Atmospheric Sciences Commons^™

A Model-Based Assessment Of Potential Impacts Of Man-Made Reservoirs On Precipitation, Jesse Winchester, Rezaul Mahmood, William Rodgers, Faisal Hossain, Eric Rappin, Joshua D. Durkee, Themis Chronis

High Plains Regional Climate Center: Staff Publications

Land-use land-cover change (LULCC) plays an important role in weather and climate systems. Human modifications of land cover include building reservoirs and thus creating artificial lakes for multipurpose use. In this research, the authors have completed a Weather Research and Forecasting (WRF) Model–based assessment of impacts of two large parallel lakes on precipitation. This area is located in the western part of the states of Kentucky and Tennessee and known as the Land between the Lakes (LBL). To determine the impacts, this study has replaced the lakes with grass, deciduous forests, and bare soil and conducted model simulations for three …

The Effect Of The Dry Line And Convective Initiation On Drought Evolution Over Oklahoma During The 2011 Drought, Paul X. Flanagan, Jeffrey B. Basara, Bradley G. Illston, Jason A. Otkin

High Plains Regional Climate Center: Staff Publications

Observations from the Oklahoma Mesonet and high resolution Weather Research and Forecasting model simulations were used to evaluate the effect that the dry line and large-scale atmospheric patterns had on drought evolution during 2011. Mesonet observations showed that a “dry” and “wet” pattern developed across Oklahoma due to anomalous atmospheric patterns. The location of the dry line varied due to this “dry” and “wet” pattern, with the average dry line location around 1.5∘ longitude further to the east than climatology.Model simulations were used to further quantify the impact of variable surface conditions on dry line evolution and convective initiation (CI) …

Droughtscape, Winter 2017, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

Contents

NDMC partners with Sioux tribes to build climate resiliency

Drought intensifies in some regions of U.S. in fall

Fire danger and sequoia deaths in third quarter

2016: Year in review

MENA region forums elicit

feedback from stakeholders

Tech pass-off in Tunisia

Midwest DEWS meetings build collaboration, relationships

Workshop links drought, socioeconomic impacts/p>

Drought center helps ranchers prepare for drought

Drought tourney in Nebraska goes low tech

Evaluating Hourly Rainfall Characteristics Over The U.S. Great Plains In Dynamically Downscaled Climate Model Simulations Using Nasa-Unified Wrf, Huikyo Lee, Duane E. Waliser, Robert Ferraro, Takamichi Iguchi, Christa D. Peters-Lidard, Baijun Tian, Paul C. Loikith, Daniel B. Wright

Geography Faculty Publications and Presentations

Accurate simulation of extreme precipitation events remains a challenge in climate models. This study utilizes hourly precipitation data from ground stations and satellite instruments to evaluate rainfall characteristics simulated by the NASA-Unified Weather Research and Forecasting (NU-WRF) regional climate model at horizontal resolutions of 4, 12, and 24 km over the Great Plains of the United States. We also examined the sensitivity of the simulated precipitation to different spectral nudging approaches and the cumulus parameterizations. The rainfall characteristics in the observations and simulations were defined as an hourly diurnal cycle of precipitation and a joint probability distribution function (JPDF) between …

Investigating The Atmospheric Production Of Perchlorate: Inference From Polar Ice Cores, Thomas S. Cox

Electronic Theses and Dissertations

Perchlorate (ClO₄) in the environment is of concern, because of potential health risks to humans, among other reasons. Evidence suggests that the majority of environmental perchlorate is formed in the atmosphere (likely in the stratosphere), in chemical processes involving ozone and stratospheric chlorine. A lack of knowledge in regards to the processes has resulted in a limited understanding of the environmental conditions and variables that influence perchlorate production and consequently perchlorate prevalence and variability in the environment. In this study, perchlorate was measured, using an established ion chromatography-­‐electrospray ionization-­‐tandem mass spectrometry (IC-­‐ESI-­‐ MS/MS) technique, in over 1,600 snowpit …

Quantification Of Urban Atmospheric Boundary Layer Greenhouse Gas Dry Mole Fraction Enhancements In The Dormant Season: Results From The Indianapolis Flux Experiment (Influx), Natasha Miles, Scott Richardson, Thomas Lauvaux, Kenneth J. Davis, Nikolay V. Balashov, Aijun Deng, Jocelyn Turnbull, Colm Sweeney, Kevin R. Gurney, Risa Patarasuk, Igor Razlivanov, Maria Obiminda L. Cambaliza, Paul B. Shepson

