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Ali Chase

Senior Oceanographer

Email

achase@apl.uw.edu

Phone

206-543-7836

Biosketch

Ali Chase joined APL-UW in the summer of 2020 as a Washington Research Foundation Postdoctoral Fellow. She is collaborating with oceanographers Kyla Drushka and Peter Gaube as a member of the (Sub)mesoscale Group on several projects related to observing phytoplankton in the open ocean using optics and linking phytoplankton community composition to physical ocean features. Before beginning postdoc research in the summer of 2020, Chase earned a PhD at the University of Maine. Working there in the MISC Lab with Emmanuel Boss and Lee Karp-Boss, her dissertation was on methods to observe phytoplankton in the open ocean using optics, flow cytometry, and pigments.

During postdoc studies, Chase is working on algorithm development to detect phytoplankton community composition from ocean color satellite measurements. The approach to this challenge has two components: 1) estimate phytoplankton accessory pigment concentrations from hyperspectral remote-sensing reflectance spectra, and 2) use phytoplankton group information from imaging-in-flow cytometry to determine predictive relationships via neural networks between phytoplankton communities and ocean environmental parameters.

Education

B.A. Geology and Environmental Studies, Bowdoin College, 2009

M.S. Oceanography, University of Maine, 2014

Ph.D. Oceanography, University of Maine, 2020

Ali Chase's Website

http://alichase.com

Publications

2000-present and while at APL-UW

Phytoplankton composition from sPACE: Requirements, opportunities, and challenges

Cetinic, I., and 28 others including A.P. Chase and P. Gaube, "Phytoplankton composition from sPACE: Requirements, opportunities, and challenges," Remote Sens. Environ., 302, doi:10.1016/j.rse.2023.113964, 2024.

More Info

1 Mar 2024

Ocean color satellites have provided a synoptic view of global phytoplankton for over 25 years through near surface measurements of the concentration of chlorophyll a. While remote sensing of ocean color has revolutionized our understanding of phytoplankton and their role in the oceanic and freshwater ecosystems, it is important to consider both total phytoplankton biomass and changes in phytoplankton community composition in order to fully understand the dynamics of the aquatic ecosystems. With the upcoming launch of NASA's Plankton, Aerosol, Clouds, ocean Ecosystem (PACE) mission, we will be entering into a new era of global hyperspectral data, and with it, increased capabilities to monitor phytoplankton diversity from space. In this paper, we analyze the needs of the user community, review existing approaches for detecting phytoplankton community composition in situ and from space, and highlight the benefits that the PACE mission will bring. Using this three-pronged approach, we highlight the challenges and gaps to be addressed by the community going forward, while offering a vision of what global phytoplankton community composition will look like through the "eyes" of PACE.

Toward a synthesis of phytoplankton communities composition methods for global-scale application

Kramer, S.J., and 14 others including A.P. Chase, "Toward a synthesis of phytoplankton communities composition methods for global-scale application," Linmol. Oceanogr. Methods, EOR, doi:10.1002/lom3.10602, 2024.

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23 Feb 2024

The composition of the marine phytoplankton community has been shown to impact many biogeochemical processes and marine ecosystem services. A variety of methods exist to characterize phytoplankton community composition (PCC), with varying degrees of taxonomic resolution. Accordingly, the resulting PCC determinations are dependent on the method used. Here, we use surface ocean samples collected in the North Atlantic and North Pacific Oceans to compare high-performance liquid chromatography pigment-based PCC to four other methods: quantitative cell imaging, flow cytometry, and 16S and 18S rRNA amplicon sequencing. These methods allow characterization of both prokaryotic and eukaryotic PCC across a wide range of size classes. PCC estimates of many taxa resolved at the class level (e.g., diatoms) show strong positive correlations across methods, while other groups (e.g., dinoflagellates) are not well captured by one or more methods. Since variations in phytoplankton pigment concentrations are related to changes in optical properties, this combined dataset expands the potential scope of ocean color remote sensing by associating PCC at the genus- and species-level with group- or class-level PCC from pigments. Quantifying the strengths and limitations of pigment-based PCC methods compared to PCC assessments from amplicon sequencing, imaging, and cytometry methods is the first step toward the robust validation of remote sensing approaches to quantify PCC from space.

Informing ocean color inversion products by seeding with ancillary observations

Bisson, K.M., P.J. Werdell, A.P. Chase, S.J. Kramer, B.B. Cael, E. Boss, L.I.W.McKinna, and M.J. Behrenfeld, "Informing ocean color inversion products by seeding with ancillary observations," Opt. Express, 31, 40,557-40,572, doi:10.1364/OE.503496, 2023.

More Info

15 Nov 2023

Ocean reflectance inversion algorithms provide many products used in ecological and biogeochemical models. While a number of different inversion approaches exist, they all use only spectral remote-sensing reflectances (Rrs(λ)) as input to derive inherent optical properties (IOPs) in optically deep oceanic waters. However, information content in Rrs(λ) is limited, so spectral inversion algorithms may benefit from additional inputs. Here, we test the simplest possible case of ingesting optical data (‘seeding’) within an inversion scheme (the Generalized Inherent Optical Property algorithm framework default configuration (GIOP-DC)) with both simulated and satellite datasets of an independently known or estimated IOP, the particulate backscattering coefficient at 532 nm (bbp(532)). We find that the seeded-inversion absorption products are substantially different and more accurate than those generated by the standard implementation. On global scales, seasonal patterns in seeded-inversion absorption products vary by more than 50% compared to absorption from the GIOP-DC. This study proposes one framework in which to consider the next generation of ocean color inversion schemes by highlighting the possibility of adding information collected with an independent sensor.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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