Oceanography and Atmospheric Sciences and Meteorology Commons^™

Representing Post-Fire Reality: An Empirically Informed Temperature Index Approach To Post-Fire Hydrologic Modeling In Oregon's Western Cascades, Logan Hastings

Dissertations and Theses

The invaluable water resources stored in snowpack face mounting threats from rising temperatures, drought, shifts in precipitation regimes, and increased fire frequency, which pose challenges to operational hydrologic modeling in Oregon's sensitive maritime snowpacks. The gridded temperature index (GTI) approach in operational models like the Hydrological Engineering Center's Hydrologic Modeling System (HEC-HMS) from the U.S. Army Corps of Engineers remains in common use for its minimal data requirements, but how GTI parameterizations should adapt to post-fire conditions is largely unknown.

This research assessed the impact of the 2020 Lionshead Fire on HEC-HMS performance in the North Santiam River basin across …

Evolution Of Global Sea‐Level Rise Projections And Their Uncertainty, Andra J. Garner, Amy Appollina, Jessica Slotter, Gregory G. Garner, Aimée B. A. Slangen, Robert E. Kopp, Benjamin P. Horton

School of Earth, Environment, and Society Faculty Publications and Presentations

For more than 40 years, scientists have projected future sea‐level change. Documenting how sea‐level projections have evolved is vital for tracking progress, uncertainties, and future research needs. Here, we update and analyze a database of global‐mean sea level (GMSL) projections dating from 1982 to 2025, identifying five key findings. First, GMSL projection generation has been concentrated in a small number of developed countries, with 95% of projections produced in the United States, United Kingdom, European Union, or Australia. Second, while GMSL projections for 2050 and 2100 have been published regularly since the early 1980s, only 30 of 103 studies have …

Aquatic Invasive Species Survey And Treatment On Lake Umatilla And Lake Celilo 2024-2025 Report, Jacob Rose, Gabriel E. Campbell

Center for Lakes and Reservoirs Publications and Presentations

Flowering Rush (Butomus umbellatus) is an invasive aquatic plant in the Pacific Northwest that threatens salmon habitat. The Center for Lakes and Reservoirs staff surveyed for this and other aquatic species from 2024 and 2025 in the Columbia River in Lake Umatilla and Lake Celilo. This document summarizes their survey efforts including their protocols, data, and small-scale removal efforts.

Characterizing Meteorological Patterns For Oregon's Winter Elevated Pm2.5 Concentrations From 2000-2023, Arielle Golda Sherbak

Dissertations and Theses

Valleys and basins are uniquely susceptible to the buildup of air pollution during the wintertime due to cool, dense air pooling under favorable meteorological conditions, a common occurrence in the Intermountain West. In Oregon, wintertime anthropogenic air pollution is primarily from woodburning stoves and heaters and although efforts have been made to reduce wintertime pollution, stagnation events continue to result in decreased air quality. This analysis aims to understand the relationship between air pollution in six Oregon counties and the associated meteorology in the cool season (November-March) using a 2000-2023 climatology.

This is completed through a composite analysis using key …

The Effect Of Mesoscale Frontal Waves On Landfalling Atmospheric Rivers And Their Associated Precipitation Over The Green River Watershed, Washington, Joseph Michael Riedl

Dissertations and Theses

In this study, the effect of mesoscale frontal waves (MFWs) on extreme precipitation (EP) in the Upper Green River Watershed (UGRW), Washington is investigated. 205 EP days (>95th percentile) are identified in the UGRW between the years 1980 and 2021. To characterize the range of large-scale meteorological conditions associated with EP days, the self-organizing map (SOM) approach is used to cluster daily integrated water vapor transport (IVT) on EP days. To further diagnose the meteorological drivers, composites of several other diagnostic fields are constructed for each SOM node and the preceding days. Together, these results illustrate common orientations of …

Synoptic-Scale Meteorological Patterns Associated With Extreme Precipitation Over The Contiguous United States And Concomitant Seasonal And Regional Variability, Amy M. Johnson

