International coordinated observation of hectors at the tropical region in the northern Australia

距离澳大利亚北领地的中心城市达尔文离岸约50-100公里，两个岛屿（布瑟斯特，梅尔维尔），被称为提维群岛，隔着一个狭窄的海峡。非常典型的孤立型巨大积雨云称为赫克托出现在这些岛屿。2001年10月至12月，我们在达尔文附近开展了国际共同观测活动（DAWEX：达尔文区域波实验），以研究积雨云（Hector）对大气波的产生。我们与澳大利亚气象局（BOM）、莫纳什大学和阿德莱德大学合作，开展了无线电探空仪观测活动。为了研究Hector大气波的水平传播特性，我们选择了3个气球发射点：提维群岛的Garden Point，达尔文和凯瑟琳，它们排列在一条近似直线上，最大距离约为400 km。我们总共发射了40枚 关于我们 10月中旬为相对平静的旱季（10/13-18），11月下旬（11/15-20）和12月中旬（12/11-16）为海克特活动期。根据气球破裂高度的统计，3/4以上的气球破裂高度达到25 km，约2/3的气球破裂高度超过30 km。由于三个观测点之间几乎没有相位差，因此该波似乎具有很大的水平尺度。11月和12月也出现了类似的波浪活动。我们提取了垂直尺度小于3 km的大气重力波，并从风速和温度波动中估计了波的能量。在15-20 km和25-30 km处波能量增强，而在20-25 km处重力波能量显著降低。波能的总体结构似乎与背景纬向风有关，但其物理机制尚未阐明。少

About 50-100 km offshore from Darwin, which is the central city on the Northern Territory, Australia, the two islands (Buthurst, Melville), called Tiwi Islands, are facing across a narrow strait. The very characteristic isolated type huge cumulonimbus cloud called Hector appears over these islands. We carried out the international common observation campaign (DAWEX: Darwin Area Wave Experiment) around Darwin in October to December, 2001, in order to study the generation of atmospheric waves by cumulonimbus clouds (Hector). In collaboration with the Australian Bureau of Meteorology (BOM), Monash university, and the university of Adelaide, we conducted radiosonde observation campaigns. In order to investigate the horizontal propagation characteristic of the atmospheric waves from the Hector, we selected 3 balloon launch sites; Garden Point on the Tiwi Islands, Darwin and Katherine, which are aligned on a nearly straight line with maximum distance of about 400km. We launches a total of 40 … More radiosondes every 3 hours from the 3 places for over 5 days in 3 periods; the comparatively calm dry season in the middle of October (10/13-18), and the active Hector periods in the second half of November (11/15-20) and mid-December (12/11-16). According to statistics of the balloon burst height, more than 3/4 reached the 25km, about 2/3 exceeded 30km.From a preliminary analysis of the observed profiles, we detected near the tropopause a persistent wave phenomenon with an oscillation period of about 84 hours. Since there is almost no phase difference among three observation points, this wave seems to have a large horizontal scale. Similar wave activities were also seen in November and December. We extracted the atmospheric gravity waves with a vertical scale smaller than about 3km, and estimated the wave energy from wind velocity and temperature fluctuations. The wave energy was enhanced at 15-20 km and 25-30 km, but, the gravity waves were considerably depressed at 20-25 km. The overall structure of the wave energy seems to correlate with the background zonal winds, though the underlying physical mechanism has not been clarified yet. Less