Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Institution
Articles 1 - 30 of 36
Full-Text Articles in Entire DC Network
Analysis Of Fire-Induced Circulations During The Fireflux2 Experimental Burn And Operational Rate Of Spread Models, Jeremy Tyler Benik
Analysis Of Fire-Induced Circulations During The Fireflux2 Experimental Burn And Operational Rate Of Spread Models, Jeremy Tyler Benik
Master's Theses
In this study, the fire-induced circulations were analyzed during the FireFlux2 (FF2) experimental burn using WRF-SFIRE to directly quantify the effects of the fire on local conditions. We utilized observational data from the FF2 burn and numerical simulations to assess the impacts of fire on local micrometeorology under ∼12m/s winds. Two simulations were executed. One in a two-way coupled mode and one in a one-way coupled mode. The difference between the simulations was used to quantify the fire impacts on the circulation at the head and flanks of the fire. The fire-induced horizontal winds indicated the strongest fire-induced flow at …
Sundowners And Mountain Wave Activity: Selected Observations From The Sundowner Winds Experiment (Swex), Kiera L. Malarkey
Sundowners And Mountain Wave Activity: Selected Observations From The Sundowner Winds Experiment (Swex), Kiera L. Malarkey
Master's Theses
Wildfires in complex terrain have resulted in tragic loss and have highlighted the vulnerability of communities over the past several years. The added intensity created by downslope windstorms, and the lack of high temporal and spatial resolution of ground observations motivates the ongoing need to understand and increase predictability of Sundowners. Sundowners, downslope windstorms that are typically intensified around sunset, are a common and significant weather phenomenon observed along the Santa Barbara coastline and are known to increase challenges during wildfire events. The Sundowner Winds EXperiment (SWEX) was a six-week field campaign from 01 April to 15 May 2022 in …
An Analysis Of Fire-Induced Conditions During Large Wildfires And Within Steep Canyons, Justin Mirabilis Haw
An Analysis Of Fire-Induced Conditions During Large Wildfires And Within Steep Canyons, Justin Mirabilis Haw
Master's Theses
For this study, fire-induced winds from a wind-driven fire (Thomas Fire) and a plume dominated fire (Creek Fire) were analyzed. Then, the small-scale fire-induced circulations within steep canyons were examined. This study used two different WRF-SFIRE simulations, one without the fire present, and the other with fire. The fire-induced conditions were calculated by subtracting a given variable from the “No Fire Run” from the “Fire Run” (Fire - No Fire). Wind speed and geopotential height fields were analyzed to assess spatial and temporal variability. Furthermore, cloud water mixing ratio, precipitation, and fuel moisture were analyzed for the Creek Fire to …
Evaluation Of The Offline-Coupled Gfs-Cmaq In Recent Wildfires In Northern California, Joyce Leung
Evaluation Of The Offline-Coupled Gfs-Cmaq In Recent Wildfires In Northern California, Joyce Leung
Master's Theses
As wildfires become more frequent and severe under climate change, there is a growing need to simulate the impact of fires on air quality and human health using numerical models. The National Air Quality Forecast Capability is an operational air quality forecasting system that provides nationwide ozone and particulate matter (PM2.5) prediction. It is made up of a chemical transport model – the Community Multiscale Air Quality (CMAQ) model – driven by a meteorological model. Recently, the Global Forecast System (GFS) replaced the North American Mesoscale Forecast System (NAM) to drive CMAQ. In addition to these two modeling systems, the …
The Influence Of Aerosols On Ice And Mixed-Phase Clouds Based On In-Situ Observations And Cam6 Simulations, Flor Vanessa Maciel
The Influence Of Aerosols On Ice And Mixed-Phase Clouds Based On In-Situ Observations And Cam6 Simulations, Flor Vanessa Maciel
Master's Theses
Clouds have a large impact on Earth’s radiation budget, and although there is aconsiderable amount of research on them, there are still uncertainties concerning how thermodynamics, dynamics, and aerosol indirect effects impact their microphysical properties. The lack of observational analysis on cirrus and mixed-phase cloud controlling factors, i.e., temperature, relative humidity, vertical velocity, and aerosol number concentrations, limits our understanding of how these properties impact their microphysical properties and, therefore, complicates how they are simulated within climate models. With seven flight campaigns funded by the National Science Foundation (NSF) and five funded by the National Aeronautics and Space Administration (NASA), …
