[A-OS18] Kuroshio Large Meander

[AOS18-P03] Eddy separation from the Kuroshio Large Meander in 2020

*Toru Miyama¹, Yasumasa Miyazawa¹, Sergey M Varlamov¹, Zhang Ruochao¹ (1.Japan Agency for Marine-Earth Science and Technology, Application Laboratory)

Keywords:kuroshio Large Meander, Eddy, ocean reanalysis, predictability

The Kuroshio Large Meander has been continuing since 2017. The large eddy was detached from the Meander in October 2020. The Large Meander temporarily ended. Correspondingly, Kushimoto-Urakami sea level difference, whose smallness is an indicator of the Large Meander, increased. Subsequently, the small meanders that existed east of Kyushu developed into the Large Meander by moving eastward and replacing the previous eddy, resulting in the continuation of the Large Meander. The Kushimoto-Urakami sea level difference decreased again. Alternatively, the eddy detached moved westward and formed a small meander by joining the Kuroshio southeast of Kyushu from the end of January to the beginning of February 2021. This behavior is different from the eddy HARUKAZE after the Harukaze Maru of the Kobe Marine Observatory, which was observed it in 1978 during the great Kuroshio Large Meander period of 1975–1980. In 2020, the Kuroshio Large Meandering Current was in a state of instability. Therefore, several small eddies shredded before the large eddy detachment described above. The instability was due to the small meander east of Kyushu and high sea level anomaly extended from the Kuroshio Extension. In this presentation, I will discuss the dynamics and predictability of the unstable Kuroshio Large Meander.