In April 2013, the AUV (“Bluefin”) successfully ran a test science mission in Saanich Inlet. Operated by engineers from the UVic’s Ocean Technology Lab, led by Dr. Colin Bradley, the AUV enhances capabilities of VENUS – the coastal ocean observatory of Ocean Networks Canada.
For test deployment in Saanich Inlet the AUV was equipped with key oceanographic sensors, oxygen and temperature, and a multibeam sonar to scan the seafloor. The test mission focused on mapping the Inlet structure to assess both the early spring conditions and whether any mid or deep water intrusions have occurred.
According to Dr. Jody Klymak, an oceanographer from the UVic’s School of Earth and Ocean Science, who helped to organize the science mission, the main objective of the mission was to fully assess capabilities of the mini-sub. “It is an advanced multipurpose tool, and we would like to see it support ongoing research programs at SEOS”. The AUV is capable of powered flight in waters down to 200m depth and can run for up to 8 hours gathering valuable data from the geographically dispersed areas.
Preliminary assessment of the test-mission data from several weeks ago clearly shows that the deep water renewal event in Saanich Inlet has not occurred yet. The event, a long studied natural phenomena, is a harbinger of the spring-coming in Saanich Inlet, when oxygen-rich waters and nutrients finally reach the seasonally hypoxic fjord.
We celebrate our successes with all of our researchers, partners, and a dedicated staff that continues to develop new and exciting systems that will reveal new features of our coastal ocean in the years to come.
The figure shows the temperature and dissolved oxygen concentration from the VENUS Instrument Platform (VIP) in Saanich Inlet located at approximately 97 metres depth, for the period of January 28 through to February 3, 2013. The temperature is dropping and the oxygen increasing, a sign that top-down and lateral mixing has finally penetrated our study area to bring upper water-column conditions down to our sensors and experiments at 97m. In the late summer and early fall (August-October), dense salty water enters Saanich Inlet and flows to the deepest portions of the basin, displacing upwards the very low oxygen (hypoxic) water residing there. This displacement causes the mid-depth waters (where VENUS sensors are located) to become hypoxic, a condition that has now persisted for over four months (since late September 2012). Surface cooling and tidal exchanges gradually mix down higher oxygen and lower temperature water from nearer the ocean surface, where cold atmospheric weather cools the oxygen-rich surface waters. This “ventilation” of higher oxygen water is particularly late this year (2013). Previously (2007-2012), the low oxygen conditions at this depth/study area persisted just into the new year, with transition to lower temperatures and higher oxygen levels occurring in early January. The “State of the Ocean” plot suggests the 2012-13 fall/winter exhibited both the coolest and most sustained low oxygen conditions in seven years of monitoring on the VENUS network.
Stacked in the image are 48 plots generated from 16 sensors of the VENUS Ferry System installed on a BC Ferries M/V Queen of Alberni. The comprehensive system monitors oceanographic and atmospheric conditions while the ferry transits between Nanaimo (Duke Point) and Vancouver (Tsawwassen).
Oceanographic parameters collected by the system include seawater temperature, salinity, density, dissolved oxygen, turbidity, and the relative concentration of chlorophyll.
Meteorological measurements focus on marine atmospheric boundary layer conditions and include air temperature, humidity, pressure, wind speed and direction, incoming solar radiation, and out-going irradiance.
The image shows a day of data collected on Jan 5th, 2013. For each parameter, data are plotted in a number of distinct ways to show alternate characteristics of the geospatial and temporal nature of the variations.
The data collected by the ferry system are retrieved daily through a series of communications over the cellular network between the ferry and VENUS shore station. Check out the latest ferry data plots at the BC Ferry plots page.
View full-resolution image (right-click link to download) to see the full-sized plots.
Daily Data Snapshot from the VENUS Ferry System.
The VENUS data team adds another animated data product to its data plots gallery.
This animated image depicts measurements of the surface ocean currents in the Strait of Georgia over a recent 24-hour period.
The currents are measured using a “CODAR” (Coastal Ocean Dynamics Applications Radar) system. The VENUS CODAR system consists of two antennae, one at the Iona Wastewater Treatment plant, near Vancouver Airport, the other at the Westshore Coal Terminal, near the BC Ferries port at Tsawwassen. These are labelled in the image as “VION” and “VCOL”, respectively.
Each image in the sequence shows the current averaged over an hour. The size of the arrows is proportional to the current magnitude. The location of each measurement is at the midpoint of the corresponding arrow.
The depicted measurements span an entire tidal cycle, but the flood and ebb tides seen in the animation are not symmetric: the southward-trending ebb tide is considerably stronger than the northward-trending flood tide. This is most likely due to the prevailing winds over the last few days which have been from the NW, pushing surface currents to the south. The ebb tide reinforces this flow and thus appears very strong, while the flood tide works against the wind driven flow and thus appears weaker.
Over the last two weeks VENUS and NRCan have been assessing the event through replaying the marine traffic scenarios, taking sediment cores, conducting multibeam surveys, assessing private vessel provided sonar data and most recently side-scan surveys of the area. On June 28, Adrian Round, working with Terra Remote, conducted 500kHz side-scan surveys that located the platform about 60m from its original location.
Although further diagnoses will continue, we plan to recover and assess the condition of the entire package during our August maintenance cruise. Dr. Gwyn Lintern at NRCan is investigating the cause of the event and we anticipate some interesting research results. For our initial investigations we are thankful to Department of Fisheries and Oceans scientists and crew on board the CCGS John P. Tully for collecting sediment cores, the crew of the University of New Brunswick survey vessel Heron for multibeam survey, the core analysis facility at Geological Survey of Canada Pacific for a quick response, a captain of a local Seaspan commercial vessel who sent in his observations, and the Marine Communications and Traffic Services, Canadian Coastguard.
On Jun. 28, 2012 at approximately 02:55:47 UTC the icListen Low Frequency Hydrophone on the VENUS hydrophone array at our Strait of Georgia East site (170m depth) picked up an earthquake. According to the Natural Resources Canada earthquake website (http://www.earthquakescanada.nrcan.gc.ca/recent/maps-cartes/index-eng.php?tpl_region=swbc), this signal corresponds to an 0.4 magnitude earthquake 21 km WSW of Tsawwassen, BC. The data is shown below.
Between Jun. 26, 2012 11:26:00 UTC and 11:47:00 UTC the VENUS hydrophone array at our Strait of Georgia East site (170m depth) picked up whale sounds. Some representative examples (30 seconds in length) from Hydrophone #1 (HighTech) of the array and an example (five minutes in length) from the icListen Low Frequency Hydrophone on the array are shown below.
Note: the raw data from the icListen has been amplified for playback. The unaltered .wav file is available for download.
Deployed at our Delta Dynamics Laboratory location in the Strait of Georgia are various sonar systems. In addition to the upward looking echo-sounder (200 kHz ZAP), we have a downward looking scanning sonar built by Imagenex. Shown here is a series of single scan images, and when compiled into an animation, the time lapsed set of hourly images shows the changes detected by the sonar. This scanning sonar sweeps out a radial scan of the ocean bottom to detect and monitor changes in the bedforms. Seen in these images is the corner of the VIP platform (lower left corner), and bottom roughness out towards the right. In the animations from May and June, we also see the daily occurrence of a high concentration of suspended sediment, when the entire image shows yellow and orange backscatter. These events, which occur during the peak freshet of the Fraser River, are associated with the downward settling of the river sediment after low tide. Similar events were documented in earlier Images of the Week (May 14, 2012 and June 20, 2011).
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