Atmospheric Sciences Commons^™

Characterizing The Earth's Magnetosheath With In Situ Measurements, Hector A. Salinas

Physics Dissertations - Archive

Earth’s magnetosheath is a region of shocked plasma that mediates energy and momentum transfer from the solar wind to the magnetosphere. The dynamics and thus the plasma structures of this region are highly dependent on upstream solar wind conditions. As such, the region is often characterized as a turbulent environment, with the most intense periods of turbulence occurring often under quasi-parallel bow shock conditions. This magnetosheath turbulence displays as variable and large-scale fluctuations with in-situ measurements. Given that turbulence is a characteristic feature of the magnetosheath, this dissertation asks two questions: (1) How are plasma structures inside the sheath affected …

Using Convolutional Neural Networks To Identify Rare Weather Events: Application To Kona Low Classifications With Large-Scale Wind Pattern, Anadhi Sharma

Electronic Theses & Dissertations (2024 - present)

Extreme events pose challenges in prediction on account of their low frequency and erratic nature. Among these events, Kona lows are rare subtropical cyclones that significantly impact the weather pattern of Hawaii, sometimes causing heavy rainfall, strong winds, and coastal flooding. In the past, studies have used traditional statistical methods such as synoptic climatology, regression analysis, and manual classification that rely on expert judgment to identify Kona lows; however, they often struggle to capture the complex spatial patterns of the Kona storms. Convolutional Neural Networks (CNNs) exhibit a property called translation invariance, which allows them to learn and recognize Kona …

Limitations Of The High-Resolution Rapid Refresh Gust Algorithm, Alex M. Glasser

Electronic Theses & Dissertations (2024 - present)

ABSTRACT:

Accurate wind and gust forecasts are crucial in operational meteorology, yet there is a distinct gap in the literature regarding the verification of operational gust forecasts. In the present work, we assess the performance of the High-Resolution Rapid Refresh's (HRRR) gust potential, verifying it against the Automated Surface Observing System's (ASOS) observed gusts across the Continental United States (CONUS). The HRRR gust's diurnal cycle reveals a significant underprediction of the gust during daylight hours and a slight overprediction of the gust during hours of darkness. The daytime underprediction undermines the assumption that forecasts represent a potential that tends to …

Using The High Resolution Rapid Refresh To Validate A Novel Forecast Methodology, Sylvia M. Garmong

Electronic Theses & Dissertations (2024 - present)

NOAA’s High-Resolution Rapid Refresh (HRRR) is frequently used by forecasters for short term predictions and although the model performs well in many metrics, previous study (Fovell and Gallagher 2020) identified temperature and windspeed biases within the boundary layer using radiosonde and surface observations. The current work uses a forecast drift metric to study how model forecasts evolve with time and distance to radiosonde sites. The metric is calculated by subtracting model analysis from forecasts at the same valid time, creating a proxy for bias. HRRR data on native model levels are obtained from the Google Cloud and Amazon Web Services …

Misoscale Vortices In The Eyewall Boundary Layer Of A Tropical Cyclone In A Large Eddy Simulation, Emily A. Lucy

Electronic Theses & Dissertations (2024 - present)

Since the late 1980s, there have been numerous observations of extreme updrafts, gusts, and small-scale rotation in the eyewall of tropical cyclones (TCs). Research aircraft, dropsondes, and, more recently, mobile radars have collected these observations, most often from within the boundary layer. Previous studies have documented dropsondes associated with extreme gusts and updrafts, while others have discussed specific incidents of misoscale features in tropical cyclones. Several high-resolution numerical simulations of TCs have documented similar features. This study uses one such simulation from Worsnop et al. (2017). A small but intense tropical cyclone in a quiescent environment is simulated.

This simulation …

"Assessment Of The Likelihood To Stay Below 2 Degree Celsius Warming: Combining Modeling And Scenario Uncertainty.", Peter M. Booker

Electronic Theses & Dissertations (2024 - present)

ABSTRACT

Uncertainty in how much the Earth will warm in response to rising atmospheric CO₂ concentrations remains a major challenge for climate science and policy. In particular, estimates of equilibrium climate sensitivity (ECS) and transient climate response (TCR) directly affect projections of global mean surface temperature (GMST) and the allowable carbon budget for limiting warming to 2°C by 2100.

