Lagrangian‐Eulerian time‐scale ratios estimated from constant volume balloon flights past a tall tower

Abstract

AbstractThe ratio of Lagrangian and Eulerian time scales of motion in the planetary boundary layer is estimated from radar observations of 35 constant volume balloons (tetroons) flown past the 460 m high BREN tower at the Nevada Test Site. On the average, the peak energies of the Eulerian and tetroon vertical velocity spectra occur at periods near 6 and 18 minutes, yielding a mean Lagrangian‐Eulerian scale ratio, β, of about three, β increases with increase in wind speed, decreases with increase in r.m.s. vertical velocity, and is inversely related to vertical turbulence intensity, with β ranging from 4.5 at a turbulence intensity of 0.05 to 2.5 at turbulence intensities exceeding 0.3.