Physics Faculty Publications

We assess the detectability of city emissions via a tower-based greenhouse gas (GHG) network, as part of the Indianapolis Flux (INFLUX) experiment. By examining afternoon-averaged results from a network of carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) mole fraction measurements in Indianapolis, Indiana for 2011–2013, we quantify spatial and temporal patterns in urban atmospheric GHG dry mole fractions. The platform for these measurements is twelve communications towers spread across the metropolitan region, ranging in height from 39 to 136 m above ground level, and instrumented with cavity ring-down spectrometers. Nine of the sites were deployed as of January …

Upper Water Structure And Mixed Layer Depth In Tropical Waters: The Seats Station In The Northern South China Sea, Jen-Hua Tai, George T. F. Wong, Xiaoju Pan

OES Faculty Publications

The variability of the upper water hydrographic structure, the efficacy of the different schemes for estimating the mixed layer depth (MLD), the inter-comparability estimation of the MLDs and diurnal and intra-annual MLD climatology in the tropical waters in the northern South China Sea were accessed in 702 depth-profiles of potential temperature (θ) and salinity collected in 64 cruises between 17.5 and 18.5°N and 115.3 and 116.3°E from 1997 to 2013. The hydrographic structure may be subdivided into three principal types: the classical type, with quasi-isopycnal surface mixed layer followed by an abrupt increase in the depth-gradient in θ and potential …

Studies Of Direct Solar Irradiance And Aerosol Optical Depth Using An Mfrsr And A Microtop Sunphotometer In The El Paso-Juarez Airshed, Arjun Aryal

Open Access Theses & Dissertations

The study of Solar Irradiance and Aerosol Optical Depth (AOD) plays an important role in understanding the regional and global climate distribution, and is also important in air pollution studies. In this work an MFRSR (Multi-Filter Rotating Shadowband Radiometer) and a Portable Microtop Sunphotometer were used to measure irradiances and to obtain optical depth values for the El Paso-Juarez Airshed. The Langley method applied on the MFRSR irradiance data was used to calculate the AOD values. The spatial distribution of AOD for this region was obtained using a Microtop Sunphotometer. The graphs were generated using GIS Shapefiles. In addition, the …

Spaceborne Synthetic Aperture Radar Survey Of Subsidence In Hampton Roads, Virginia (Usa), D.P.S. Bekaert, B. D. Hamlington, B. Buzzanga, C. E. Jones

CCPO Publications

Over the past century, the Hampton Roads area of the Chesapeake Bay region has experienced one of the highest rates of relative sea level rise on the Atlantic coast of the United States. This rate of relative sea level rise results from a combination of land subsidence, which has long been known to be present in the region, and rising seas associated with global warming on long timescales and exacerbated by shifts in ocean dynamics on shorter timescales. An understanding of the current-day magnitude of each component is needed to create accurate projections of future relative sea level rise upon …

A Climatological And Multiscale Analysis Of Cold Air Outbreaks In The Northeast United States, Zachary Baker Murphy

Legacy Theses & Dissertations (2009 - 2024)

The results of a climatological and multiscale analysis of cold air outbreaks (CAOs) that impacted the Northeast U.S. during 1948–2015 are presented. This climatological and multiscale analysis was based on daily minimum temperature data extracted from the National Centers for Environmental Information (NCEI) Global Historical Climatology Network-Daily dataset for 53 stations that were distributed throughout nine climate regions defined by the NCEI. A CAO is diagnosed whenever two or more stations within an NCEI climate region experience three or more consecutive days where the daily minimum temperatures at a station fall below the 31-day centered moving average of the fifth …

Understanding Climatic Adjustments To Variations In Tropical Ocean Heat Transport, Michael Cameron Rencurrel

Legacy Theses & Dissertations (2009 - 2024)

