オーストラリア、メルビル島、巨大積乱雲の降水機構 - ビデオゾンデ観測 -
The precipitation process of thunderstorms over Melville Islands near Darwin, Australia - Videosonde observation -

氏名: 杉山正佳
指導教官: 高橋劭


 The family of tall (up to 20km) cumulonimbus complexes develop almost daily over the Melville Islands in the Maritime Continent region north of Darwin, Australia's Northern Territory, that are known locally as "Hector".

 The Maritime Continent Thunderstorm Experiment (MCTEX) was conduced from 13 November to 10 December 1995. The Kyushu University observational group participated in this project, and performed the videosonde observation. The structure and evolution of Hectors shows that the initial bands may be aligned east to west by the sea breezes' convergence in mid-afternoon. Soon the cloud system takes on a north-south orientation and westward propagation characteristic of a tropical squall line. The precipitation processes were identified through the analysis of this Hector as follows.

 In the front of the Hector it was known that in the lower layer of the cloud, raindrop with a maximum size of 8mm exist, as well as many frozen drops, resulting from Warm Rain-Freezing process to have the RE-circulation.

 In the rear part of the Hector it was known that in the upper layer of the cloud, enormous ice crystals and graupels existed, and high ice crystal concentration was reported.

 It is suggested that the formation of secondary ice multiplication during graupel-graupel collisions and the form of graupel are very active. On the other hand, since many raindrops were shown in the lower layer, it may have been infkuenced by the maritime Warm Rain process at Phuket during summer monsoon in Thailand. It is suggested that the precipitation process in Phuket is far different from that of Melville Island.