Ice And Supercooled Liquid Distributions Based On In Situ Observations And Climate Model Simulations, Ching An Yang
Ice And Supercooled Liquid Distributions Based On In Situ Observations And Climate Model Simulations, Ching An Yang
Master's Theses
Three climate models are evaluated using in situ airborne observations from the SouthernOcean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES) campaign. The evaluation targets cloud phases, microphysical properties, thermodynamic conditions, and aerosol indirect effects from -40°C to 0°C. Compared with 580-s averaged observations (i.e., 100 km horizontal scale), the Community Atmosphere Model version 6 (CAM6) shows the most similar result for cloud phase frequency distribution and allows more liquidcontaining clouds below -10°C compared with its predecessor—CAM5. The Energy Exascale Earth System Model (E3SM) underestimates (overestimates) ice phase frequencies below (above) -20°C. CAM6 and E3SM show liquid and ice water contents …
Environmental Influences On Large Daily Wildfire Growth In California, Holt S. Hanley
Environmental Influences On Large Daily Wildfire Growth In California, Holt S. Hanley
Master's Theses
Wildfires have become a major environmental, social, and economic problem in California. The consequences can be especially detrimental when they exhibit behavior like very large daily growth (an individual fire burning >10,000 acres over a 24-hour period). Environmental conditions influencing the risk of large daily growth include weather variables such as temperature, wind, relative humidity, and precipitation; fuel variables such as type, loading, availability, and moisture content; as well as topographic variables such as slope, aspect, elevation, and shape. However, there remains great uncertainty in the importance of these variables relative to each other and the existence of any threshold …
An Empirical Assessment Of Environmental Variable Combinations For Use In Fire Weather Forecasts, Daniel Sunvold
An Empirical Assessment Of Environmental Variable Combinations For Use In Fire Weather Forecasts, Daniel Sunvold
Master's Theses
Predicting high fire danger conditions is paramount to mitigating the impacts caused by wildfires. Such warning systems as red flag warnings (RFWs) and the National Fire Danger Rating System (NFDRS) utilize atmospheric and fuel moisture properties to warn public and government entities about conditions that may lead to the ignition or rapid growth of wildfires. In this study, we use high-resolution reanalysis and wildfire growth data from 2003-2020 in California to test a variety of different variables to determine if a more viable variable combination exists that could be used to create a better warning index which would allow for …
A Study On The Relationship Of Arctic Oscillation With Atmospheric Rivers And Snowpack In The Western United States Using Forty-Year Multi-Platform Dataset, Samuel Liner
Master's Theses
Atmospheric rivers (ARs) are affected by large-scale climate variability. We investigate how ARs and snowpack are shaped by arctic oscillation (AO) by examining the synoptic conditions and characteristics of ARs and snowpack in the different phases of AO using forty years (1980-2019) of Integrated Multi-satellite Retrievals for Global Precipitation Measurement (IMERG) data, Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA2) reanalysis data, and in-situ observation data over the eastern Pacific and western U.S. region. More precipitation is found in lower latitudes during negative AO months and farther north in latitude during positive AO months. These are associated with …
Assessing Wrf Precipitation Forecasts Of Atmospheric Rivers In Northern California Using 4d-Var Data Assmiliation Of Cosmic-2 Gps Radio Occultation Profiles, Paul R. Zechiel
Master's Theses
Atmospheric Rivers (ARs) can provide much needed water to drought-ridden locations, however, can also lead to potential devastating flooding events. Thus, AR forecasts must be improved to keep the public safe. This case study used the Weather Research and Forecasting (WRF) model to compare the impact of including COSMIC-2 GPS Radio Occultation (RO) measurements using 4D-VAR data assimilation techniques. Each WRF simulation analyzed the vertical motion, pressure, mixing ratios with respect to ice, rain, and vapor, and precipitation fields. To provide observational precipitation data for model comparison, the Integrated Multisatellite Retrievals for Global Precipitation Measurement (IMERG) satellite and the Santa …
