The global three-dimensional variational(3D-Var)data assimilation is implemented on a new quasi-uniform overset(Yin-Yang)grid on sphere.As a quasi-uniform spherical grid,it covers the sphere by overlapping two perpend...The global three-dimensional variational(3D-Var)data assimilation is implemented on a new quasi-uniform overset(Yin-Yang)grid on sphere.As a quasi-uniform spherical grid,it covers the sphere by overlapping two perpendicularly oriented grid components which is nothing but low latitude region of the usual latitude-longitude grid.Based on this characteristic of the Yin-Yang grid,it enables us to implement the regional 3D-Var system efficiently and accurately on the Yin or Yang component grid,respectively.The global analysis could update directly from the regional analysis since they have the same configurations like the precondition of eigenvalue decomposition for vertical direction,recursive filtering for horizontal direction,minimization method and observation operator and so on.However,the balance equation and vector wind are needed to be paid more attention on the Yin grid analysis due to its coordinate transformation.How to spread the observation information near the boundary of Yin and Yang grid is a key to the 3D-Var analysis.Extending double the horizontal correlation length distance in the overset boundary of Yin and Yang grid has successfully solved the problem.The results show that the analysis on the Yin-Yang grid is reasonable and similar to the result on the latitude-longitude(LAT-LON)grid.This paper provides a promising strategy for the development of a 3D-Var global system for overset grids.展开更多
This paper proposes a new method for data assimilation of the surface radial current observed by High Frequency ground wave radar and optimization of the bottom friction coefficient.In this method,the shallow water wa...This paper proposes a new method for data assimilation of the surface radial current observed by High Frequency ground wave radar and optimization of the bottom friction coefficient.In this method,the shallow water wave equation is introduced into the cost function of the multigrid three-dimensional variation data assimilation method as the weak constraint term,the surface current and the bottom friction coefficient are defined as the analytical variables,and the high spatiotemporal resolution surface radial flow observed by the high-frequency ground wave radar is used to optimize the surface current and bottom friction coefficient.This method can effectively consider the spatiotemporal correlation of radar data and extract multiscale information from surface radial flow data from long waves to short waves.Introducing the shallow water wave equation into the cost function as a weak constraint condition can adjust both the momentum and mass fields simultaneously to obtain more reasonable analysis information.The optimized bottom friction coefficient is introduced into the regional ocean numerical model to carry out numerical experiments.The test results show that the bottom friction coefficient obtained by this method can effectively improve the accuracy of the numerical simulation of sea surface height in the offshore area and reduce the simulation error.展开更多
