AMT Atmospheric Measurement Techniques AMT Atmos. Meas. Tech. 1867-8548 Copernicus Publications Göttingen, Germany 10.5194/amt-5-1637-2012 Consistency between Fourier transform and small-volume few-wave decomposition for spectral and spatial variability of gravity waves above a typhoon Lehmann C. I. 1 Kim Y.-H. 2 Preusse P. 1 Chun H.-Y. 2 Ern M. 1 Kim S.-Y. 2 3 Institut für Energie- und Klimaforschung (IEK-7), Forschungszentrum Jülich, Jülich, Germany Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea Next Generation Model Development Center, Seoul, South Korea 17 07 2012 5 7 1637 1651 Copyright: © 2012 C. I. Lehmann et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://amt.copernicus.org/articles/5/1637/2012/amt-5-1637-2012.html The full text article is available as a PDF file from https://amt.copernicus.org/articles/5/1637/2012/amt-5-1637-2012.pdf

Convective gravity wave (GW) sources are spatially localized and emit at the same time waves with a wide spectrum of phase speeds. Any wave analysis therefore compromises between spectral and spatial resolution. Future satellite borne limb imagers will for a first time provide real 3-D volumes of observations. These volumes will be however limited which will impose further constraints on the analysis technique. In this study a three dimensional few-wave approach fitting sinusoidal waves to limited 3-D volumes is introduced. The method is applied to simulated GWs above typhoon Ewiniar and GW momentum flux is estimated from temperature fluctuations. Phase speed spectra as well as average profiles of positive, negative and net momentum fluxes are compared to momentum flux estimated by Fourier transform as well as spatial averaging of wind fluctuations. The results agree within 10–20%. The few-wave method can also reveal the spatial orientation of the GWs with respect to the source. The relevance of the results for different types of measurements as well as its applicability to model data is discussed.

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