Volume-imaging UHF radar measurement of atmospheric turbulence

Abstract

The Turbulent Eddy Profiler (TEP) is a volume-imaging 915 MHz radar designed for atmospheric boundary-layer turbulence studies. TEP is a pulsed, phased-array radar using digital beamforming techniques to provide four-dimensional images of refractive index fluctuations and wind vectors on grid scales comparable to those of large-eddy simulations. During October 1999, TEP was deployed during the Cooperative Atmospheric Surface Exchange Study (CASES'99) held near Wichita, KS. In this paper we present observations from this experiment which focused on the evolution and dynamics of the stably-stratified nocturnal boundary layer. Unlike the convective boundary layer, radar echoes are characterized by intermittent bursts of shear-induced turbulence. The scales of turbulence features are generally smaller than the resolution of the UHF radar. This is demonstrated by comparison with a co-located S-band FMCW radar. Estimation of turbulence intensity is also complicated by the presence of significant bird and insect scatter.