Study on equatorial cumulous convection and atmospheric waves using radiosonde observations and data assimilation modeling

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In the equatorial region, cumulous convections are extremely active which generate atmospheric waves. These waves propagate upward, affecting the circulations in the lower and middle atmospheres, as well as transporting energy into the thermosphere. In this study, we clarified the mechanisms underlying the convection and the atmospheric waves by comparing the details of the observational results and the four dimensional dataset produced by the numerical modeling by means of data assimilation technique. We, first, analyzed the observational dataset accumulated so far, and then new dataset collected by a novel precise observation techniques is utilized. Precise water vapor measurement around the tropopause was carried out in Indonesia, and the transport associated with the convective activity has been clarified. Airglow imaging observation over one year in Indonesia has revealed the climatology of small scale gravity waves in the mesopause region for the first time, and clear association with horizontal distributions of cumulous clouds has been found. A long term observation by the MLT radars clarified the relation between the intraseasonal variations in the MLT region and atmospheric wave activity in the lower atmosphere. Three dimensional modeling using these observational data clearly showed the gravity waves excited by the cumulous convection propagate into the mesospause region and break there. Further comparisons with the airglow imaging observations clarified the mechanism of gravity wave generation, propagation, breaking and associated atmospheric instability. Input from the new satellite data and further improvement of modeling such as extension of the simulation space and improvement of resolutions would greatly contribute to the understanding of global impact of the atmospheric waves in the lower and middle atmosphere.