Thompson Cruise Report August 18-20
15:30 August 21

Starting August 18, we have been covering five E/W transects to study the region of the jet and high chl at the outer edge and south of of Heceta Bank between Lines 6 (44 13.5 N) and just south of Line 7 ( 44N).

These are located at 44 11.5, 44 6.5, 44 1.5, 43 56.5 and 43 51.5 N. For each transect we do an ADCP run W/E and then profile (turbulence, chemistry, optics, and FRRF in the E/W direction. During the ADCP run we have been stopping for a pump station in the region of high Chl (which has usually been on the shoreward side of the offshore jet).

As we proceed south (in space, and maybe also in time) the location of the jet has varied. There seems to be two bands of high Chl offshore in addition to the band close to shore.

Date Transect Jet Location Jet Strength Chl surface max (longitude)

8-18 44 11.5 124.9 weak 124.66-124.74 (two strong bands close together)
8-18 44 6.5 124.8 moderate 124.76 (weak), 124.69 to 124.8 (strong)
8-19 44 1.5 124.97 strong 124.87 (weak), 124.69 to 124.8 (strong)
8-20 43 56.5 124.69 moderate 124.87 (weak), 124.71 to 124.79 (strong)
8-21 43 51.5 124.7 to 124.8 (strong), 124.25 to 124.55 (moderate)

From the ADCP transect early this morning along 43 51.5 N the offshore jet is centered at 124.82. We did not see a jet inshore although there is a weak southward flow inshore and a nothward flow flrom 124.4 to 124.65. Profiling in the westward direction, we got as far as 124.65 W and then the weather picked up. Burke's pump was in danger of being pulled under the ship. We are running now to 125 W to try profiling in the W/E direction instead. Among other things, this will be a test of our ability to profile with the rougher weather we might expect for the winter downwelling cruise.

If we are able to complete the fifth line, then we will repeat ADCP transects of the five lines in the northward direction. We will use the results to determine if and how we might sample along the core of the jet (or offshore flow from the bank) profiling from north/south.

Pat Wheeler
Chief Scientist, Thomaposn