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.
KeywordsStructure Function Gravity Wave Potential Temperature Zonal Velocity Haar Wavelet
Unable to display preview. Download preview PDF.
- Bacmeister, J. T., S. D. Eckermann, P. A. Newman, L. R. Lait, K. R. Chan, M. Loewen- stein, M. H. Proffitt and B. L. Gary, Stratospheric horizontal wavenumber spectra of winds, potential temperature and atmospheric tracers observed by high-altitude aircraft. J. Geophys. Res., 101, 9441–9470, 1996.CrossRefGoogle Scholar
- Daubechies, I., Orthonormal bases of compactly supported wavelets, Comm. Pure Appl. Google Scholar
- Math., 41, 909-996, 1988. Daubechies, I., Ten lectures on wavelets, 357 pp., CBMS-61, SIAM, Philadelphia, 1992. Davis, A., A. Marshak, W. Wiscombe and R. Cahalan, Multifractal characterizations of nonstationarity and intermittency in geophysical fields: Observed, retrieved, or simulated, J. Geophys. Res., 99, 8055-8072, 1994.Google Scholar
- Frisch, U., Turbulence: the legacy of A. N. Kolmogorov, 296 pp., Cambridge Univ. Press., New York, 1995.Google Scholar
- Loewenstein, M., J. R. Podolske, K. R. Chan, and S. E. Strahan, Nitrous Oxide as a dynamical tracer in the 1987 Airborne Antarctic Ozone Experiment.,/. Geophys. Res., 94, 11,589-11, 598, 1989.Google Scholar
- Murphy, D., Time offsets and power spectra of the ER-2 data set from the 1987 Airborne Antarctic Ozone Experiment, J. Geophys. Res., 94, 16737–16748, 1989.Google Scholar
- Pierrehumbert, R. T., Tracer microstructure in the large-eddy dominated regime, in Chaos applied to fluid mixing, ed. H. Aref, M. S. El Naschie; Pergamon/Elsevier, 347-365, 1995. Press, W. H., S. A. Teukolsky, W. T. Vetterling, and B. P. Flannery, Numerical Recipes in FORTRAN, 2nd ed., 963 pp. Cambrige University Press, Cambridge, UK, 1992.Google Scholar
- Proffitt, M. H., M. J. Steinkamp, J. A. Powell, R. J. McLaughlin, O. A. Mills, A. L. Schmeltekopf, T. L. Thompson, A. F. Tuck, T. Tyler, R. H. Winkler, and K. R. Chan, In situ ozone measurements within the 1987 ozone hole from a high-altitude ER-2 aircraft, J. Geophys. Res., 94, 16547-16556, 1989.Google Scholar