Airborne measurements in a stable boundary layer over the Larsen Ice Shelf, Antarctica

We present aircraft measurements of boundary-layer structure and surface turbulent fluxes from a flight over the Larsen Ice Shelf, Antarctica. Warm advection, associated with föhn flow, led to the formation of a stable boundary layer over the ice shelf, with a well-defined low-level jet at the top of the surface inversion. The strong shear associated with the jet kept the gradient Richardson number small and maintained a turbulent boundary layer over a depth of at least 600 m. The net surface energy balance amounted to 52 Wm−2, equivalent to a melt rate of 13 mm water per day, with net radiation (48 Wm−2) making the largest contribution to melt. The contribution from the sensible heat flux (13 Wm−2) was largely balanced by an upwards latent heat flux (−9 Wm−2). These measurements provide insight into the processes that control surface melt rates in an area that has experienced recent rapid warming and deglaciation.

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