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Full-Text Articles in Physical Sciences and Mathematics
Large-Scale Flow Patterns Conducive To Central American Extreme Precipitation Events During Autumn, Alexander Kyle Mitchell
Large-Scale Flow Patterns Conducive To Central American Extreme Precipitation Events During Autumn, Alexander Kyle Mitchell
Legacy Theses & Dissertations (2009 - 2024)
Extreme precipitation events (EPEs), characterized by daily widespread heavy rainfall exceeding the 95th percentile across Central America, can have large impacts on agriculture, life, and property during the rainy season. EPEs during the Northern Hemisphere (NH) autumn, however, have been observed to be influenced by both tropical and extratropical originating phenomena such as easterly waves and cold surges, respectively. Given the limited research in this area, the novelty of this work is to apply a systematic approach for identifying and better understanding EPEs, and investigating their associated synoptic-scale variability using daily high-resolution observations and reanalysis products over Central America. An …
A Comparative Analysis Of The Impact Of Low-Level Jets And Atmospheric Rivers In The Central U.S, Nabindra Gyawali
A Comparative Analysis Of The Impact Of Low-Level Jets And Atmospheric Rivers In The Central U.S, Nabindra Gyawali
Legacy Theses & Dissertations (2009 - 2024)
Atmospheric Rivers (AR) are the primary source of poleward moisture transport globally. In theUnited States, much recent attention has been placed on Pacific Coast ARs which occur between December and March. However, the central US is also substantially impacted by warm-season AR. An open question is whether these warm-season ARs are synonymous with Great Plains low-level jets (LLJs) that have long served as a focal point of mesoscale atmospheric research. In this study, we perform a comparative analysis of ARs and LLJs in the central U.S using ECMWF’s climate-quality reanalysis of the 20th century, CERA-20C. The aim is to identify …
Dynamic Impacts Of Hadley Circulation On Saharan Desert Warming Amplification, Alejandro Manuel Ayala
Dynamic Impacts Of Hadley Circulation On Saharan Desert Warming Amplification, Alejandro Manuel Ayala
Legacy Theses & Dissertations (2009 - 2024)
Changes in temperature due to climate change are not spatially uniform, and deserts and other drylands, which are greatly underrepresented in climate studies, are warming at a much faster rate than much of the globe with increasing concentrations of greenhouse gases. This strong warming amplification over deserts, termed Desert Amplification (DA), is most pronounced over the world’s largest and driest Sahara Desert and the Arabian Peninsula. The Sahara and Arabian deserts are formed in the subtropical subsiding branch of the Hadley Circulation (HC) and so the changes in large-scale subsidence associated with adiabatic heating could impact the DA dynamically. While …
A Synoptic-Dynamic Analysis Of The Structure And Evolution Of Persistent North Pacific Wintertime Ridge Regimes, Tyler Christopher Leicht
A Synoptic-Dynamic Analysis Of The Structure And Evolution Of Persistent North Pacific Wintertime Ridge Regimes, Tyler Christopher Leicht
Legacy Theses & Dissertations (2009 - 2024)
Along the west coast of North America (NA), a majority of the precipitation for the entire year falls during winter as a result of approximately a dozen cyclones or atmospheric rivers. However, persistent upper-level ridges can prevent the occurrence of wintertime precipitation events and lead to extended drought, significant water shortages, and adverse economy-wide impacts for major population centers in California. An increased understanding of the dynamical and thermodynamical processes that govern upper-level ridge formation, persistence, and dissipation during the rainy season along western NA would allow decision makers to better manage water resources and motivates this thesis. Persistent upper-level …
The Contributions Of Dynamical And Diabatic Processes Preceding And Accompanying Major Greenland Ice-Melt Events, Scott Feldman
The Contributions Of Dynamical And Diabatic Processes Preceding And Accompanying Major Greenland Ice-Melt Events, Scott Feldman
Legacy Theses & Dissertations (2009 - 2024)