Dissertations and Theses

Seasonal and spatial variations of synoptic-scale weather patterns concurrent to extreme precipitation days, defined as days above the seasonal 95th percentile of the daily precipitation distribution, are characterized over a 44-year period (1980-2023) for the Contiguous United States (CONUS). Using atmospheric reanalysis data and a grid-cell centered approach, we construct seasonal anomaly composite patterns for sea level-pressure (SLP), integrated water vapor transport, 500 hPa geopotential height (Z500), and 300 hPa wind speed. Atmospheric variables known to be important for extreme precipitation. By interpolating composites for each grid cell onto the same polar coordinate grid relative to the grid cell we …

Characterizing Rainfall Variability Within A Series Of Storms Over Northern California In February 2017, Parker Jan Malek

Dissertations and Theses

In February 2017, a series of storms with associated atmospheric rivers (ARs) made landfall in the US state of California, dropping large amounts of precipitation over the Sierra Nevada Mountains and their western foothills. The rainfall from these ARs, long, narrow bands of water vapor that transport large amounts of water vapor from the tropics to the mid-latitudes, instigated the near-failure of the Oroville Dam located at the southeastern edge of the Feather watershed outside the city of Oroville in the state's Central Valley. This case study provides a synoptic and mesoscale diagnosis of the drivers of rainfall pulses that …

Predicting Cloud-To-Ground Lightning In The Western United States From The Large-Scale Environment Using Explainable Neural Networks, Dmitri A. Kalashnikov, Frances V. Davenport, Zachary M. Labe, Paul C. Loikith, John T. Abatzoglou, Deepti Singh

Geography Faculty Publications and Presentations

Lightning is a major source of wildfire ignition in the western United States (WUS). We build and train convolutional neural networks (CNNs) to predict the occurrence of cloud-to-ground (CG) lightning across the WUS during June-September from the spatial patterns of seven large-scale meteorological variables from reanalysis (1995-2022). Individually trained CNN models at each 1° × 1° grid cell ( = 285 CNNs) show high skill at predicting CG lightning days across the WUS (median AUC = 0.8) and perform best in parts of the interior Southwest where summertime CG lightning is most common. Further, interannual correlation between observed and predicted …

Synoptic Drivers Of Extreme Precipitation In The Upper Yuba Watershed Of California, Emma Nichole Russell

Dissertations and Theses

The United States state of California is vulnerable to both droughts and extreme precipitation events due to the timing and processes of precipitation in the region. California's annual precipitation is dependent on a few strong storms and in addition to its Mediterranean climate, leads to great variability in precipitation both within and across years. While efforts to reduce the impacts of extreme precipitation events have been implemented, forecasting for these events remains a challenge in regions with complex terrain and dynamic meteorological drivers. In order to improve forecasting and preparedness for such events, it is important to understand the range …

Scale-Dependent Effects Of Urban Canopy Cover, Canopy Volume, And Impervious Surfaces On Near Surface Air Temperature In Portland, Or, Carson Ralls

Geography Masters Research Papers

Cities are significantly warmer than their surrounding rural environments. Known as the ‘urban heat island effect’, it can affect the health of urban residents and lead to increased energy use. Although this effect is extensively researched, less is known about how landscape characteristics within cities affect local temperature variation. With a warming climate and the need for heat mitigation strategies becoming more urgent, having a finer detailed understanding of the effects on temperature is critical to guide proper management policies. This study examined how tree canopy cover, canopy volume, and impervious surface cover affect daytime near surface air temperature, and …

An Index Of Biotic Integrity For Macroinvertebrate Stream Bioassessment Conducted By Community Scientists, Patrick M. Edwards, Daniel Bedell, Shannon Hubler, Chad A. Larson, Kate H. Macneale, Elisa Mickelson, Chris Prescott, Elinore Webb, Jo Wilhelm

Environmental Science and Management Faculty Publications and Presentations

Community science bioassessment has great potential to inform comprehensive stream management plans, but regional analytical tools are needed to evaluate macroinvertebrate data collected through community science programs. To this end, we modified a pre-existing professional index of biotic integrity (IBI) to create a community science IBI (CS-IBI), designed for stream macroinvertebrate data collected by community scientists with minimal training. We used data collected by both professional and community scientists to develop, calibrate, and validate the CS-IBI at 76 streamsites in the Puget Lowland andWillamette Valley ecoregions of the PacificNorthwest in theUnited States. Community science data were taxonomically coarser andmore variable …

Atmospheric Circulation, Climate Change, And Related Impacts Over The Western United States, Graham Patrick Taylor