This study assesses the performance of a two-layer energy balance model (EBM) in reproducing TCR and ECS values under CMIP6 forcing scenarios, with a focus on SSP2-4.5. EBM outputs are compared against General Circulation Models (GCMs), and agreement is evaluated using …

Buoy-Based Eddy Covariance Drag Coefficient At A Near-Shore And Offshore Site, David P. Marcial

Electronic Theses & Dissertations (2024 - present)

An eddy covariance (EC) flux system was integrated onto a Navy Oceanographic Meteorological Automatic Device (NOMAD) floating lidar buoy fitted for measuring the offshore wind resource. The EC flux system consisted of two sonic anemometers and an inertial measurement unit that together provided high-frequency (10 Hz) motion-corrected wind measurements. To assess possible impacts of flow distortion, EC momentum fluxes (10 min) were calculated in gravity-aligned, natural, and planar fit (PF) coordinate frames. The buoy was anchored near the Martha’s Vineyard Coastal Observatory Air-Sea Interaction Tower (ASIT; near-shore) for validation of the buoy-based EC fluxes against the fixed tower measurements before …

Cover Crops Can Reduce Greenhouse Gas Emissions From No-Till Maize In Southern Brazil: Insights From A Long-Term Field Experiment, Guilherme Rosa Da Silva, Adam J. Liska, Cimélio Bayer

Adam Liska Papers

Brazil is one of the countries that has the most agricultural area under no-till (NT) management. This research study aims to evaluate life-cycle greenhouse gas (GHG) emissions from maize (M) grain production in agroecosystems that used different cover crops under NT management in southern Brazil. The data for this study were from a long-term 41-year field experiment in southern Brazil. The long-term experiment evaluated the effects of fallow (F) and cover crops (oat (O), vetch (V), cowpea (B), pigeon pea (P), and lablab (L)) on nitrous oxide and methane emissions and soil carbon (C) sequestration in maize agroecosystems. Five cropping …

The Response Of Tropopause Phenomena To Stratospheric Variability: Rossby Wave Breaking And Tropopause Polar Vortices, Cameron R. Paquette

Electronic Theses & Dissertations (2024 - present)

Variability in the high-latitude wintertime stratospheric flow, often referred to as the stratospheric polar vortex, can precede anomalous conditions in tropospheric flow on subseasonal-to-seasonal (S2S) timescales and impact surface weather. The range of stratospheric impacts on tropospheric conditions range from shifts in the North Atlantic storm tracks, formation of cold spells, and development of extreme precipitation. Impacts of stratospheric variability are known to persist for up to 60 days, providing ample windows of opportunity in forecasting on S2S timescales. This dissertation focuses on the stratospheric impacts on tropopause-level processes, such as Rossby wave breaking (RWB) events and tropopause polar vortices …

Light Absorbing Aerosol Interactions With Warm Clouds, Shreya Joshi

Dissertations, Master's Theses and Master's Reports

Atmospheric particles such as biomass-burning aerosols, including black carbon - are critical in altering the Earth's energy balance through interactions with light and clouds. Biomass-burning aerosols also contain organic carbon, a diverse mix of organic compounds. As these aerosols age, they evolve by interacting with other atmospheric species, including cloud water, leading to changes in particle morphology and the development of coatings that impact their lifetime and ability to interact with clouds and light.

Some biomass-burning aerosols serve as cloud condensation nuclei. When cloud water droplets form, the properties of the nucleating particles can change. Many clouds evaporate before precipitating, …

Convective Modes Associated With Precipitation Exceeding Postfire Debris Flow Thresholds In The Southwestern United States, Anya M. Aponte Torres

Graduate Research Theses & Dissertations

Postfire debris flows can occur when surface-water runoff dislodges and carries a slurry of loose sediment and vegetation downslope, usually in steep, recently burned terrain. Short-duration, high-intensity rainfall embedded within short or long-duration rainstorms (e.g., thunderstorms and atmospheric rivers) is most commonly associated with this mode of debris-flow initiation. The typical horizontal grid spacings of global numerical weather prediction and general circulation models are too coarse to resolve these convective precipitation features, which poses an obstacle to short-term forecasting and investigating future trends in the frequency, magnitude, and characteristics of debris-flow generating rainfall. For this study, 15-minute precipitation and simulated …

A Dynamically Adapting Forecast Cone Based On Ensemble Spread, Michael N. Barletta

Electronic Theses & Dissertations (2024 - present)

Dynamically based ensemble prediction systems have gained considerable attention because they can provide a greater range of possible forecast outcomes and quantify the uncertainty in forecasts. In turn, forecasters can convey clearer messages to the public on the range of forecast scenarios and display inherent uncertainty in weather forecasts, which can be difficult to do with deterministic forecasts. Although global ensemble prediction systems have demonstrated skill in their probabilistic track predictions, the information contained within them is not always fully utilized beyond the mean forecast and standard deviation (i.e., spread). One way that these ensembles could be better employed is …

Analysis Of Extreme Rainfall And Streamflow Events In The Catskill/Delaware Catchment Using The New York State Mesonet, Ada Ellingworth

Electronic Theses & Dissertations (2024 - present)

