The El Niño-Southern Oscillation (ENSO) is the most significant year-to-year climate variation, affecting weather and climate systems worldwide. However, current prediction models, both dynamic and statistical, struggle with accuracy due to the complex mechanism of ENSO. This study introduces a regional temperature and salinity prediction method using a Long Short-Term Memory (LSTM) deep learning model, which is well-suited for identifying long-term patterns in sequential data. The model is applied to three specific regions using in-situ data from Argo floats: the central-eastern Pacific, the central tropical Pacific Niño 3.4 region, and the Western Pacific Warm Pool (WPWP). These regions are chosen because they play key roles in ENSO dynamics. Results show that the LSTM model performs best in the WPWP, where the average mean squared error (MSE) is low (0.03), indicating high accuracy and stability. This is likely due to lower noise in the original data. In contrast, the model performs poorly in the central-eastern Pacific, where the average MSE is much higher (7.03), suggesting instability due to high noise in original data. These findings highlight the potential of deep learning for regional climate predictions and suggest that LSTM models could improve local weather forecasting and fisheries management.

Oceanic currents drive all the world’s major climatic, biological, pollutant and sediment transport patterns. Many complex forces interact to produce the intricate movements of the ocean’s waters. Tidal rectification, a phenomenon caused by the spinning reference frame of the Earth acting together with island geometry and friction, is one such process which dictates how water is circulated around islands, seamounts, and other bathymetric shapes when tidal oscillations are present. Tidal rectification has been described mathematically and compared with physical measurements for many islands, but these islands fall into a few distinct categories. Many are either large and restricted to central latitudes, or small in diameter and found in far northern latitudes. Non-Island formations, such as guyots, and smaller bathymetric features in more central latitudes are not rigorously characterized through the lens of tidal rectification. This study expands the practical characterization of tidal rectification by comparing current speed data around a guyot near Namonuito Atoll, south of Guam, to a theoretical scaling of the potential forces acting on the guyot. I hypothesized that friction-based circulation would dominate over Coriolis-based circulation due to the guyot’s low latitude. Current velocity data was collected along a circular transect around the guyot by the R/V Thomas G. Thompson in December 2024. Preliminary findings, based on a scale analysis, suggest that these two cases are difficult to distinguish. Further research is needed to derive the nature of rectified circulation for small low-latitude islands. A rigorous practical analysis of the effects of tidally-rectified circulation is critical for a deeper understanding of biological processes, sediment transport, and pollutant concentrations around island communities.

The world’s oceans are witnessing a surge in plastic pollution, a consequence of human activities and the growing urbanization of coastal regions. Urban estuaries are complex habitats that are especially good at trapping sediment, carbon, and pollutants, such as plastics. However, our understanding of the extant of plastic accumulation within estuarine sediments remains limited. We determined the first quantification of the total amount of microplastics (>5 mm) in Main Basin Puget Sound, WA – a heavily urbanized estuary – and identified deposition hotspots related to current hydrodynamics. To measure plastic concentrations, we collected both shoreline and shipboard sediment samples and density extracted microplastics using an NaI solution. Extracted plastics were counted and categorized under a microscope. To complement these plastic analyses, energy of the environment was determined using both grain size analysis and extraction of current velocities from LiveOcean, a hydrodynamic model of Puget Sound. We found that plastic concentrations are the highest near land-water interfaces, which are correlated with human population. A range of 50-716 particles per kilogram of sediment was recorded in bottom samples and as much as 1180 particles/ kg were found in shoreline samples. The dominant source of microplastics came from fibers shed from clothing, giving a well-sorted particle size distribution. Furthermore, using the plastic concentration data we developed a predictive model of plastic distribution that relies on Puget Sound currents and could be adapted for other estuarine systems. Providing a comprehensive analysis of the sources and sinks of microplastics in main basin Puget Sound that can be used to inform preventative management on the negative impacts of urban waste.

