Langmuir turbulence in the Arctic Ocean: Insights from a coupled sea ice-wave model

Abstract

Upper-ocean mixing regulates the vertical transport of heat, momentum, and tracers in the ocean surface boundary layer. Langmuir turbulence (LT), generated by the interaction of wind stress and wave-induced Stokes drift, is a dominant mixing mechanism in the open ocean. Observations of LT in leads, polynyas, and the marginal ice zone (MIZ) confirm its presence in ice-covered regions, but its Arctic-wide occurrence and modulation by sea ice and waves remain limited in characterization. Here we present the first pan-Arctic assessment of LT mixing potential using a coupled sea ice-wave model integrating neXtSIM and WAVEWATCH III. Using wind-wave forcing metrics, we show that LT-relevant forcing beneath sea ice is spatially confined and highly intermittent. Conditions favorable for LT largely occur within the seasonal MIZ and arise episodically. Sea ice concentration sets the mean balance between wave- and shear-driven turbulence, but does not uniquely determine LT variability. The realization of wave-driven mixing depends on wave conditions and ice structure, while wind-wave misalignment plays a secondary role. As a result, LT in the Arctic MIZ typically occurs within mixed-forcing regimes, where wave-driven and shear-driven processes coexist. Our findings highlight the importance of wave-ice interactions and intermittency in shaping upper-ocean mixing under partial ice cover.