Presentation Information
[ACG68-P11]Turbulent Mixing Induced by Topography over the Chukchi Plateau
*EunYae Son1, Yusuke Kawaguchi2, EIJI WATANABE3, Motoyo Itoh3, Hiromichi Ueno1 (1.Hokkaido University, Faculty of Fisheries Sciences, 2.Kitami Institute of Technology, 3.Japan Agency for Marine-Earth Science and Technology)
Keywords:
Arctic Ocean,Turbulent mixing,Topographic rossby wave
The Arctic Ocean is characterized by weak turbulent energy due to the presence of sea ice, which suppresses atmospheric forcing and limits internal wave generation, one of the primary drivers of vertical mixing. As a result, turbulence dissipation rates often approach the noise threshold of microstructure measurements, leading to weak ventilation beneath the mixed layer. In this study, we investigate an alternative wave-driven mixing mechanism in the western Arctic Ocean, focusing on topographically induced processes associated with geostrophic currents along the continental slope. We analyzed observations from the R/V Mirai cruise conducted in summer 2020 along a 75oN transect crossing the Chukchi Plateau, including TurboMAP microstructure, XCTD, and CTD measurements. To overcome the spatially limited nature of the observations, we performed numerical modeling to reconstruct topographic Rossby waves (TRWs). The model reproduced TRW activity at depths of 180-230 m, consistent with enhanced turbulence dissipation rates of ~10-8-10-9 W kg-1 observed in the microstructure data, while nearby regions remained near instrumental noise levels. Historical mooring data located ~30 km west of the study area recorded persistent eastward currents during summer, suggesting a recurring regional flow pattern favorable for TRW generation. These results indicate that TRWs can locally enhance turbulent mixing in the stratified interior, providing an alternative pathway for vertical exchange in the ice-covered Arctic Ocean.