Characterizing Intermittency in the Stable Arctic Atmospheric Boundary Layer

To elucidate the physics of surface-atmosphere exchange in Polar Regions, our understanding of the stable atmospheric boundary layer, where buoyancy damps turbulent kinetic energy, needs to advance significantly. We seek to understand the intermittent turbulence regime observed in the strongly stable case. In this regime, the atmospheric surface layer (ASL) is characterized by abrupt transitions between the turbulent and the laminar state. In this study, we analyze atmospheric turbulence data from Utqiaġvik, Alaska, to detect intermittent periods based on non-dimensional statistics. We reveal three clusters of turbulence regimes: Two correspond to the weakly turbulent periods featuring intermittent behavior (cluster 1: intermittent, cluster 2: transitional); the third cluster corresponds to a mildly stability-damped fully turbulent regime (cluster 3). We then investigate the origins of intermittent bursts based on analyses of the Turbulent Kinetic Energy (TKE) budget equation over these bursts in the TKE time series and assess the combination of velocity and length scales needed in the eddy diffusion theory under intermittent conditions.