An ensemble-based assimilation method is proposed for correcting the subsurface temperature field when nudging the sea surface temperature(SST) observations into the Max Planck Institute(MPI) climate model,ECHAM5/MPI-...An ensemble-based assimilation method is proposed for correcting the subsurface temperature field when nudging the sea surface temperature(SST) observations into the Max Planck Institute(MPI) climate model,ECHAM5/MPI-OM. This method can project SST directly to subsurface according to model ensemble-based correlations between SST and subsurface temperature. Results from a 50 year(1960–2009) assimilation experiment show the method can improve the subsurface temperature field up to 300 m compared to the qualitycontrolled subsurface ocean temperature objective analyses(EN4), through reducing the biases of the thermal states, improving the thermocline structure, and reducing the root mean square(RMS) errors. Moreover, as most of the improvements concentrate over the upper 100 m, the ocean heat content in the upper 100 m(OHT100 m)is further adopted as a property to validate the performance of the ensemble-based correction method. The results show that RMS errors of the global OHT100 m convergent to one value after several times iteration,indicating this method can represent the relationship between SST and subsurface temperature fields well, and then improve the accuracy of the simulation in the subsurface temperature of the climate model.展开更多
With the aid of Meteorological Information Composite and Processing System (MICAPS), satellite wind vectors derived from the Geostationary Meteorological Statellite-5 (GMS-5) and retrieved by National Satellite Meteor...With the aid of Meteorological Information Composite and Processing System (MICAPS), satellite wind vectors derived from the Geostationary Meteorological Statellite-5 (GMS-5) and retrieved by National Satellite Meteorology Center of China (NSMC) can be obtained. Based on the nudging method built in the fifth-generation Mesoscale Model (MM5) of Pennsylvania State University and Na- tional Center for Atmospheric Research, a data preprocessor is developed to convert these satellite wind vectors to those with specified format required in MM5. To examine the data preprocessor and evaluate the impact of satellite winds from GMS-5 on MM5 simulations, a series of numerical experimental fore- casts consisting of four typhoon cases in 2002 are designed and implemented. The results show that the preprocessor can process satellite winds smoothly and MM5 model runs successfully with a little extra computational load during ingesting these winds, and that assimilation of satellite winds by MM5 nudging method can obviously improve typhoon track forecast but contributes a little to typhoon intensity forecast. The impact of the satellite winds depends heavily upon whether the typhoon bogussing scheme in MM5 was turned on or not. The data preprocessor developed in this paper not only can treat GMS-5 satellite winds but also has capability with little modification to process derived winds from other geostationary satellites.展开更多
通过在WRF(Weather Research and Forecasting)模式中运用松弛逼近方法(Nudging)同化NCEP-FNL资料,对中国西北地区夏季3次对流降水过程进行了模拟试验,检验了模式运用谱逼近(Spectral Nudging,SN)和格点逼近(Grid Nudging,GN)方案后对...通过在WRF(Weather Research and Forecasting)模式中运用松弛逼近方法(Nudging)同化NCEP-FNL资料,对中国西北地区夏季3次对流降水过程进行了模拟试验,检验了模式运用谱逼近(Spectral Nudging,SN)和格点逼近(Grid Nudging,GN)方案后对研究区域内降水过程的模拟性能。结果表明:SN和GN试验相对于控制试验,模拟的降水结果更接近于站点观测。在降水落区和量级的模拟效果上都有显著提高,且SN试验所得结果优于GN试验。通过分析两个同化试验在降水时段的基本要素场(湿度、温度和风速)变化,在近地面层,GN试验模拟的风速和温度较SN试验更接近观测;但700 hPa上,SN试验中风速、风向、温度、湿度的增量场变化及分布同降水的模拟结果存在较好的对应关系。最后,从物理诊断量—水汽通量散度的空间垂直变化来看,SN试验中600 hPa和700 hPa的水汽通量散度的正负分布有效调节降水的空间分布,更逼近观测。因此700 hPa的物理量场变量增量是降水模拟效果改善的主要原因之一。展开更多
