复杂地形下局地山谷风环流的理想数值模拟  

Idealized Numerical Simulation of Local Mountain-Valley Winds over Complex Topography

作　　者：姜平 刘晓冉[1] 朱浩楠 朱宇[2] 曾文馨 JIANG Ping;LIU Xiaoran;ZHU Haonan;ZHU Yu;ZENG Wenxin(Chongqing Climate Center,Chongqing 401147,China;Sun Yat-sen University,Guangzhou 510275,Guangdong,China)

机构地区：[1]重庆市气候中心,重庆401147 [2]中山大学,广东广州510275

出　　处：《高原气象》2019年第6期1272-1282,共11页Plateau Meteorology

基　　金：重庆市气象局青年基金项目(QNJJ-201907);重庆市气象局智慧气象技术创新团队项目(ZHCXTD-201808);重庆市悦来新城海绵城市建设科研项目(城科字2015第2-10号)

摘　　要：利用计算流体力学手段,结合基于气象站观测事实并理想化的初始条件,对重庆复杂地形下局地山谷风环流进行高精度数值模拟,探讨因复杂地形而导致的热力差异对山谷风环流形成的影响。结果表明,仅仅由地形高低起伏导致的热力差异能够在局地形成山谷风环流。在白天,受太阳辐射作用,山坡升温幅度比山谷明显,在同一海拔处形成温度差异,形成谷风环流。理想的谷风在山脊两侧坡度较大的近地面最为明显,风速可达0. 15 m·s^-1,但在山坡和山谷地势较为平坦的区域则不显著。在凌晨,山谷的保温作用明显,且山坡辐射冷却较强,故产生由山坡吹向山谷的山风环流。模拟的山风特征与谷风基本一致,但强度稍小(0. 1 m·s^-1),方向相反。扩大山坡与山谷热力差异的敏感性试验表明,白天的谷风环流能明显增强,近地面全风速可达0. 4 m·s^-1,且对应的垂直速度以及边界层高度均有所增加;但晚上山风环流的增强则不明显。This study used observational data to carry out a high-resolution simulation on mountain-valley winds over complex topography with a computational fluid dynamics model. Results show that the thermal contrast by topography could form the mountain-valley winds. During daytime( T16),the temperature at mountain top increases faster than the foot by the solar radiation,which result in thermal contrast at a same level,and thus forms a clear valley-wind circulation. The near-surface wind is strong at both edges of mountain ridge,and the magnitude can reach0. 15 m · s^-1. However,the winds at flat areas of mountain top and valley are not observable. In the evening( T04),the valley keeps warm and mountain top cools by radiation,which forms the mountain wind blowing from the valley. The simulated mountain winds are similar to valley wind,but with a smaller magnitude( ~ 0. 1 m·s^-1)and an opposite direction. Two sensitive tests show that enlarging the amplitude of the thermal difference between mountain top and valley could enhance valley winds at daytime. The near-surface winds can be as large as 0. 4 m·s^-1,and the corresponding vertical winds and boundary layer height both increase obviously. However,the mountain-wind circulation do not show similar variations.

关 键 词：复杂地形 山谷风 热力差异 计算流体力学 

分 类 号：P435[天文地球—大气科学及气象学] P445