Extratropical cyclones and/or short-wave disturbances can reinforce Greenland blocking through upper-level flow amplification and can increase poleward heat and moisture transport into the Arctic. Increased poleward heat and moisture transport into the Arctic may enhance Greenland ice melt during the spring, summer, and fall months. The need to better understand the underlying dynamical and diabatic processes that may contribute to Greenland ice melt motivates this thesis. The purpose of this thesis is to investigate: 1) the role of advective warming due to poleward heat and moisture transport into the Arctic in facilitating Greenland ice melt, 2) the role of adiabatic …
Objective Methodology To Identify The Sea Breeze Circulation And Associated Low-Level Jet In The New York Bight, Elizabeth J. Mccabe
Objective Methodology To Identify The Sea Breeze Circulation And Associated Low-Level Jet In The New York Bight, Elizabeth J. Mccabe
Legacy Theses & Dissertations (2009 - 2024)
While the sea breeze has been studied for decades, in a complicated mid-latitude coastal region such as the New York Bight (NYB), the general thermodynamic structure and dynamics of the circulation is poorly characterized. The East Coast of the United States has become a critical area for offshore wind farm development, including a generally favorable wind resource, relatively shallow waters on an extensive continental shelf, frequent warm season sea breezes, and proximity to large populated areas. Thus the sea breeze will play a key role in the new energy economy, given the favorable wind speeds and capacity factors during periods …
Diagnosing High Sinuosity Regimes Associated With Anomalous Greenland Ice-Melt Events Using Self-Organizing Maps, Mansour El Riachy
Diagnosing High Sinuosity Regimes Associated With Anomalous Greenland Ice-Melt Events Using Self-Organizing Maps, Mansour El Riachy
Legacy Theses & Dissertations (2009 - 2024)
Sinuosity, a metric that describes the waviness of the circumpolar flow, is adapted to quantify modification of the tropospheric polar vortex within longitudinal sectors by localized incursions of warm, moist air from middle latitudes associated with Arctic cyclones (ACs). In this thesis, we identify four corridors of high AC track frequency, on which we center 90° longitudinal sectors comprising the following regions: Pacific, West of Greenland, Atlantic, and Asian. Sectorial sinuosity is calculated for the West of Greenland sector and is used to quantify the amplitude of the 300-hPa flow associated with anomalous Greenland ice-melt events.
The Significance Of The Nontraditional Coriolis Terms In Tropical Large-Scale Dynamics, Heng Wang
The Significance Of The Nontraditional Coriolis Terms In Tropical Large-Scale Dynamics, Heng Wang
Legacy Theses & Dissertations (2009 - 2024)
The nontraditional Coriolis terms (NCTs) turn eastward motion upward and upward motion westward, and vice versa. NCTs are omitted in most of the current global atmospheric models. However, NCTs are significant in tropical large-scale dynamics in at least three aspects. 1) Using an idealized model that can switch NCTs on or off, omitting NCTs biases large-scale flow response to prescribed diabatic forcing mimicking the intertropical convergence zone (ITCZ). The omission yields a westerly wind bias in the heating region ~ 10% of the westerly jet stream. This bias is due to lack of westward NCT when heating-induced upward motion is …
Detection And Attribution Of Wind Energy Changes In The Contiguous United States, North Atlantic Ocean And European Sector In The Twentieth Century, Shengzhe Chen
Legacy Theses & Dissertations (2009 - 2024)
Wind power is playing a greater role as an alternative energy resource to fossil fuels. The prediction skills for hourly and daily forecasts of hub-height (80 – 100 m) wind power are increasingly reliable. However, regarding historical trends in wind energy availability (an important variable for determining wind farm capacity factors), little is known about the interannual and decadal variability of the hub-height wind speed. With climate change uncertainty now incorporated into wind energy resource assessment, insight into the relative contribution from the internal variability of the climate system versus the external forcing is presently lacking. Here, Empirical Orthogonal Function …
An Examination Of North Pacific Jet Regimes Conducive To Landfalling Atmospheric Rivers Along The West Coast Of North America, Eli Jacob Turasky