One of the outstanding problems within the climate community has been how to reconcile the geological proxy records of past warm, equable climates, characterized by both an increase in the global mean surface temperature and a decrease in the equator-to-pole temperature gradient, with numerical simulations of the same period. Recent work has shown that tectonic driven changes in the meridional ocean heat transport (OHT) may have played a signicant role in the warming. Here, we study the adjustment of the climate to variations in OHT using a suite of slab-ocean aquaplanet GCM simulations spanning 24 different imposed variations in OHT …

Hurricane Bonnie (1998) : Maintaining Intensity During High Vertical Wind Shear And An Eyewall Replacement Cycle, Erin Dougherty

Legacy Theses & Dissertations (2009 - 2024)

Hurricane Bonnie (1998) was an unusually resilient hurricane that maintained intensity in 12–16 ms-1 vertical wind shear and during an eyewall replacement cycle from 23 – 25 August. This remarkable behavior was examined using observations from flight-level data, microwave imagery, radar, and dropsondes over the two-day period. The symmetric and asymmetric aspects of Bonnie’s eyewall replacement cycle were documented and compared to eyewall replacement cycles in other hurricanes. Similar to other observed eyewall replacement cycles, Bonnie exhibited the development, strengthening, and dominance of a secondary eyewall while a primary eyewall decayed. However, Bonnie’s structure was highly asymmetric due to strong …

A Synoptic Climatology Of Combined Severe/Weather/Flash Flood Events, Kyle James Pallozzi

Legacy Theses & Dissertations (2009 - 2024)

Classical forms of severe weather such as tornadoes, damaging convective wind gusts, and large hail, as well as flash flooding events, all have potentially large societal impacts. This impact is further magnified when these hazards occur simultaneously in time and space. A major challenge for operational forecasters is how to accurately predict the occurrence of combined storm hazards, and how to communicate the associated multiple threat hazards to the public. A seven-year climatology (2009-2015) of combined severe weather/flash flooding (SVR/FF) events across the contiguous United States was developed in attempt to study the combined SVR/FF event hazards further.

Rossby Wave Breaking And Widespread Extreme Precipitation Events In The Central And Eastern U.S, Benjamin John Moore

Legacy Theses & Dissertations (2009 - 2024)

This dissertation examines climatological and dynamical linkages between widespread extreme precipitation events (EPEs) in the central and eastern U.S. and Rossby wave breaking (RWB), and assesses forecast skill for EPEs occurring in conjunction with RWB. The analysis primarily focuses on linkages of EPEs to LC1 (anticyclonic) and LC2 (cyclonic) RWB.

Ensemble Variability In Rainfall Forecasts Of Hurricane Irene (2011), Molly Becker Smith

Legacy Theses & Dissertations (2009 - 2024)

As tropical cyclones (TCs) move into the midlatitudes, they are often associated with extensive heavy precipitation. This precipitation can lead to widespread flooding events, such as occurred with Hurricane Irene (2011) over the northeastern United States. Despite the high-impact nature of these events, there are relatively few studies that explore the sensitivity of precipitation forecasts to model initial conditions, beyond focusing on the variability in forecast TC track.

Influence Of Volcanic Eruptions On Tropical Hydroclimate During The Last Millennium, Christopher Colose

Legacy Theses & Dissertations (2009 - 2024)

Volcanic eruptions exert the most important radiative forcing on Earth’s climate during the pre-industrial interval of the last millennium. In this thesis, I investigate the role of volcanic eruptions in altering tropical climate, including temperature and rainfall. I primarily use forced transient simulations of the last millennium as a tool to explore how explosive volcanic events project onto the hydrologic cycle, as well as the imprint of water isotopologues (H216O, H218O) associated with rainfall. Attention is given to the South American continent specifically (in chapter 2), and to the entire tropics (in chapter 3).

Climate Fingerprints Of The Interdecadal Pacific Oscillation, Bo Dong

Legacy Theses & Dissertations (2009 - 2024)

The Interdecadal Pacific Oscillation (IPO) is a multi-decadal quasi-oscillation seen primarily in tropical and extratropical Pacific sea surface temperatures (SSTs). Interacting with the atmosphere, the IPO has been shown to affect global and regional climate. However, a quantitative global synthesis of the IPO’s climate fingerprints and the underlying mechanisms are still lacking. Based on observational and reanalysis data and atmospheric model simulations, this dissertation investigates the IPO’s influence on regional climates over the globe, and its interactions with El Niño-Southern Oscillation (ENSO) and global warming.

