GEOTRACES Japanese cruise GP02 in the northern North Pacific completed

The GEOTRACES GP02 (R/V Hakuho Maru KH-12-4) cruise in the northern North Pacific Ocean has just finished. The cruise was nicknamed “Big Dipper (BD) Expedition”, which consisted of the following two legs: Leg-1: from Tokyo, Japan (23 Aug. 2012) to Dutch Harbor, USA (13 Sept. 2012) and leg-2: from Dutch Harbor (17 Sept. 2012) to Vancouver, Canada (3 Oct. 2012).

Thirty three scientists including technical supporting staffs and graduate students joined the cruise. It is a pity that we had to omit several stations along 47°N during the leg-2 (see the figure below) due to severe weather conditions. Seawater samples were taken at each station from surface to bottom by clean CTD hydrocasts (with Teflon-coated Niskin-X 12L bottles) using a Ti-armored cable and by large volume (250L) water sampling. Bottom sediments were also sampled by using a multiple corer. Measurements of chemical constituents and isotopes were and will be performed in clean rooms on board the ship and in shore-based laboratories. Inter-calibration was also conducted by comparing the GEOTRACES-recommended Kevlar wire hydrocast with the R/V Hakuho Maru’s titanium wire hydrocast.

We visited a baseline station, K2 (BD-7) (47°N, 160°E) in the northwest Pacific Ocean, taking seawater samples not only for shipboard scientists but also for other international scientists who will be interested in measuring some of the GEOTRACES key parameters for comparison. We hope that the obtained data by this cruise will play an important role in the GEOTRACES program as a first zonal data in the North Pacific Ocean.


Figure : GP02 cruise track
Click on the image to view it in high resolution

Pl: Toshi Gamo.