Climatological study of the latitudinal, longitudinal, and height distribution of atmospheric gravit wave energy

1.用GPS掩星技术分析重力波利用GPS掩星技术获得的温度资料，研究了大气重力波的全球分布。这项研究首次揭示了重力波振幅的全球分布[Tsuda等人，2000年a]。我们还可以观察到来自山脉的重力波[Hocke等人，2002年]。还揭示了对流层顶的全球形态[Nishida et al.，2000年]。我们可以进一步表明，电离层零星E层的出现与平流层中重力波的活动相关[Hocke等人，2002年]。上述GPS观测结果得到了Shigaraki MU雷达和美国白色Sands雷达的证实[Nastrom，2000年]。我们进一步表明，重力波的破碎有时会导致短距离内风速的大空间变化[中村等人，2002年]。在印度尼西亚用MF雷达研究了低纬度的重力波，以显示其年际和超季节变化[Isoda等人，2002; Tsuda等人，2002年]。研究了利用气象雷达推断重力波激发的方法[Horinouchi，2002].对印度尼西亚的长期观测数据进行了分析，以显示对流层上部重力波的季节性变化[Shimizu等人，2001年]。还研究了重力波振幅的垂直变化[亚历山大等人，2002年]。光学观测用CCD成像仪研究了中低温层区域的重力波，揭示了其主要传播方向的季节变化[Tsuda et al.，2000 b，中村，200 l]。

1. Analyses of the gravity waves with the GPS occultation techniqueThe global distribution of the atmospheric gravity waves was investigated with temperature data obtained by using the occultation technique for the GPS (Global Positioning System)signals. This study revealed the global distribution of the amplitude of gravity waves for the first time [Tsuda et al., 2000a]. We could also observe gravity waves from mountain ranges [Hocke et al., 2002]. Also revealed is the global morphology of the tropopause [Nishida et al., 2000]. We could further show that the occurrence of the ionospheric sporadic E layer is correlated with the activity of gravity waves in the stratosphere [Hocke et al., 2002].2. Radar observationsThe results with the GPS observations mentioned above was confirmed with the MU radar at Shigaraki and the White Sands radar in the United States [Nastrom, 2000]. We further showed that the breaking of gravity waves sometimes cause a large spatial variation of wind speed in a short distance [Nakamura et al., 2002]. Gravity waves in low latitudes were investigated with the MF radar in Indonesia to show their inter-annual and ultra-seasonal variability [Isoda, et al., 2002; Tsuda et al.,2002]. Methods to infer gravity wave excitation using meteorological radars were investigated as well [Horinouchi, 2002].3. Radio sonde observationsLong-term observational data in Indonesia was analyzed to show seasonal variability of the gravity waves in the upper troposphere [Shimizu et al.,2001]. Latitudinal variation of the gravity wave amplitude was also investigated [Alexander et al., 2002].4. Optical observationGravity waves in the mesopause-lower thermosphere region were investigated with CCD imagers,and the seasonal variation of their dominant propagation direction was revealed [Tsuda et al., 2000b, Nakamura, 200l].