[A-CG44] Kuroshio Large Meander

[ACG44-P02] Analysis and forecast of the Kuroshio path with JMA's operational system for monitoring and forecasting coastal and open-ocean states around Japan

*Yuki Inoue¹, Akiko Shoji¹, Toshiyuki Sakurai¹, Kumi Yoshita¹, Kentaro Tsuji¹, Ayako Yamane¹, Chihiro Kawamura¹, Koji Yagi¹, Masakazu Takami¹ (1.Japan Meteorological Agency)

Keywords:JPN system, JPN, the Kuroshio, Kuroshio Large Meander

Japan Meteorological Agency (JMA) provides various information about ocean conditions including the Kuroshio. For example, JMA provides charts of ocean current and temperature around the Kuroshio, and the distance from coasts to the axis of the Kuroshio current every day, which is based on JMA's ocean model results. Moreover, about every 10 days, JMA provides ocean current analysis and one-month forecasts of the Kuroshio path: the southernmost position off the Tokai coast, main current position around the Izu Islands and off the coast of Japan from Cape Toi to the Boso Peninsula.^*
On October 28, 2020, JMA introduced a new ocean data assimilation and forecasting system (JMA's operational system for monitoring and forecasting coastal and open-ocean states around Japan, JPN System). The JPN system has a higher horizontal resolution than the previous system, from 10 km to 2 km, and introduces various new physical processes such as tides, sea level changes due to atmospheric pressure, and river water runoff, etc. The JPN system also adopts a four-dimensional variational (4DVAR) assimilation scheme in order to assimilate observation data more accurately.
In this presentation, we verify how the reproducibility and forecast accuracy of the Kuroshio path have changed with the introduction of the JPN system from the perspective of operational use, and show that the JPN system is useful for monitoring of the Kuroshio path variation such as the Kuroshio Large Meander.

*) https://www.data.jma.go.jp/kaiyou/shindan/index_curr.html