| 修正WRF次网格地形方案及其对风速模拟的影响 |
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| 引用本文： | 刘郁珏,苗世光,刘磊,胡非.修正WRF次网格地形方案及其对风速模拟的影响[J].应用气象学报,2019,30(1):70-81. |
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| 作者姓名： | 刘郁珏 苗世光 刘磊 胡非 |
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| 作者单位： | 1.中国气象局北京城市气象研究所, 北京 100089 |
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| 基金项目： | 国家重点研究发展计划（2016YFC0208802），国家自然科学基金项目（41705006，11472272），北京市科技计划（D171100000717003） |
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| 摘 要： | 复杂地形区域风场模拟的准确率一直是风能研究领域的难点和重点。WRF模式是目前风能评估领域应用最广泛的天气数值模式之一，但该模式在复杂地形区域存在对平原、山谷风速高估且对山顶风速低估的系统性误差，并有研究建立次网格地形方案以订正误差。而次网格地形方案在不同水平分辨率下常出现错误的修正结果，该文基于高精度地形高程数据分析了方案失效的主要原因，发现其方程组中判断山体形态特征的阈值-20在过低和过高水平分辨率下均失去参考性。针对这一原因，将方案中影响关键参数Ct的地形高度算子与模式水平分辨率进行拟合，形成地形高度算子与水平分辨率相依赖的线性关系，获得不同分辨率下更适合的山体形态阈值。通过与自动气象站10 m风速对比分析了修正前后WRF对低层风速的模拟效果，结果显示:修正后的次网格地形方案能够分别在较低和较高分辨率下，部分矫正原方案错误的订正结果，使低层风速模拟更接近实况。修正后的次网格地形方案可为复杂地形区域开展高分辨率风场模拟提供参考。
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| 关 键 词： | WRF 复杂地形 次网格地形方案 高分辨率模拟 |
| 收稿时间： | 2018/5/16 0:00:00 |
| 修稿时间： | 2018/8/10 0:00:00 |
Effects of a Modified Sub-grid-scale Terrain Parameterization Scheme on the Simulation of Low-layer Wind over Complex Terrain |
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| Liu Yujue,Miao Shiguang,Liu Lei and Hu Fei.Effects of a Modified Sub-grid-scale Terrain Parameterization Scheme on the Simulation of Low-layer Wind over Complex Terrain[J].Quarterly Journal of Applied Meteorology,2019,30(1):70-81. |
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| Authors: | Liu Yujue Miao Shiguang Liu Lei and Hu Fei |
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| Affiliation: | 1.Institute of Urban Meteorology, CMA, Beijing 1000892.State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 1000293.University of Chinese Academy of Sciences, Beijing 100049 |
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| Abstract: | Due to the limited representation of observation over complex terrain, high resolution model becomes a favorable tool. Fine numerical simulation of wind field is quite important for micro-siting wind farms and wind energy resources assessment, especially in the complex terrain area. The accuracy of low-layer wind simulation over mountain area is one of the difficulties and key points in the field of wind energy research. The state-of-the-art WRF (Weather Research and Forecasting) model is one of the most widely used mesoscale numerical weather models for wind energy assessment in recent years. However, effects of sub-grid-scale topographic shape on surface wind field are not considered. With the new WRF version 3.4.1, a sub-grid-scale terrain parameterization scheme named Jiménez scheme is added into the YSU (Yonsei University) planet boundary layer parameterization scheme. The Jiménez scheme is designed aiming to reduce the systematic error of wind speed overestimation over valleys or plains and underestimation over hills conversely. However, correction effects of original WRF simulated 10 m wind speed by Jiménez scheme show great differences under different horizontal resolutions, particularly when over high hills. A series of sensitive numerical experiments are carried out under windy days for the Taihang Mountains in the west of Beijing-Tianjin-Hebei area. The main purpose of these experiments is to address some of issues regarding Jiménez scheme and try to solve the existing problems by establishing a relationship between the key topographic parameter Ct and the model grid spacing(dx/dy) to fit different numerical simulation for high resolution based on secondly SRTM topographic dataset. The simulated 10 m wind speed results of WRF without Jiménez scheme, with original Jiménez scheme and modified Jiménez scheme version are compared with observations of 3 automatic weather stations during the MOUNTAOM (MOUNtain Terrain Atmospheric Observations and Modeling) campaign which is prepared for 2022 winter Olympic Games. Results show that the modified Jiménez scheme can partially correct the error of the original Jiménez scheme at lower and higher resolutions. The simulated 10 m wind speed near the ground by modified version is closer to the actual condition. The correction method for Jiménez sub-grid-scale terrain scheme can provide reference for high resolution wind simulations over complex terrain and help users to obtain more detailed information on the surface wind field for wind energy related researches and applications. |
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| Keywords: | WRF complex terrain sub-grid-scale terrain parameterization scheme fine-resolution simulation |
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