[A-OS12] 全球海洋観測システムから迫る海洋科学

[AOS12-P05] Observed abyssal temperature variability modulated by mesoscale eddies

*WANG SHUYA¹、太田 雄策^1,2、木戸 元之³、富田 史章^1,3、日野 亮太² (1.東北大学 変動海洋エコシステム高等研究所、2.東北大学 大学院理学研究科、3.東北大学 災害科学国際研究所)

キーワード：海底温度、中規模渦

The ocean bottom temperature (OBT) in the Kuril Trench was collected by temperature sensors at three stations on the seafloor for nearly two years, where the water depth is over 7000 m. The observational results indicate low-frequency variability of the OBT with a period longer than one month. Combining the analysis on grided altimetry products, we find that the 60-day lowpassed OBT anomaly shows good consistency with the 60-day lowpassed sea level anomaly (SLA). Specifically, the large positive OBT anomaly is found as an anticyclonic mesoscale eddy stays around the observational stations. Such a long-lived eddy could induce downwelling through isopycnal depression, which is preliminarily evidenced by field CTD observations along the A-line across the eddy. Additionally, the lag correlation between the bandpassed OBT and SLA with a period of 30-60 days is high when the eddy center gets close to the observational sites. Fluctuations of OBT in this band are likely caused by topographic Rossby waves, which are triggered by the interaction between the anticyclonic eddy and the continental slope west of the Kuril Trench. Our results demonstrate the important role of mesoscale eddies in modulating the variability in the abyssal ocean.