基于WRF-LES的干旱湖区近地面风场模拟与敏感性研究  

Near-Surface Wind Simulation over Acrid Lakeshore Area and Sensitivity Studies using the WRF-LES

作　　者：孙学金[1] 李岩[1,2] 张燕鸿[2] 宁辉[2] 唐敬[2] 文元宏 苗青建 

机构地区：[1]解放军理工大学气象海洋学院,南京211101 [2]西北核技术研究所,西安710024

出　　处：《高原气象》2017年第3期835-844,共10页Plateau Meteorology

基　　金：国家国家高技术研究发展计划(863计划)项目(2014AA7054034);国家自然科学基金项目(41575020)

摘　　要：基于6层嵌套的WRF-ARW模式,在新疆博斯腾湖某湖岸地区进行了实际大气条件下的LES近地面风场数值模拟,并依据该地观探测资料开展了模拟结果的比对分析。为了探讨该地陆面特征对模拟结果的影响,分别针对地形分辨率、土壤湿度和地表粗糙度开展了敏感性试验。研究结果表明,在所关注的小尺度研究区域内,WRF-LES通过对大气边界层内大尺度湍涡的直接解析,相比于中尺度模拟,模拟结果更能体现出近地层风场的高度起伏性,进而提高数值模拟的真实性和准确性。为达到预期应用效果,WRF-LES需要与之相匹配的高分辨率的地形数据,此外土壤湿度数据会通过改变地表热通量分配来影响日间大尺度湍涡的发展,进而影响近地面风场模拟结果,而地表粗糙度对WRF-LES近地面风速模拟的影响则较为复杂。Because of the relative larger mesh-grids,meso-scale atmospheric models cannot fully capture the spatial and temporal variability of near-surface wind fields over complex terrain,whereas the large turbulence-eddy resolving LES is a more promising model to account for this challenge. This paper performs a real-case near-surface wind simulation test over acrid lakeshore area close to Bosteng Lake in Xinjiang province utilizing the WRFLES model with six nested domains. The simulation period is 28 hours and the model results were verified and analyzed against in-situ observations for one day. To assess the sensitivity of model results to local land-surface characteristics,three sensitivity tests were conducted by varying parameters such as the terrain resolution,soilmoist and surface roughness. For one sensitivity test,two digital elevation datasets were used,one is ASTER GDEM with 1 sec resolution and the other is MODIS with 30 sec resolution. For the other two sensitivity tests,disturbance factor with values 0. 4 through 2. 8 was used respectively to change the properties of land-surface.The test results demonstrate that the WRF-LES is more capable to regenerate the near-surface wind than mesoscale simulations in small-scale region with complex terrain owing to its explicit resolving of large atmospheric turbulence eddies. Thus the time series of wind speeds and wind directions more resemble the real atmosphere than those of meso-scale simulations. And the spectra of wind speeds is also more preferable. The sensitivity tests showed that the resolution of terrain data can affect the simulation results significantly so it should be treated with care. By increasing soil-moist the allocation of daytime land-surface heat fluxes is altered,thus the strength of large eddies is increased and so do the near-surface wind speeds,whereas the impact of surface roughness on model results is more complex. For one hand,increasing Z0 will enhance the transportation of momentum from upper air to near-surface flow,for another hand,la

关 键 词：近地面风场 复杂地形 WRF 大涡模拟 陆面参数 

分 类 号：P435.1[天文地球—大气科学及气象学]