DIRECT COMPARISON BETWEEN IN-SITU AND VHF OBLIQUE RADAR MEASUREMENTS OF REFRACTIVE-INDEX SPECTRA - A NEW SUCCESSFUL ATTEMPT

A direct comparison between in situ and radar measurements of temperat ure spectra of atmospheric turbulence was performed by Dalaudier er al . [1989]. The widely accepted hypothesis of scattering from isotropic turbulence in the inertial subrange was used for the oblique reconstru ctions. However, the results were ''puzzling'' because neither the sha pe, the dynamic range, nor the power level was correctly reproduced. O ther investigations were thus needed in order to determine the causes of these disagreements. A new attempt was performed using essentially the same method based on the same model and a more extensive and impro ved data set. The results, presented here, are now very satisfying for most of measurements. This agreement allows us to understand that som e errors and technical problems were at the origin of the discrepancie s described by Dalaudier et al. [1989]. From the new results it can be concluded that the method used, based on the isotropic model in the i nertial subrange, is adequate to fairly reproduce most of the VHF rada r measurements at 15 degrees from the zenith.