pH is an important parameter for determining the health of aquatic ecosystems in freshwater and marine environments. pH is naturally basic (~8.1) in marine environments, and is controlled by carbonate buffering, carbon dioxide concentrations, and temperature. This differs from freshwater environments, where temperature plays the largest role in determining pH, resulting in naturally more acidic waters with pH levels ranging from 6.5 to 7.8. Global warming is causing rapid temperature changes, which profoundly impact freshwater pH, harming ecosystem food chains. However, long-term lake pH monitoring is limited, largely because robust and pressure-tolerant pH sensing technology have been typically designed for marine environments. This gap in technology limits the technical assessment of marine pH sensors in freshwater settings. Before large-scale and long-term use of pH sensors can begin in freshwater environments, extensive tests need to be completed to ensure the data represents the environment. To conduct this study, we tested the Ion Sensitive Field Effect Transistor (ISFET) pH sensing technology using the Deep SeapHOx™ V2 pH sensor, manufactured by Sea-Bird Scientific, over three months in Portage Bay, off the University of Washington’s Marine Science Building Dock. We collected bi-weekly water samples from the deployment location to determine pH using spectrophotometric analysis, to assess the accuracy and stability of the Deep SeapHOx™ V2 pH readings. Our findings indicated that the Deep SeapHOx™ V2 was functional in freshwater environments but with the regular factory calibration, consistently produced readings approximately 1 pH unit different from the true measurements. Additionally, the sensor exhibited a linear drift over the test period. Both issues could be easily corrected with an in-situ calibration after the sensor had equilibrated to the environment (approximately 1 week). This study contributes to the advancement of freshwater research by expanding the pH sensor technology available for monitoring these ecosystems.

Deuterium is the naturally occurring, heavier stable isotope of hydrogen, which comprises a known proportion of the hydrogen in seawater. As evaporated water travels inland, heavier molecules containing deuterium are rained out preferentially. The deuterium/hydrogen ratio (δ2H) in precipitation is controlled by climatic and geographic factors such as temperature, elevation, and latitude. Terrestrial plants use rainwater as their primary source of hydrogen, so this climatic and topographic marker is recorded in their compounds, which allows for their use in the sedimentary record as paleoclimate proxies. In this study I examine δ2H in n-alkanes, the hydrocarbon chains that make up leaf waxes, extracted from plants, leaf litter (duff), and soils across Washington state. Due to rainout effects influenced by the Cascade Mountains’ rain shadow, δ2H is expected to show a trend of depletion across the state. Samples were collected from sites along an east-west transect across the Cascades. I have processed these samples for isotope analysis and am now conducting literature review to compare our results with a global dataset. Preliminary results show the expected depletion of deuterium across the transect and correlation with rainwater δ2H, modeled using the Online Isotopes in Precipitation Calculator (OIPC). My goal is to assess the local trend of δ2H depletion across this gradient through comparison with existing literature, and to examine the poorly-studied pathway of isotopic signature from plant tissue into soils. I am to provide new insight into the pattern of isotopic signals preserved from live plants into soils and sedimentary rocks, and to further explore and refine the use of hydrogen isotopes in sedimentary n-alkanes as paleoclimate indicators. This research is part of a larger study on the persistence of the isotopic signal of the Cascade Mountains’ rain shadow into the rock record to potentially constrain the timing of their uplift. 