Dissertations and Theses

This dissertation characterizes the range of atmospheric circulation patterns and select associated meteorology impacting the northwest United States, the onset timing of rain and wind relevant to wildfire across the western United States, and how these may respond to global warming. The ability of a suite of models contributing to the sixth phase of the Coupled Model Intercomparison Project (CMIP6) to simulate observed large-scale atmospheric circulation patterns over the Pacific Northwest of North America is evaluated. Climate model projections of atmospheric circulation patterns, their frequency, and associated temperature and precipitation anomalies under a high-end global warming scenario are assessed over …

Multiscale Variability Of Heavy Metals In A Western U.S. Snowpack, Kelsey Hefner

Student Research Symposium

Natural and anthropogenically sourced particulates are deposited from the atmosphere to landscapes via dry and wet deposition, making frozen winter snowpack a natural archive of atmospheric elemental composition. Wildfires in the Western United States are increasing in extent, duration, and severity, especially in alpine regions. Severe fires remove forest canopy and can impact how atmospheric elements are dispersed and stored across snow-dominated watersheds. We evaluated Al, V, Cr, Mn, Ni, Cu, As, Zn, Se, Mo, Cd, and Pb concentrations in 394 winter snow core samples. We collected samples in 2019 and 2020 from a chronosequence of eight forests that burned …

Tidal Bed Stress Asymmetry And Sediment Transport In Estuaries, Austin Scott Hudson

Dissertations and Theses

Rivers and estuaries provide numerous ecological, economic, and cultural resources. The value of these resources is greatly influenced by sediment transport processes, which can be affected by human activities and climate variability. A key driver of sediment transport in tidal rivers and estuaries is tidal asymmetry of velocity and bed stress, which can manifest from both non-linear tidal interactions and linear interactions among astronomical tidal constituents.

In this study, an analytical framework is developed to examine and describe the dynamics of bed stress asymmetry in semidiurnal, diurnal, and mixed-tide estuaries (Chapter 1). While tidal velocity asymmetry has been previously analyzed, …

Using Biometrics, Behavioral Observations, And Multiple Molecular Techniques To Assess The Impacts Of Changes In Temperature And Salinity On The Common Bay Mussel (Mytilus Trossulus), Casey Martin

Dissertations and Theses

The intertidal zone is a place of rapid and frequent change that is home to a variety of creatures who are essential to the integrity of the habitat. Mussels are robust sessile bivalves that anchor to the rocks of the intertidal. The prominent species on the Oregon Coast, the Common Bay Mussel (Mytilus trossulus), plays an essential role as a coastal food source, water column filter, and barrier to prevent erosion due to wave action. Mytilus trossulus withstands daily shifts in temperature, salinity, and tide, as well as seasonal changes. Global climate change due to excess carbon emissions …

The Impact Of Climate Change On Selected Pnw Watersheds Through The Lens Of Western Red Cedar Habitat, Jordan T. Hamann

Dissertations and Theses

Climate change is a real phenomenon that is exacerbating existing natural processes and developing into a new normal for the planet. This change may be devastating for Pacific Northwest populations of Western Red Cedar (WRC) west of the Cascade Mountain range in the states of Oregon and Washington. WRC is a valuable tree species for reasons both economic and cultural. Dieback among WRC is following an accelerating trend. Since dieback is usually followed by tree mortality, understanding its causes and distribution is beneficial to the overall success of the species going into the future.

Through the use of ESRI's ArcGIS …

The Role Of The Armed Forces Of The Philippines (Afp) In Disaster Response And Adaptation Strategies To Climatic Disasters In Manila, Edmundo Nicolas Jr.

Geography Masters Research Papers

This study described the roles of the Armed Forces of the Philippines (AFP) in Disaster Risk Reduction Management (DRRM) in Metro Manila and how climate-induced hazards impact the role of the military. It used a qualitative approach, which involved semi- structured interviews among AFP officers and barangay leaders with expertise and experience in DRRM and an analysis of selected policy documents and military doctrine. These methods revealed that: (1) the military acts as a political first-aid, since they are the first responders – thus, the face of the local government – in climactic disasters during peacetime; (2) the military is …

