Wind profiler direct observations of an atmospheric rotor: T-REX IOP3

The Terrain-Induced Rotors Experiment, held in Spring, 2006 in Owens Valley, California, included observations by three boundary layer wind profilers. These measurements formed part of a large observing network that included aircraft, in-situ soundings, lidars and sodars, surface meteorological stations and towers, and others. The third IOP of T-REX included a strong mountain wave event with associated reverse flow at the surface – a strong indication of a rotor.

This presentation will focus on the wind profiler observations. The profilers were sited in an “L” configuration, forming an along-valley pair on the western side of Owens Valley, and a cross-valley pair from the west to the center of the valley. Each profiler observes vertical air motion, horizontal winds, and turbulence strength estimated from small scale motions. These observations are over both time and height. The cross-valley pair allows us to see changes related to the wavelength, position, and strength of the mountain wave. The along-valley pair shows local variations of the wave due to upstream terrain and local terrain or atmospheric features.

Results so far include 1. An observed relationship between the position of wave upward motion, strong turbulence, and reverse or stagnant flow; 2. Observed couplets of small-scale “towards and away” radial velocity indicative of intermittent rotor flows. These are positioned beneath the wave crest, and will provide high resolution information on the rotor time and spatial scales.