Conditional Wavelet Technique Applied to Aircraft Data Measured in the Thermal Internal Boundary Layer During Sea-Breeze Events

Jean-Luc Attié (1) , Pierre Durand (2)

1 LAERO - Laboratoire d'aérologie
2 CNRM - Centre national de recherches météorologiques

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

Mots clés: Conditional sampling; Sea breeze; Thermal internal boundary layer; Turbulent flux; Wavelet analysis

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]; Météorologie

Jean-Luc Attié, Pierre Durand. Conditional Wavelet Technique Applied to Aircraft Data Measured in the Thermal Internal Boundary Layer During Sea-Breeze Events. Boundary-Layer Meteorology, 2003, 106 (3), pp.359-382. ⟨10.1023/A:1021262406408⟩. ⟨hal-00137512⟩