基于WRF/CALMET模型的河谷地形近地面风场的数值同化研究

WRF/CALMET model-based study on numerical assimilation of near-surface wind field in river valley

处于河谷之中的大型水利枢纽所产生的泄洪雾化在一定程度上受到河谷地形局部风场的影响。由于泄洪雾化所引起风场的变化范围属于微小尺度的范围,WRF/CALMET模式难以达到河谷风场的精细化解析。以河谷风场的精细化解析为研究目标,提出WRF/CALMET模式的数值同化方法,并针对一个典型河谷地形——安宁河谷,进行了数值试验研究。为对比分析WRF、WRF/CALMET风场数据数值同化的影响,设置了4组试验方案。结果表明:对于安宁河谷2009年7月4日2:00-20:00的风场,应用WRF/CALMET模式的数值同化方法所得到的风速更接近观测值,风速模拟值和观测值的相关系数为0.56,平均绝对误差为0.79 m/s,均方根误差为1.01 m/s。将WRF/CALMET模式和数值同化方法结合,能够有效地提高河谷地形局部风场的模拟精度,为模拟泄洪雾化所形成的局地风场提供了一种新方法。

The discharge atomization caused by the large-scale water control project located in river valley is impacted by the local wind-field of the valley terrain therein to some extent.Due to the variation range of the wind-field caused by the discharge atomization belonging to a micro-scale range,the refined analysis of the valley wind-field cannot be achieved by WRF/CALMET mode.The refined analysis of the valley wind-field is taken as the study target,a WRF/CALMET mode-based method of numerical assimilation is proposed herein,and then a numerical experimental study is carried out on a typical valley terrain—Anninghe River Valley.In order to comparatively analyze the numerical assimilation effects of WRF and WRF/CALMET wind field data,four sets of experiment schemes are set up.The results show that the wind speed obtained with the numerical assimilation method of WRF/CALMET mode is more close to that from the observation on the wind field of Anninghe River Valley in the period of 2:00-20:00 on July 4,2009,for which the correlation coefficient between the wind speed simulation value and the observed value is 0.56 with the mean absolute error of 0.79 m/s and the root mean square error of 1.01 m/s.Combining WRF/CALMET mode with the numerical assimilation method cannot only effectively enhance the simulation accuracy of local wind field in river valley terrain,but can also provide a new method to simulate the local wind field formed by the flood discharge atomization.