基于WRF(Weather Research and Forecasting)模式及其3DVAR(3-Dimentional Variational)资料同化系统,采用36 km、12 km、4 km三层嵌套网格进行逐3 h资料同化和快速更新循环预报,对2011年5月8日鲁中一次局地大暴雨过程进行了资料同化敏...基于WRF(Weather Research and Forecasting)模式及其3DVAR(3-Dimentional Variational)资料同化系统,采用36 km、12 km、4 km三层嵌套网格进行逐3 h资料同化和快速更新循环预报,对2011年5月8日鲁中一次局地大暴雨过程进行了资料同化敏感性试验。试验结果表明,地面观测资料同化和快速更新循环对本次降水的预报起到了关键性作用。在快速更新循环预报时不同化地面观测资料,或同化全部观测资料进行冷启动预报,模式均不能预报出山东的降水。同化地面观测资料后,显著改进了模式降水落区预报。地面观测资料同化可以影响到700 hPa高度以上温压湿风要素的变化,从而改变了大气初始场的温湿结构,导致模式预报的700 h Pa附近高空大气湿度和热力不稳定增强,700 hPa以下低层风场更强,850 h Pa鲁中以南风速较无观测资料同化的偏强2～4 m·s-1,低层风场的动力作用触发高空的不稳定大气,降水出现在山东。展开更多
随着预报准确度要求以及同化分析循环周期的缩短,具有高时空分辨率的地面观测资料在同化系统中也越来越受到重视,而且一个好的资料同化系统应该能够给出模式近地面动力、热力和湿度状况的合理分析。利用GRAPES区域同化预报系统(GRAPES—...随着预报准确度要求以及同化分析循环周期的缩短,具有高时空分辨率的地面观测资料在同化系统中也越来越受到重视,而且一个好的资料同化系统应该能够给出模式近地面动力、热力和湿度状况的合理分析。利用GRAPES区域同化预报系统(GRAPES——Global and Regional Assimilation and Prediction Enhanced System),在近地层Monin_Obukhov相似理论的基础上,考虑了边界层的动力和湿热力约束,建立新的地面风场观测算子。将此新方案与目前GRAPES系统使用的三次样条插值的地面同化方案进行高度场预报试验、统计试验以及降水预报的TS评分比较,结果表明,加入新方案地面风场资料同化后,预报效果和对降水的预报能力都比旧方案有所提高。展开更多
Seasonal and interannual changes in the Earth's gravity field are mainly due to mass exchange among the atmosphere,ocean,and continental water sources.The terrestrial water storage changes,detected as gravity chan...Seasonal and interannual changes in the Earth's gravity field are mainly due to mass exchange among the atmosphere,ocean,and continental water sources.The terrestrial water storage changes,detected as gravity changes by the Gravity Recovery and Climate Experiment(GRACE) satellites,are mainly caused by precipitation,evapotranspiration,river transportation and downward infiltration processes.In this study,a land data assimilation system LDAS-G was developed to assimilate the GRACE terrestrial water storage(TWS) data into the Community Land Model(CLM3.5) using the POD-based ensemble four-dimensional variational assimilation method PODEn4 DVar,disaggregating the GRACE large-scale terrestrial water storage changes vertically and in time,and placing constraints on the simulation of vertical hydrological variables to improve land surface hydrological simulations.The ideal experiments conducted at a single point and assimilation experiments carried out over China by the LDAS-G data assimilation system showed that the system developed in this study improved the simulation of land surface hydrological variables,indicating the potential of GRACE data assimilation in large-scale land surface hydrological research and applications.展开更多
文摘基于WRF(Weather Research and Forecasting)模式及其3DVAR(3-Dimentional Variational)资料同化系统,采用36 km、12 km、4 km三层嵌套网格进行逐3 h资料同化和快速更新循环预报,对2011年5月8日鲁中一次局地大暴雨过程进行了资料同化敏感性试验。试验结果表明,地面观测资料同化和快速更新循环对本次降水的预报起到了关键性作用。在快速更新循环预报时不同化地面观测资料,或同化全部观测资料进行冷启动预报,模式均不能预报出山东的降水。同化地面观测资料后,显著改进了模式降水落区预报。地面观测资料同化可以影响到700 hPa高度以上温压湿风要素的变化,从而改变了大气初始场的温湿结构,导致模式预报的700 h Pa附近高空大气湿度和热力不稳定增强,700 hPa以下低层风场更强,850 h Pa鲁中以南风速较无观测资料同化的偏强2～4 m·s-1,低层风场的动力作用触发高空的不稳定大气,降水出现在山东。
文摘随着预报准确度要求以及同化分析循环周期的缩短,具有高时空分辨率的地面观测资料在同化系统中也越来越受到重视,而且一个好的资料同化系统应该能够给出模式近地面动力、热力和湿度状况的合理分析。利用GRAPES区域同化预报系统(GRAPES——Global and Regional Assimilation and Prediction Enhanced System),在近地层Monin_Obukhov相似理论的基础上,考虑了边界层的动力和湿热力约束,建立新的地面风场观测算子。将此新方案与目前GRAPES系统使用的三次样条插值的地面同化方案进行高度场预报试验、统计试验以及降水预报的TS评分比较,结果表明,加入新方案地面风场资料同化后,预报效果和对降水的预报能力都比旧方案有所提高。
基金supported by the National Natural Science Foundation of China(Grant Nos.41075062,91125016)the National Basic Research Program of China(Grants Nos.2010CB951001,2010CB428403)
文摘Seasonal and interannual changes in the Earth's gravity field are mainly due to mass exchange among the atmosphere,ocean,and continental water sources.The terrestrial water storage changes,detected as gravity changes by the Gravity Recovery and Climate Experiment(GRACE) satellites,are mainly caused by precipitation,evapotranspiration,river transportation and downward infiltration processes.In this study,a land data assimilation system LDAS-G was developed to assimilate the GRACE terrestrial water storage(TWS) data into the Community Land Model(CLM3.5) using the POD-based ensemble four-dimensional variational assimilation method PODEn4 DVar,disaggregating the GRACE large-scale terrestrial water storage changes vertically and in time,and placing constraints on the simulation of vertical hydrological variables to improve land surface hydrological simulations.The ideal experiments conducted at a single point and assimilation experiments carried out over China by the LDAS-G data assimilation system showed that the system developed in this study improved the simulation of land surface hydrological variables,indicating the potential of GRACE data assimilation in large-scale land surface hydrological research and applications.
