Wecoma report 29 May

We completed a 3-line "smallbox" survey on Heceta Bank around 10pm Monday. The high-chl pool over Heceta Bank extended across all three lines (44 22.9' to 44 6.6'N), and was strongest around the longitude of CP-4 (124 28.1'W). A surface SST front and associated jet was found between 124.5 and 124.7 W, inshore of the highest offshore parts of the Bank. Warming has occurred closest to the coast, compared with the coldest water found there during our 24-26 Bigbox survey. A subsurface (at ~10-30m) chl feature was found on the outer edge of the Bank, presumably being carried southward on the outer flank of the equatorward jet. When we return to the southern study region on Thursday, we intend to investigate alongshore continuity of this flow and how/whether it leaves the Bank on the southern edge of the Bank.

We transited to the CH line during the night and commenced a 2-line survey at 6am. We produced hydro, velocity and chl sections for use by the dye team to help them choose an injection location. The isotherms showed slumping down right near the coast, the Columbia River influence extended to right near shore in a layer about 10m deep, and there was northward flow right near the coast. All of these are consistent with a relaxation event. The chl field showed that phytoplankton had been moved down in the water column, presumably by the downwelling circulation right near shore.

We met up with the R/V Elakha at 1pm off Neskowin (just N or Cascade Head) and they delivered a replacement nutrient channel analyzer and a spare ac-9. We handed them plots in return. It was a beautiful, sunny day off the picturesque Oregon coastline. After the xfer, we proceeded north to start a second Bigbox survey and the scientists aboard Elakha proceeded with the dye injection. There's a chance that we'll detect the dye as we come back onshore on line 2 (the CH line). Dale Hubbard installed the replacement colorimeter and we now have all nutrients back on line. The rest of the instruments on the SeaSoar are working fine and the instruments in the flow-through, with the exception of the pCO2 system, are working fine. We expect to complete the second Bigbox late on Thursday, and then we'll survey around the CP line occupied by the Thompson. We plan to work the southern Bank region until the Thompson departs for Newport.

---jack