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23rd Asia simulation Conference, AsiaSim 2024

作者： Yang, Fan Ma, Ping Li, Wei Tao, Chao Yang, Ming Zhang, Jianchao Cheng, Huichuan Control and Simulation Center Harbin Institute of Technology Harbin150080 China National Key Laboratory of Complex System Modeling and Simulation Harbin150080 China Chinese Aeroengine Research Institute Beijing101304 China

ISBN: (纸本)9789819772247

Validation for complex system simulation faces the challenges of a large amount of validation data, which comes in the form of extensive samples and prolonged time series. To address this issue, this paper proposes an intelligent simulation result validation method based on Variational Autoencoder (VAE), achieving model validation through intelligent feature extraction and feature consistency metrics. Initially, we present the overall validation framework, which consists of feature extraction and simulation result validation, and detail the steps of the validation process. Subsequently, the principles and procedures of the feature extraction and simulation result validation methods are thoroughly discussed. The feature extraction is achieved by learning the distribution parameters of the latent space using a VAE model. Feature differences across various aspects are measured by three distance metrics and are further converted into simulation credibility. Finally, the effectiveness and superiority of this method are demonstrated through a case study on validating a drone delivery model. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Digital elevation model

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Skylon airframe aerodynamics and SABRE plumes 20th

Skylon airframe aerodynamics and SABRE plumes

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20th AIAA International Space Planes and Hypersonic systems and Technologies Conference, 2015

作者： Mehta, Unmeel Aftosmis, Michael Bowles, Jeffrey Pandya, Shishir NASA Ames Research Center Moffett FieldCA94035 United States NASA Advanced Supercomputing Division United States Applied Modeling and Simulation Branch United States System Analysis Branch United States Fundamental Modeling and Simulation Branch United States

ISBN: (纸本)9781624103209

An independent partial assessment is provided of the viability of the Skylon aerospace plane concept, developed by Reaction Engines Limited (REL). The objectives are to verify REL’s engineering estimates of airframe aerodynamics during powered flight and to assess the impact of Synergetic Air-Breathing Rocket Engine (SABRE) plumes on the aft fuselage. Airframe lift and drag coefficients derived from simulations conducted with Euler equations for unpowered flight compare very well with those REL computed with engineering methods. The REL coefficients for powered flight are increasingly less acceptable as the freestream Mach number is increased beyond 8.5, because the engineering estimates did not account for the increasing favorable (in terms of drag and lift coefficients) effect of under-expanded rocket engine plumes on the aft fuselage. At Mach numbers greater than 8.5, the thermal environment around the aft fuselage is a potential high-risk issue. The adverse effects of shock waves on the aft fuselage and plume-induced flow separation are other potential design and performance risks. The mitigation of these risks may require changes in the design of the Skylon concept and its operation during flight. © 2015, AIAA American Institute of Aeronautics and Astronautics. All rights Reserved.

关键词： Rockets

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Projection of China’s future runoff based on the CMIP6 mid-high warming scenarios

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Science China Earth Sciences 2023年第3期66卷 528-546页

作者： Jiayue ZHOU Hui LU Kun YANG Ruijie JIANG Yuan YANG Wei WANG Xuejun ZHANG Department of Earth System Science Ministry of Education Key Laboratory of Earth System ModelingInstitute for Global Change StudiesTsinghua UniversityBeijing 100084China National Tibetan Plateau Data Center State Key Laboratory of Tibetan Plateau Earth System and Resource EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Center for Western Weather and Water Extremes Scripps Institution of OceanographyUniversity of California San DiegoSan Diego 92037USA Changjiang Institute of Survey PlanningDesign and ResearchWuhan 430010China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China Research Center on Flood and Drought Disaster Reduction of the Ministry of Water Resources Beijing 100038China

The latest Coupled Model Intercomparison Project Phase 6(CMIP6)proposes new shared pathways(SSPs)that incorporate socioeconomic development with more comprehensive and scientific experimental designs;however,few studies have been performed on the projection of future multibasin hydrological changes in China based on CMIP6 *** this paper,we use the Equidistant Cumulative Distribution Function method(EDCDFm)to perform downscaling and bias correction in daily precipitation,daily maximum temperature,and daily minimum temperature for six CMIP6 models based on the historical gridded data from the high-resolution China Meteorological Forcing Dataset(CMFD).We use the bias-corrected precipitation,temperature,and daily mean wind speed to drive the variable infiltration capacity(VIC)hydrological model,and study the changes in multiyear average annual precipitation,annual evapotranspiration and total annual runoff depth relative to the historical baseline period(1985–2014)for the Chinese mainland,basins and grid scales in the 21st century future under the SSP2-4.5 and SSP5-8.5 *** study shows that the VIC model accurately simulates runoff in major Chinese basins;the model data accuracy improves substantially after downscaling bias correction;and the future multimodel-mean multiyear average annual precipitation,annual evapotranspiration,and total annual runoff depth for the Chinese mainland and each basin increase relative to the historical period in near future(2020–2049)and far future(2070–2099)under the SSP2-4.5 and *** new CMIP6-based results of this paper can provide a strong reference for extreme event prevention,water resource utilization and management in China in the 21st century.