Greater than 70% of the volcanism on Earth occurs along mid-ocean ridge spreading centers and plays a significant role in cycling elements into and out of the seafloor due to hydrothermal circulation. My study investigated how temperature and chlorinity/conductivity were changing in two submarine hot springs (hydrothermal vents) from September 12, 2023 – January 7, 2025, with linkages to earthquake activity. I chose this time interval due to heightened seismic activity and inflation of the volcano in recent time indicating an impending eruption at Axial Seamount is likely within a year. These data inform the underlying plumbing system and were utilized to test the hypothesis that the plumbing systems of two ~350°C hydrothermal vents (Escargot and Diva) are not interconnected in the shallow subsurface. Data utilized were from the Ocean Observatories Initiative – Regional Cabled Array (OOI-RCA) underwater observatory and Axial Seamount Earthquake Catalog. These allowed for examination of phase separation and perturbations occurring in each vent. The RCA Instruments utilized were two sensors that stream live temperature and resistivity (converted to chlorinity/conductivity) measurements from the volcano 300 miles offshore. These data, in addition to pressure data from a Bottom Pressure-Tilt sensor (BOTPT) and the Axial Seamount Earthquake catalog are being analyzed with Python to correlate earthquakes to temperature and chlorinity/conductivity and examine lunar-driven tides. Five statistically significant perturbations/events were documented and analyzed. Findings from an additional perturbation showed the occurrence of possible brine release from the subseafloor due to heightened inflation from the magma chamber. This work helped inform on process linkages leading up to an eruption and the sequestration of subsurface brines and their possible release post eruption into the overlying ocean with impacts on novel brine and metal tolerant organisms in these extreme environments. 

In the Equatorial Pacific, tropical instability waves (TIWs) are a dominant form of upper ocean variability during the La Niña phase of the El Niño-Southern Oscillation (ENSO). Cold water along the equator is moved westward by strengthened trade winds forming TIWs off the edges of the cold tongue. TIWs have an average period of one month, a wavelength of 1,000 km, and often are characterized by their unique sea surface temperature patterns. It is critical to understand the complex physical dynamics occurring underneath TIWs as they regulate subsurface dynamics (i.e., mixing and internal waves) and ENSO. Here, we investigated the impact of stratification on both the mixed layer and vertical velocity across the TIW field utilizing a Seaglider, an autonomous buoyancy-driven underwater vehicle. In November 2024, we deployed a Seaglider near the equator to sample the TIW field during the La Niña phase for three months as a part of the University of Washington’s Student Seaglider Center. The Seaglider transected numerous TIW fronts collecting oceanographic data along its 1,000 m dives. We used the temperature, pressure, Seaglider velocity, and biogeochemical variables reported by the Seaglider to explore water column stratification and vertical velocities during TIWs. Preliminary results suggest that increased mixing across the submesoscale fronts of TIWs is associated with higher vertical velocities and increased nutrient levels near the surface. The in situ Seaglider data was also compared to data subsampled from the Global Ocean Physics Reanalysis (GLORYS), a dataset from modeled and observational data, to provide large-scale background context. This study increases in situ observation of submesoscale fronts within TIWs which is critical to further resolving small-scale processes within models.

Student-run environmental research organizations allow students to gain real-world experience while conducting research that leads to a greater understanding of the environment. These programs suffer from high turnover when students graduate and take the knowledge they have acquired with them. Loss of institutional knowledge is a major issue for organizations that rely on students and mitigating this loss is essential to ensure the success and longevity of a program. This project finds how student-run environmental research organizations can better preserve institutional knowledge through a case study with the Student Seaglider Center (SSC): a student-run lab at the University of Washington’s School of Oceanography. My research is centered around studying the efficacy of a new training class for students interested in joining the SSC through tracking how self-reported competency in various subject areas changes throughout the quarter. Their results are compared to students who are already in the lab and did not take the class. This research helps determine effective methods to transfer knowledge from experienced members to newer ones, which helps the SSC operate efficiently in the future and continue to do impactful environmental research. It also benefits other student-run research programs by providing recommendations on how they can reduce the loss of institutional knowledge when students graduate.