基于全球海洋模式OGCTM(Ocean General Circulation and Tide Model),利用19年(1992—2011年)的卫星高度计资料调和分析得到全球分潮调和常数回报逐时正压潮水位;采用Nudging(牛顿松弛逼近)方法进行潮汐同化,针对Nudging松弛项的差分方...基于全球海洋模式OGCTM(Ocean General Circulation and Tide Model),利用19年(1992—2011年)的卫星高度计资料调和分析得到全球分潮调和常数回报逐时正压潮水位;采用Nudging(牛顿松弛逼近)方法进行潮汐同化,针对Nudging松弛项的差分方案以及松弛系数进行了数值试验研究。一系列试验结果表明,不论采用显式还是隐式Nudging松弛方案,模式结果的偏差会随着松弛系数的增加先减小后增大,松弛系数最优值为1×10^(-5);当松弛系数太大时,会造成模式的溢出。Nudging松弛项采用隐式差分方案可以显著提高松弛系数的阈值;松弛系数在适当的取值范围内时,加入Nudging松弛项的数值试验描述的潮汐特征要明显优于未加Nudging松弛项的数值试验描述的潮汐特征;在最优Nudging松弛方案下,Nudging松弛方法对全日分潮的振幅模拟准确度可提高50%,对半日分潮的振幅模拟准确度可提高56%。试验结果也表明了Nudging方法作为一种简单的同化方法的可行性和有效性。展开更多
Considerable efforts are being made to transition current lithium-ion and sodium-ion batteries towards the use of solid-state electrolytes.Computational methods,specifically nudged elastic band(NEB)and molecular dynam...Considerable efforts are being made to transition current lithium-ion and sodium-ion batteries towards the use of solid-state electrolytes.Computational methods,specifically nudged elastic band(NEB)and molecular dynamics(MD)methods,provide powerful tools for the design of solid-state electrolytes.The MD method is usually the choice for studying the materials involving complex multiple diffusion paths or having disordered structures.However,it relies on simulations at temperatures much higher than working temperature.This paper studies the reliability of the MD method using the system of Na diffusion in MgO as a benchmark.We carefully study the convergence behavior of the MD method and demonstrate that total effective simulation time of 12 ns can converge the calculated diffusion barrier to about 0.01 eV.The calculated diffusion barrier is 0.31 eV from both methods.The diffusion coefficients at room temperature are 4.3×10^(-9) cm^(2)⋅s^(−1) and 2.2×10^(-9) cm^(2)⋅s^(−1),respectively,from the NEB and MD methods.Our results justify the reliability of the MD method,even though high temperature simulations have to be employed to overcome the limitation on simulation time.展开更多
This work investigates an uncertainty quantification(UQ)framework that analyses the uncertainty involved in modelling control systems to improve control strategy performance.The framework involves solving four problem...This work investigates an uncertainty quantification(UQ)framework that analyses the uncertainty involved in modelling control systems to improve control strategy performance.The framework involves solving four problems:identifying uncertain parameters,propagating uncertainty to the quantity of interest,data assimilation and making decisions under quantified uncertainties.A specific group of UQ approaches,known as the ensemble-based methods,are adopted to solve these problems.This UQ framework is applied to coordinating a group of thermostatically controlled loads,which relies on simulating a second-order equivalent thermal parameter model with some uncertain parameters.How this uncertainty affects the prediction and the control of total power is examined.The study shows that uncertainty can be effectively reduced using the measurement of air temperatures.Also,the control objective is achieved fairly accurately with a quantification of the uncertainty.展开更多
WRF(Weather Research and Forecast)模式作为新一代的中尺度气象模式,在预测和分析中尺度气象方面具有良好的适用性。台风过程作为极端恶劣的中尺度气象现象,往往会造成巨大的人身和财产的损失。本文利用WRF模式对2011年的某次台风过...WRF(Weather Research and Forecast)模式作为新一代的中尺度气象模式,在预测和分析中尺度气象方面具有良好的适用性。台风过程作为极端恶劣的中尺度气象现象,往往会造成巨大的人身和财产的损失。本文利用WRF模式对2011年的某次台风过程进行了模拟,分析模拟区域的选择,Nudging方法对台风路径模拟的影响,并和实际结果进行对比。展开更多
基金The National Key R&D Program of China under contract No. 2017YFA0604201the National Natural Science Foundation of China under contract Nos 41876012 and 41861144015.
