Mapping Oxygen and Water Properties on the Vancouver Island Shelf

The UVic Ocean Physics Group embarked on the R/V Falkor for a 12 day cruise, 18 Aug to 31 Aug 2013 mapping water masses on the Vancouver Island shelf as part of an ONC-sponsored cruise.

Our mapping had us investigating the west side of the “Juan de Fuca Eddy”, where coastal water interacts with water that has been trapped in the eddy. The water in the eddy is low in O2, likely because it is “old” and respiration has used it up. In itself, this is relatively surprising because there are lots of mechanisms to mix in the vertical in this region. Why the eddy is so impervious to lateral mixing is an interesting question for future study.

However, the most important observation (so far), is that water traveling south along the shelf is pushed offshore and replaced by Barkley Canyon water. Water usually follows isobaths, and so this departure from the norm was unexpected. It is also important because it means “young” water is able to replace the older shelf water, breathing new life into the inner shelf water masses.