SCALE EXPONENTS OF ATMOSPHERIC TURBULENCE UNDER DIFFERENT STRATIFICATIONS

Wavelet analysis is used to measure directly the scale exponents of atmospheric turbulence at inertial range under different stratifications. It is found that the average values of the scale exponents under different stratifications are clearly different and are all lower than the Kolmogorov 1941 value of 1/3. The difference shows that, according to the intermittent turbulence model, turbulence under stable stratification behaves more intermittently than under unstable stratification. The reason may be that the gravity wave, which could exist only under stable stratification, modulates the state of nocturnal surface layer and causes this kind of intermittence.