采用WRF(Weather Research and Forecasting)模式三维变分资料同化系统,引入雷达资料同化方法,对2019年8月9日发生在内蒙古巴彦淖尔地区的一次典型冰雹天气过程进行了数值模拟与资料同化分析。为评估雷达资料同化对强对流天气预报效果...采用WRF(Weather Research and Forecasting)模式三维变分资料同化系统,引入雷达资料同化方法,对2019年8月9日发生在内蒙古巴彦淖尔地区的一次典型冰雹天气过程进行了数值模拟与资料同化分析。为评估雷达资料同化对强对流天气预报效果的影响,设计了2组对比试验。第一组为控制试验(CTL),仅使用WRF模式对该次过程进行模拟;第二组为同化试验(DA),同化多普勒雷达反射率和径向风数据。试验结果表明,雷达资料同化后的海平面气压场梯度增强、等压线密集,形成了与此次对流天气相对应的低压系统;同化试验中,雷达回波强度更接近实际观测值,但回波中心位置仍存在一定偏差;雷达资料同化试验后模拟出700 hPa和500 hPa高度上风场均有较强的风速切变,且风向有明显的气旋式切变。展开更多
目的探讨3D打印技术在小儿后天性肘内翻畸形截骨矫形术中的临床应用价值。方法收集2016年6月至2018年8月由重庆大学附属三峡医院小儿外科收治的16例肘内翻畸形患者作为研究对象,均行截骨矫形手术治疗。其中男童10例,女童6例,平均年龄7....目的探讨3D打印技术在小儿后天性肘内翻畸形截骨矫形术中的临床应用价值。方法收集2016年6月至2018年8月由重庆大学附属三峡医院小儿外科收治的16例肘内翻畸形患者作为研究对象,均行截骨矫形手术治疗。其中男童10例,女童6例,平均年龄7.7岁。术前根据HSS(Hospital for Special Surgery)肘关节评分标准评价肘关节功能,行肘关节CT扫描,建立数字模型,按照1∶1等比例打印3D实体模型,在模型上设计截骨平面,术中参照3D模型实施截骨矫形。手术后6个月复查,采用HSS肘关节评分标准评价肘关节功能,拍摄肘关节正侧位X线片测量肘关节提携角、肱骨前倾角和鲍曼角,并与术前设计进行比较,评价矫形效果是否符合预期。结果16例患者均在全麻下顺利完成手术,术后均获随访,所有患者获骨性愈合,肘内翻畸形获得矫正,无神经血管损伤、术区感染、克氏针移位等并发症发生。3D模型模拟手术效果:提携角范围为9°~19°,平均(13.57±2.62)°;手术后6个月X线片结果:提携角范围为9°~19°,平均(14.34±3.28)°,前倾角范围为24°~51°,平均为(40.08±7.44)°,鲍曼角范围为55°~76°,平均为(67.54±6.10)°。3D模拟手术与实际手术后提携角对比,差异无统计学意义(t=1.76,P=0.1)。术后6个月随访时肘关节功能评定:优10例,良0例,一般5例,差1例。肘关节功能评分:69~100分,平均(89.00±11.62)分;与术前肘关节功能评分比较,差异无统计学意义(t=1.03,P=0.32)。结论在小儿肘关节畸形截骨矫形术中运用3D打印技术,有助于评估畸形形态和精确设计截骨角度,截骨矫形效果符合预期。展开更多
风云四号B星(FY-4B)是中国最新一代的静止轨道气象卫星,其资料具有更高的时空分辨率。为了进一步推进FY-4B云导风资料在数值模式中的应用,以FY-4B云导风资料为主要研究对象,结合FY-4A云导风资料进行对比,首先分析了其观测误差的垂直分...风云四号B星(FY-4B)是中国最新一代的静止轨道气象卫星,其资料具有更高的时空分辨率。为了进一步推进FY-4B云导风资料在数值模式中的应用,以FY-4B云导风资料为主要研究对象,结合FY-4A云导风资料进行对比,首先分析了其观测误差的垂直分布情况,以此更新WRFDA(Weather Research and Forecasting model Data Assimilation system)同化系统中默认观测误差,随后进一步探究了云导风资料同化对2022年台风“梅花”的预报影响。研究结果表明:FY-4B云导风资料U、V分量的观测误差整体上小于FY-4A;同化FY-4A云导风资料后,模拟的台风路径逐渐偏西;而同化FY-4B云导风资料使得台风中心动力场信息更加完善,分析场对流层中高层西风增强,预报的台风路径更接近实况;相较于同化FY-4A云导风资料,同化FY-4B云导风资料对降水预报的改善效果更好。展开更多
基金National Key R&D Program of China(2017YFC1501901,2017YFA0603901)。
文摘The global three-dimensional variational(3D-Var)data assimilation is implemented on a new quasi-uniform overset(Yin-Yang)grid on sphere.As a quasi-uniform spherical grid,it covers the sphere by overlapping two perpendicularly oriented grid components which is nothing but low latitude region of the usual latitude-longitude grid.Based on this characteristic of the Yin-Yang grid,it enables us to implement the regional 3D-Var system efficiently and accurately on the Yin or Yang component grid,respectively.The global analysis could update directly from the regional analysis since they have the same configurations like the precondition of eigenvalue decomposition for vertical direction,recursive filtering for horizontal direction,minimization method and observation operator and so on.However,the balance equation and vector wind are needed to be paid more attention on the Yin grid analysis due to its coordinate transformation.How to spread the observation information near the boundary of Yin and Yang grid is a key to the 3D-Var analysis.Extending double the horizontal correlation length distance in the overset boundary of Yin and Yang grid has successfully solved the problem.The results show that the analysis on the Yin-Yang grid is reasonable and similar to the result on the latitude-longitude(LAT-LON)grid.This paper provides a promising strategy for the development of a 3D-Var global system for overset grids.
