Current Postdoctoral Researchers

Mariona headshotMariona Claret

PhD, Physical Oceanography, Joint Program University of Las Palmas de Gran Canaria and Institut de Ciències del Mar, ES, 2012. My current research focuses on changes in ocean circulation with climate variability that have an impact on the oceanic carbon cycle, and oxygen availability. Additionally, I’m fascinated by the physics of smaller scales such as sub-mesoscales, and internal waves, and their interaction with marine biogeochemistry. I use state-of-the-art ocean models to explore questions within these topics that are well-motivated by observations.

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.

Hannah Horowitz headshotHannah Horowitz

PhD, Earth and Planetary Sciences, Harvard, 2017. Dr. Horowitz is working with Drs. Cecelia Bitz and Lyatt Jaegle, of the UW Department of Atmospheric Sciences, on the first study to examine climate change impacts on the sea ice source of sea-salt aerosol, and to estimate the direct and indirect climate impacts of potential changes to sea-salt aerosol resulting from changing sea ice and warming ocean temperatures in a future climate scenario. Horowitz will investigate the full range of cascading chemistry-climate effects: from changes to sea-salt aerosol production, to reactive halogens and atmospheric oxidant concentrations, and finally to impacts on the greenhouse gases methane and ozone and the toxic pollutant mercury. The process-level understanding gained from these results will improve future studies of chemistry-climate interactions and climate change impacts and inform parameterizations in simpler, computationally inexpensive models. Drs. Jaegle and Bitz submitted a pending NSF proposal focusing on past climate changes, while Horowitz’s focuses on future climate change. These two projects have the potential to be complementary and synergistic.

julieta headshotJulieta Martinelli

PhD, Biological Sciences, Macquarrie University, 2015. Dr. Martinelli is a marine scientist interested in ecological and applied questions that lie at the interface between biology and paleobiology. She uses methods and tools from both disciplines and focus on mollusks because they are ecologically and economically important, very abundant, and have good preservation potential. Martinelli’s main project at JISAO involves using a conservation paleobiology approach to inform restoration practitioners about historical baselines for Olympia oysters. ‘Olys’ are the only native oyster to the eastern North Pacific and were severely overexploited during the gold rush in the mid 1800s. She is compiling information from historical (pre 1800) assemblages to increase our understanding on what healthy oyster beds looked like and what the environmental conditions these oysters thrived in. This information will be applied by restoration managers and practitioners working with Olympia oysters in Washington State.

Cristi Proistosescu headshotCristian Proistosescu

PhD, Earth and Planetary Sciences, Harvard, 2017. Dr. Proistosescu is working on a research project that will investigate the interaction between ocean heat uptake and regional climate feedbacks across a range of temporal and spatial scales, with the aim of exploring the prospects for (and limitations of) what can be learned about Earth’s climate sensitivity from the instrumental and paleo records of climate variability and change. Further, his research will build a process-level understanding of how modes of climate variability (such as the PDO, AMOC and ENSO) have consequences for Earth’s global energy budget. These are timely and important topics, given the recent evidence that climate sensitivity is variable, and that future warming may be underestimated from modern climate observations. His research interests dovetail perfectly with several ongoing projects to understand the operation of climate feedbacks under climate variability and change, with Dr. Gerard Roe, UW Earth and Space Sciences, and Dr. Kyle Armour, UW Oceanography.

Sarah's headshotSara Sanchez

PhD, Oceanography (specialization Climate Science), Scripps Institution of Oceanography, 2018. Dr. Sanchez is interested in paleo-climate variability, tropical climate dynamics, and the development of geochemical archives to interpret past change in Earth’s climate system. Dr. Sanchez is working with Dr. Greg Hakim, UW Atmospheric Sciences, and Dr. Casey Saenger, JISAO, on a coral-based paleoclimate data assimilation project aiming to reconstruct climate variability in the tropical oceans. Climate models indicate that the tropics host some of the most robust responses to climate change, but monitoring low frequency change in the tropical oceans is difficult given the sparsity of observations prior to the satellite era. This work offers a new means of assessing of tropical climate variability; the results of this work will improve understanding of historical hydroclimate and surface temperature variations, the response of the tropics to forced change, and coral geochemistry- instrument calibration.

Hannah Zanowski headshotHannah Zanowski

PhD, Atmospheric and Oceanic Sciences, Princeton, 2017. Dr. Zanowski is working with Drs. Cecelia Bitz, UW Atmospheric Sciences, and Kyle Armour, UW Oceanography, here on campus, and with Dr. Greg Johnson of NOAA Pacific Marine Environmental Laboratory, on a research project that will include both observational analysis of decade-to-decade historical water-mass changes in the Southern Ocean as well as diagnosis of model output, specifically to study full-depth southern ocean responses to changes in wind and freshwater (buoyancy) forcing when they are applied in the open ocean vs. along the coast. By comparing observations and different climate models (developed at GFDL and NCAR), Dr. Zanowski hopes to elucidate key mechanisms for variability in the Southern Ocean limbs of the meridional overturning

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