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Imaging Doppler interferometry and the measurement of atmospheric turbulence
Author(s) -
Roper R. G.,
Brosnahan J. W.
Publication year - 1997
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/97rs00089
Subject(s) - turbulence , physics , buoyancy , dissipation , doppler effect , zenith , radiance , computational physics , range (aeronautics) , mechanics , optics , meteorology , materials science , thermodynamics , astronomy , composite material
Data taken by an imaging Doppler interferometer (IDI) 3.175‐MHz radar during the Arecibo Initiative on Dynamics of the Atmosphere in 1989 is interpreted in terms of turbulence parameters. The rms random velocity determined from scatterers within 2° of the zenith for the interval 1200–1416AST on April 10, 1989, is used to calculate the rate of dissipation of turbulent energy using two formulations, one based on an estimate of the lifetime (∼100 s) of the intermittent scatterers identified by the IDI technique, and another based on the turbulent structure function. Both techniques yield upper limit values of 0.01–0.06 W kg −1 for the rate of dissipation of turbulent energy, increasing with height over the range from 72 to 90 km. The energy‐bearing eddy scale of turbulence, neglecting buoyancy, is found to vary with height, being a minimum at 75 km (200 m) and a maximum at 90 km (400 m). The effects of buoyancy are discussed in detail, and the buoyancy, or outer scale, is found to vary from 300 m at 75 km to a maximum of 900 m at 90 km. The Kolmogorov microscale, or inner scale, is found to increase from 1 m at 72 km to 10 m at 93 km. Estimates of the vertical eddy diffusion coefficient are also made, and the values obtained are shown to be highly dependent on the assumptions underlying the calculations.