基金supported by the National Natural Science Foundation of China (Nos. 41506039, 41776004, 41775100 and 41606039)the National Key Research and Development Program of China (No. 2016YFC1401800)+1 种基金the Fundamental Research Funds for the Central Universities (No. 2016B12514)the National Programme on Global Change and Air-Sea Interaction of China (No. GASI-IPO VAI-04)
文摘This paper proposes a new method for data assimilation of the surface radial current observed by High Frequency ground wave radar and optimization of the bottom friction coefficient.In this method,the shallow water wave equation is introduced into the cost function of the multigrid three-dimensional variation data assimilation method as the weak constraint term,the surface current and the bottom friction coefficient are defined as the analytical variables,and the high spatiotemporal resolution surface radial flow observed by the high-frequency ground wave radar is used to optimize the surface current and bottom friction coefficient.This method can effectively consider the spatiotemporal correlation of radar data and extract multiscale information from surface radial flow data from long waves to short waves.Introducing the shallow water wave equation into the cost function as a weak constraint condition can adjust both the momentum and mass fields simultaneously to obtain more reasonable analysis information.The optimized bottom friction coefficient is introduced into the regional ocean numerical model to carry out numerical experiments.The test results show that the bottom friction coefficient obtained by this method can effectively improve the accuracy of the numerical simulation of sea surface height in the offshore area and reduce the simulation error.
文摘采用WRF(Weather Research and Forecasting)模式三维变分资料同化系统,引入雷达资料同化方法,对2019年8月9日发生在内蒙古巴彦淖尔地区的一次典型冰雹天气过程进行了数值模拟与资料同化分析。为评估雷达资料同化对强对流天气预报效果的影响,设计了2组对比试验。第一组为控制试验(CTL),仅使用WRF模式对该次过程进行模拟;第二组为同化试验(DA),同化多普勒雷达反射率和径向风数据。试验结果表明,雷达资料同化后的海平面气压场梯度增强、等压线密集,形成了与此次对流天气相对应的低压系统;同化试验中,雷达回波强度更接近实际观测值,但回波中心位置仍存在一定偏差;雷达资料同化试验后模拟出700 hPa和500 hPa高度上风场均有较强的风速切变,且风向有明显的气旋式切变。
文摘目的探讨3D打印技术在小儿后天性肘内翻畸形截骨矫形术中的临床应用价值。方法收集2016年6月至2018年8月由重庆大学附属三峡医院小儿外科收治的16例肘内翻畸形患者作为研究对象,均行截骨矫形手术治疗。其中男童10例,女童6例,平均年龄7.7岁。术前根据HSS(Hospital for Special Surgery)肘关节评分标准评价肘关节功能,行肘关节CT扫描,建立数字模型,按照1∶1等比例打印3D实体模型,在模型上设计截骨平面,术中参照3D模型实施截骨矫形。手术后6个月复查,采用HSS肘关节评分标准评价肘关节功能,拍摄肘关节正侧位X线片测量肘关节提携角、肱骨前倾角和鲍曼角,并与术前设计进行比较,评价矫形效果是否符合预期。结果16例患者均在全麻下顺利完成手术,术后均获随访,所有患者获骨性愈合,肘内翻畸形获得矫正,无神经血管损伤、术区感染、克氏针移位等并发症发生。3D模型模拟手术效果:提携角范围为9°~19°,平均(13.57±2.62)°;手术后6个月X线片结果:提携角范围为9°~19°,平均(14.34±3.28)°,前倾角范围为24°~51°,平均为(40.08±7.44)°,鲍曼角范围为55°~76°,平均为(67.54±6.10)°。3D模拟手术与实际手术后提携角对比,差异无统计学意义(t=1.76,P=0.1)。术后6个月随访时肘关节功能评定:优10例,良0例,一般5例,差1例。肘关节功能评分:69~100分,平均(89.00±11.62)分;与术前肘关节功能评分比较,差异无统计学意义(t=1.03,P=0.32)。结论在小儿肘关节畸形截骨矫形术中运用3D打印技术,有助于评估畸形形态和精确设计截骨角度,截骨矫形效果符合预期。
文摘风云四号B星(FY-4B)是中国最新一代的静止轨道气象卫星,其资料具有更高的时空分辨率。为了进一步推进FY-4B云导风资料在数值模式中的应用,以FY-4B云导风资料为主要研究对象,结合FY-4A云导风资料进行对比,首先分析了其观测误差的垂直分布情况,以此更新WRFDA(Weather Research and Forecasting model Data Assimilation system)同化系统中默认观测误差,随后进一步探究了云导风资料同化对2022年台风“梅花”的预报影响。研究结果表明:FY-4B云导风资料U、V分量的观测误差整体上小于FY-4A;同化FY-4A云导风资料后,模拟的台风路径逐渐偏西;而同化FY-4B云导风资料使得台风中心动力场信息更加完善,分析场对流层中高层西风增强,预报的台风路径更接近实况;相较于同化FY-4A云导风资料,同化FY-4B云导风资料对降水预报的改善效果更好。
