covis (cabled observatory vent imaging system): the first two years
DESCRIPTION
COVIS (Cabled Observatory Vent Imaging System): the first two years. Karen Bemis Russ Light, Peter Rona, Darrell Jackson, Guangyu Xu 12/1/12 NEPTUNE Canada Endeavour Workshop. COVIS is at the Endeavour site on the NEPTUNE Canada Observatory showing cable system. - PowerPoint PPT PresentationTRANSCRIPT
Karen BemisRuss Light, Peter Rona, Darrell Jackson, Guangyu Xu
12/1/12 NEPTUNE Canada Endeavour Workshop
COVIS is at the Endeavour site on the NEPTUNE Canada Observatory showing cable system.
COVIS’s beam coverage over the bathymetry of the Grotto vent cluster in the Main Endeavour Field.
Distance (m)
Depth (m)
Distance (m)
COVIS
MEF instrument site
North Tower
The COVIS systemThe sonar sits atop a 4 m tripod platform with 3 motors to control orientations
Products3D images of plume(s)Plume bending
characterizationVertical velocity and
volume fluxMaps of diffuse flow
distribution
Products of the basic software turned over to NEPTUNE Canada
plume quick look diffuse flow quick look
Bathymetry from MBARI 2008 cruise thanks to D. Clague.
Fancy Work
Preliminary estimates of plume bending
Estimating the plume centerline uses Gaussian fitting on horizontal slices
The centerline inclination (bending from vertical) and declination (compass direction of bending) vary over time
Inclination Declination
Periodogram of Angles
by Guangyu Xu
by Jeff Rabinowitz
Spectral analysis of the plume bending data and the currents from RSN-N support both tidal and other forcing.
Plume bending Spectrum
• Dominant (blue) peaks in plume bending angle spectrum match ambient currents and modeled semi-diurnal tides.
• One secondary peak may be found in ambient current as well; another is unique to the plume.
• Best explanation of secondary peaks is rift valley inflow
Ambient current
Across Rift Valley
Along Rift Valley
Pressure
data from S. Mihaly Thomson et al, 2005 JGR
Plume bending
Changes in plume bending patterns2010
2010
2011
COVIS mapping mode focuses on detecting regions with diffuse flow based on decorrelation.
spatial distributions of diffuse flow change in area over time
a map
by Peter Lin, undergraduate intern, summer 2011
Diffuse flow influenced by tidal cycle: searching for mechanisms
2011-2012 area estimates Strong semi-diurnal peak
Oct 2010 area estimates
250
0
Area (m2)
10/2/11 1/1/12Time (days)
220
0
Area (m2)
10/1/10 10/26/10Time (days)
But not in Oct 2010. why?
The Doppler mode quantifies vertical flow rates and estimates volume flux.
preliminary analyses• detection of plumes• estimation of vertical velocity and volume flux
Mean Volume Flux Mean Vertical Velocity
volume flux2010 to 2012
Plume Over North Tower Plume Over In-Situ Site