An Observational Investigation of Penetrative Convection

Data taken during the Air Mass Transformation Experiment (AMTEX) by the NCAR Electra aircraft have proven useful for investigating the structure of thermals penetrating into the turbulent inversion layer which caps the convective mixed layer. Variances, covariances, spectra and cospectra of potential temperature, the three air velocity components, and humidity are computed to illustrate the dynamic processes occurring in this region. Two spectral maxima occur in vertical velocity and temperature: one at a wavelength of about 1.5 times the mixed layer depth and the other at about 200-300 m, which seems to be related to the characteristic size of a penetrating thermal