Extreme rainfall and streamflow often lead to increased turbidity in reservoirs in the Catskill/Delaware catchment, which is part of the New York City water supply system. To better understand extreme events that lead to increased turbidity, this study takes a dual approach: first, we identify hydrologic conditions during extremes to understand when and why extremes occur. Next, we evaluate an identified extreme case to evaluate mesoscale model skill in this region. Measurements from the New York State Mesonet and United States Geological Survey are used to identify hydrologic conditions from 2017-2024 associated with three extreme event types: rainfall, streamflow, and …

The Large-Scale Flow Dynamics And Controls On Recurving Eastern North Pacific Tropical Cyclones, Alexander Kyle Mitchell

Electronic Theses & Dissertations (2024 - present)

While eastern North Pacific (EPAC) tropical cyclones (TCs) most often move westward over open water, a subset deviates from this typical path, recurving toward higher latitudes or making landfall along the North American coastline. Because such events are relatively rare, they have received less attention, despite their significant contributions to rainfall and wildfire activity across the southwestern United States. This dissertation identifies and characterizes the spatial variability of EPAC TC tracks, analyzes the synoptic environments associated with TC recurvature near the North American coast, presents a detailed case study of two recurving EPAC TCs from late September to early October …

Deep Convection, Lightning, And Inertio-Gravity Waves: An Analysis Of Precipitation And Wave Dynamics In The Congo Basin, Stephen L. Solimine

Electronic Theses & Dissertations (2024 - present)

The lack of an extensive in situ observation network throughout equatorial Africa makes it difficult to monitor the Congo climate system. Model and reanalysis products have been used to fill informational gaps but often produce disparate results. To improve model representation of deep convection over the Congo, it’s important to first understand the influence of various thermodynamic and dynamic forces that may be underrepresented. Although satellite based remote sensing retrievals and reanalysis have their own set of limitations, they can offer a great deal of insight into the climate of regions otherwise lacking in observational networks.

The first section of …

Understanding The Dynamical Mechanisms Governing Northern Hemisphere Wintertime Persistent Flow Regimes And Their Associated Extreme Weather Events, Tyler Christopher Leicht

Electronic Theses & Dissertations (2024 - present)

Weather regimes are characterized as patterns of low-frequency variability in the middle to upper troposphere of the extratropics. Weather regimes can also be linked to variations in surface weather, making the study of weather regimes a bridge between traditional synoptic-dynamic meteorology and subseasonal-to-seasonal variability. This dissertation identifies and categorizes persistent flow regimes (PFRs), analyzes the dynamics underpinning PFR formation, identifies the linkages to atmospheric teleconnections, and examines the occurrence of surface weather extremes before and during PFRs.

PFRs are identified from 1979–2022 and grouped into five clusters using k-means clustering, which then allows for time-lag composite analysis to determine the …

Cloud Condensation Nuclei Activity Of Fresh And Aged Phenolic Acid Aerosol Particles, Emily A. Nortmann

Honors Undergraduate Theses

In recent years, the incidence of wildfires has considerably increased, with fire seasons starting earlier and ending later than usual due to changes in snowpack, precipitation, and temperature, which are attributed in part to climate change. Wildfires are responsible for the emission of a variety of gases and organic aerosol particles in the atmosphere with profound impacts on air quality, visibility, and human health. The aerosol particles produced by wildfires can contribute to climate change by scattering or absorbing solar radiation, affecting the radiative balance of the planet through cooling or warming effects, or by acting as cloud condensation nuclei …

Validating Atmospheric Freezing Level Heights Using Purdue University Weather Balloon Data, Danielle Harr

The Journal of Purdue Undergraduate Research

No abstract provided.

A Meteorological Investigation Of A Tornado- Producing, “Hybrid” Supercell-Multicell Storm Near Delphi, Indiana, On May 8, 2023, Evelyn Rose K. Girardi

The Journal of Purdue Undergraduate Research

No abstract provided.

Discrimination The Roles Of Anthropogenic Greenhouse Gases And Aerosols On Tropical Cyclone Frequency From Downscaling Cmip6 Models, George Gyabaah

Theses and Dissertations

Tropical cyclones (TCs) are devastating disasters, yet predicting their future activity remains highly uncertain. To better understand the impacts of different anthropogenic forcings, specifically greenhouse gases (GHG) and aerosols on the TCs, I downscaled the single forcing experiments of 11 CMIP6 models in the Columbia HAZard Model (CHAZ). This analysis focused on changes in the distribution of the North Atlantic (ATL) and Western North Pacific (WNP) basins and explored the shift in environmental variables that drive them. We then used the formulation of the genesis component of CHAZ as a constraint to quantify the relative contribution of each predictor relative …