An Analysis of the Clear Air Planetary Boundary Layer Wind Synthesized from NSSL'S Dual Doppler-Radar Data,

摘要

Clear air dual Doppler-radar experiments conducted at the National Severe Storms Laboratory have defined wind fields in the planetary boundary layer through detection of the motion of the atmosphere's diffuse intrinsic scatterers. Acquisition of wind data and synthesis of the data to grid points are discussed,and it is shown by correlation techniques that the theoretically estimated velocity variance at a grid point caused by measurement technique is small enough to detect true kinematic features in the perturbation wind fields. The kinematic structure of these perturbation wind fields is analyzed and compared to results produced by analytical and numerical models. Spatial spectrum analysis and band-pass filtering of the Doppler synthesized winds are used to aid in interpreting the structure of the wind fields. It is shown that the data are consistent with model predictions for a convectively unstable and moderately sheared PBL that existed during data collection. In addition,the spatial spectra of Doppler data show statistical agreement with tower wind measurement assuming the Taylor hypothesis. Finally,it is shown that the wind perturbations are 'frozen'with a lifetime of about 60minutes.