Free convection frequency spectra of atmospheric turbulence over the sea

Abstract

Frequency spectra of atmospheric turbulenceSα(f) in the inertial subrange are considered in the free convection regime over the sea surface in a case of motionless instrument measurements (Eulerian frequency spectra). The frequency spectra formulaef*Sα(f)/σα2 =cα(f*/f)5/3 for wind velocity (α=1–3), temperature (α=t) and humidity (α=e) fluctuations are derived on the basis of similarity theory and the “−5/3 law”. These relations also can be derived from a consideration of convective large-scale advection of small eddies. The frequency scalef* = (N1β2/∈)1/2 ≈ (βH/z2)1/3 is the lower bound of the inertial subrange and it is of order 10−2 Hz.