The Influence Of Teleconnection Patterns On Renewable Energy Resources, John Kyle Bergerson
The Influence Of Teleconnection Patterns On Renewable Energy Resources, John Kyle Bergerson
Master's Theses
Energy providers are shifting their supply from carbon based forms of energy to renewable sources in response to policy changes aimed at reducing pollution and anthropogenic influence on the environment. Wind and solar energies are notable sources that have been adopted around the globe and are increasing in installation and efficiency, but relying on weather-dependent sources of energy has limitations. Variability in energy supply and demand becomes further dependent on the state of the climate, and thus predictability of that state is critical. Climate modes are correlated with climate variables and are used to make mid-term (>10 days), seasonal, …
Fire Weather Associated With The 2019 Northern California Public Safety Power Shutoff Events, Scott Purdy
Fire Weather Associated With The 2019 Northern California Public Safety Power Shutoff Events, Scott Purdy
Master's Theses
Recent high impact wildfire events across California have piloted the implementation of grid de-energization by utilities across the state. The largest utility, Pacific Gas and Electric (PG&E), deployed this tactic on seven separate occasions during 2019, four of which occurred in October. This recent ploy has been established in the wake of many deadly wildfires such as the 2018 Camp Fire as an ignition mitigation tactic. Conditions such as the state of the fuels, meteorological conditions, and the consequent fire danger were evaluated as the primary triggers for the October de-energizations. It was determined that the fuels were critically dry …
Cirrus Cloud Microphysical Properties And Aerosol Indirect Effects Using Airborne Observations And A Global Climate Model, Ryan Patnaude
Cirrus Cloud Microphysical Properties And Aerosol Indirect Effects Using Airborne Observations And A Global Climate Model, Ryan Patnaude
Master's Theses
Cirrus clouds are strong controllers of the global radiation budget, but significant uncertainties remain regarding the thermodynamic, dynamic, and aerosol indirect effects on their microphysical properties. The lack of observational analysis on cirrus cloud controlling factors, i.e., temperature, relative humidity, vertical velocity, and aerosol number concentrations (Na), limits our understanding of their impact on cirrus microphysical properties, making quantification and parameterization of cirrus clouds in climate models difficult. Using seven flight campaigns funded by the National Science Foundation (NSF), impacts of cirrus controlling factors and their regional distributions are individually quantified, and used to evaluate the National Center for Atmospheric …
Observations And Simulations Of Fire Weather Phenomena Across Scales, Matthew James Brewer
Observations And Simulations Of Fire Weather Phenomena Across Scales, Matthew James Brewer
Master's Theses
The need for a better understanding of wildfires and how the atmosphere affects them provided the motivation for this work. The November 2018 Camp Fire quickly became the deadliest and most destructive wildfire in California history. In chapter 1, we investigate the contribution of meteorological conditions and a downslope windstorm event that occurred during the 2018 Camp Fire. Results show that this event was associated with mid-level and surface synoptic scale processes which created conditions favorable for a North wind event. Sustained surface winds between 3–6 m s-1 were observed with gusts of over 25 m s-1. The meteorological conditions …
Understanding The Role Of Eddy Vorticity Fluxes On The Rapid Intensification Of Hurricane Irma(2017) And Michael (2018), Alrick L. Green
Understanding The Role Of Eddy Vorticity Fluxes On The Rapid Intensification Of Hurricane Irma(2017) And Michael (2018), Alrick L. Green
Master's Theses
Rapid Intensification (RI) in TCs still remains one of the most challenging tasks for forecasters. The lack of understanding of the physical mechanisms and complexities in charge of these events, limits our understanding and makes it more difficult for weather models to resolves and forecast RI events. The Hurricane Weather Research and Forecasting (HWRF) model was used to examine the connection between rapid intensification and environmental forcing for Hurricane Irma (2017) and Hurricane Michael (2018). The tangential wind momentum budget was used for a comparative analysis for these two cases to identify similarities and differences in the pathways to intensification …
