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Articles 181 - 210 of 254

Full-Text Articles in Atmospheric Sciences

Understanding Predictive Skill Of Arctic Sea Ice And Its Linkage With Mid-Latitude Weather And Climate In The Ncep Climate Forecast System, Colleen Mchugh Jan 2017

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 Jan 2017

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 Jan 2017

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 Jan 2017

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 …


Tropical Cyclone Intensification Under Moderate Vertical Wind Shear, Rosimar Rios-Berrios Jan 2017

Tropical Cyclone Intensification Under Moderate Vertical Wind Shear, Rosimar Rios-Berrios

Legacy Theses & Dissertations (2009 - 2024)

Deep-layer (200–850 hPa) vertical wind shear is generally an inhibiting factor for tropical cyclone intensification. Multiple studies—ranging from case studies to climatological analyses—have consistently shown that the chances of tropical cyclone intensification decrease with increasing vertical wind shear magnitude. However, tropical cyclones can intensify under moderate shear—the range of shear magnitudes that are neither too weak to have negligible influence on intensity nor too strong to completely halt intensification. Intensity, track, and precipitation forecasts of tropical cyclones under moderate shear can be highly uncertain; therefore, explaining how tropical cyclones evolve under seemingly unfavorable conditions is an important step towards improved …


Influence Of Topography On Convective Patterns Across The Greater Capital Region Of New York, Rachel O’Donnell May 2016

Influence Of Topography On Convective Patterns Across The Greater Capital Region Of New York, Rachel O’Donnell

Atmospheric & Environmental Sciences

The greater Albany region is unique in regards to its terrain. The various mountain ranges and river valleys play a significant role in convective patterns due to modification of flow. The purpose of this research is to compare the days of convection, both severe and non-severe, to the large scale flow pattern. Lightning data from the National Lightning Detection Network was used to analyze the role terrain plays in organizing convection and the associated lightning. The greater Capital Region was divided into 0.1° grid boxes, and the number of total lightning strikes (both cloud-to-cloud and cloud-to-ground) was recorded within that …


The Tropical Cyclone Diurnal Cycle, Jason Paul Dunion Jan 2016

The Tropical Cyclone Diurnal Cycle, Jason Paul Dunion

Legacy Theses & Dissertations (2009 - 2024)

The research presented in this thesis explores a phenomenon referred to as the tropical cyclone (TC) diurnal cycle (TCDC) and presents satellite, numerical modeling, and observational perspectives pertaining to how it can be monitored, its evolution in time and space, its relevance to TC structure and intensity, and how it manifests in numerical simulations of TCs. Infrared satellite imagery was developed and used to investigate diurnal oscillations in TCs and finds a diurnal pulsing pattern that occurs with notable regularity through a relatively deep layer from the inner core to the surrounding environment. A combination of satellite, numerical model simulations, …


Understanding The Dependence Of Radiative Feedbacks And Clouds On The Spatial Structure Of Ocean Heat Uptake, Lance Rayborn Jan 2016

Understanding The Dependence Of Radiative Feedbacks And Clouds On The Spatial Structure Of Ocean Heat Uptake, Lance Rayborn

Legacy Theses & Dissertations (2009 - 2024)

Ocean heat uptake and radiative forcing are important for understanding transient climate change. Differences in efficacy of ocean heat uptake (suppression of surface warming per unit energy flux into the deep oceans relative to CO2 forcing) account for a substantial fraction of the spread in transient warming between models. Rose et al. (2014) studied the dependence of efficacy on the spatial pattern of ocean heat uptake in an ensemble of aquaplanet simulations with prescribed ocean heat uptake, and found large differences in model responses to high versus low latitude uptake. This study accurately quantifies these model responses through the use …


Examination Of Water Vapor Characteristics During The 2013 Colorado Flood, Hannah Kristine Huelsing Jan 2016

Examination Of Water Vapor Characteristics During The 2013 Colorado Flood, Hannah Kristine Huelsing

Legacy Theses & Dissertations (2009 - 2024)

During September 9-16, 2013, the Front Range region of Colorado experienced heavy rainfall which resulted in severe flooding. Precipitation totals during the event exceeded 450mm in Boulder, Colorado, 9 lives were lost, and damages to public and private properties were estimated to be over $2 billion. This study analyzes the characteristics of water vapor surrounding the event, including the abnormality of total column water vapor, the sources of moisture, and the relationship between water vapor and precipitation characteristics. It was found that the atmosphere was very near saturation during the duration of the event and monthly-averaged precipitable water (PW) was …


Air-Sea Carbon Dioxide Exchange In The Southern Ocean And Antarctic Sea Ice Zone, Brian Butterworth Jan 2016

