オホーツク海の十年変動 : 海氷と上層水温

• Main Authors: 佐々木, 克徳, 見延, 庄士郎
• Format: Article in Journal/Newspaper
• Language: Japanese
• Published: 北海道大学低温科学研究所
• Subjects: 431.67; Bering Sea; Okhotsk; Pacific; okhotsk sea; Sea ice; Siberia
• Online Access: http://hdl.handle.net/2115/20451

オホーツク海の海氷と上層水温の十年変動についての時空間構造と、その大気との関係について解析を行った。冬季の海氷の十年変動はオホーツク海北部で大きい振幅を持ち、1980年代の初めから1990年代中頃までは減少傾向、それ以降は海氷増加の傾向を示す。この海氷変動は秋季の大気変動に強く影響されている。一方、オホーツク海南部の夏期(5-10月)の上層水温の十年変動はクリル海盆付近で大きい振幅を持ち、概ね十年毎に温暖のピークを持つ準十年変動を示す。この上層水温の十年変動はその前の冬季の大気変動に強く影響されている。 We investigate decadal-scale variations in the wintertime (February-March) sea-ice concentration and warm-season (May-October) water temperature in the upper 200m of the Okhotsk Sea, as well as their relation to atmospheric circulation. Large decadal-scale variation in wintertime sea-ice occurs in the northern Okhotsk Sea; this variability showed a decreasing trend from 1980 to the mid-1990s and an increasing trend from the mid-1990s to the early 2000s. This sea-ice variation is thermodynamically influenced by the atmospheric conditions during the late autumn (October-November). The atmospheric conditions in late autumn for the positive sea-ice anomalies exhibit cold air-temperature anomalies over the Okhotsk Sea from Siberia. These atmospheric conditions in late autumn are related to 700-hPa geopotential height differences between the Bering Sea and northern Eurasia. The dominant upper-ocean temperature fluctuations in the southern Okhotsk Sea have a monopole structure with the maximum amplitude in the Kuril Basin; corresponding time series exhibit prominent quasi-decadai variability over the period 1958-94. This variability is closely related to wintertime differences in sea-level pressure between northern Eurasia and the northern North Pacific. 1章 10年～100年スケールの気候変動の観測, 気候復元とモニタリング