- 著者
-
川合 英夫
Hideo Kawai
- 出版者
- 日本海洋学会
- 雑誌
- 海の研究 (ISSN:09168362)
- 巻号頁・発行日
- vol.10, no.4, pp.351-359, 2001-07-05
- 参考文献数
- 12
江戸時代中期の瀬戸内海では「潮汐界」(シヲサカヒ) は, その両側で上げ潮時の潮流が逆向きとなる潮汐の境界を意味していた (森 幸安, 1754)。内海舟運で行われた潮待などの実際面で「潮汐界」の情報が役立ったため, この語が使われたのだろう。北原 (1912, 1921) は「潮合(線)」を寒暖二流 (実は二水塊) の境界という意味で使っていた。「潮境」を浮遊物の集積する海流収斂線や異色水塊の境界という意味で, 最初に使ったのは宇田 (1931) である。しかし宇田が傾倒してやまない北原が使った「潮合(線)」の代わりに「潮境」を使い始めた動機は謎である。もしかすると, すでに「潮境」が外海漁業者の間で広く使われていたという経緯も考えられる。「潮合(線)」も「潮境」も海軍水路部の重松や岸人らでは使われず, 水産試験機関の北原や宇田らに限って使われたことは,「潮合(線)」「潮境」の情報が水産試験研究の実際面で役立ったためだろう。A term "Shiwo-Sakahi" (潮汐界), used in the Seto Inland Sea, Japan in the middle Edo Period (Mori, 1754), is interpreted to mean a boundary zone, on both sides of which the current direction from the low tide to the high tide becomes opposite. This term must have spread, because such information on tidal currents was useful for the practical aspect, related to the waiting in port until the tidal current shifts to a favorable direction. Kitahara (1912, 1921) used terms "Shio-Ai" (潮合) and "Shio^Ai-Sen" (潮合線) to mean a boundary between warm and cold currents, but actually warm and cold water-masses. While Nagatsuka (1906) used a term "Shio-Me" (潮目, current-rip) to mean a boundary between cold river water and warm seawater in his traditional Japanese poem, Uda (1929a) used this term to mean a line of accumulation of drifting matter accompanied by a thermal front in his scientific report. Uda (1931) also used a term "Shio-Zakai" (潮境) for the first time to mean a line of current convergence or a boundary between two water-masses with different colors. However, the motive for Uda, an ardent admirer of Kitahara, to have started using "Shio-Zakai" instead of "Shio-Ai-Sen" used by Kitahara, is still mysterious. Possibly "Shio-Zakai" might have already spread among fishermen in open seas. The terms "Shio-Ai" and "Shio-Zakai" were not used by Shigematsu and Kishindo of the Hydrographic Office, Japanese navy, but were used by Kitahara and Uda of fisheries experimental organizations. This is probably because these terms were useful for the practical aspect of the fisheries oceanography.