Turbulence In The Upper Levels Of Tropical Cyclones, Michaela Leigh Rosenmayer

Legacy Theses & Dissertations (2009 - 2024)

Turbulence in the cirrus canopy of tropical cyclones (TCs) can give an indication about the physical processes that occur in this expansive cloud deck. The low stability and/or large shear that likely coincides with turbulent layers can be produced by radiative forcing, convective forcing, and sublimation of frozen precipitation from the cirrus canopy. As a result, turbulence in the cirrus canopy can give an indication about the impact of various physical processes in tropical cyclones.

A Multiscale Analysis Of Major Transition Season Northeast Snowstorms, Rebecca Blair Steeves

Legacy Theses & Dissertations (2009 - 2024)

Major transition season Northeast snowstorms have the potential to cause widespread socioeconomic disruption in the form of transportation delays, infrastructure damage, and widespread power outages. Because heavy, wet snow tends to occur in transition season Northeast snowstorms, lesser accumulations can result in greater disruption than if the same accumulation occurred in winter season Northeast snowstorms. This study is motivated by the opportunity to improve scientific understanding and forecaster situational awareness of this class of snowstorms by means of a multiscale analysis. The multiscale analysis focuses on documenting: 1) the planetary-to-synoptic-scale flow patterns occurring prior to and during major transition season …

Linkages Between Tropopause Polar Vortices And The Development Of Cold Air Outbreaks Over Central And Eastern North America, Kevin Biernat

Legacy Theses & Dissertations (2009 - 2024)

Coherent vortices in the vicinity of the tropopause, referred to as tropopause polar vortices (TPVs), may be extracted from high latitudes in conjunction with high-latitude upper-level ridge amplification. Once extracted, TPVs may interact with and strengthen midlatitude jet streams, as well as act as precursor disturbances for the development of intense midlatitude cyclones. Cold pools that may accompany TPVs as they are transported to middle latitudes may lead to widespread cold air outbreaks (CAOs), which may result in significant socioeconomic impacts. The purpose of this study is to investigate 1) the equatorward transport of TPVs and cold pools to middle …

Evaluation Of Lightning Jumps As A Predictor Of Severe Weather In The Northeastern United States, Pamela Eck

Legacy Theses & Dissertations (2009 - 2024)

Severe weather events in the northeastern United States can be challenging to forecast, given how the evolution of deep convection can be influenced by complex terrain and the lack of quality observations in complex terrain. To supplement existing observations, this study explores using lightning to forecast severe convection in areas of complex terrain in the northeastern United States. A sudden increase in lightning flash rate by two standard deviations (2σ), also known as a lightning jump, may be indicative of a strengthening updraft and an increased probability of severe weather.

Determination And Analysis Of Dscovr-Eipc Satellite-Retrieved Radiance From Cloud Geometric And Optical Properties, Emily Christine Morgan

Legacy Theses & Dissertations (2009 - 2024)

Using simulations and numerical fitting, this work sought to describe the satellite-retrieved radiance of clouds as a function of their thermodynamic and optical properties. Subsequently, this understanding can then be used in a look-up-table to determine the properties of clouds imaged by the EPIC sensor in the NASA DSCOVR satellite. In this study, background oxygen absorption was modeled in a radiative transfer model and convolved with EPIC filter functions for two absorption-reference pairs for Oxygen A- and B-band. This absorption profile was established as the primary vertical coordinate in this study, leveraging the similarity principle to allow for intercomparison of …

Variations In Potential Vorticity Streamer Activity : Development Pathways, Environmental Impacts, And Links To Tropical Cyclone Activity In The North Atlantic Basin, Philippe Pierre Papin

Legacy Theses & Dissertations (2009 - 2024)

This dissertation examines the climatological occurrence of potential vorticity streamers (PVSs) during the tropical cyclone (TC) season that occur in the upper troposphere in the North Atlantic (NATL) basin, assessing how their variations in frequency, area, and intensity impact the synoptic environment, how they are induced by different synoptic-dynamic patterns, and how they modify TC activity and genesis pathways.

