14th Conference on Middle Atmosphere

P6.3

Observation of Gravity Waves by infra-red limb-sounding from satellites

Xiuping Yan, University of Leicester, Leicester, United Kingdom; and N. Arnold and J. Remedios

In global-scale models of the atmosphere, realistic representation of gravity waves is limited by a lack of observations of the global distribution of gravity wave sources, propagation, growth and breakdown. Therefore, developing a global climatology of gravity waves has great implications for weather and climate and atmospheric chemistry applications. Satellite observation of gravity waves is in an advantageous position because of its consistent global coverage and high spatial resolutions. HIRDLS (HIgh Resolution Dynamics Limb Sounder), due to its high vertical resolution (1 km) and high along-track sampling, is suitable for observing vertical propagating gravity waves. An approach to observing gravity waves is being developed that includes two components: i) a radiative transfer model, linkable to various gravity wave algorithms, which simulates expected radiance variances for given input waves; ii) a wave algorithm which examines variances in observed temperature data and attributes variances to wave types. Results will be shown for the radiative transfer simulations for idealized waves in order to illustrate the way in which gravity waves are observed through the radiative transfer process. These also enable tests of methods for extracting gravity wave amplitudes from both radiances and retrieved temperatures. Using these results, examples will be shown of applications to observed HIRDLS temperature data which in the present study focuses on isolating gravity waves from other types of non-stationary waves. The analysis of this study indicates that the variance has contributions mainly from three types of waves, transient small scale waves which are gravity waves, transient linear large scale waves and transient nonlinear large scale waves. The last two large scale waves that are mixed with gravity waves in the atmosphere are mostly planetary and there are also contributions from tides.

Poster Session 6, Gravity Wave Observations, Modeling and Parameterization
Thursday, 23 August 2007, 3:30 PM-5:30 PM, Holladay

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