Comparison of Spatial Pattern and Mechanism between Convexity and Gap Winds

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Author(s)

    • Nishi Akifumi
    • Graduate School of Life and Environmental Sciences, University of Tsukuba

Abstract

<p>This study uses a numerical model to examine how a convex feature and a gap feature in a mountain range affect the leeward wind field. In the "convexity case", the mountain ridge has a convex feature (viewed from above). In the "gap case", the mountain ridge has a gap. The results show that both cases have local winds at the surface exceeding 8 m s<sup>−1</sup>, and both have similar spatial flow-patterns. However, the momentum budgets at the strong-wind regions differ between the cases. In the convexity case, the downdrafts are important in the momentum balance, whereas in the gap case, both the downdrafts and the pressure-gradient force are important. Thus, although their spatial patterns of surface wind are similar to each other, their mechanisms for producing a strong local wind differ.</p><p>Sensitivity experiments of <i>Fr<sub>m</sub></i> show that strong-wind appears in both the convexity and gap cases when <i>Fr<sub>m</sub></i> is between 0.42 and 1.04. In contrast, when <i>Fr<sub>m</sub></i> is 0.21, strong winds only appear in the gap case because the flow can go around the gap. When <i>Fr<sub>m</sub></i> exceeds 1.25, strong surface winds appear in the entire leeward plain.</p>

Journal

  • SOLA

    SOLA 15(0), 12-16, 2019

    Meteorological Society of Japan

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