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Craig McNeil

Principal Oceanographer

Affiliate Assistant Professor, Oceanography

Email

cmcneil@apl.washington.edu

Phone

206-543-2157

Projects

APL-UW Involvement in the Coastal Margin Observation and Prediction Science and Technology Center (CMOP)

AUVs will be deployed by a newly formed APL-UW AUV group as part of CMOP's experimental observation network which consists of multiple fixed and mobile platforms equipped with oceanographic sensors.

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15 Jun 2012

The Center for Coastal Margin Observation and Predication (CMOP) has purchased from Hydroid, LLC two Autonomous Underwater Vehicles (AUVs) for its studies. The REMUS (Remote Environmental Measuring Units) 100 (see Figure 1) is a compact, light-weight, AUV designed for operation in coastal environments up to 100 meters in depth. The AUVs will be deployed by a newly formed APL-UW AUV group as part of CMOP's experimental observation network which consists of multiple fixed and mobile platforms equipped with oceanographic sensors. The AUVs will be used, primarily, to study the Columbia River plume and estuary region. The AUVs will be deployed periodically throughout each operational year. We also plan to allow customization of the AUVs by integrating novel biogeochemical sensors to meet specific scientific objectives for the CMOP program.

Autonomous Lagrangian Floats for Oxygen Minimum Zone Biogeochemistry

Researchers are developing a new, in situ, autonomous tool for studying N loss in oxygen minimum zones (OMZs). It will allow observation of variability over a range in temporal and spatial scales that are critical for understanding controlling processes and better estimating the magnitude of N loss. The sustained deployments possible with autonomous platforms will be critical for detecting any response of OMZs to climate change.

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31 May 2012

Intense oxygen minimum zones of the world's oceans, though constituting a small fraction of total oceanic volume, host critical biogeochemical processes and are central to understanding the ocean's N cycle and its biogeochemical and isotopic signatures. OMZs are sites for a large portion of marine combined N loss to N2 (25 to 50%) and dominate the ocean N isotope budget through cogeneration of 15N and 18O enriched NO3.

Parameterization of Gas Flux at High Wind Speed (Hurricane)

This goal of this project is to improve current parameterizations of air-sea gas transfer for high wind speeds.

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This goal of this project is to improve current parameterizations of air-sea gas transfer for high wind speeds. This will involve continued field work in hurricanes during the 2008-2009 seasons. We also participated in the UK SOLAS Deep Ocean Gas Exchange Experiments (DOGEE), which involved two experiments in the North Atlantic (winter 2006 and Spring 2007). The data from these cruises are being used to validate our new water-side O2 covariance measurement technique based on fast-response O2 measurements on the floats.

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Publications

2000-present and while at APL-UW

A gas tension device for the mesopelagic zone

Reed, A., C. McNeil, E. D'Asaro, M. Altabet, A. Bourbonnais, and B. Johnson, "A gas tension device for the mesopelagic zone," Deep Sea Res. 1, 139, 68-78, doi:10.1016/j.dsr.2018.07.007, 2018.

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1 Sep 2018

Highlights

- A new gas tension device (GTD) improves on previous designs of GTDs.

- The new GTD can operate up to 1000 m depth with no pressure dependency.

- Two GTDs successfully measured total dissolved gases in an Oxygen Minimum Zone.

- The GTDs were accurate to ±0.6% compared with independent dissolved gas data.

Innovative nitrogen sensor maps the North Pacific oxygen minimum zone

McNeil, C., E. D'Asaro, A. Reed, M.A. Altabet, A. Bourbonnais, and C. Beaverson, "Innovative nitrogen sensor maps the North Pacific oxygen minimum zone" in New Frontiers in Ocean Exploration (special issue), Oceanography, 31, 96, doi:10.5670/oceanog.2018.supplement.01, 2018.

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1 Mar 2018

Oxygen minimum zones (OMZs) play important roles in regulating the ocean's global carbon and nitrogen cycles. In these functionally anoxic waters, denitrifying and anammox (short for anaerobic ammonium oxidation) microbes remove nitrogenous nutrients from the biosphere by transformation to biologically unavailable nitrogen gas (N2). A newly developed sensor can detect this "excess" N2 in OMZ regions in order to quantify these nitrogen-loss processes. The near-term goal is to explore OMZs and collect high-quality excess N2 data to document their baseline inventories. The long-term objective is to determine if excess N2 inventories in OMZs are increasing as a result of ocean deoxygenation.

On the role of sea-state in bubble-mediated air-sea gas flux during a winter storm

Liang, J.-H., S.R. Emerson, E.A. D'Asaro, C.L. McNeil, R.R. Harcourt, P.P. Sullivan, B. Yang, and M.F. Cronin, "On the role of sea-state in bubble-mediated air-sea gas flux during a winter storm," J. Geophys. Res., 122, 2671-2685, doi:10.1002/2016JC012408, 2017.

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1 Apr 2017

Oceanic bubbles play an important role in the air-sea exchange of weakly soluble gases at moderate to high wind speeds. A Lagrangian bubble model embedded in a large eddy simulation model is developed to study bubbles and their influence on dissolved gases in the upper ocean. The transient evolution of mixed-layer dissolved oxygen and nitrogen gases at Ocean Station Papa (50°N, 145°W) during a winter storm is reproduced with the model. Among different physical processes, gas bubbles are the most important in elevating dissolved gas concentrations during the storm, while atmospheric pressure governs the variability of gas saturation anomaly (the relative departure of dissolved gas concentration from the saturation concentration). For the same wind speed, bubble-mediated gas fluxes are larger during rising wind with smaller wave age than during falling wind with larger wave age. Wave conditions are the primary cause for the bubble gas flux difference: when wind strengthens, waves are less-developed with respect to wind, resulting in more frequent large breaking waves. Bubble generation in large breaking waves is favorable for a large bubble-mediated gas flux. The wave-age dependence is not included in any existing bubble-mediated gas flux parameterizations.

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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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