Changes in oceanic dynamics in the Tropical Pacific Ocean can have an influence on large-scale patterns like El Niño-Southern Oscillation (ENSO) dynamics and global climate. Understanding the magnitude of ocean temperature and salinity changes in this region in recent decades can help us understand the impacts of climate change and inform predictions. This study compares temperature and salinity in the Tropical Pacific during the winter and spring of 2025 to ship transects from the 1950s-1980s. Seaglider data were collected by the UW Student Seaglider Center’s Seaglider SG195 which was deployed off of the R/V Sikuliaq in November 2024. The Seaglider gathered data on temperature, salinity, and depth-averaged currents along a transect from the Equatorial Pacific (4° 39' 24”, -139° 53' 34") to Honolulu, Hawaii (21° 15' 0", -157° 52' 0"). These data were compared to CTD data from historic ship-based datasets, obtained from NOAA world ocean database, covering the same region and season (Winter to Spring). Preliminary analysis shows a connection between subsurface changes and the current ENSO phase. Since temperature variability in the Tropical Pacific is a key driver of ENSO dynamics, this research can support others in understanding whether the Tropical Pacific may be trending toward La Niña or El Niño baseline conditions and thus what the Equatorial Pacific will look like in upcoming decades.

Ocean eddies contribute significantly to the transfer of heat and energy throughout the world’s oceans, playing a key role in regulating climate. Eddies are observed predominantly through Earth-orbiting satellites that collect data on sea surface height (SSH), a metric that can be used to estimate eddies on a global scale. Historically, satellites could only capture point-wise measurements, resulting in low-resolution SSH maps, which led to underestimations of small-scale eddy strength. Launched in 2022, NASA’s Surface Water and Ocean Topography (SWOT) satellite now provides groundbreaking 2D SSH imagery with higher resolution relative to existing SSH products. However, there are only two years of SWOT data available, unlike other satellites with decades-long records. Here, we considered how the recent SWOT data could be deployed to improve the spatial resolution of SSH products from the preceding 30 years. To achieve this, we trained an image-to-image U-Net neural network to predict the high-resolution SSH from an existing low-resolution product (NeurOST). We used SWOT high-resolution data as a ground truth to train this neural network and minimize the mean squared error of the SSH output with respect to the SWOT data. By evaluating the accuracy of the SSH output maps against an independent withheld satellite, we demonstrated that our method improves the spatial resolution of the SSH product compared to the NeurOST dataset. We next plan to test the accuracy of our method when applied to years before SWOT was launched. Overall, our research highlighted how leveraging deep learning and SWOT can enhance the spatial resolution of a decades-long eddy observation time series, enabling more accurate studies of eddies and their climate impact.

The marine cyanobacterium, Prochlorococcus, is the most abundant photosynthetic organism in the world. Prochlorococcus is composed of two main clades, High Light (HL) and Low Light (LL). Within the clades, further subdivisions exist as differentiated populations adapted to their environment (ecotypes). Although these organisms can be found in most global surface oceans, the ecotypes are not equally distributed latitudinally nor vertically. Furthermore, the inter-specific relationship between the ecotypes and how the proportion of each one corresponds with different environmental conditions are not well understood. Therefore, in this study I investigate the intra- and interseasonal environmental conditions (e.g. temperature, light, and nutrients) that affect the distribution of Prochlorococcus ecotypes in the North Pacific Ocean. Using python coding, I analyzed the correlation of environmental data to datasets from a series of cruises that contain optical and molecular properties of Prochlorococcus. I utilized sequenced and mapped community samples of RNA from a published dataset, also known as metatranscriptomes, to identify present Prochlorococcus ecotypes and their associated relative abundances. Additionally, I used flow cytometry data to analyze forward scatter (cell size) and red fluorescence (chlorophyll) of each Prochlorococcus cell that is captured in a sample. Expected results of this study are that 1) light and temperature will be the most important factors determining the distribution shifts between the HL and LL clades, 2) temperature will be the most important factor differentiating the HL ecotypes, and 3) nutrient levels will be the most important factor differentiating the LL ecotypes. This study will enhance our understanding of how environmental conditions influence Prochlorococcus ecotypes in the North Pacific, though the findings may not represent global patterns. Furthermore, the results suggest that Prochlorococcus strains more susceptible to environmental changes may experience ecological shifts, an issue likely to intensify as climate change impacts the ocean.