The Impact Snow Albedo Feedback Over Mountain Regions As Examined Through High-Resolution Regional Climate Change Experiments Over The Rocky Mountains, Theodore Letcher

Legacy Theses & Dissertations (2009 - 2024)

As the climate warms, the snow albedo feedback (SAF) will play a substantial role in shaping the climate response of mid-latitude mountain regions with transient snow cover. One such region is the Rocky Mountains of the western United States where large snow packs accumulate during the winter and persist throughout the spring. In this dissertation, the Weather Research and Forecast model (WRF) configured as a regional climate model is used to investigate the role of the SAF in determining the regional climate response to forced anthropogenic climate change. The regional effects of climate change are investigated by using the pseudo …

Impacts Of Internal Variability On Climate Trends In Large Ensemble Simulations By Two Climate Models, Christine Bloecker

Legacy Theses & Dissertations (2009 - 2024)

Internal climate variability (ICV) can influence trends in observations and model simulations over periods spanning decades, making it difficult to quantify the response of the climate system to external forcing. We analyze two large ensembles of climate simulations from 1950-2100 by two fully coupled climate models, namely the CanESM2 and CESM1, to quantify the effects of ICV on apparent trends in annual surface air temperature (T) and precipitation (P) over different time periods and regions. In comparison with observations, the CanESM2 overestimates the global T and P trends during 1979-2014 while they fall within the ICV-induced range of the CESM1. …

Sensitivity Of Meiyu Front To Aerosol Spatial Distribution Over Yangtze-Huai River Valley, Chu-Chun Huang

Legacy Theses & Dissertations (2009 - 2024)

The observed contrasts in both aerosol number and size associated with frequent north-polluted-south-clean (NPSC) conditions over Yangtze-Huai River Valley (YHRV) during the Meiyu season may induce different aerosol-cloud-radiation interactions within the region causing different evolution of the Meiyu system. This aspect was studied by conducting WRF sensitivity simulations with different configurations of north-south aerosol number and size contrasts. Results show that when the Meiyu system develops at YHRV, more aerosols in the north (than the south) cause more but smaller cloud droplets to form, resulting in stronger radiative cooling at north part of the Meiyu system. Subsequently, the differential cooling …

Understanding Predictive Skill Of Arctic Sea Ice And Its Linkage With Mid-Latitude Weather And Climate In The Ncep Climate Forecast System, Colleen Mchugh

Legacy Theses & Dissertations (2009 - 2024)

Arctic climate is undergoing significant change, particularly rapid decline of sea ice. Arctic sea ice plays an important role in local, regional, and global climate through a variety of physical processes as seen in observational analysis as well as modeling studies. Recent research suggested that decreasing autumn and winter Arctic sea ice extent (SIE) has been shown to have an effect on mid-latitude weather patterns during the winter months. Therefore, accurate forecasts of Arctic sea ice extent and the associated teleconnections with the mid-latitudes are important for accurate seasonal climate prediction. The NCEP Climate Forecast System version 2 (CFSv2) is …

Agricultural Drought Transition Periods In The United States Corn Belt Region, Nicholas Joseph Schiraldi

Legacy Theses & Dissertations (2009 - 2024)

Agricultural drought in the U.S. Corn Belt region (CBR) has tremendous global socioeconomic implications. Unfortunately, the weather and climate factors that contribute to transition events toward or away from such droughts, and how well those factors are predicted, are poorly understood. This dissertation focuses on the atmospheric circulation signals associated with agricultural drought transitions periods in the CBR that evolve over 20 and 60 days, and how well those circulation signals are predicted on seasonal to sub-seasonal time scales.

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 …

Investigating The Effects Of Ice-Forming Saharan Dust Aerosols On Tropical Deep Convection Using Spectral Bin Microphysics, Matthew Scott Gibbons

Legacy Theses & Dissertations (2009 - 2024)

Aerosol effects on cloud and precipitation formation remain a significant source of uncertainty in the study of weather and climate. Aerosols can impact cloud and precipitation formation by functioning as cloud condensation nuclei (CCN), giant cloud condensation nuclei (GCCN) and/or ice nuclei (IN) affecting subsequent cloud microphysical processes. Aerosol effects on clouds are tightly interconnected with cloud dynamic and thermodynamic variables, some of which are currently impossible or infeasible to observe with existing sensors. Numerical models can be used to untangle aerosols effects from cloud dynamics and thermodynamics, but model results can be affected by the complexity of the parameterizations …