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Case Study of an Intense Wind Event Associated with a Mesoscale Convective System in West Sumatera during the HARIMAU2006 Campaign

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Title: Case Study of an Intense Wind Event Associated with a Mesoscale Convective System in West Sumatera during the HARIMAU2006 Campaign
Authors: Kawashima, Masayuki Browse this author
Fujiyoshi, Yasushi Browse this author
Ohi, Masayuki Browse this author
Mori, Shuichi Browse this author
Sakurai, Namiko Browse this author
Abe, Yoshiko Browse this author
Harjupa, Wendi Browse this author
Syamsudin, Fadli Browse this author
Yamanaka, Manabu D. Browse this author
Issue Date: 5-May-2011
Publisher: Meteorological Society of Japan
Journal Title: Journal of the Meteorological Society of Japan
Journal Title(alt): 気象集誌
Volume: 89A
Start Page: 239
End Page: 257
Publisher DOI: 10.2151/jmsj.2011-A15
Abstract: In this study, the processes responsible for an intense wind event that occurred in west Sumatera on November 19, 2006, during the first campaign of the Hydrometeorological ARay for Isv-Monsoon AUtomonitoring (HARIMAU) were investigated. Strong winds of 17 m s^[-1] and a sudden temperature drop of 5 K were observed at an X-band Doppler radar site associated with the passage of a convective system, and some houses were severely damaged. The convective system developed under an environment of strong low-level easterly vertical shear associated with the easterly region of an equatorial Rossby wave. The northern part of the convective system possessed qualitatively similar structures to midlatitude bow echoes, including the convex shape of the convective line, a descending rear-inflow jet positioned at its apex, and mesoscale vortices on both sides of the rear-inflow jet. The low-level wind behind the convective system formed a channel of strong easterly wind as it passed through an area of relatively low topography in the mountain range. The enhanced easterly wind was thought to contribute to the formation of the bow echo-like structure in the northern part of the convective system. This easterly rear-inflow jet was further accelerated in the convective system and descended near the leading edge, forming divergent strong winds at the surface. The sounding data that were taken after the passage of the convective system indicated that dry air appeared in the lower troposphere associated with an enhancement of the southerly component of the wind. An analysis of objective reanalysis data suggests that the southerly was probably associated with westward-propagating mixed Rossby-gravity waves with a period of approximately 5 days. It is suggested that the dry air intruded into the convective system across the back edge of the precipitation area and caused enhanced evaporative cooling, which resulted in the effective downward transport of the enhanced easterly momentum.
Type: article
URI: http://hdl.handle.net/2115/46899
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 川島 正行

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