Planktonic protists (unicellular eukaryotes) play essential roles in open-ocean biogeochemical cycles and food webs, functioning as phototrophs, heterotrophs, or mixotrophs depending on the species. However, cultured representatives of protists from the Pacific Ocean are scarce, limiting our understanding of protists within the largest ocean on Earth. In this study, we analyze seven cultured protist strains isolated from the tropical Pacific Ocean from the upper ocean from 30 °N to 4 °S and from 120 to 140 °W, including seven haptophytes, five pelagophytes, and four dinoflagellates. We examine transcriptomes from laboratory cultures of these isolates. We construct a phylogenetic tree of the isolates based on single-copy marker genes to infer evolutionary relationships. We examine correlations between phylogenetic relatedness and the latitude and depth of isolation. An additional objective of this work is to resolve the species-/strain-level taxonomy of these isolates, enabling their integration into the Marine Functional Eukaryotic Reference Taxa database. This will improve our ability to characterize marine protist diversity and function in metagenomes and -transcriptomes.

Ocean microbial communities are sensitive to temperature fluctuations. This study examines the direct and indirect effects of temperature on bacterial abundance off the coast of Guam (4°N-16°N, 149°E). Water samples were collected at 10m depth and the Deep Chlorophyll Maximum (DCM) to assess bacterial abundance and its relationship with temperature and chlorophyll concentration. Results show a strong positive correlation between bacterial abundance and temperature at 10m, suggesting warmer conditions enhance microbial growth. However, no significant correlation was found at the DCM, indicating other factors, such as mixing and nutrient availability, influence deeper bacterial communities. A notable anomaly at 8°N was linked to strong currents that redistributed bacteria, concentrating them at about 200m. These findings highlight the interplay between temperature, primary production, and ocean currents in regulating microbial abundance, offering insight into how microbial ecosystems may respond to climate-driven ocean changes.

Key drivers for primary productivity vary on latitudinal scales, such as nutrient and light. Nutrient variation can be seen at differing latitudes, such as lower nitrate to phosphate concentrations in the tropics (23°26’N to 23°26’S) compared to higher nitrate to phosphate concentrations in temperate regions (35° to 50° N and S) (Lønborg et al., 2021). With consistent differences by latitude of nutrient concentrations and abundance, it prompts the question of whether a nutrient-dependent entity such as phytoplankton biomass can be attributed to latitude change. To determine a correlation between nutrient availability and phytoplankton biomass, limiting nutrients and nutrient variations by latitude were investigated within the mixed layer determined by thermoclines from 4°N to 16°N along 149°E in Guam. The limiting nutrient of phytoplankton biomass was determined using on-deck incubators consisting of three conditions: + 1uM nitrate, +0.2uM phosphate, and a control with no added nutrients. Total chlorophyll served as a proxy for phytoplankton biomass, and was measured for three incubation sets from three different sampling stations. Nutrient concentrations were collected at every degree from 4°N to 16°N and compared by latitude to determine a relation between nutrient variability to latitude. Chlorophyll rate of change and mean total chlorophyll from nitrate incubations were significantly greater than phosphate and control incubations, pointing to nitrate as the limiting nutrient of primary productivity. No statistical correlation was established between nutrient variability and latitude, but there was a statistical correlation between size-fractionated chlorophyll and N:P ratios at the same latitude, signaling a latitudinal correlation. I hypothesized that the intensity of bottom-up control on primary productivity will increase with increasing latitude across a ten degree transect due to concentration variation of the limiting nutrient of chlorophyll.

