May 24 Wecoma Report

Wecoma sailed at 1300 on Wed 5/23. We proceeded north, marking crab pots along the inshore ends of our SeaSoar grid. Passed the Thompson close inshore on the Cascade Head line. Beautiful evening with weak winds from the south. At about 1900 we deployed SeaSoar, the 4-frequency hydroacoustics sled and the iron sampler on the inshore end of line 1. We sampled along lines 1-3. On line 1 there was a classic upwelling jet with speeds above 30 cm/s, centered on 124.125 (depth=100m) and a total width of about 25km. Chlorophyll fluorescence on line 1 showed very high values near the surface inshore of the jet. The jet region had low chl, but offshore of the core a subsurface chl max existed around 20-40m. On line 2, the Cascade Head line, the equatorward jet was centered at 124.175, speeds in excess of 40 cm/s, but southward flow existed quite far offshore (to around 124.6W). Inshore of the upwelling jet, flow was to the north and isopycnals sloped downward at the inshore end of the line, presumably due to the light southerly winds. Chl was very similar to line1.

This morning (5/24) winds picked up to the south up to 25 knots. We are continuing SeaSoaring along lines 4 and 5. In the underway flo-thru we are measuring 9-wavelength light absorption and scattering, T, S, chl fluorescence and doing chl extractions for fluorometer calibration every 2 hours or so. The iron samping is going well. We lost the nitrate/nitrite colorimeter, so Dale Hubbard switched the phosphate colorimeter onto the nitrogen line. We will finish Bigbox 1 with nitrate, nitrite and silicate. We are exploring ways to get a replacement colorimeter out to the ship. Bill Peterson is examining zooplankton from the flo-thru as we sample along the NH line (line 4). The MicroSoar fast-response conductivity sensor worked for the early part of the grid, but failed around 1300 today. Anatoli is working on a fix, but for now we'll continue SeaSoaring without the MicroSoar C sensor.

We expect to finish Bigbox 1 late on Friday and then will transit back to the CH line to join Thompson for a day of joint sampling. We'll do fine-resolution SeaSoar sampling around the Thompson, and then Bill Peterson et al will do vertical net tows for zooplankton along line 2.

We were buzzed by the UNC aircraft around 2020 when we were just off Newport. We were busy watching for crab pots in the dusk, but it was fun to see the aircraft pass close overhead then bank to head for Corvallis.

---Jack Barth