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

澳大利亚北部热带地区赫克托尔的国际协调观测

基本信息

批准号：
13573005
负责人：
TSUDA Toshitaka
金额：
$ 7.81万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

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

距离澳大利亚北领地中心城市达尔文近海约50-100公里，两个被称为提维群岛的岛屿（布瑟斯特岛和梅尔维尔岛）隔着一条狭窄的海峡相望，该海峡被称为非常有特色的孤立型巨大积雨云。 2001年10月至12月，我们在达尔文周围开展了国际共同观测活动（DAWEX：达尔文区域波实验），以研究大气波的产生。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，以研究赫克托大气波的水平传播特征。选定的 3 个气球发射地点；位于提维群岛、达尔文和凯瑟琳的花园点，它们几乎排成一条直线，最大距离约为 400 公里。我们总共发射了 40 个气球。无线电探空仪从 3 个地点每 3 小时进行一次，持续 5 天以上，分 3 个时段进行；10 月中旬相对平静的旱季（10/13-18），以及 11 月下旬的活跃赫克托时段（11/15-15）； 20）和12月中旬（12/11-16）根据气球爆裂高度统计，超过3/4达到25公里，约2/3超过30公里。通过对观测剖面的初步分析，我们在对流层顶附近检测到了振荡周期约为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相似波。 11月和12月也出现了活动，我们提取了垂直尺度小于3km左右的大气重力波，并根据风速和温度波动估算了波浪能量，其中波浪能量在15-20公里和25-30公里处增强。 km，但是，重力波在 20-25 km 处明显减弱。尽管潜在的物理机制尚未阐明，但波浪能量的整体结构似乎与背景纬向风相关。