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Darrell Jackson

Principal Engineer Emeritus

Research Professor Emeritus, Electrical Engineering

Email

drj@apl.washington.edu

Phone

206-543-1359

Biosketch

Darrell Jackson is engaged in theoretical and experimental research in ocean acoustics. This includes random scattering in the ocean, acoustic remote sensing of the ocean bottom, and related signal processing methods.

Department Affiliation

Acoustics

Education

B.S. Electrical Engineering, University of Washington, 1960

M.S. Electrical Engineering, University of Washington, 1963

Ph.D. Electrical Engineering, University of Washington, 1966

Ph.D. Physics, California Institute of Technology, 1977

Publications

2000-present and while at APL-UW

The path to COVIS: A review of acoustic imaging of hydrothermal flow regimes

Bemis, K.G., D. Silver, G. Xu, R. Light, D. Jackson, C. Jones, S. Ozer, and L. Liu, "The path to COVIS: A review of acoustic imaging of hydrothermal flow regimes," Deep Sea Res. II, 121, 159-176, doi:10.1016/j.dsr2.2015.06.002, 2015.

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1 Nov 2015

Acoustic imaging of hydrothermal flow regimes started with the incidental recognition of a plume on a routine sonar scan for obstacles in the path of the human-occupied submersible ALVIN. Developments in sonar engineering, acoustic data processing and scientific visualization have been combined to develop technology which can effectively capture the behavior of focused and diffuse hydrothermal discharge. This paper traces the development of these acoustic imaging techniques for hydrothermal flow regimes from their conception through to the development of the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS has monitored such flow eight times a day for several years. Successful acoustic techniques for estimating plume entrainment, bending, vertical rise, volume flux, and heat flux are presented as is the state-of-the-art in diffuse flow detection.

Time-series measurements of hydrothermal heat flux at the Grotto mound, Endeavor Segment, Juan de Fuca Ridge

Xu, G., D.R. Jackson, K.G. Bemis, and P.A. Rona, "Time-series measurements of hydrothermal heat flux at the Grotto mound, Endeavor Segment, Juan de Fuca Ridge," Earth Planet. Sci. Lett., 404, 220-231, doi:10.1016/j.epsl.2014.07.040, 2014.

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15 Oct 2014

Continuous time-series observations are key to understanding the temporal evolution of a seafloor hydrothermal system and its interplay with thermal and chemical processes in the ocean and Earth interior. In this paper, we present a 26-month time series of the heat flux driving a hydrothermal plume on the Endeavour Segment of the Juan de Fuca Ridge obtained using the Cabled Observatory Vent Imaging Sonar (COVIS). Since 2010, COVIS has been connected to the North East Pacific Time-series Underwater Networked Experiment (NEPTUNE) observatory that provides power and real-time data transmission. The heat flux time series has a mean value of 18.10 MW and a standard deviation of 6.44 MW. The time series has no significant global trend, suggesting the hydrothermal heat source remained steady during the observation period. The steadiness of the hydrothermal heat source coincides with reduced seismic activity at Endeavour observed in the seismic data recorded by an ocean bottom seismometer from 2011 to 2013. Furthermore, first-order estimation of heat flux based on the temperature measurements made by the Benthic and Resistivity Sensors (BARS) at a neighboring vent also supports the steadiness of the hydrothermal heat source.

Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar

Xu, G., D.R. Jackson, K.G. Bemis, and P.A. Rona, "Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar," Geochem. Geophys. Geosyst., 14, 2369-2382, doi:10.1002/ggge.20177, 2013.

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1 Jul 2013

We present a 26 day time series (October 2010) of physical properties (volume flux, flow velocity, expansion rate) of a vigorous deep-sea hydrothermal plume measured using our Cabled Observatory Vent Imaging Sonar (COVIS), which is connected to the Northeast Pacific Time Series Underwater Experiment Canada Cabled Observatory at the Main Endeavour Field on the Juan de Fuca Ridge. COVIS quantitatively monitors the initial buoyant rise of the plume from inline image to inline image above the vents. The time series exhibits temporal variations of the plume vertical volume flux ( inline image), centerline vertical velocity component ( inline image) and expansion rate ( inline image); these variations have major spectral peaks at semidiurnal ( inline image cycle/day) and inertial oscillation ( inline image cycle/day) frequencies. The plume expansion rate (average inline image) is inversely proportional to the plume centerline vertical velocity component (coefficient of determination inline image). This inverse proportionality, as well as the semidiurnal frequency, indicates interaction between the plume and ambient ocean currents consistent with an entrainment of ambient seawater that increases with the magnitude of ambient currents. The inertial oscillations observed in the time series provide evidence for the influence of surface storms on the dynamics of hydrothermal plumes.

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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