The signature of waves and rotors in wind profilers: Results of the Sierra Rotors Project

Two boundary layer wind profilers participated in the 2004 Sierra Rotors Project in Owens Valley, CA. One, the NCAR Multiple Antenna Profiler (MAPR) collects continuous vertical data while measuring the horizontal wind using a spaced-antenna (SA) technique. The other, part of a mobile version of the NCAR Integrated Sounding System, uses the more traditional Doppler beam swinging (DBS) technique. Owens Valley was relatively data rich during SRP, with a dense network of surface measurement stations, rawinsonde launches during times of interest, and an intensive numerical modeling and forecasting effort focused on the valley.

The first and second moments of the wind profiler's Doppler spectra will be examined for signatures of mountain waves and rotors. Stationary (mountain) waves can be seen as persistent vertical motions in time-height cross-sections of the first moment (radial velocity). The second moment (spectral width) contains information about the radial velocity variance within the radar pulse volume and over the spectral dwell (integration) time. There are several possible contributions to large spectral width. We will correct for the beam- and shear-broadening effects and examine the residual for evidence of spectral broadening by rotors during times other instruments or models suggest a rotor is present.