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

距澳大利亚北领地中心城市达尔文约50-100公里的海上，两个岛屿（布瑟斯特岛和梅尔维尔岛）被称为提维群岛，它们对面是一个狭窄的海峡。被称为赫克托的极具特色的孤立型巨大积雨云出现在这些岛屿上。2001年10 - 12月，我们在达尔文市附近开展了国际共同观测运动（DAWEX: Darwin Area Wave Experiment），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，开展了无线电探空观测活动。为了研究赫克托大气波的水平传播特性，我们选择了3个气球发射场；蒂维群岛上的花园点，达尔文和凯瑟琳，它们几乎排成一条直线，最大距离约为400公里。我们每3小时从3个地点发射40个以上的无线电探空仪，为期5天，分3个时段；相对平静的旱季在10月中旬（10月13日至18日），赫克托耳活跃期在11月下半月（11月15日至20日）和12月中旬（12月11日至16日）。据统计，超过3/4的气球达到了25km，约2/3超过了30km。通过对观测剖面的初步分析，我们在对流层顶附近发现了一个振荡周期约为84小时的持续波现象。由于三个观测点之间几乎没有相位差，因此该波似乎具有较大的水平尺度。11月和12月也出现了类似的海浪活动。我们提取了垂直尺度小于3km的大气重力波，并通过风速和温度波动估算了波能。在15 ~ 20 km和25 ~ 30 km处，波能增强，而在20 ~ 25 km处，重力波明显减弱。波浪能量的整体结构似乎与背景纬向风有关，尽管其潜在的物理机制尚未明确。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