Spatial And Temporal Effects Of Dry Air On Tropical Cyclone Intensity And Tracks Over The Eastern Atlantic Ocean Basin, Amy Ip
Master's Theses
This study aims to understand how often dry air occurs or co-exists with a tropical cyclone (TC) and to what degree dry air will affect the way the TC proceeds. Four tropical cyclones of 2015 were chosen: Hurricane Fred, Hurricane Danny, Tropical Storm (TS) Grace and Tropical Depression (TD) 9 as their formation and tracks were located within the eastern Atlantic Ocean region. Relative humidity (RH) from MERRA-2 and NCEP-FNL datasets were compared within 3 days of the highest storm status and looking forward 3 days on the storm path. Results at 700 hPa suggested that dry air (≤30% RH) …
Mobile Ka-Band Polarimetric Doppler Radar Observations Of Wildfire Smoke Plumes, Taylor Brianna Aydell
Mobile Ka-Band Polarimetric Doppler Radar Observations Of Wildfire Smoke Plumes, Taylor Brianna Aydell
Master's Theses
Remote sensing techniques have been more recently used to study and track wildfire smoke plume structure and evolution; however, knowledge gaps remain due to the limited availability of observational datasets aimed at understanding the fine-scale fire-atmosphere interactions and plume microphysics. In this study, we present a new mobile millimeter-wave (Ka-band) Doppler radar system acquired to sample the fine-scale kinematics and microphysical properties of active wildfire smoke plumes from both wildfires and large prescribed fires. Four field deployments were conducted in the fall of 2019 during two wildfires in California and one prescribed burn in Utah. An additional dataset of precipitation …
Observations Of Fire Behavior On A Grass Slope During A Wind Reversal, Dianne Hall
Observations Of Fire Behavior On A Grass Slope During A Wind Reversal, Dianne Hall
Master's Theses
This experiment studied fire-atmospheric interactions and wildland fire behavior on a slope. A grass slope was instrumented with both in situ and remote instruments to record both meteorological conditions and the fire behavior. A headfire was lit and allowed to burn upslope through the instruments. The data collected were analyzed to determine the fire behavior, specifically fire spread (direction and rate) and flame characteristics (length, height, and angle). During the first several minutes of the experiment, fire behavior was as expected with an upslope rate of spread at 0.1 m s-1 and flame lengths between 1 m and 4 m. …
Evaluating Tropical Tropospheric Ozone And Water Vapor In Merra-2, Era-Interim, And Cam-Chem Using Aircraft Observations From The Western Pacific, Kathryn Steinmann
Evaluating Tropical Tropospheric Ozone And Water Vapor In Merra-2, Era-Interim, And Cam-Chem Using Aircraft Observations From The Western Pacific, Kathryn Steinmann
Master's Theses
Tropospheric ozone (O3) negatively is a greenhouse gas, affecting global climate. To improve climate predictions, the behavior of O3 and the mechanisms affecting its distribution must be understood and accurately represented in model simulations. This study evaluates O3 and water vapor (H2O) observations from the Convective Transport of Active Species in the Tropics (CONTRAST) campaign with data from the National Center for Atmospheric Research’s (NCAR) Community Atmospheric Model with Chemistry (CAM-Chem), the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2), and the European Centre for Medium-Range Weather Forecast (ECMWF) Re-Analysis-Interim (ERA-Interim). In the tropical middle troposphere, CAM-Chem shows …
Numerical Simulations Of Atmospheric Rivers And The Rain Shadow Over The Santa Clara Valley, Jesse Dalton Behringer
Numerical Simulations Of Atmospheric Rivers And The Rain Shadow Over The Santa Clara Valley, Jesse Dalton Behringer
Master's Theses
This study investigated precipitation distribution patterns in association with atmospheric rivers (ARs). The Weather Research and Forecasting (WRF) model was employed to simulate two strong atmospheric river events. The precipitation forecasts were highly sensitive to cloud microphysics parameterization schemes. Thus, radar observed and simulated Z_H and Z_DR were evaluated to provide information about the drop-size distribution (DSD). Four microphysics schemes (WSM-5, WSM-6, Thompson, and WDM-6) with nested simulations (3 km, 1 km, and 1/3 km) were conducted. One of the events mostly contained bright-band (BB) rainfall and lasted less than 24 h, while the other contained both BB and non-bright-band …