An Examination Of North Pacific Jet Regimes Conducive To Landfalling Atmospheric Rivers Along The West Coast Of North America, Eli Jacob Turasky
Legacy Theses & Dissertations (2009 - 2024)
Every year, the west coast of North America experiences significant economic damage and societal disruption due to the extreme precipitation associated with landfalling atmospheric rivers (ARs). ARs not only may produce significant economic and societal impacts, but also may contribute disproportionately to precipitation anomaly statistics along the west coast of the North America. The purpose of this study is to investigate: 1) the average state and evolution of the NPJ prior to AR landfall for selected categories of landfalling ARs; and 2) the dynamical processes applicable to the aforementioned categories of landfalling ARs that are linked to NPJ variability in …
Dry Air, Midlevel Flow, And The Persistence Of Deep Convection In Atlantic Tropical Disturbances, Charles Helms
Dry Air, Midlevel Flow, And The Persistence Of Deep Convection In Atlantic Tropical Disturbances, Charles Helms
Legacy Theses & Dissertations (2009 - 2024)
An analysis of dropsonde-observed relative humidity in the Tropical Storm Gabrielle (2013) pregenesis disturbance suggests the presence of a layer of dry air that is being advected into the disturbance from the north. The focus of this study is on this and similar dry air layers, termed dry air inflow pathways (DAIPs), that are characterized by unidirectional disturbance-relative flow drawing dry air into a tropical disturbance. It is hypothesized that DAIPs act to prevent the establishment of persistent deep convection by importing midlevel
Surface Air Temperature Biases And Other Associated Biases In Gfdl Am4.0 Model, Yilin Lu
Surface Air Temperature Biases And Other Associated Biases In Gfdl Am4.0 Model, Yilin Lu
Legacy Theses & Dissertations (2009 - 2024)
The Atmospheric Model version 4.0 (AM4) is the atmospheric component of the latest climate and Earth system models (CM4 and ESM4) developed by NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey. The AM4 makes some improvements in its radiative flux simulations. As a new model, its performance needs to be evaluated. We analyzed the model’s historical simulations (ten-year simulations from 2001 to 2010), in order to evaluate the diurnal cycle of surface air temperature (Tas) simulated by the AM4 model and perform some diagnostic analyses of the surface energy fluxes to help understand the temperature biases. In comparison …
What Affects The Phase Speed Of Madden-Julian Oscillation Convection, Robert Setzenfand
What Affects The Phase Speed Of Madden-Julian Oscillation Convection, Robert Setzenfand
Legacy Theses & Dissertations (2009 - 2024)
The Madden-Julian Oscillation (MJO) is the main source of convective and circulation variability on intraseasonal timescales and planetary spatial scales within the tropics. Although the phase speed of the MJO convective envelope is often stated as 5 m s–1, MJO events that occur over the Indo-Pacific warm pool can have a range of phase speeds. This study uses a wavelet to identify MJO convective events with specified phase speeds in a satellite-derived outgoing longwave radiation (OLR) dataset during boreal winter. The wavelet-filtered OLR index is then regressed against basic meteorological variables to extract information about MJO events or signals propagating …
Climate Change On The Quelccaya Ice Cap, Central Andes, And Its Relationship With The Large-Scale Circulation, Christian Pedro Yarleque Galvez
Climate Change On The Quelccaya Ice Cap, Central Andes, And Its Relationship With The Large-Scale Circulation, Christian Pedro Yarleque Galvez
Legacy Theses & Dissertations (2009 - 2024)
Glaciated areas over the central Andes are highly sensitive to atmospheric forcings, as demonstrated by their current accelerated retreat in response to global warming. The present Thesis is focused on quantifying and assessing future climate change impacts over Quelccaya ice cap (QIC), the world-largest tropical ice body, which is considered as a representative case of the tropical Andean cryosphere. I focused my study on characterizing large-scale forcing and future changes of precipitation and temperature, since they represent the most important variables for accumulation and ablation processes in glaciated mountain regions. In my research I developed tools to overcome the lack …
