CODAR installation for Race Rocks

Juan de Fuca _CODAR_backgrounder

Today Guy drove me out to Race Rocks with Kevin Bartlett, Marine Equipment, Specialist with Ocean Networks Canada. They had installed equipment earlier in the year but had ro change the frequency of broadcasting before it is operational. Kevin was making repairs, one being fixing the conduit at the base of the tower which had been disturbed by sealions. When this equipment is fully operational it will give acurate current vectors for the eastern entrance of the Strait of Juan de Fuca.

 

 

Sample from a similar station now  in operation:

 see animation here

 

 

 

It was has been noticeable this year that instead of hauling out on the neighbouring islets of the Race Rocks Archipelago, the sealions are hauled out entirely on the main island of Great Race Rock. They have heavily impacted the vegetated areas .

Tidal Currents and Current Measurement at Race Rocks

The current at Race Rocks had just changed to a flood – it would be getting up to 6 knots in a few hours, so it was probably at about 5 knots at this time.

currentnowsTidal Current Predictions for  Race Passage
Prediction: Graph 

 

Race Passage Current tables, 2021

 

 

 

ADCP6Along with the installation of the Tidal Current turbine,  an ADCP was installed to give real time profiles of the Currents at Race Rocks. See the attached file for the type of profile that was generated:Sample of the result of the data analysis at Site 1:

 

sw24mThe Creation of the Race Passage Current Tables

 

 

 

Map of Currents at Race Rocks from ADCP tests

 

 

 

 

awac2See the video on wave and current measurement using the Acoustic Wave and Current instrument.

 

 

waterpropertiesWater Properties in Juan de Fuca

 

 

 

 

cursymbField Lab on Current Studies using Drogues.

 

 

 

tomiondeck1stomiondeck1sOceanographic
Research on Mixing in upwellings
of Race Rocks

 

 

kallesKalle Kallestrom’s essay on The biotic associations on the Current meter Block

 

 

 

deweysStratified Tidal Flow over a Bump
Richard Dewey,et al–Interactions of stratified flow on an isolated topographic feature: a bump to the east of Race Rocks.

 

ebbs MATLAB charts of barotropic currents to the east of Race Rocks.

 

 

 

generatorsLink to the Tidal Current Power Project

 

Turbulence and Mixing Estimates Using a Towed Horizontal microstructure Profiler

Paul Macoun: Turbulence and Mixing Estimates Using a Towed Horizontal microstructure Profiler

Turbulence and mixing estimates using a towed horizontal microstructure profiler.
Paul Macoun

The Ocean Turbulence Laboratory

University of Victoria

The Purpose

Mixing is the key element in the redistribution of salt, heat and energy in the ocean. Understanding the mechanisms and magnitude of turbulence and other mixing processes is crucial to the improvement of models that predict oceanic and atmospheric change. Our elusive goal is the parameterization of the vertical fluxes of salt and heat based upon the physics of oceanic mixing processes.

The horizontal profiler TOMI (Towed Ocean Microstructure Instrument) is used to make simultaneous measurements of temperature, conductivity, vertical velocity, and their fluctuations. The measurement of vertical velocity provides a means of estimating the rate of dissipation of turbulent kinetic energy. The respective products of instantaneous velocity and temperature, and that of velocity and conductivity, provide a direct measure of the vertical fluxes of heat and salt.

Simultaneous vertical profiles of current and its shear from a ship mounted ADCP (Acoustic Doppler Current Profiler) provide a means to relate the measured fluxes to the Froude Number and the Buoyancy Reynolds Number over a wide range of these parameters. The efficiency of mixing, the ratio of buoyancy-to-kinetic energy production, reaches 0.5 in near coastal regions and is generally much larger than the value of 0.2 assumed to apply to the open ocean.

This analysis is to be the first task to undertake with respect to the data set collected at Race Rocks on August 17th, 2000. At present, the processing is at a preliminary stage.

The Instrument

TOMI is a towed oceanographic vehicle designed to measure turbulence in both shallow and deep water. TOMI can support a multitude of instruments, from sonar to underwater cameras. Its primary oceanographic and electronic sensors are as follows:

1) Four airfoil shear probes and two fast-response thermistors on the nose.

2) A seabird temperature and conductivity sensor adjacent to the nose probes.

3) A seabird temperature and conductivity sensor, and a flowmeter, on the upper mast.

4) A seabird temperature and conductivity sensor, and a flowmeter, on the lower mast.

5) A pressure sensor mounted mid-body, internally.

6) An inertial motion sensor package, internal.

The sample rates for these instruments vary from 64 samples per second up to 512 samples per second. The airfoil shear probe is a unique instrument that measures the cross-stream component of velocity. The force generated by cross-stream flow bends a tiny ceramic bi-morph beam, which generates a voltage that is amplified and recorded. The motion sensor contains accelerometers and gyros. Its presence is required because of low frequency body motion contamination that finds its way into the shear probe signals. By having a record of the vehicle’s behaviour, the probe signals can be decontaminated through processing.

(Photos to be added)

Return to P. Macoun- Oceanographic Research

Pearson College students plot tidal currents at Race Rocks

n April of 1996, the Pearson College Environmental Systems Class planned a field lab which would enable us to present a profile of the currents around the Race Rocks Ecological Reserve. We had acquired a number of drogues as surplus which were used in current studies after the Alaskan Oil Spill. We have fitted them with radar reflectors so that we can determine the distances from the islands in our plotting process.

 

Field Lab on Currents- Environmental Systems Class 1995

curgrp
curarun
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n April of 1996, the Pearson College Environmental Systems Class planned a field lab which would enable us to present a profile of the currents around the Race Rocks Ecological Reserve. Michal and Arunas loading a drogue.A square piece of black plastic with lead weights attached to the bottom, hangs under the drogue in the water. Subsurface currents vary from the surface where wind driven currents may predominate. Michal and Arunas loading a drogue.
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Symbala lifts a drogue into the boat. We obtained these drogues as surplus from the Alaskan Oil Spill.
The drogues were released on an ebb tide between North Race Rock and Great Race Rock. Here the class has a drogue drifting in the background. We also take time out to study the behavior of the sea lions hauled out on the islands of the Ecological Reserve at Race Rocks
currr We have fitted the  drogues  with radar reflectors so that we can determine the distances from the islands in our plotting process. The drogues were released on an ebb tide between North Race Rock and Great Race Rock. The students were able to map the current direction through the islands using the radar on the boat docked at the jetty