A case study of atmospheric boundary layer mean structure for flow parallel to the ice edge: Aircraft observations from CEAREX

Abstract

This paper describes a case study of the mean structure of the atmospheric boundary layer (ABL) in the marginal ice zone of the Barents Sea for flow nearly parallel to the ice edge. Data were collected by the NOAA P‐3 Orion research aircraft on March 24, 1989. The geostrophic wind above the boundary layer was oriented approximately 15° off‐ice with a speed of 12 m s−1, and the atmosphere above the ABL showed little cross‐ice‐edge variability. A lidar on the aircraft revealed (over the water) the downward slope of a stratocumulus deck toward the ice edge. The associated inversion continued to slope downward over the ice, creating large thermal wind effects within the boundary layer. The inversion slope, combined with horizontal boundary layer temperature gradients, produced a factor‐of‐2 decrease in surface geostrophic wind from water to ice. Below the inversion the data revealed an ABL that remained well mixed for 100 km into the ice. A gust probe system on the aircraft provided a mapping of low‐level fluxes from a 200‐km leg perpendicular to the ice edge.