Comparisons Of Upper Tropospheric Ozone At A Coastal And Urban Site And The Impact Of Local Surface Emissions, Chloe Anne Gore
Comparisons Of Upper Tropospheric Ozone At A Coastal And Urban Site And The Impact Of Local Surface Emissions, Chloe Anne Gore
Master's Theses
This study quantified the impact of urban emission sources on the enhancement of ozone (O3) in the troposphere using data from simultaneous ozonesonde launches at Half Moon Bay (HMB), CA and San Jose (SJ), CA on eleven dates in July and August 2018. The urban O3 enhancement in the SJ vertical profile was derived by subtracting out HMB, which represents baseline O3, from the SJ profile. This enhancement was averaged into 1 km layers and statistically analyzed with surface emission concentration data from three locations in SJ, however this did not reveal any discernable trends between the surface and O3 …
Asian Long-Range Transport In Relation To Atmospheric Rivers In Northern California, Catherine Liu
Asian Long-Range Transport In Relation To Atmospheric Rivers In Northern California, Catherine Liu
Master's Theses
The study investigated the effect of aerosol long-range transport on precipitation over northern California during atmospheric river (AR) events in the 2017 cold season (January-April). ARs in 2017 were among the strongest to date and the intense precipitation associated with the ARs resulted in flooding, destruction of property, and contamination of water supplies. The aerosol optical depth (AOD) from Moderate Resolution Imaging Spectroradiometer (MODIS) data showed Asian dust traveling across the northern Pacific Ocean along with AR events. Aerosol measurements in California, provided by the Interagency Monitoring of Protected Visual Environments (IMPROVE), showed that more Asian dust tends to be …
Mesoscale Controls On The Shasta County Convergence Zone, Matthew Thomas Roberts
Mesoscale Controls On The Shasta County Convergence Zone, Matthew Thomas Roberts
Master's Theses
The Shasta County Convergence Zone (SCCZ) is a poorly understood terrain-forced convergence zone that develops at the northern terminus of California’s Sacramento Valley during cool season (Oct.-Apr.) trough passages. While terrain-flow interactions clearly factor into the SCCZ development, the nature of these interactions is unknown as are the mesoscale processes affecting event duration and orientation. Level-II NEXRAD radar data are used to examine the onset, duration, orientation, geographical extent, and precipitation rate of 23 SCCZ events during the 2016-2017 cool season. The analyses reveal distinct event morphologies including (1) isolated convective bands over the topography, (2) isolated convective bands displaced …
Cloud Microphysical Properties Based On Airborne In Situ Observations And Evaluation Of A Weather Forecasting Model And A Global Climate Model, John D'Alessandro
Cloud Microphysical Properties Based On Airborne In Situ Observations And Evaluation Of A Weather Forecasting Model And A Global Climate Model, John D'Alessandro
Master's Theses
Global cloud coverage has a substantial impact on local and global radiative budgets. It is necessary to correctly represent clouds in numerical weather models to improve both weather and climate predictions. This study evaluates in situ airborne observations of cloud microphysical properties and compares results with the Weather Research and Forecasting model (WRF) and Community Atmosphere Model version 5 (CAM5). Dynamical conditions producing supersaturated conditions with respect to ice at high altitudes in regions diagnosed by convective activity are explored using observations taken from the Deep Convective Clouds and Chemistry (DC3) campaign, and results are compared with simulated data from …
The Diablo Winds Of Northern California: Climatology And Numerical Simulations, Carrie Lynn Bowers
The Diablo Winds Of Northern California: Climatology And Numerical Simulations, Carrie Lynn Bowers
Master's Theses
Extreme fire behavior in the San Francisco Bay Area (SFBA) has historically been associated with strong offshore wind events referred to locally as Diablo winds. A 17 year surface-based climatological analysis was performed to establish a definition of Diablo winds and to identify their frequency and spatial distribution. Synoptic composites of events were constructed using North American Regional Reanalysis, and high resolution Weather Research and Forecasting (WRF) model simulations were used to investigate the mesoscale dynamics of three significant Diablo wind events. Diablo winds were defined as dry northeasterly, downslope winds that occur in the SFBA with minimum sustained wind …