文摘An ensemble-based assimilation method is proposed for correcting the subsurface temperature field when nudging the sea surface temperature(SST) observations into the Max Planck Institute(MPI) climate model,ECHAM5/MPI-OM. This method can project SST directly to subsurface according to model ensemble-based correlations between SST and subsurface temperature. Results from a 50 year(1960–2009) assimilation experiment show the method can improve the subsurface temperature field up to 300 m compared to the qualitycontrolled subsurface ocean temperature objective analyses(EN4), through reducing the biases of the thermal states, improving the thermocline structure, and reducing the root mean square(RMS) errors. Moreover, as most of the improvements concentrate over the upper 100 m, the ocean heat content in the upper 100 m(OHT100 m)is further adopted as a property to validate the performance of the ensemble-based correction method. The results show that RMS errors of the global OHT100 m convergent to one value after several times iteration,indicating this method can represent the relationship between SST and subsurface temperature fields well, and then improve the accuracy of the simulation in the subsurface temperature of the climate model.
基金Supported by Major State Basic Research Development Program of China (973 Program, No.2005CB4223-01) and Key Technologies R & D Program of China (No.2001BA603B-01).
文摘With the aid of Meteorological Information Composite and Processing System (MICAPS), satellite wind vectors derived from the Geostationary Meteorological Statellite-5 (GMS-5) and retrieved by National Satellite Meteorology Center of China (NSMC) can be obtained. Based on the nudging method built in the fifth-generation Mesoscale Model (MM5) of Pennsylvania State University and Na- tional Center for Atmospheric Research, a data preprocessor is developed to convert these satellite wind vectors to those with specified format required in MM5. To examine the data preprocessor and evaluate the impact of satellite winds from GMS-5 on MM5 simulations, a series of numerical experimental fore- casts consisting of four typhoon cases in 2002 are designed and implemented. The results show that the preprocessor can process satellite winds smoothly and MM5 model runs successfully with a little extra computational load during ingesting these winds, and that assimilation of satellite winds by MM5 nudging method can obviously improve typhoon track forecast but contributes a little to typhoon intensity forecast. The impact of the satellite winds depends heavily upon whether the typhoon bogussing scheme in MM5 was turned on or not. The data preprocessor developed in this paper not only can treat GMS-5 satellite winds but also has capability with little modification to process derived winds from other geostationary satellites.
