[A-OS17] Physical Oceanography (General)

[AOS17-P04] Development of new parameterization for turbulent diffusivity and heat transfer of the Arctic Ocean

*EunYae Son¹, Yusuke Kawaguchi¹ (1.University of Tokyo)

Keywords:Arctic, Turbulence, parameterization

The Arctic Ocean has been known for the low turbulent energy due to the presence of sea ice, which acts as a barrier to prevent atmospheric force from coming in the water (Rainville and Winsor, 2008). In past decades, the western part of the Arctic Ocean has shown the striking change according to the climate change (Parkinson et al., 2013). The most distinctive variation can be recognized by sea ice reduction. Among the areas, the western Arctic where is connected to the northern Pacific showing the drastic sea ice reduction in summer season (Graversen et al., 2011). It represents the sea ice reduction can be crucial factor that changes ocean interior mixing by increased open surface that can absorb atmospheric force. In this study, we attempt to assess the turbulent energy level in the western Arctic Ocean, including the Chukchi Sea, the Canada Basin and the Beaufort Sea. Also, we are going to parameterize variables of turbulence dissipation rate (e) and eddy diffusivity based on vertical profiles of density and horizontal current by comparing with the direct microstructure observations. For the development of optimal parameterization, the microstructure profiles and shipboard ADCP velocity were simultaneously acquired in the region of Chuckchi and Beaufort Sea in the year of 2019 to 2021, using R/V Mirai of JAMSTEC. We are developing the fine-scale parameterization on the basis of the existing models of Gregg (1989) and Kunze et al. (2006). In the experimental calculation, the best-performance function and constants are optimally selected. For the future perspective, we plan to apply the model for the quantification of turbulent levels in broader areas of the western Arctic. The method will be applied to the dataset of temperature, salinity and horizontal velocity that were autonomously collected by the ice-tethered profiler with velocity (ITP-V), developed by the Woods Hole Oceanographic Institution (Krishfield et al. 2006; Toole et al. 2007; Son et al., submitted). In this study we were able to confirm that the energy level of the Canada Basin is near to molecular level with the e near 10^-10 W kg^-1. On the other hand, the turbulent mixing was enhanced at the area of Alaska shelf slope where is the entrance of the Pacific origin water to the Canada Basin. Also e increases over the Northwind Ridge by enhanced internal wave.