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An improved interpretation of VHF oblique radar echoes by a direct balloon C 2 n estimation using a horizontal pair of sensors
Author(s) -
Luce Hubert,
Crochet Michel,
Dalaudier Francis,
Sidi Claude
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 - 10.1029/97rs00053
Subject(s) - isotropy , radar , anisotropy , computational physics , optics , resolution (logic) , wavelength , spectral resolution , physics , materials science , spectral line , astronomy , artificial intelligence , telecommunications , computer science
Successful comparisons between VHF oblique (15°) radar echo profiles and reconstructed ones deduced from high‐resolution temperature balloon measurements were presented by Luce et al. [1996]. The method was based on the evaluation of the three‐dimensional isotropic refractive index spectrum at the Bragg wavelength from the available temperature profiles (“spectral method”). However, the isotropic hypothesis is questionable, especially in regions where temperature sheets [ Dalaudier et al. , 1994] are observed. Indeed, the associated anisotropic temperature fluctuations should contribute to the one‐dimensional vertical temperature spectrum at small scales. In the present paper, another method, less sensitive to anisotropic contaminations, is used. This method is based on an estimation of the temperature structure constant C 2 T from variances of horizontal differences of temperature measured by two high‐resolution sensors 1 m apart horizontally (“horizontal variance method”). It is shown that the main differences between the C 2 T estimations obtained from the two methods are mainly observed at high resolution in stable regions where few turbulent fluctuations in the temperature field are observed. However, the two methods give approximately equivalent results at the radar range resolution (600 m) and the quality of the comparisons with the radar observations is slightly improved with the horizontal variance method. In order to demonstrate the full advantages of this technique, the use of radars with more powerful capabilities is suggested for future investigations.