A Gridded Co2 Emissions Inventory For Portland, Or, James E. Powell

Dissertations and Theses

Here we develop a new high resolution inventory of CO₂ emissions for the three Oregon counties which comprise the bulk of the City of Portland, Oregon, USA. Locally curated and long-running data collection efforts for on-road traffic activity and emission rates are used to model on-road emissions, and a new survey of the area's natural gas network informs the building energy model. The inventory estimates total emissions of CO₂ for each hour of the year 2018 in the on-road, residential, and commercial building sectors at 1 km² resolution. The onroad inventory compares to within 3% with an …

Short Warm-Side Wet-Bulb Temperature Distribution Tails Lead To Accelerated Increases In Extreme Threshold Exceedances Under Global Warming, Yianna Sotirios Bekris

Dissertations and Theses

Humid-heat extremes threaten human health and are increasing in frequency with global warming, so elucidating factors affecting their rate of change is critical. This thesis examines the role of historical (1985-2014) wet-bulb temperature distribution tail shape on the probability of wet-bulb temperature extreme threshold exceedances under 2°Celsius global warming. Analysis of global climate models and reanalysis reveals that non-Gaussian wet-bulb temperature distribution tails are common worldwide across extensive, spatially coherent regions. More rapid increases in the number of days exceeding the historical 95th percentile are projected in locations with shorter-than-Gaussian warm-side tails. Of the two primary components of wet-bulb temperature, …

New Opportunities And Untapped Scientific Potential In The Abyssal Ocean, Jeffrey J. Marlowe, Rika E. Anderson, Anna-Louise Reysenbach, Jeffrey S. Seewald, Timothy M. Shank, Andreas P. Teske, V. Dorsey Wanless, S. Adam Soule

Biology Faculty Publications and Presentations

The abyssal ocean covers more than half of the Earth’s surface, yet remains understudied and underappreciated. In this Perspectives article, we mark the occasion of the Deep Submergence Vehicle Alvin’s increased depth range (from 4500 to 6500 m) to highlight the scientific potential of the abyssal seafloor. From a geologic perspective, ultra-slow spreading mid-ocean ridges, Petit Spot volcanism, transform faults, and subduction zones put the full life cycle of oceanic crust on display in the abyss, revealing constructive and destructive forces over wide ranges in time and space. Geochemically, the abyssal pressure regime influences the solubility of constituents such as …

Inverse Modeling Of Atmospheric Ch4 And Δ13C-Ch4 Measurements From Surface Observation Sites To Understand Trends In Global Methane Emissions Over More Than Three Decades, Sayantani Karmakar

Dissertations and Theses

Methane (CH₄) is the second most important greenhouse gas with a radiative forcing of 0.97 W/m² including both direct and indirect effects and a global warming potential of 28 over a 100-year time horizon. Unlike CO₂ whose rate of growth in the atmosphere has remained positive and increased in recent decades, the behavior of atmospheric methane is considerably more complex and is much less understood on account of the spatiotemporal variability of its emissions which include biogenic (e.g., wetlands, ruminants, rice agriculture), thermogenic (fossil fuels), and pyrogenic (i.e., biomass burning) sources. After sustained growth during most …

Stakeholder Perceptions Of Microplastics Management In Oregon, Maya Hurst-Mayr

Environmental Science and Management Professional Master's Project Reports

There is currently no federal policy in the United States that specifically addresses microplastics (MPs) pollution. However, states are beginning to act on this issue; California's SB 1422 initiates measurement of MPs in drinking water resources and Senate Bill 1263 requires the state to adopt a strategy to reduce the ecological impact of MPs in marine ecosystems. Other West Coast states like Oregon and Washington are expected to follow California's example. It is important to know what the actors who are a part of shaping MPs policy in Oregon would see as barriers and opportunities to doing so. We conducted …

The Imperative For Climate Action At Portland State University, Stephen Percy

Office of the President Publications and Presentations

Portland State University President Stephen Percy announces the formation of the Climate Change Initiative.

