metz
Persistence And Dissipation Of Lake Michigan-Crossing Mesoscale Convective Systems, Nicholas Metz
Legacy Theses & Dissertations (2009 - 2024)
This thesis investigates mature mesoscale convective systems (MCSs) that traversed Lake Michigan to elucidate synoptic-scale and Lake Michigan-related features that discriminate between persistence and dissipation. Of the 110 coherent MCSs that crossed Lake Michigan during the warm seasons (April–September) of 2002–2007, 47 (43%) persisted, while 63 (57%) dissipated. Persistence was favored during July and August, when Lake Michigan was warmer and during the evening and overnight, when the low-level jet (LLJ) was most intense. However, a number of MCSs also persisted during the early warm season when the Lake Michigan water temperature was cooler than the surrounding land.
Retrieval Of Atmospheric Elemental Carbon Records Using Lake Sediments : Implications In Radiative Forcing, Tanveer Ahmed
Retrieval Of Atmospheric Elemental Carbon Records Using Lake Sediments : Implications In Radiative Forcing, Tanveer Ahmed
Legacy Theses & Dissertations (2009 - 2024)
Elemental or black carbon (EC or BC) aerosols produced during incomplete combustion strongly absorb solar radiation and contribute to global warming, and cause cardiopulmonary disease. Long-term atmospheric EC measurements, [EC]atm, are needed to validate global climate models to estimate the impact of EC on earth's temperature. Such data is sparse.
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.
Effect Of Noise In Principal Component Analysis With An Application To Ozone Pollution, Katerina G. Tsakiri
Effect Of Noise In Principal Component Analysis With An Application To Ozone Pollution, Katerina G. Tsakiri
Legacy Theses & Dissertations (2009 - 2024)
This thesis analyzes the effect of independent noise in principal components of k normally distributed random variables defined by a covariance matrix. We prove that the principal components as well as the canonical variate pairs determined from joint distribution of original sample affected by noise can be essentially different in comparison with those determined from the original sample. However when the differences between the eigenvalues of the original covariance matrix are sufficiently large compared to the level of the noise, the effect of noise in principal components and canonical variate pairs proved to be negligible. The theoretical results are supported …
African Easterly Waves And Convection, Gareth James Berry
African Easterly Waves And Convection, Gareth James Berry
Legacy Theses & Dissertations (2009 - 2024)
In this research the physical mechanisms relating synoptic scale African Easterly Waves (AEWs) and convection are explored using a variety of analysis techniques.
Measurement Of Atmospheric Ammonia Species : Development, Validation, And Field Applications Of An Analytical Method, Jian Hou
Legacy Theses & Dissertations (2009 - 2024)
Ammonia is the primary base in the atmosphere. It reacts readily with atmospheric acids such as sulfuric acid, nitric acid, and hydrochloric acid to form ammonium salts that occur predominantly in the fine aerosol particle (PM2.5) fraction. The ability to measure ammonia species (NHx, the sum of gaseous NH3 and particulate NH4+) is essential for the investigation of atmospheric behaviors of NHx. In this dissertation work, a highly sensitive technique has been developed for the measurement of atmospheric NHx species. The method is based on aqueous scrubbing of the atmospheric NH3 and NH4+ using …
The Investigation Of Snowfall Rate Using Optical Techniques, Gerald J. Mulvey
The Investigation Of Snowfall Rate Using Optical Techniques, Gerald J. Mulvey
Atmospheric and Environmental Sciences Theses and Dissertations
Experiments involving the attenuation of light by falling snow, or hydrometeors in general, lend themselves to the study of at least two problems of meteorological interest. The first problem is that of visibility in adverse weather conditions, and the second is that of finding a better method to measure precipitation. From the late 1940's through the late 1960's, various investigators have attempted to apply forward light scattering theory in the geometric optics range (α ≥ 200, where α = (2π_r)/λ, λ=wavelength and r = radius)* to quantitatively describe the attenuation of a light beam, and thereby visibility changes due to …