Air-Sea Carbon Dioxide Exchange In The Southern Ocean And Antarctic Sea Ice Zone, Brian Butterworth

Legacy Theses & Dissertations (2009 - 2024)

The Southern Ocean is an important part of the global carbon cycle, responsible for roughly half of the carbon dioxide (CO2) absorbed by the global ocean. The air-sea CO2 flux (Fc) can be expressed as the product of the water-air CO2 partial pressure difference (ΔpCO2) and the gas transfer velocity (k), an exchange coefficient which represents the efficiency of gas exchange. Generally, Fc is negative (a sink) throughout the Southern Ocean and Antarctic sea ice zone (SIZ), but uncertainty in k has made it difficult to develop an accurate regional carbon budget. Constraining the functional dependence of k on wind …


Chilean Coastal Orographic Precipitation Experiment : A Tale Of Two Rain Regimes, Adam Massmann Jan 2016

Chilean Coastal Orographic Precipitation Experiment : A Tale Of Two Rain Regimes, Adam Massmann

Legacy Theses & Dissertations (2009 - 2024)

The Chilean Coastal Orographic Precipitation Experiment Pilot Project (CCOPE-2015) was an exploratory field campaign to better understand the mechanisms of orographic precipitation enhancement in the Nahuelbuta Mountains of Southern Chile (38 deg. S.). Observations collected include: (1) surface rainfall from a network of 10 data logging rain gauges, (2) vertical precipitation profiles from a pair of K-band Micro Rain Radars, (3) rain drop size distributions from an optical disdrometer, (4) upstream wind and thermodynamic profiles from radiosonde launches, and (5) aerosol number concentration and size distribution measurements from a condensation particle counter and an ultra-high sensitivity aerosol spectrometer.


Hydroclimate Changes In The South-Central Great Plains Of The United States : A Synoptic Approach, Pawel Slaski Jan 2016

Hydroclimate Changes In The South-Central Great Plains Of The United States : A Synoptic Approach, Pawel Slaski

Legacy Theses & Dissertations (2009 - 2024)

Hydroclimate changes over the Southern Central Great Plains (SCGP) of the United States have been occurring throughout the last century. These changes have had a major impact on the local ecosystems, agriculture, and human society in the region by, e.g., producing a higher frequency of drought over the last century. Climate models project further increases of drought in the 21st century over this region under increasing greenhouse gases. This study analyzes climate model simulations to examine changes in synoptic conditions associated with the projected drought increases over the SCGP. Synoptically, mesoscale convective complexes (MCCs) produce a large portion of the …


The Network Average Gust Factor, Its Measurement And Environmental Controls, And Role In Gust Forecasting, Alexander Austin Gallagher Jan 2016

The Network Average Gust Factor, Its Measurement And Environmental Controls, And Role In Gust Forecasting, Alexander Austin Gallagher

Legacy Theses & Dissertations (2009 - 2024)

There exists a strong, well documented linear relationship between network averaged sustained (or mean) wind and gust speeds within the San Diego Gas and Electric (SDGE) mesonet that is characterized by the slope of the linear regression between the two known as the network average gust factor (GF). The network average GF potentially contains information on the average obstruction of the stations within the network and when paired with numerical model output, may be used for gust prediction. Using the network average GF for gust prediction can also result in the correction of biases due to poorly resolved terrain or …


Diagnosis Of The Source Of Medium-Range Forecast Errors For An Extratropical Cyclone, William Lamberson Jan 2015

Diagnosis Of The Source Of Medium-Range Forecast Errors For An Extratropical Cyclone, William Lamberson

Legacy Theses & Dissertations (2009 - 2024)

Medium-range forecasts of an extratropical cyclone set to impact Western Europe on 16 Dec 2011 consistently predicted that the cyclone would be intense, with a minimum pressure as low as 930-hPa and an expansive area of high winds. In actuality, the cyclone never deepened below 965-hPa and its impact on Western Europe was minimal.