Regional Characteristics And Variability Of Extreme Precipitation And Atmospheric Rivers In Past, Present, And Future Climates Over The Contiguous United States, Emily Anne Slinskey

Dissertations and Theses

This dissertation examines the regional and seasonal variability of extreme precipitation and atmospheric rivers (ARs) across the contiguous United States (CONUS) in past, present, and future climates. An extreme precipitation categorization scheme, designed to monitor and track the multi-scale variability of extreme precipitation, is applied to a range of precipitation measurement products as an assessment of observational uncertainty. To investigate the importance of ARs across the CONUS, an objective AR identification algorithm is applied to global reanalysis to identify and characterize AR characteristics regionally over the observational record. Projected change in AR day frequency, geometry, intensity, and associated precipitation is …

Climate Model Evaluation Of Atmospheric Rivers Over The Contiguous United States, Ilan González-Hirshfeld

Dissertations and Theses

Atmospheric rivers (ARs)--long corridors of intense atmospheric water vapor transport--significantly influence the hydrologic cycle and regional hydrometeorological extremes across the contiguous United States (CONUS). Ongoing and future climate change may alter AR characteristics and impacts, making confident climate model projections of future change, especially at regional scales, of critical importance. In order to better constrain uncertainty in such projections of future change, we perform a comprehensive climate model evaluation of AR climatology over the CONUS. Using an established AR detection algorithm, we evaluate the representation of ARs in historical simulations (1984-2013) from a suite of models participating in the sixth …

Projections Of Large-Scale Atmospheric Circulation Patterns And Associated Temperature And Precipitation Over The Pacific Northwest Using Cmip6 Models, Graham Patrick Taylor

Dissertations and Theses

Projections of 500 hPa geopotential height (Z500) patterns over the Pacific Northwest of North America and their associated surface temperature, precipitation, and frequency of occurrence are assessed using models from the 6th phase of the Coupled Model Intercomparison Project (CMIP6). The self-organizing maps approach is applied to reanalysis data from the Modern-Era Retrospective Analysis for Research and Applications, version-2 (MERRA-2) to cluster daily Z500 anomalies into 12 representative patterns that span the range of historical circulation patterns. CMIP6 data for daily Z500 anomalies are mapped to each node for historical and end of century global warming experiments, and the resulting …

Do Secondary Cyclones Increase The Category Scale Of Atmospheric Rivers?, Edgar Sanchez Fausto

University Honors Theses

Atmospheric rivers (ARs) play a crucial role in delivering precipitation worldwide. This makes them an important phenomenon for water resource specialists to study. One such interest is to understand what mechanisms make ARs produce significant rainfall and associated hazards such as flooding. One possible mechanism is that AR duration or intensity may increase when it interacts with a secondary cyclone, either of which can increase the AR category scale. The purpose of this study is to determine whether AR and secondary cyclone interactions increase the category scale ARs. Out of 52 AR events analyzed, 32 events contained at least one …

Altimetry For The Future: Building On 25 Years Of Progress, Saleh Abdalla, Abdolnabi Kolahchi, Micheal Ablain, Susheel Adusumilli, Suchandra Aich Bhowmick, Eva Alou-Font, Laiba Amarouche, Ole Baltazar Andersen, Edward Zaron, Multiple Additional Authors

Civil and Environmental Engineering Faculty Publications and Presentations

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the …

Niche Partitioning Of Low-Light Adapted Prochlorococcus Subecotypes Across Oceanographic Gradients Of The North Pacific Subtropical Front, Anne W. Thompson, Kathleen Kouba, Nathan A. Ahlgren

Biology Faculty Publications and Presentations

The cyanobacterium Prochlorococcus is the most abundant photosynthetic cell on Earth and contributes to global ocean carbon cycling and food webs. Prochlorococcus is known for its extensive diversity that falls into two groups of ecotypes, the low‐light (LL) and high‐light (HL) adapted ecotypes. Previous work has shown niche partitioning of the very abundant HL adapted ecotypes and subecotypes across oceanographic gradients including temperature, nutrients, and day length. However, niche partitioning of subecotypes within the LL adapted ecotypes has not been studied as well because they are less abundant and less accessible than surface, HL populations. Through high‐throughput, cyanobacterial‐specific, sequencing of …

Projections Of Change In Frequency And Persistence In Atmospheric Ridging Over The Pacific Northwest Using Cmip6 Models, Ellen Koukel

University Honors Theses

The hydroclimatology of the Pacific Northwest is characterized by wet winters and dry summers; however, the end of the rainy season is subject to considerable year-to-year variability. Early onset of the dry season can introduce challenges for water resource managers. Historically, anomalously dry springs are the result of persistent atmospheric ridging, with notable examples in May 2015 and 2018. As climate change may affect the persistence and frequency of ridges, it is important to understand potential changes in springtime ridging. Future changes will have implications for the length of the rainy season and consequently freshwater availability throughout the region. Therefore, …