Climatology of boundary layer wind patterns from clear air radar echoes in Germany

Long term observations of shallow convection in the atmospheric boundary layer are rare and difficult to obtain, making it hard to evaluate the capabilities of weather models to accurately represent such features. In this study, we demonstrate that clear air radar reflectivities from insects can be exploited to visualize the horizontal structure of convective cells and rolls over Germany. The patterns observed over a 7 year period are analyzed in terms of their spatial scale, orientation and anisotropy using a two-dimensional wavelet transform. Comparable characteristics can be computed from the near-surface windfields of the convection-permitting regional reanalysis COSMO-REA2. We show that, despite the proximity to the gray zone of turbulence, the reanalysis reproduces a surprisingly realistic diurnal cycle in the spatial patterns and may thus give hints on the wind structures during the unobserved part of the timeseries.