It’s the penultimate science day aboard Falkor for this cruise, and the team is working hard to tick off the boxes next to jobs that still need to be accomplished. Yesterday they ran the coastal front next to Vancouver Island, then they zig zagged yet again along the continental shelf break. After that it was on to a nice tidal time series over the Zeppelin Bank and then across the Tully canyon.
Tomorrow will be the final MVP survey, then it’s one more CTD cast and Falkor will be on her way back to the port in Victoria. The analysis work is by no means finished, but the data gathering almost is.
The CTD data have shown that there are at least 4 distinct water masses swirling around and mixing over the continental shelf west of Vancouver Island. There is fresh, cold, high-oxygen water coming out of the Juan de Fuca Strait; warm, fresh, high-oxygen surface water coming from Cape Flattery; mixed low-oxygen water in the central shelf, also known as eddy water; and warm, salty offshore water along the shelf break.
There may be three other “source” waters, which the data collected have hinted at. The possibilities include a northern cool salty shelf water mass, a deep, cool, salty, low-oxygen layer down in the 800m depth range; and a warmer, deep, low-oxygen layer coming northward as an undercurrent to the surface California Current.
Though the team worked diligently to process the data coming through so that they could identify key features they needed to study most closely, there is still much to do. In the coming weeks, the data should allow them to tease out how these confusing mixes of water masses are interacting. But, that will mean some careful investigation of both the basic CTD and MVP profile data as well as the added information from things like carbon and nutrient analyses of the water samples collected using the CTD.
Check back in tomorrow for some final thoughts on what they’ve found so far.