Modulation Of East African Precipitation By The Indian Ocean Dipole (Iod) And Enso, Ahmed Shaaban Jan 2015

Modulation Of East African Precipitation By The Indian Ocean Dipole (Iod) And Enso, Ahmed Shaaban

Legacy Theses & Dissertations (2009 - 2024)

Tropical East Africa is influenced by two main rainy seasons, during autumn and spring. During autumn, tropical East African precipitation is clearly influenced by Indian Ocean Dipole (IOD) and/or ENSO. During spring, there is no clear SST pattern in the Indian Ocean. The association between El Niño and positive IOD phases is much stronger than the association between La Niña and negative IOD during October and November. During October, the association between El Niño and wet condition over tropical eastern Africa is stronger than association between La Niña and dry conditions. During November, the association between positive IOD and eastern …


An Analysis Of High-Impact, Low-Predictive Skill Severe Weather Events In The Northeast U.S, Matthew Thomas Vaughan Jan 2015

An Analysis Of High-Impact, Low-Predictive Skill Severe Weather Events In The Northeast U.S, Matthew Thomas Vaughan

Legacy Theses & Dissertations (2009 - 2024)

An objective evaluation of Storm Prediction Center slight risk convective outlooks, as well as a method to identify high-impact severe weather events with poor-predictive skill are presented in this study. The objectives are to assess severe weather forecast skill over the northeast U.S. relative to the continental U.S., build a climatology of high-impact, low-predictive skill events between 1980–2013, and investigate the dynamic and thermodynamic differences between severe weather events with low-predictive skill and high-predictive skill over the northeast U.S. Severe storm reports of hail, wind, and tornadoes are used to calculate skill scores including probability of detection (POD), false alarm …


Extreme Hydrometeorological Events In The Peruvian Central Andes During Austral Summer And Their Relationship With The Large-Scale Circulation, Juan Carlos Sulca Jan 2015

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 …


The Variability Of Madden-Julian Oscillation Convection And The Role Of The Western Hemisphere Circulation, Naoko Sakaeda Jan 2015

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 …


The Intensification Of Sheared Tropical Cyclones, Leon Nguyen Jan 2015

The Intensification Of Sheared Tropical Cyclones, Leon Nguyen

Legacy Theses & Dissertations (2009 - 2024)

Environmental vertical wind shear has been shown to have a generally detrimental impact on tropical cyclone (TC) intensity change. However, many cases of rapidly intensifying (RI) sheared TCs have been observed, and TCs in moderate (5-10 m s-1) shear often have the largest intensity forecast errors. Thus, advancing the understanding of TC-shear interactions is vital to improving TC intensity forecasts, which have not seen much improvement over the past few decades. This dissertation employs both observational and high-resolution numerical modeling approaches to investigate how some TCs are able to resist shear and intensify.


Evaluating Preferred Direction Tropical Cyclone Track Variability In An Operational Global Ensemble Prediction System, Travis Elless Jan 2015

Evaluating Preferred Direction Tropical Cyclone Track Variability In An Operational Global Ensemble Prediction System, Travis Elless

Legacy Theses & Dissertations (2009 - 2024)

Ensemble forecasts of Tropical Storm Debby and Hurricane Sandy (2012) highlight instances where variability in tropical cyclone (TC) position forecasts are stretched along a preferred direction. The goal of this thesis is to analyze this stretching of variability in a global ensemble prediction system, particularly the European Centre for Medium-Range Weather Forecasts (ECMWF), to determine how often and under what conditions does variability stretching occur, and ultimately what feature(s) are responsible for generating this variability.


The Impacts Of Varability In Temperature And Humidity On Electricity Consumption In New York State, Eric Adamchick Jan 2015

The Impacts Of Varability In Temperature And Humidity On Electricity Consumption In New York State, Eric Adamchick

Legacy Theses & Dissertations (2009 - 2024)

A seasonal harmonic linear regression approach is presented to model the seasonal and diurnal relationships between surface weather observations and electricity load data in New York State. The relationships between dry-bulb, dew point, and wet-bulb temperatures with electricity load were evaluated using the correlation coefficient to test the strength of the relationships, while the regression slope coefficient provided an interpretable scale for those relationships. We found that the strongest seasonal and diurnal relationships occur during boreal summer from the afternoon through the overnight hours, while similar but negative relationships are observed during the winter. Using the same seasonal harmonic linear …


The Effects Of Downsloping On Storm Precipitation Distributions In The Capital District Of New York State, Kyle James Pallozzi May 2014

The Effects Of Downsloping On Storm Precipitation Distributions In The Capital District Of New York State, Kyle James Pallozzi

Atmospheric & Environmental Sciences

Downsloping is a process which has an impact on many precipitation events in the Capital District of New York State. This study examines the effect of 850 hPa and 925 hPa mean vector wind direction, as well as the individual 850 hPa and 925 hPa wind directions observed through soundings, during precipitation events on precipitation distributions in the Capital District of New York State. Results from this study suggests that 850 hPa and 925 hPa mean vector wind as well as the 850 hPa and 925 hPa wind favor downsloping off of the Greens and Taconics, and therefore lower precipitation …


Global View Of The Role Of The Itcz/Monsoon Trough In Tropical Cyclogenesis, Steven Fuhrman Jan 2014

