Ray-tracing simulation of gravity waves forced by tropical convection in comparison with SABER satellite observations
Abstract
Gravity waves (GW) are responsible for driving large scale circulations like Brewer-Dobson circulation, contribute to the wave driving of the QBO in the tropics, and are also known as a coupling mechanism between tropospheric sources and the upper stratosphere to mesosphere region. Convection is a dominant source for tropical GWs, but also one of the most difficult and dynamic GW sources to understand. Therefore, we present the results of GW ray-tracing calculations from tropospheric (convective) sources up to the mesosphere. We used the Gravity wave Regional Or Global RAy-Tracer (GROGRAT) to perform the GW trajectory calculations and the convective GW source scheme from Yonsei University (South Korea) to quantify the excitation by convection. Heating rates, cloud data, and atmospheric background data were provided by the MERRA dataset for the calculation of convective forcing by deep convection and for the atmospheric background of the ray-tracing calculations afterwards. In order to validate our findings we compare our simulation results with satellite measurements of temperature amplitudes and momentum flux from the SABER instrument over a 10 years period. Simulation and measurements are in good agreement for the tropics throughout the whole simulated period and show similar seasonal behavior. Additionally, the observational filter of the instrument was taken into account and its influences are discussed. The modulation of GW momentum flux by the background winds and in particular the influence of the QBO is investigated. GW drag at various altitudes is calculated and compared to the drag required for the forcing of the QBO. Further, we show the results of a non-orographic background parameterization used as start conditions for the ray-tracer to emphasize the improvements of our coupled convective GW source model over non-orographic GW parameterizations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.A23F0381K
- Keywords:
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- 3334 ATMOSPHERIC PROCESSES Middle atmosphere dynamics