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

在赤道地区，积累性对流非常活跃，产生了大气波。这些波向上传播，影响低层和中层大气的环流，并将能量输送到热层。在这项研究中，我们通过比较观测结果和利用数据同化技术产生的四维数据集的细节，阐明了对流和大气波动的机制。我们首先分析了目前积累的观测数据集，然后利用一种新的精密观测技术收集了新的数据集。印度尼西亚对对流层顶周围的水汽进行了精确测量，并弄清了与对流活动有关的输送。印度尼西亚一年多的气辉成像观测首次揭示了中层顶区小尺度重力波的气候学特征，并发现与累积云的水平分布有明显的联系。MLT雷达的长期观测阐明了MLT区域的季节内变化与低层大气波活动之间的关系。利用这些观测数据进行的三维模拟清楚地显示了由累积对流激发的重力波传播到中层顶区并在那里破裂。与气辉成像观测的进一步比较阐明了重力波的产生、传播、破裂和相关的大气不稳定的机制。新卫星数据的输入和模拟的进一步改进，如扩展模拟空间和提高分辨率，将大大有助于理解中、低层大气波的全球影响。

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.