Katabatic winds strongly influence turbulent heat fluxes over glaciers, yet the turbulent length scales governing these fluxes remain poorly understood. The height of the wind speed maximum (\ (h₉₄ₓ\) ) has been proposed as a relevant turbulent length scale for some katabatic flows, while scaling based on distance from the surface (law-of-the-wall scaling) may apply when \ (h₉₄ₓ\) exceeds the Obukhov length (\ (\) ). However, these relations remain underexplored for glacier surfaces and katabatic flows more broadly. In this study, we use cospectral analysis of near-surface eddy covariance measurements and kite-borne wind profiles from a glacier site to identify dominant turbulent length scales and assess their relation with \ (h₉₄ₓ\). We introduce a filtering method to remove non-turbulent contributions — such as internal gravity waves — from the cospectra, improving the reliability of length scale detection. For comparison, we investigate tower-based data from a non-glacierized site with deep katabatic flows. Our results reveal a one-to-one relation between the streamwise temperature flux length scale (\ (Lₔₓ\) ) and the smaller of \ (h₉₄ₓ\) and \ (\), defining two regimes: \ (h₉₄ₓ\) –scaling and \ (\) –scaling, with \ (h₉₄ₓ\) –scaling dominant at the glacier site. This relation indicates that it may be possible to detect katabatic jet height from near-surface observations from a single sensor. Neither site exhibited classical boundary layer scaling: turbulent mixing lengths scaled with distance from \ (h₉₄ₓ\) rather than height above the surface. These findings challenge conventional turbulence scaling assumptions for katabatic flows.
Lord-May et al. (Mon,) studied this question.