EFFECTS OF VERTICAL SHEAR ON ARCTIC DOUBLE DIFFUSIVE STAIRCASES

Abstract

Double diffusive convection through Arctic staircases has been shown to play a role in the melting of Arctic sea ice. However, there have been no studies exploring the effects of shear on these staircases. We simulated these staircases numerically in the presence of vertical shear to determine its effects on the heat flux and structure of the staircases. Results from this study imply the heat flux increases 20% to 30% above cases with no shear. Simulations yielded an unexpected result that, with the addition of shear, a turbulent motion occurs inside the interfaces between staircase layers that typically are devoid of vertical motion in the absence of shear. These features are attributed to the recently discovered thermohaline-shear instability. An investigation of turbulent kinetic energy indicates that the intensity of this instability may depend on both Richardson number and density ratio. Understanding the effects of vertical shear on the staircases, and in particular on the associated heat flux, may lead to more accurate mixing parameterizations in global climate models.