Understanding and predicting changes in primary productivity depend on both upper ocean warming and nutrient supply from the ocean interior. Fronts, where distinct water masses converge, are hotspots for these vertical exchanges, transporting nutrients upward and supporting diverse ecosystems. These fronts create sharp gradients in temperature and salinity, generating strong vertical velocities that upwell nutrients and biomass. However, the exact dynamics of frontogenesis (the formation of fronts) remain poorly understood. Additionally, these processes occur at scales too fine to be resolved in global climate models and are only marginally captured by high-resolution ocean simulations. This underscores the need for observational studies to characterize frontogenesis and test existing theoretical frameworks. In this study, we diagnose frontal dynamics using Petterson’s frontogenesis function, which quantifies the roles of divergence and strain. Using NcCut, a GUI developed by our group, we compiled a unique dataset capturing the full life cycle of numerous ocean fronts in front-following coordinates from a state-of-the-art ocean simulation. Our results indicate that for mesoscale (~100 km) fronts, strain dominates over divergence, aligning with classical theories. In contrast, submesoscale (~10 km) fronts exhibit shorter life cycles and no clear dominant driver of frontogenesis within the Petterson framework. We also identified key limitations in conventional diagnostics and improved our analysis by masking the front from its surrounding environment before diagnosing its drivers. This enhancement provides a more accurate representation of frontogenesis dynamics. In the future, we plan to apply our method to satellite observations to study real-world ocean fronts, validate ocean models, and improve predictions of primary productivity changes. Our findings highlight the importance of refining frontogenesis diagnostics to better capture the small-scale dynamics critical to ocean biogeochemistry and climate predictions.

This study investigates the Namonuito region of Micronesia to determine whether the many guyots and atolls in this region contain specific slope conditions suitable for cobalt crust growth. This project also investigates whether there is a relationship between suitable zones and general bathymetry. The primary research focused on NAM-2 Atoll and Enterprise, Essex, and Namonuito Guyots. After collecting multibeam and sub-bottom data, the slopes were analyzed for slope angle, optimal slope distribution and composition. Then the results were compared with each other to determine if there are any similarities or correlations. Among all the guyots it was found that almost all the optimal zones were found in gullies, ridge slopes, and at the bottom of areas that experience slope failures. However, there isn’t a clear correlation between mean slope angle, optimal slope distribution and slope face orientation. In addition, sub-bottom data showed that almost all the guyots northern slopes were covered by a single thick pelagic layer, while the southern slopes of Namonuito and Enterprise contained thin pelagic layers with zones of exposed hard substrate. NAM-2 Atoll also was entirely covered in a single thick pelagic layer. Overall, by conducting a geomorphology and sub-bottom comparison test it is possible to narrow down locations of interest that can be further surveyed. The implications of cobalt crust research are that cobalt crusts are another natural source of cobalt which is becoming increasingly difficult to obtain on land. If the Namonuito region contains a large cobalt crust and the cobalt crusts can be extracted, it could have a huge impact of global technology and manufacturing industries.

This study investigates the physical mechanisms driving spatiotemporal variability of

barrier layers in the Western Tropical Pacific (WTP) along 149°E, with a specific focus on the

La Niña phase of the El Niño-Southern Oscillation (ENSO). Barrier layers, which separate the

surface mixed layer from the thermocline, regulate ocean-atmosphere interactions and influence

climate dynamics. This research assesses the relative contributions of freshwater input from

precipitation, and wind stress on barrier layer formation and thickness. Data were collected

during a research cruise in January 2025 aboard the R/V Thomas G. Thompson from an

Underway Conductivity Temperature and Density (UCTD) sensor for temperature profiles, and

public-source meteorological data for atmospheric conditions (ERA5). Seven stations, spaced

two degrees apart in latitude, were sampled along a transect from 4°N to 15°N. Each station

provided data to analyze barrier layer thickness, with spatiotemporal variability determined by

comparing different formation mechanisms across stations. Spearman Correlation analyses were

used to determine dominant factors influencing barrier layer thickness and variability. We found

that barrier layer thickness in the WTP shows a general positive but statistically insignificant

relationship with freshwater (ρ 0.32 and p-value 0.48), and a general negative but statistically

insignificant relationship with wind stress (ρ 0.18 and p-value 0.70). During La Niña conditions,

these effects are expected to drive variability, with thicker layers forming in regions of high

precipitation and weak wind stress. Increased freshwater input enhances stratification, while

strong wind stress likely promotes surface and subsurface mixing, leading to barrier layer

thinning. Understanding these dynamics has implications for improving ocean-atmospheric

interaction climate models in the tropical Pacific.