李超. 2019. 一种改进的平缓-混合地形追随坐标在GRAPES-Meso模式中的应用研究[J]. 气象学报, (0):-, doi:10.11676/qxxb2019.068
一种改进的平缓-混合地形追随坐标在GRAPES-Meso模式中的应用研究
Research on the application of an improved terrain-following vertical coordinates on GRAPES model
投稿时间:2018-03-15  修订日期:2018-10-23
DOI:10.11676/qxxb2019.068
中文关键词:  GRAPES模式 平缓-混合坐标 动力框架 数值模式
英文关键词:GRAPES Model, Terrain-following coordinate, Dynamic Core, Numerical Modelling
基金项目:国家自然科学基金
作者单位E-mail
李超 数值预报中心 lic@cma.gov.cn 
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中文摘要:
      平缓-混合地形追随坐标(简称T-F坐标)可以减小坐标面上的地形作用隆起带来的各种计算误差。以三角函数为基函数的平缓-混合坐标(简称COS坐标)高层坐标面水平,计算误差较小,但是底层坐标面之间的厚度较薄,增大了计算误差,对模式稳定性及模拟效果带来较大的影响。设计一种改进的COS坐标,使底层坐标面垂直分布更加均匀,应用于GRAPES—Meso模式进行理想试验和实际模拟试验。结果表明:改进的COS坐标相对COS坐标,中高层计算误差相当,底层地形作用衰减的垂直变化更加均匀,减小了计算误差,提高了计算稳定性;地形重力波试验结果显示,改进的COS坐标重力波破碎相对COS坐标有一定缓解,更接近解析值;批量模拟试验结果显示,改进的COS坐标各个层次上的月平均模拟偏差比单尺度的平缓-混合坐标(简称SLEVE1坐标)更小,均方根误差有所减小,距平相关系数有所增加。改进的COS坐标有效地解决了COS坐标的计算问题,提高了模拟预报效果。
英文摘要:
      Errors caused by topographic feathers of the coordinate planes can be reduced with the Smoothed-level terrain-following coordinate(T-F coordinate for short). On higher layors,coordinate planes of T-F coordinate based on trigonometric function of cos (COS coordinate for short)are horizontal with almost none errors. However,on the lower layers,thickness between planes is too small to keep the model stability。At the same time,it will bring larger calculating errors which result in bad performance of the model.Considering all above,an improved COS coordinate is designed to average the thickness of COS coordinate planes. Ideal and real case tests are conducted with the GRAPES_Meso model using the improved COS coordinate.The results of the tests indicate that:compared with the COS coordinate, the improved COS coordinate ,on one hand ,keep the planes horizontal on the higher layers ,on the other hand, lead the distribute of the coordinate planes more uniformity , which greatly reduced the errors on the lower layers;The coordinate can reproduce in general the mountain induced gravity waves in comparison to the analytic solution. However, the shapes,vertical?structures and intensity of the waves are better simulated by the improved COS coordinate, in the lower levels where the COS coordinate didn’t behave so better. In the one-month real case tests, the improved COS coordinate gives the better results in terms of smaller forecast bias and root mean square error, and higher anomaly correlation coefficients than the COS coordinate. In conclusion, the improved COS coordinate solves the calculation problems of the COS coordinate ,and improves the prediction ability.
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