The correlation velocity: On the possibility to measure fluxes of latent and sensible heat with radar wind profilers and sodars

First-principle theory of the Doppler shift of radar wind-profiler echoes from turbulent refractive-index perturbations in the clear air shows that the ensemble average of the Doppler velocity (Doppler shift divided by Bragg wavenumber) is generally not equal to the ensemble average of the radial wind velocity within the observation. On the other hand, the assumption of the equalness of Doppler velocity and radial wind velocity has formed the basis of 25 years of wind profiling. The leading term in the difference between Doppler velocity and radial wind velocity is what we call the "correlation velocity". The correlation velocity is proportional to the Bragg wave vector component of the imaginary part of the spatial cross spectrum of refractive index and radial wind velocity. In this contribution, the theory is presented, and the magnitude of the correlation velocity is estimated. Moreover, the possibility to retrieve fluxes of sensible and/or latent heat from measurements of the correlation velocity is discussed.