海洋深層水研究　Vol. 2 No. 1　1-8頁　(2001)

駿河湾300m層の流動と水温の変動

Temporal Variations of Current and Temperature at 300 m in Suruga Bay

稲葉栄生・勝間田高明・安田訓啓

Hideo Inaba, Takaaki Katsumata and Kuniaki Yasuda

Abstract

In order to investigate the temporal variations of the current and temperature at 300 m in Suruga Bay, the current and temperature data obtained from a moored ADCP observation in the sea at the eastern part of the bay mouth were analyzed. Observed maximum current speed of the inflow and outflow were 57 cm/sec and 40 cm/sec, respectively. The mean current throughout the whole observing period was less than 1 cm/sec. The maximum and minimum observed temperature were 12.7 ℃ and 7.0 ℃, respectively. The range of the temperature variation was as large as 5.7 ℃. Comparing with those values to those off Cape Muroto-misaki, those at Suruga Bay were 2.9 ℃ higher for maximum, 1.1 ℃ lower for minimum and 4 ℃ larger for the range. Therefore, the deep sea water at 300 m in the bay can not be low temperature and constant.

Key Words: Suruga Bay, deep ocean water, current, temperature

要 旨

駿河湾口東部において15ヶ月の長期に亘る係留式ADCP観測により取得した資料の最下層である300m層の流動および水温の解析を行って，それらの変動の実状を調べた．その結果，流入と流出の最大値は57 cm/secと40 cm/secで，全期間の平均流は1 cm/sec以下の極めて小さい値である．水温の最大値と最小値は12.7 ℃と7.0 ℃で，変動幅は5.7 ℃に及ぶ．これらを高知県室戸岬沖の320m層の観測地と較べると，同湾は最大値で2.9 ℃高く，最小値で1.1 ℃低く，変動幅は4.0 ℃も大きい．流動は短周期では半日および1日の潮汐，中周期では18日と37日が卓越し，長周期は微弱である．水温は短周期では半日および1日の潮汐，中周期では25日が卓越する．同湾の300m層の流動および水温は内部潮汐の影響による潮汐周期と黒潮変動の影響による中周期変動，さらに水温には季節変動も加わって時間変動が激しい．従って，同湾300m層海洋深層水は必ずしも低温安定性に富むとは言えない．

キーワード： 駿河湾，海洋深層水，流動，水温

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