Examining Variability In Model Skill During The 7 January 2013 Sudden Stratospheric Warming Event, Jonathan Lee Blufer
Examining Variability In Model Skill During The 7 January 2013 Sudden Stratospheric Warming Event, Jonathan Lee Blufer
Legacy Theses & Dissertations (2009 - 2024)
Recent analyses of numerical weather prediction models have shown that stratospheric regime changes (e.g. strong and weak vortex events) are not skillfully predicted at medium-range lead times. Motivated by these recent analyses, this thesis investigates the sources of variability in stratospheric forecast skill amongst several operational models initiated at different lead times prior to the 7 January 2013 sudden stratospheric warming (SSW). This study extends upon a previous analysis by the Stratospheric Network for the Assessment of Predictability (SNAP), which concluded that a change in forecast lead-time from 15 to 10 days increased model skill in predicting the 2013 SSW …
The Variability Of Madden-Julian Oscillation Convection And The Role Of The Western Hemisphere Circulation, Naoko Sakaeda
The Variability Of Madden-Julian Oscillation Convection And The Role Of The Western Hemisphere Circulation, Naoko Sakaeda
Legacy Theses & Dissertations (2009 - 2024)
The convective initiation of the Madden-Julian Oscillation (MJO) over the Indian basin is often associated with eastward-propagating intraseasonal circulation approaching from the Western Hemisphere (WH), which is suggested to influence the onset of MJO convection. This dissertation first documents the event-to-event variability in the characteristics of MJO convection, which shows a geographical discrepancy in the relative roles of moist and dry dynamics on MJO convection. This dissertation then examines the structural evolution and dynamics of the intraseasonal upper-tropospheric circumnavigating circulation over the WH and its subsequent impact on MJO convection over the Indian basin, where MJO convective characteristics are highly …
Extreme Hydrometeorological Events In The Peruvian Central Andes During Austral Summer And Their Relationship With The Large-Scale Circulation, Juan Carlos Sulca
Extreme Hydrometeorological Events In The Peruvian Central Andes During Austral Summer And Their Relationship With The Large-Scale Circulation, Juan Carlos Sulca
Legacy Theses & Dissertations (2009 - 2024)
In this Master's dissertation, atmospheric circulation patterns associated with extreme hydrometeorological events in the Mantaro Basin, Peruvian Central Andes, and their teleconnections during the austral summer (December-January-February-March) are addressed. Extreme rainfall events in the Mantaro basin are related to variations of the large-scale circulation as indicated by the changing strength of the Bolivian High-Nordeste Low (BH-NL) system. Dry (wet) spells are associated with a weakening (strengthening) of the BH-NL system and reduced (enhanced) influx of moist air from the lowlands to the east due to strengthened westerly (easterly) wind anomalies at mid- and upper-tropospheric levels. At the same time extreme …
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 …
Associations Between The Madden-Julian Oscillation, Equatorial Rossby Waves, And Extratropical Northern Hemisphere Predictability, Lawrence Gloeckler
Associations Between The Madden-Julian Oscillation, Equatorial Rossby Waves, And Extratropical Northern Hemisphere Predictability, Lawrence Gloeckler
Legacy Theses & Dissertations (2009 - 2024)
The Madden-Julian oscillation (MJO), the leading mode of tropical convective and circulation variability on intraseasonal time scales, has become increasingly leveraged to improve empirical prediction of the global atmospheric circulation. Significant progress has been made in recent years to advance subseasonal (10-30-day) prediction of atmospheric circulation anomalies, and much of this progress can be attributed to the inclusion of information about the phase and amplitude of the MJO in various forecast processes. Despite this progress, however, forecasts based only on the state of the MJO omit information about other important tropical convective and circulation anomalies, and coherent MJO signals are …
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).
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 …
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 …