Mesoscale variability in the boundary layer during ASCOS

The role of mesoscale motion is often partially or fully neglected in studies of the atmospheric boundary layer - for both theoretical and practical reasons. Since the 1950's it has been believed that the atmosphere exhibits an energetic spectral gap in the mesoscales; it has even been suggested to define the mesoscale. During the past decades, however, these observations are being disputed by several authors.

The summer lower Arctic atmosphere is usually configured with a boundary layer that is close to neutral, though only a few hundred meters deep, as it is capped by a relatively strong and thick elevated inversion. This configuration appears to be favorable for mesoscale phenomena, such as gravity waves, that may exist in the prevailing stably stratified inversion.

In the present study we analyze observations made during the ASCOS campaign in the central Arctic basin using current wavelet methods with a focus on meso¬scale motion. We use the wavelet technique on for example high-resolution surface-pressure observations to identify episodes of wave activity and then on the eddy-correlation turbulence observations to quantify possible impacts on the surface energy and momentum fluxes. We will also examine, for example, the sodar observations during such episodes for evidence of wave-like motions.