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A numerical study of the orographic effect of the Taebak mountains on the increase of the downslope wind speed near Gangnung area

태백산맥의 지형적인 효과와 관련된 강릉 지역의 강풍 사례에 대한 수치모의 연구

  • 이재규
  • Published : 2003.12.01

Abstract

A numerical simulation for 11 February 1996 has been done to grasp main mechanisms of the occurrence of strong downslope winds near Gangnung area. The simulation performed by using ARPS (Advanced Regional Prediction System) showed that enhanced surface winds were not related with a reflection of vertically propagating gravity waves. Froude numbers were about 1.0, 0.4 and 0.6 for the atmosphere above Daekwanryoung and above a place located 220km upstream, and above another place located 230km downstream from the Taebak mountains, respectively. This suggested that as a subcritical flow ascended the upslope side of the Taebak mountains, Froude numbers would tend to increase according to the increase in wind speed, and near the crest the flow would become supercritical and continue to accelerate as it went down the downslope side until it was adapted back to the ambient subcritical conditions in a turbulent hydraulic jump. Simulated Froude numbers corroborated the hydraulic jump nature of the strong downslope wind. In addition, the inversion was found near the mountain top height upstream of the mountains, and it was favorable for the occurrence of strong downslope winds.

Keywords

Hydraulic jump;Downslope wind;Froude number;Orographic effect;Subcritical flow;Supercritical flow;Inversion layer;Numerical simulation

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