Global View Of The Role Of The Itcz/Monsoon Trough In Tropical Cyclogenesis, Steven Fuhrman

Legacy Theses & Dissertations (2009 - 2024)

ABSTRACT


Northeast Cool-Season Cyclones Associated With Significant Upper-Level Easterly Wind Anomalies, Adrian Mitchell Jan 2014

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 Jan 2014

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 …


Seasonal Variations Of Wind Farm Impacts On Land Surface Temperature And Vegetation Over Northern Illinois, Lauren Slawsky Jan 2014

Seasonal Variations Of Wind Farm Impacts On Land Surface Temperature And Vegetation Over Northern Illinois, Lauren Slawsky

Legacy Theses & Dissertations (2009 - 2024)

Operating wind turbines enhance near surface turbulence and alter the exchanges of surface energy, water, and momentum, thus affecting local micrometeorology. Climatic impacts of three wind farms in northern Illinois are assessed using land surface temperature (LST) from the Moderate Resolution Imaging Spectroradiometer (MODIS) data onboard the Terra and Aqua satellites for the period 2003-2013. Changes in LST between two periods (before and after construction of the wind turbines) and between wind farm pixels (WFPs) and nearby non wind farm pixels (NNWFPs) are quantified. An increase in LST is observed at nighttime over each wind farm, with the pattern of …


A Climatology Of Central American Gyres, Philippe Pierre Papin Jan 2014

A Climatology Of Central American Gyres, Philippe Pierre Papin

Legacy Theses & Dissertations (2009 - 2024)

Central American gyres (CAGs) are large, low-level, cyclonic circulations that are observed over Central America during the tropical cyclone (TC) season. CAGs often occur in conjunction with TCs, and can result in torrential rainfall over portions of Central America, the Caribbean Islands, and eastern United States. The lack of prior research on CAGs, their apparent links to TC activity, and their association with high- impact weather motivates this study.


Upper-Tropospheric Precursors Associated With Subtropical Cyclone Formation In The North Atlantic Basin, Alicia Marie Bentley Jan 2014

Upper-Tropospheric Precursors Associated With Subtropical Cyclone Formation In The North Atlantic Basin, Alicia Marie Bentley

Legacy Theses & Dissertations (2009 - 2024)

Oceanic cyclones exhibiting properties of both tropical and extratropical systems have been categorized as subtropical cyclones (STCs) since the early 1950s. The opportunity to investigate the roles of baroclinic and diabatic processes during the evolution of STCs from a potential vorticity (PV) perspective motivates this study. This study investigates the roles of baroclinic and diabatic processes during the evolution of STCs by calculating three PV metrics from the National Centers for Environmental Prediction Climate Forecast System Reanalysis 0.5° gridded dataset. The three PV metrics quantify the relative contributions of lower-tropospheric baroclinic processes, midtropospheric diabatic heating, and upper-tropospheric dynamical processes during …


An Analysis Of Arctic Climate, The Intense Arctic Cyclone Of Early August 2012, And Middle To High Latitude Snowcover, Adam H. Turchioe Jan 2014

An Analysis Of Arctic Climate, The Intense Arctic Cyclone Of Early August 2012, And Middle To High Latitude Snowcover, Adam H. Turchioe

Legacy Theses & Dissertations (2009 - 2024)

On 03 August 2012, a cyclone formed over Central Siberia and progressed northeastwards. By 0000 UTC 05 August, the cyclone reached the Arctic Ocean with a mean sea-level pressure (MSLP) of 984 hPa. Once over the Arctic Ocean, the cyclone rapidly intensified and reached a minimum pressure of 966 hPa on 06 August near 83°N and 170°W. The cyclone slowly weakened, and on 0000 UTC 10 August once again had a minimum MSLP of 984 hPa. The motivation for this presentation is driven by the likelihood that this cyclone is one of the most intense storm systems to ever impact …


On The Mjo And Anticyclonic Wavebreaking, Kyle Macritchie Jan 2014

On The Mjo And Anticyclonic Wavebreaking, Kyle Macritchie

Legacy Theses & Dissertations (2009 - 2024)

The Madden Julian oscillation (MJO) is the primary mode of intraseasonal variability in the tropics. The MJO often couples with convection as it moves over the Indian Ocean and decouples as it leaves the west Pacific Ocean. The association between convection coupled to the MJO and the midlatitude flow pattern has been the primary focus of numerous studies. In particular, it has been shown that there is a statistical relationship between the position and strength of the MJO and anticyclonic wavebreaking (AWB). This study expands on this statistical relationship by examining, in detail, the two-way relationship between the MJO and …