A numerical study on severe downslope windstorms occurred on 5 April 2005 at Gangneung and Yangyang, Korea

Wook Jang, Hye-Yeong Chun

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Severe downslope windstorms occurred on 5 April 2005 in the Taebaek Mountain Range, located in the eastern coast of Korea, are examined using the Weather Research and Forecasting (WRF) model. Strong winds are observed at Gangneung and Yangyang during two separate periods with a rapidly decreasing period in between. These downslope windstorms are reproduced in the simulation reasonably well, although the rapidly decreasing surface wind speed after the second windstorm could not be captured at Yangyang. It is found that the generation mechanisms of the downslope windstorms in these two periods are somewhat different. The severe wind in the first period is likely due to the reflection of the mountain waves from a critical level that locates nearz = 8-9 km. Upward-propagating waves and reflected downward-propagating waves interact constructively in a duct between the critical level and the surface, resulting in strong surface wind. In the second period, the hydraulic-jump theory can be applied in that the wave breaking above the downstream induces a well-mixed region, and severe downslope wind is developed beneath this turbulent region as the streamlines descend along the downstream. Simultaneous lee wave structure is also reproduced during the second windstorm period. The sensitivity of the downslope wind speed to the change in the land-cover map showed that the absorption of trapped lee waves in the boundary layer reduces the downslope wind speed significantly after the second windstorm at Gangneung, improving the model performance, although with no significant impact at Yangyang.

Original languageEnglish
Pages (from-to)155-172
Number of pages18
JournalAsia-Pacific Journal of Atmospheric Sciences
Volume46
Issue number2
DOIs
Publication statusPublished - 2010 May 1

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lee wave
wind velocity
surface wind
trapped wave
wave breaking
land cover
boundary layer
hydraulics
weather
mountain
coast
simulation
critical level
mountain range

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

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abstract = "Severe downslope windstorms occurred on 5 April 2005 in the Taebaek Mountain Range, located in the eastern coast of Korea, are examined using the Weather Research and Forecasting (WRF) model. Strong winds are observed at Gangneung and Yangyang during two separate periods with a rapidly decreasing period in between. These downslope windstorms are reproduced in the simulation reasonably well, although the rapidly decreasing surface wind speed after the second windstorm could not be captured at Yangyang. It is found that the generation mechanisms of the downslope windstorms in these two periods are somewhat different. The severe wind in the first period is likely due to the reflection of the mountain waves from a critical level that locates nearz = 8-9 km. Upward-propagating waves and reflected downward-propagating waves interact constructively in a duct between the critical level and the surface, resulting in strong surface wind. In the second period, the hydraulic-jump theory can be applied in that the wave breaking above the downstream induces a well-mixed region, and severe downslope wind is developed beneath this turbulent region as the streamlines descend along the downstream. Simultaneous lee wave structure is also reproduced during the second windstorm period. The sensitivity of the downslope wind speed to the change in the land-cover map showed that the absorption of trapped lee waves in the boundary layer reduces the downslope wind speed significantly after the second windstorm at Gangneung, improving the model performance, although with no significant impact at Yangyang.",
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A numerical study on severe downslope windstorms occurred on 5 April 2005 at Gangneung and Yangyang, Korea. / Jang, Wook; Chun, Hye-Yeong.

In: Asia-Pacific Journal of Atmospheric Sciences, Vol. 46, No. 2, 01.05.2010, p. 155-172.

Research output: Contribution to journalArticle

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