1 November 2005 Observing properties of gravity waves from space: moving beyond average temperature variance
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Because gravity wave effects control middle atmosphere circulation patterns, and because those effects depend sensitively on the properties of the waves, reseachers have been trying for decades to ascertain the global properties of gravity waves to better constrain global circulation models. Space-based observations hold promise for providing the needed information, but the small scales of gravity waves have posed observational challenges. Traditional analyses of averaged temperature variance do not provide the needed information. We will present statistics from alternative analyses of Atmospheric Infrared Sounder (AIRS) images of gravity waves in the stratosphere. The high spatial resolution of the AIRS observations permit resolution of gravity waves with horizontal wavelengths as small as 50 km. We present the results of wavelet analyses of AIRS images at 667cm-1 (in the CO2 15 μm band) that spatially resolve gravity wave amplitudes, horizontal wavelengths, and propagation directions. These analyses reveal both local maximum amplitudes as well as frequencies of wave occurrence, while in contrast these quantities are inseparably blended within traditional wave temperature variance or Fourier analysis methods. The AIRS observations are known to detect only long vertical wavelength waves, whose occurrences are in turn known to be highly dependent on the strength of background wind speeds. The AIRS data permit for the first time detailed studies of the relationships between the occurrence of these waves and their propagation directions relative to the background winds.
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M. Joan Alexander, M. Joan Alexander, Christopher Barnet, Christopher Barnet, } "Observing properties of gravity waves from space: moving beyond average temperature variance", Proc. SPIE 5979, Remote Sensing of Clouds and the Atmosphere X, 59792A (1 November 2005); doi: 10.1117/12.627669; https://doi.org/10.1117/12.627669

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