Gravity Waves - Experimental Constraints, Intercomparison and Effects of the Sun

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In the recent time it has been recognized that the vertical coupling by gravity waves (GWs) is one of the major uncertainties in general circulation models (GCMs) and there is a need for experimental constraints regarding the representation of GWs in GCMs. The first scientific objective of this proposal is to provide these kind of constraints. Data of the HIRDLS satellite instrument will be used to derive best estimate values of GW momentum flux using the technique employed before by Ern et al. (2004) for the CRISTA instrument. A climatology of GW momentum flux, as well as horizontal and vertical wavelengths will be derived. The second subject of this proposal is to estimate long term variations of the global GW distribution. Large part of the variation of the GW distribution can be attributed to the filtering of the GW source distribution by the atmospheric background. Based on this approximation long term variations (e.g., due to solar influences or the quasi biennial oscillation) of the global GW distribution in the lower stratosphere will be estimated using ERA-40 atmospheric background conditions and the Warner and McIntyre GW parameterization as well as global GW ray tracing with the GROGRAT ray tracer. The results will be compared to the long-term data set of SABER GW variances.