Current Postdoctoral Researchers

CICOES Fellowship Postdoctoral Scholars:

Colleen headshotColleen Hoffman

PhD, Earth Sciences, University of Minnesota, 2018. Dr. Hoffman is working with Dr. Randelle Bundy, UW School of Oceanography, and Dr. Jospeh Resing, JISAO-NOAA, to examine the mechanisms and kinetics of how diffuse flow hydrothermal iron in the Southern Pacific Ocean is stabilized and potentially upwelled in the Southern Ocean, fueling phytoplankton primary production. Phytoplankton are key players in the global carbon cycle but are often growth limited due to iron-poor surface waters. Hydrothermal vents could, therefore, be a previously unrecognized nutrient source to the surface ocean and play an important role in the global carbon cycle. Currently, two mechanisms, nanoparticles and organic complexation, are hypothesized to be responsible for basin-scale transport of hydrothermal iron. Dr. Hoffman will investigate iron-ligand (e.g. organics) relationships, ligand characterization, and kinetics of these reactions in hydrothermal plumes. The results from this research will advance our current understanding of how hydrothermal vents influence global geochemical cycles, and impact phytoplankton growth in the surface waters. Personal website

Laramie headshotLaramie Jensen

PhD, Oceanography, Texas A&M University, 2020. Dr. Jensen is working with Dr. Rebecca Woodgate (APL/UW Oceanography), Dr. Randelle Bundy (UW Oceanography), and Dr. Ryan McCabe (CICOES/NOAA PMEL) to investigate Arctic circulation using conservative and non conservative tracers. Specifically, we hope to use trace metal and nutrient data to complement existing hydrographic data to further elucidate surface and deep water circulation in the Western Arctic. This work will focus primarily on constraining sources of Pacific-derived water through the Bering Strait and how that water mixes with Atlantic-derived waters in the basin using these additional tracers. Creating a water mass mixing model of the Western Arctic and taking new measurements along the Chukchi Shelf will also allow us as biogeochemists to compare the magnitude of in situ processes such as biological production, regeneration, and scavenging on trace metal micronutrient inventory in the surface against the role of advective mixing in intermediate and deeper waters. The results of this project will bridge new insights from Arctic biogeochemistry with our more established understanding of water mass formation and circulation in the Arctic Ocean from a physical perspective.

Jack's headshotJack Reeves Eyre

PhD, Hydrometeorology, University of Arizona, 2020. Dr. Reeves Eyre is working with Dr. Meghan Cronin (NOAA Pacific Marine Environmental Laboratory), Dr. Dongxiao Zhang (CICOES/NOAA) and Dr. Shuyi Chen (UW) to study how the ocean and atmosphere exchange heat, water and momentum. I am using Saildrone uncrewed surface vehicles to look at how these exchanges vary on small scales, particularly how the atmosphere responds to sharp sea surface temperature gradients (on the scale of a few miles). The oceans act as the major heat reservoir in the climate system, and ocean currents move huge amounts of heat energy around the globe. Research over the last few decades has greatly increased our knowledge of global patterns of ocean-atmosphere exchanges, but less is known about the variation at smaller scales. This research, capitalizing on the new observational capacities of Saildrone alongside weather and climate models, will help advance global climate monitoring and prediction.

Other CICOES Postdoctoral Scholars:

Zack headshotZachary Gold

PhD, Ecology and Evolutionary Biology, UCLA, 2020. Dr. Gold is collaborating with Dr. Kim Parsons (NOAA Alaska Fisheries Science Center) and Professor Ryan Kelly (UW School of Aquatic and Fisheries Science) to develop novel environmental DNA (eDNA) methods for elucidating population genetics of harbor porpoises and southern resident killer whales to inform successful management of these economically and culturally important species. Current methods to investigate population genetic structure of marine mammals are either invasive, requiring tissue biopsies, or infrequent and haphazard, relying on opportunistic sampling of stranded individuals. However, eDNA approaches provide a non-invasive genomic sampling method relying on the collection and sequencing of sea water around the target marine species. We are specifically developing these conservation genomic tools to help inform population structure of harbor porpoises in Southeast Alaska to better inform bycatch management of these ecologically important species, In addition, we aim to use eDNA methods to better monitor population structure and connectivity of both southern resident killer whales and killer whales globally to better inform conservation and management efforts of these iconic species.

Sean in front of a mapSean McAllister

PhD, Marine Biosciences, University of Delaware, 2019. Dr. McAllister is working with Dr. Carol Stepien, Ocean Environment Research Division Leader at NOAA/PMEL, and Dr. Dave Butterfield, UW JISAO, researching species composition, diversity, and connectivity of microbial, fish, and invertebrate communities in chemosynthetic hydrothermal environments, a.k.a. the dark biosphere. Hydrothermal plumes and methane seeps are habitats with a high flux of reduced chemicals that can be used by chemoautotrophic bacteria and archaea to produce energy for growth, supporting a broader biological community. Understanding the links between these communities and the hydrothermal environment is key to understanding their impacts on coastal fisheries and the blue economy. Dr. McAllister’s research uses eDNA metabarcoding, RADSeq of selected taxa, and metagenomics to address these interests.

