Physical Sciences and Mathematics Commons^™

High-Resolution Simulation Of A Tornado In Bangladesh On 13 May 1996, Katherine Hollinger

Atmospheric & Environmental Sciences

The country of Bangladesh has been known to experience some of the deadliest tornado outbreaks in the world. The severe weather season in this region only spans from late March to early May, but can produce significant severe weather outbreaks in that short time. Even with these outbreaks occurring, there has not been extensive analysis completed to evaluate the environmental parameters on these tornado event days in this region.

The goal of this project is to use a Weather Research and Forecasting (WRF) model simulation to evaluate a significant tornado that occurred in the Tangail and Jamalpur districts in Bangladesh …

Examining Terrain Effects On Upstate New York Tornado Events Utilizing High-Resolution Model Simulations, Luke Lebel

Atmospheric & Environmental Sciences

The region at the intersection of the Mohawk and Hudson valleys of New York is characterized by complex terrain. It has been hypothesized that this complex terrain may have an impact on the development and evolution of severe convection in the region. Specifically, previous research has hypothesized that terrain-channeled flow in the Hudson and Mohawk valleys contributed to increased low-level wind shear and instability in the valleys during past severe weather outbreaks. However, a lack of observations in the region prevented this hypothesis from being robustly tested.

The goal of this study is to further examine this hypothesis and complement …

The Rapid Weakening Of Hurricane Fred (2009), Christina Talamo

Atmospheric & Environmental Sciences

This research project discusses the rapid weakening of Hurricane Fred, a major Category 3 hurricane that occurred in the Atlantic basin during the 2009 Atlantic hurricane season. Between the days of 9 September and 13 September, Fred remained stationary off the coast of Africa in the Atlantic Ocean and never made landfall, all the while consistently weakening over open ocean from a major Category 3 hurricane to a tropical storm. In the Atlantic basin, I will define the rapid weakening, or RW, of a tropical cyclone as a decrease in the storm’s maximum sustained winds by 10.3 m s⁻¹ in …

The Impact Of Warm Conveyor Belt Forecast Uncertainty On Downstream Predictability, Jeremy Berman

Legacy Theses & Dissertations (2009 - 2024)

Perturbations to the potential vorticity (PV) waveguide can lead to the downstream radiation of Rossby waves, and in turn high-impact weather events. The PV waveguide is often perturbed in association with cyclogenesis, largely due to the latent heat release within the cyclone’s warm conveyor belt (WCB). Previous studies have hypothesized that forecast uncertainty associated with diabatic heating in WCBs can result in large downstream forecast variability; however these studies have not established a direct connection between the two. This hypothesis is evaluated for six cyclogenesis events characterized by highly amplified flow over the North Atlantic using ensemble model simulations.

Examining The Impact Of Synoptic-Scale Waves On Stratospheric Polar Vortex Variability From An Ensemble Forecast Perspective, Michael E. Main

Legacy Theses & Dissertations (2009 - 2024)

Major Sudden Stratospheric Warming (SSW) events are characterized by rapid warming of the polar regions at 10 hPa and are accompanied by a reversal of the 10-hPa zonal-mean zonal wind at 60˚N from westerly to easterly. Following an SSW event, stratospheric thermal and momentum anomalies can progress downward and linger near the tropopause for up to 60 days. These anomalies have major impacts on tropospheric sensible weather including increased likelihood of cold air outbreaks and heavy precipitation events. SSW events are largely forced by upward propagation of planetary-scale Rossby waves from the troposphere to the stratosphere. Synoptic-scale waves can contribute …

Ozone And Reactive Oxidized Nitrogen Chemistry In The Northeast U.S, Matthew Ninneman

Legacy Theses & Dissertations (2009 - 2024)

Ongoing reductions in oxides of nitrogen concentrations ([NOx] = nitric oxide ([NO]) + nitrogen dioxide ([NO2])) throughout the continental United States (U.S.) have important implications for tropospheric ozone (O3) and reactive oxidized nitrogen chemistry (NOy ≈ NOx + nitric acid (HNO3) + particle nitrate (pNO3) + peroxy nitrates (PNs) + alkyl nitrates (ANs)). Specifically, decreasing [NOx] concentrations have likely (1) increased the sensitivity of O3 to the [NOx] level, and (2) affected NOy speciation and partitioning. An understanding of the impacts of continued [NOx] reductions is needed to inform current and future air pollution control strategies, especially since the National …

Factors Influencing Rainfall Over The Congo, Ajay Raghavendra

Legacy Theses & Dissertations (2009 - 2024)

