A Mechanistic Model Study of Gravity Waves Forced by Latent Heating

High resolution data of rainfall rate and infrared cloud top brightness temperature derived from TRMM (Tropical Rainfall Measurement Mission) and geostationary satellite observations have been used to construct estimates of latent heating and cloud top height every 3 hours. This heating was then used to force a mechanistic primitive equation model in order to examine the wave response to this heating. The model is configured with background zonal mean states from the NCEP analysis for two years (2005 & 2006) representing different phases of the QBO (Quasi-Biennial Oscillation). This response is rich with gravity waves (GW) of all scales. We analyze model run runs at high resolution (T80-T120) to derive characteristics of the GW momentum flux source spectrum and its evolution as the GWs propagate into the mesosphere. Use of different background zonal mean states provides information on critical level filtering of the GWs. The simulated wave spectrum will be compared to GW parameterization schemes in common use.