Conditionalwavelet technique applied to aircraft data measured in the thermal internal boundary layer during sea-breeze events

We describe a wavelet-based technique to determine the spectral turbulent contribution to the vertical flux of sensible heat in a position-wavelength representation. This technique combines a wavelet transform (Morlet wavelet) with conditional sampling. We apply this method to aircraft data collected during a sea-breeze circulation (BEMA97 experiment) with heterogeneous turbulence conditions horizontally and vertically as well. The turbulent fluxes are analysed with the conditional wavelet technique as a function of the wavelength and the horizontal distance. The turbulent processes within the thermal internal boundary layer associated with the sea breeze are clearly identified. The results exhibit the wavelength bands through which the upward flux (originating from the surface) and the downward flux (originating from the top of the boundary layer) are important.