The hydrological cycle over tropical rainforests includes some of the most intense thunderstorms and rainfall totals. The energy associated with this convective activity plays an important role in the Earth’s weather and climate system. Therefore, the interannual variability, trends, and future climate projections of the hydrological cycle over tropical rainforests are important topics for research. The Congo rainforest situated over equatorial Africa is the second largest rainforest in the world, and recent studies have documented a >30-year large-scale and long-term drying trend over the Congo since the late-1970s. However, unlike the Amazon rainforest in South America, the Congo rainforest is …

Evaluating Large-Scale And Storm-Scale Characteristics Of Rapidly Intensifying And Slowly Intensifying Tropical Cyclones Using An Analog Approach, Jannetta C. Richardson

Legacy Theses & Dissertations (2009 - 2024)

Tropical cyclone (TC) intensity change is modulated by a combination of large-scale and storm-scale processes. On the large-scale, several factors exhibit strong controls on TC rapid intensification (RI): the initial TC intensity, the environmental vertical wind shear (VWS), and the background thermodynamic environment, which determines the TC’s maximum potential intensity (MPI). Previous statistical studies comparing RI and non-RI TCs have shown that TCs undergoing RI tend to be embedded in environments of lower VWS, and have initial intensities that are farther from their MPIs. Although numerous statistical studies have compared the large-scale and storm-scale conditions of RI and non-RI TCs, …

An Analysis Of Temperature Trends In The Northeast United States : 1950-2019, Christopher Selca

Legacy Theses & Dissertations (2009 - 2024)

The warming signal associated with anthropogenic climate change shows a significant positive trend globally over the last century. Trends in the magnitude and frequency of annual mean and extreme events do not display a globally uniform signal, as some regions have shown negative trends. This study examines the trends in daily mean and extreme temperatures in the Northeast region of the United States. Station data was selected from the GHCN-D Version 3 data set, using a blend of stations from the weather forecast offices and the cooperative observing network. Station criteria included using a threshold of less than 5% of …

Improving Our Understanding Of The Relationship Between Ocean Heat Uptake And Climate Sensitivity, Michael Cameron Rencurrel

Legacy Theses & Dissertations (2009 - 2024)

One of the ultimate goals of the field of climate science is to determine exactly how sensitive the Earth is to anthropogenic forcing, with far reaching implications both from a scientific and policy standpoint. However, despite decades of observational and model analysis, large uncertainties in Earth's climate sensitivity persist. Recent advances have shown that climate feedbacks, the primary mechanism driving the sensitivity spread, are dependent on the spatial patterns of the surface response, intrinsically linked to how the ocean is working to uptake and transport energy across the globe. Given the importance of reducing the range of climate sensitivity from …

Easterly Waves Over The Eastern Pacific, Victor Manuel Torres Puente

Legacy Theses & Dissertations (2009 - 2024)

The research in this thesis explores different processes associated with the life cycle of Easterly Waves over the tropical Eastern Pacific. These include genesis, structural evolution, intensification and a dissipating stage.

Global Circulation Variability Associated With Mjo Phase Speed, Alexander Marat Tomoff

Legacy Theses & Dissertations (2009 - 2024)

Differences in the Madden–Julian oscillation (MJO) phase speed help explain some of the variability in the global circulation patterns associated with the MJO. Select mechanisms that identify these distinctive circulation signals are applied to help explain MJO variability associated with different phase speeds. Wavelet filter analysis is first used to compute regression models of the MJO at different phase speeds, isolating the associated patterns in outgoing longwave radiation (OLR), geopotential height, and upper-level wind. Covariance matrices provide a deeper understanding of how the tropical and extratropical patterns compare between two phase speeds at any point in time. Both Fourier and …

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 …

Dynamical Downscaling Of Near-Term Climate Variability And Change For The Main Hawaiian Islands Using Wrf, Katrina Marie Fandrich

Legacy Theses & Dissertations (2009 - 2024)

As climate models continue to improve, the demand from resource managers and decision-makers for more accurate climate projections is increasing. However, natural climate variability poses a limit to the confidence in regional climate change projections, particularly for the mid-21st century. The unique geographic location of the Hawaiian Islands and its regional climate provide a challenging opportunity for climate modelers. The goal of this project is to examine both the Pacific Decadal Oscillation (PDO) and anthropogenic climate change for their impacts on near-term rainfall and temperature projections for the Hawaiian Islands. Of primary interest are the questions 1) is there a …