「海−自然と文化」 東海大学紀要海洋学部 第1巻 第1号 71-77頁 (2003)
水温急上昇で捉えた駿河湾の急潮
The Kyucho in
稲葉栄生・勝間田高明
Hideo Inaba and Takaaki Katsumata
Abstract
In middle November 1993 and early January 1994,
steep temperature rises about 4.5 ℃ for a few days were observed in the eastern part of the mouth of
Suruga Bay and the western part of the bay head. The temperature rises in the
eastern part of the bay mouth were influenced by the intrusion of the Kuroshio
warm water. The intruded warm water into the bay moved cyclonically along the
bay coast. Therefore, the two steep temperature rises can be called the Kyucho. The intrusion of the Kuroshio
warm water into the bay can be caused by the northward shift of the Kuroshio
path off the bay. The moving speeds of the warm water estimated from the time
lag of steep temperature rises and the distance between two mooring stations in
middle November 1993 and early January 1994 were 39 cm/sec and 38 cm/sec,
respectively. The estimated speeds were about half that in early March 1992
(Inaba et al., 2003). The temperature
variations induced by the Kyucho has
little effect on the sea level variation in the bay.
要 旨
1993年11月中旬と1994年1月上旬，駿河湾の湾口東部と湾奥西部で，3日間に約4.5℃の水温急上昇が観測された．湾口東部の水温急上昇の原因は黒潮系暖水の流入の影響であった．湾奥西部の水温急上昇は流入した暖水が湾岸沿いに反時計回りに巡って為であった．従って，両地点での水温上昇は急潮と呼ぶ事が出来る．急潮をもたらした黒潮系外洋水の流入は同湾沖での黒潮流路の北上によりもたらされた．両地点における水温急上昇の時間差と距離から求めた2度の急潮の移動速度は1993年11月中旬は39 cm/secで1994年1月上旬は38 cm/secであった．これらは1992年3月上旬に発生した急潮（稲葉ほか，2003）の約半分に過ぎない．また，急潮に伴う水温変化は同湾の水位変動にはほとんど影響を与えない．