Shipboard Training Ⅰ
Cross section of water temperature and salinity observation by CTD【Instructor ABE】
The figures below show a vertical cross section of water temperature in a north-south line off the Pacific Ocean (left) and the same cross section in a north-south line across the Tsugaru Strait (right), both measured with an automatic temperature, salinity, and depth meter (CTD).In the left figure, warm water is observed in the southern area and cold water is observed in the northern area, reflecting the Kuroshio current and Oyashio current.
A similar water temperature contrast can be seen in the Tsugaru Strait shown on the right, where the warm water in the south reflects the water of the Tsugaru Warm Current, which has its source in the Kuroshio Current.
Seawater sampling
In this training, middle and deep seawater is sampled and analyzed. More than 10 water sampling bottles and CTDs are attached to a cylindrical frame, connected by wires, and placed into the sea by a machine called a winch and lowered underwater. After reaching the target depth, water is sampled by closing the lid of the water sampling bottle, and the wire is wound up and collected. The sampled seawater is used to measure dissolved oxygen, chlorophyll, and nutrients, as well as to verify CTD data.
Seawater sampling by CTD and automatic measurement of salinity, temperature, and depth by CTD (Reprinted from aQua, the public relations magazine of the School of Fisheries Sciences)
Nutrient analysis (Reprinted from aQua, the public relations magazine of the School of Fisheries Sciences)
Presentation of results
All students work together to analyze the seawater samples obtained during the training and convert them into data. Shared data is brought back to the group, and each group analyzes and interprets the data according to the theme set by the group. In last year's presentation, the themes included water mass analysis focusing on the difference between the Kuroshio and Oyashio currents, highly concentrated chlorophyll water observed off the coast of Tohoku, and the horizontal distribution of drifting debris.