Doppler Lidar Measurements Of Boundary Layer Heights Over San Jose, California, Matthew Robert Lloyd
Doppler Lidar Measurements Of Boundary Layer Heights Over San Jose, California, Matthew Robert Lloyd
Master's Theses
There is a need for understanding boundary layer depth and climatology over the urban area of San Jose, California. In this paper, Doppler LiDAR data are observed from San Jose. The adopted methods of vertical velocity variance and skewness are used to determine the estimated height of the convective boundary layer and to analyze sources of turbulence. The use of these methods helped identify a few types of the boundary layer that are common in San Jose. Also examined in this paper is a brief climatology of the mean maximum convective boundary layer height in San Jose over the period …
Mobile Doppler Lidar Observations Of The Convective Boundary Layer Over California, Christopher Paul Camacho
Mobile Doppler Lidar Observations Of The Convective Boundary Layer Over California, Christopher Paul Camacho
Master's Theses
A series of transects using a truck-mounted Doppler LiDAR were conducted to obtain mobile vertical profiles of the backscatter intensity and radial velocity across California. Using the backscatter and velocity profiles, several techniques were used to estimate the depth of the convective boundary layer (CBL). The CBL was estimated from the backscatter profiles using three analyses: (1) the Haar wavelet covariance, (2) the variance, (3) the gradient. These analyses were compared to vertical velocity variance, which uses a specified threshold (0.15 m2 s-2) to determine CBL height. The accuracy of the backscatter analyses was heavily dependent on strong aerosol loading …
Nocturnal Drying In Elevated Coastal Terrain Of Central California: A Fire Weather Perspective, Richard Bagley
Nocturnal Drying In Elevated Coastal Terrain Of Central California: A Fire Weather Perspective, Richard Bagley
Master's Theses
The second largest fire shelter deployment in U. S. history occurred during the Devil Fire in a remote and rugged region of the San Francisco Bay Area when relative humidity values abruptly dropped in the middle of the night, causing rapid fire growth. Nocturnal drying in the higher elevations along California’s central coast is a unique phenomenon that poses a great risk to firefighters. Single digit relative humidity with dew points below -25°C is not uncommon during summer nights in this region. In order to provide the firefighting community with knowledge of these hazardous conditions, an event criterion was established …
Measuring And Modeling Oceanic Air-Sea Fluxes, Aaron M. Rosenberg
Measuring And Modeling Oceanic Air-Sea Fluxes, Aaron M. Rosenberg
Master's Theses
There have been numerous studies evaluating model representation of the latent heat flux (LHF) over terrestrial surfaces due to LHF’s role in weather prediction, heat balance, and the hydrological cycle. However, LHF model representation over the ocean, where 86% of global evaporation occurs, has been largely untested due to the scarcity of in-situ measurements and difficulties associated with open ocean observations. This study evaluates the Weather Research and Forecasting Model (WRF) latent heat, sensible heat and momentum surface fluxes over the Sub-tropical North Atlantic Ocean from September 16 to October 30, 2012 under various surface layer and planetary boundary layer …
Exposure Assessment Of Asthma And Modeling Of Pm2.5 During The 2007 Southern California Wildfires, Areana Flores
Exposure Assessment Of Asthma And Modeling Of Pm2.5 During The 2007 Southern California Wildfires, Areana Flores
Master's Theses
A three-year study (1 Jan 07 to 31 Dec 09) was conducted for Los Angeles and Riverside counties to validate current findings on impacts of wildfires on respiratory health. A dataset developed from multiple sources containing daily rates of air pollution (O3, NO2, CO, and PM2.5) and meteorological variables (temperature, dew point, wind speed, and inversion height) was correlated with asthma emergency department (ED) visits. A second correlation was calculated for a modified dataset that excludes all episodes of wildfire events within the study period. The difference in correlations between both datasets was computed. PM2.5 was positively associated with asthma …