文摘通过在WRF(Weather Research and Forecasting)模式中运用松弛逼近方法(Nudging)同化NCEP-FNL资料,对中国西北地区夏季3次对流降水过程进行了模拟试验,检验了模式运用谱逼近(Spectral Nudging,SN)和格点逼近(Grid Nudging,GN)方案后对研究区域内降水过程的模拟性能。结果表明:SN和GN试验相对于控制试验,模拟的降水结果更接近于站点观测。在降水落区和量级的模拟效果上都有显著提高,且SN试验所得结果优于GN试验。通过分析两个同化试验在降水时段的基本要素场(湿度、温度和风速)变化,在近地面层,GN试验模拟的风速和温度较SN试验更接近观测;但700 hPa上,SN试验中风速、风向、温度、湿度的增量场变化及分布同降水的模拟结果存在较好的对应关系。最后,从物理诊断量—水汽通量散度的空间垂直变化来看,SN试验中600 hPa和700 hPa的水汽通量散度的正负分布有效调节降水的空间分布,更逼近观测。因此700 hPa的物理量场变量增量是降水模拟效果改善的主要原因之一。
文摘基于全球海洋模式OGCTM(Ocean General Circulation and Tide Model),利用19年(1992—2011年)的卫星高度计资料调和分析得到全球分潮调和常数回报逐时正压潮水位;采用Nudging(牛顿松弛逼近)方法进行潮汐同化,针对Nudging松弛项的差分方案以及松弛系数进行了数值试验研究。一系列试验结果表明,不论采用显式还是隐式Nudging松弛方案,模式结果的偏差会随着松弛系数的增加先减小后增大,松弛系数最优值为1×10^(-5);当松弛系数太大时,会造成模式的溢出。Nudging松弛项采用隐式差分方案可以显著提高松弛系数的阈值;松弛系数在适当的取值范围内时,加入Nudging松弛项的数值试验描述的潮汐特征要明显优于未加Nudging松弛项的数值试验描述的潮汐特征;在最优Nudging松弛方案下,Nudging松弛方法对全日分潮的振幅模拟准确度可提高50%,对半日分潮的振幅模拟准确度可提高56%。试验结果也表明了Nudging方法作为一种简单的同化方法的可行性和有效性。
基金supported by the National Natural Science Foundation of China (Grant Nos.12164019,11991060,12088101,and U1930402)the Natural Science Foundation of Jiangxi Province of China (Grant No.20212BAB201017).
文摘Considerable efforts are being made to transition current lithium-ion and sodium-ion batteries towards the use of solid-state electrolytes.Computational methods,specifically nudged elastic band(NEB)and molecular dynamics(MD)methods,provide powerful tools for the design of solid-state electrolytes.The MD method is usually the choice for studying the materials involving complex multiple diffusion paths or having disordered structures.However,it relies on simulations at temperatures much higher than working temperature.This paper studies the reliability of the MD method using the system of Na diffusion in MgO as a benchmark.We carefully study the convergence behavior of the MD method and demonstrate that total effective simulation time of 12 ns can converge the calculated diffusion barrier to about 0.01 eV.The calculated diffusion barrier is 0.31 eV from both methods.The diffusion coefficients at room temperature are 4.3×10^(-9) cm^(2)⋅s^(−1) and 2.2×10^(-9) cm^(2)⋅s^(−1),respectively,from the NEB and MD methods.Our results justify the reliability of the MD method,even though high temperature simulations have to be employed to overcome the limitation on simulation time.
基金the Control of Complex Systems Initiative at Pacific Northwest National Laboratory(PNNL).PNNL is operated by Battelle for the U.S.Department of Energy under contract[DE-AC05-76RL01830].
文摘This work investigates an uncertainty quantification(UQ)framework that analyses the uncertainty involved in modelling control systems to improve control strategy performance.The framework involves solving four problems:identifying uncertain parameters,propagating uncertainty to the quantity of interest,data assimilation and making decisions under quantified uncertainties.A specific group of UQ approaches,known as the ensemble-based methods,are adopted to solve these problems.This UQ framework is applied to coordinating a group of thermostatically controlled loads,which relies on simulating a second-order equivalent thermal parameter model with some uncertain parameters.How this uncertainty affects the prediction and the control of total power is examined.The study shows that uncertainty can be effectively reduced using the measurement of air temperatures.Also,the control objective is achieved fairly accurately with a quantification of the uncertainty.
文摘WRF(Weather Research and Forecast)模式作为新一代的中尺度气象模式,在预测和分析中尺度气象方面具有良好的适用性。台风过程作为极端恶劣的中尺度气象现象,往往会造成巨大的人身和财产的损失。本文利用WRF模式对2011年的某次台风过程进行了模拟,分析模拟区域的选择,Nudging方法对台风路径模拟的影响,并和实际结果进行对比。
