Relationship between High-Impact Weather Events in Japan and Propagation of Rossby Waves along the Asian Jet in July 2004

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概要

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• In July 2004, torrential rainfalls caused significant damages in parts of Japan, followed by heat waves. Our data analysis shows that both rainfall and heat wave events in late Baiu season were caused by the intensification of the subtropical anticyclone near Japan (Bonin high) and that intensity of the Bonin high was significantly influenced by propagation of Rossby waves along the subtropical jet. Hindcast experiments from 15 July were conducted to study the mechanisms and predictability of these high-impact weather events. On 17-18 July, localized rainfalls at a few locations along the coast of the Sea of Japan including Sakata and Fukui were successfully simulated in a high-resolution (21-km mesh) global hindcast simulation. These rainfall events were found to occur near the leading edge of a filament of moist and warm air advected clockwise. On 20 July, anomalously high temperature was reproduced in the high-resolution hindcast simulation. With a moderate resolution of 83km, the intensification of the subtropical anticyclone was reproduced although the fohn was much weaker. This result indicates that temperature distribution associated with fohn requires a resolution high enough to resolve major mountains. In order to investigate the predictability of propagation of Rossby waves and intensification of the Bonin high, 25-member ensemble experiments from 1 July 2004 were conducted using the moderate-resolution model. It is shown that the region along the Asian jet has twice as long predictability as the entire Northern Hemisphere. This case study suggests that the intensification of the Bonin high associated with the propagation of Rossby waves along the Asian jet could be predicted a few weeks in advance with an ensemble forecast at a moderate resolution.

• 2009-02-25

著者

• Enomoto Takeshi

  Earth Simulator Center Japan Agency For Marine-earth Science And Technology

• OHFUCHI Wataru

  Earth Simulator Center

• ENDO Hirokazu

  Meteorological Research Institute, Japan Meteorological Agency

• HARADA Yayoi

  Climate Prediction Division, Japan Meteorological Agency

• Ohfuchi Wataru

  Earth Simulator Center Japan Agency For Marine-earth Science And Technology

• Harada Yayoi

  Climate Prediction Division Japan Meteorological Agency

• Endo Hirokazu

  Meteorological Research Institute Japan Meteorological Agency

関連論文

• Relationship between High-Impact Weather Events in Japan and Propagation of Rossby Waves along the Asian Jet in July 2004
• B407 Conservative Semi-Lagrangian Transport in Spherical Coordinate and the Application in AFES
• Conservative Semi-Lagrangian Transport of Tracers in AFES
• Polar Low Genesis over the East Coast of the Asian Continent Simulated in an AGCM

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