[A-OS21] Coastal ocean circulation and material cycle

[AOS21-P04] Effects of topography and stratification on the propagation of coastal Kelvin waves.

*Kazuya Tashiro¹, Shinichiro Kida², Yuki Tanaka³ (1.Department of Earth System Science, Interdisciplinary Graduate School of Engineering Science, Kyushu University, 2.Research Institute for Applied Mechanics, Kyushu University, 3.Faculty of Marine Science and Technology, Fukui Prefectural University)

Keywords:continental shelf, wind stress forcing

The effects of topography and stratification on the propagation and decay of Coastal Kelvin waves along continental shelf breaks are examined using numerical model. Coastal Kelvin waves are considered to propagate along Japan’s southern coast and the continental shelf break of the East China Sea. When the Kuroshio Current shifts north and approaches the southern coast of Japan, a sea surface height anomaly is induced south of the Kii Peninsula, exciting topographic Rossby waves and Kelvin waves, which increase sea levels along the eastern side of the Tsushima Strait and enhance Japan Sea Throughflow transport. However, the mechanisms of propagation and decay of such sea level signals under diverse topographic conditions and stratification are not fully understood. Therefore, we constructed an idealized numerical model to investigate the dynamics of coastal Kelvin wave under multiple conditions. Two types of simplified topography, with abrupt and gradual continental slopes, are set up. Three types of vertical water temperature profiles, one resembling Japan’s southern coast, one with weaker temperature gradients, and one with uniform temperature, are also set up. Wind stress is applied near the shelf break to generate sea surface disturbance. Experiments show that the sea surface response to wind stress is enhanced when stratification is greater. Sea level disturbances also decay rapidly as shelf width narrows. We plan to conduct further experiments based on realistic water temperature variability based and topographic variations around Japan.