Jon at seaJonathan Sharp

PhD, Marine Science, University of South Florida College of Marine Science, 2020. Dr. Sharp is working with Dr. Brendan Carter (UW/CICOES), Dr. Andrea Fassbender (NOAA/PMEL), Dr. Gregory Johnson (NOAA/PMEL), and Dr. Richard Feely (NOAA/PMEL) to investigate the biogeochemistry of the California Current Large Marine Ecosystem (CCLME). Dr. Sharp is using measurements from an array of autonomous biogeochemical (BGC) profiling floats, as well as research vessels and fixed ocean moorings, to conduct his research. The CCLME is a dynamic ocean system that supports high biological production, leading to the region’s importance in the context of ocean carbon export. The CCLME is acidifying at a greater rate than the open ocean, due in part to amplification of upwelling-favorable wind stress, and is rapidly losing oxygen in subsurface waters, due in part to long-term climate warming. BGC-Argo is an expanding ocean observing program that leverages biogeochemical sensors on profiling floats to monitor a variety of ocean processes that are directly relevant to the CCLME, including the progression of ocean acidification, the expansion of oxygen minimum zones, and the intensity of ocean carbon uptake and export.

Hongjie Wang

PhD, Coastal and Marine System Science, Texas A&M University-Corpus Christi, 2018. Dr. Wang is working with Dr. Jessica Cross at NOAA Pacific Marine Environmental Laboratory and Dr. Darren Pilcher at UW-CICOES to study ocean acidification in the Pacific Arctic Region (PAR) using novel technologies. The Arctic Ocean and Bering Sea attract both scientific and public interest given the regional sensitivity to climate change. However, limited infrastructure and hazardous conditions create a paucity of data that hinders the scientific understanding of the carbon cycle in high-latitude areas. The novel Autonomous Surface Vehicle CO2 (ASVCO2) system deployed on autonomous vehicles such as the saildrone provides a unique opportunity to collect high-resolution spatiotemporal surface pCO2 data in this region. Given that the ASVCO2 measurement system and the saildrone are new technologies that have not been widely adopted across the scientific community yet, I am comparing ASVCO2 measurements with established ship-board underway systems, mooring data and atmospheric CO2 time series measurements to assess its accuracy and precision in high-latitude areas. I will also investigate the mechanisms of carbonate system variability from daily to interannual time scales. The results of this work will eventually provide important insight into the impacts of future climate change on the high-latitude coastal carbon cycle.

Samantha Wills

PhD, Atmospheric Science, Colorado State University, 2019. Dr. Wills is working with Dr. Meghan Cronin (NOAA Pacific Marine Environmental Laboratory) and Dr. Dongxiao Zhang (UW CICOES/NOAA) to study tropical Pacific air-sea interaction using high-resolution, climate-quality observations collected on Saildrone unmanned surface vehicles (USV). Saildrone USVs are autonomous wind- and solar-powered sailing drones capable of traveling far distances (~16,000 nm) for long durations of time (~12 months) and are outfitted with oceanic, atmospheric, and biogeochemical sensors. Given the capability to provide sustained, long-term observations over remote regions of the ocean, this novel platform is being explored as part of the larger Tropical Pacific Observing System (TPOS) 2020 project to enhance the existing observational network across the tropical Pacific, which was designed to better understand and predict multiscale climate variations related to the El Niño Southern Oscillation (ENSO). Using observational data collected from three Saildrone missions to the central/eastern tropical Pacific, Dr. Wills is researching air-sea interaction on smaller temporal and spatial scales of variability not previously resolved, such as wind and moisture variability associated with atmospheric cold pools. The results of this research will have important implications for understanding the effect of small-scale processes on large-scale ocean-atmosphere coupling and refining the bulk algorithms for heat and momentum fluxes at the air-sea interface, as well as the broader implementation of Saildrone technology under the TPOS-2020 project.

Jiaxu Zhang

PhD, Atmospheric and Ocean Sciences, University of Wisconsin, 2016. Dr. Zhang is a postdoc scholar of physical oceanography at UW/CICOES and NOAA/PMEL. Her current work focuses specifically on Arctic freshwater content and its distribution, Beaufort Gyre dynamics, and Arctic-Atlantic/Arctic-Pacific interactions. She finished her 3-year work at Los Alamos National Lab in February 2020 before the current position. She got her PhD from U. Wisconsin-Madison in 2016, and was working on paleoclimate modeling of the last deglaciation. Paleoclimate and biogeochemical tracers will continue to be her research interests.

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