Analysis of Intermittency in Aircraft Measurements of Velocity, Temperature and Atmospheric Tracers using Wavelet Transforms

Wavelet transforms of geophysical data are a promising new technique which may extend traditional analyses employing Fourier transforms. Here we will employ wavelet transforms to examine velocity, potential temperature, and trace gas mixing ratio measurements from high-altitude ER-2 aircraft (altitude≈20 km). Probability density functions and quantities similar to structure functions are calculated from wavelet transforms. This analysis reveals differences between the variability of meteorological quantities such as velocity and potential temperature, and that of passive atmospheric tracers. Our analysis suggests that trace gas variability contains intermittent episodes of high variability, while velocity and temperature fluctuations are more uniformly distributed. We propose a simple model consisting of two sets of variability with different degrees of “roughness” and continuity. This “bi-fractal” model is used to interpret structure functions obtained for velocity and N2O. Finally, we show a case of gravity wave-tracer filament interaction in the ER-2 data. We argue that such interactions may increase cross-isentropic mixing of trace gases by gravity waves.