关键词： CMIP6 VIC model EDCDFm Chinese basins Future hydrological changes

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Major Modes of Short-Term Climate Variability in the Newly Developed NUIST Earth system Model(NESM)

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Advances in Atmospheric Sciences 2015年第5期32卷 585-600页

作者： CAO Jian Bin WANG Baoqiang XIANG Juan LI WU Tianjie Xiouhua FU WU Liguang MIN Jinzhong Earth System Modeling Center Nanjing University of Information Science and Technology Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science and Technology International Pacific Research Center University of Hawaii at Manoa Department of Atmospheric Sciences University of Hawaii at Manoa NOAA/Geophysical Fluid Dynamics Laboratory Princeton NJ 08540 University Corporation for Atmospheric Research Boulder CO 80307 USA

A coupled earth system model（ESM） has been developed at the Nanjing University of Information Science and Technology（NUIST） by using version 5.3 of the European Centre Hamburg Model（ECHAM）, version 3.4 of the Nucleus for European Modelling of the Ocean（NEMO）, and version 4.1 of the Los Alamos sea ice model（CICE）. The model is referred to as NUIST ESM1（NESM1）. Comprehensive and quantitative metrics are used to assess the model＇s major modes of climate variability most relevant to subseasonal-to-interannual climate prediction. The model＇s assessment is placed in a multi-model framework. The model yields a realistic annual mean and annual cycle of equatorial SST, and a reasonably realistic precipitation climatology, but has difficulty in capturing the spring–fall asymmetry and monsoon precipitation domains. The ENSO mode is reproduced well with respect to its spatial structure, power spectrum, phase locking to the annual cycle, and spatial structures of the central Pacific（CP）-ENSO and eastern Pacific（EP）-ENSO; however, the equatorial SST variability,biennial component of ENSO, and the amplitude of CP-ENSO are overestimated. The model captures realistic intraseasonal variability patterns, the vertical-zonal structures of the first two leading predictable modes of Madden–Julian Oscillation（MJO）, and its eastward propagation; but the simulated MJO speed is significantly slower than observed. Compared with the T42 version, the high resolution version（T159） demonstrates improved simulation with respect to the climatology, interannual variance, monsoon–ENSO lead–lag correlation, spatial structures of the leading mode of the Asian–Australian monsoon rainfall variability, and the eastward propagation of the MJO.

关键词： coupled climate model earth system model climate variability

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Distinct response of Northern Hemisphere land monsoon precipitation to transient and stablized warming scenarios

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Advances in Climate Change research 2020年第3期11卷 161-171页

作者： CAO Jian ZHAO Hai-Kun Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and TechnologyNanjing210044China Earth System Modeling Center Nanjing University of Information Science and TechnologyNanjing210044China

To better understand the climate response under stabilized,overshoot,and transient global warming,four types of ensemble experiments on 1.5℃/2℃ global warming scenarios(i.e.,stabilized 1.5℃,1.5℃ overshoot,stabilized 2℃,and transient 2℃)are elaborately designed using the Nanjing University Information Science and Technology Earth system Model(NESM).Compared with the modern climate(1985–2014),the projected surface air temperature(SAT)change is characterized by a robust‘Northern Hemisphere(NH)-warmer than-Southern Hemisphere(SH)’and‘land-warmer than-ocean’*** projected precipitation change exhibits‘NH-wetter than-SH’pattern in the *** the response of SAT and precipitation climatology show similar pattern between stabilized and overshoot scenarios,some significant differences are still *** projected change in the Northern Hemisphere land monsoon precipitation(NHLMP)is 30% larger in the transient 2℃ experiment compared with that in the stabilized 2℃ *** more vigorous NHLMP in the transient global warming scenario is mainly due to the enhanced land-sea thermal contrast and interhemispheric temperature *** enlarged land-sea thermal contrast increases the surface pressure gradient between the NH continents and its adjacent oceans,thus enhancing the NH monsoon circulation and moisture *** enhanced interhemispheric temperature difference shifts the Hadley circulation and intertropical convergence zone northward,leading to the enhanced moisture convergence and the shifts of tropical rain band over the NH monsoon *** result highlights that climate responses may depend on different warming trajectories and,which could facilitate the strategic planning of governments.

关键词： 1.5℃/2℃global warming Monsoon precipitation NESM model Transient global warming Stabilized global warming

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A Client Selection Method Based on Loss Function Optimization for Federated Learning

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Computer modeling in Engineering & Sciences 2023年第10期137卷 1047-1064页

作者： Yan Zeng Siyuan Teng Tian Xiang Jilin Zhang Yuankai Mu Yongjian Ren Jian Wan School of Computer Science and Technology Hangzhou Dianzi UniversityHangzhou310018China Key Laboratory of Complex System Modeling and Simulation Ministry of EducationHangzhou310018China Zhejiang Engineering Research Center of Data Security Governance Hangzhou310018China Intelligent Robotics Research Center Zhejiang LabHangzhou311100China HDU-ITMO Joint Institute Hangzhou Dianzi UniversityHangzhou310018China

Federated learning is a distributedmachine learningmethod that can solve the increasingly serious problemof data islands and user data privacy,as it allows training data to be kept locally and not shared with other *** trains a globalmodel by aggregating locally-computedmodels of clients rather than their ***,the divergence of local models caused by data heterogeneity of different clients may lead to slow convergence of the global *** this problem,we focus on the client selection with federated learning,which can affect the convergence performance of the global model with the selected local *** propose FedChoice,a client selection method based on loss function optimization,to select appropriate local models to improve the convergence of the global *** firstly sets selected probability for clients with the value of loss function,and the client with high loss will be set higher selected probability,which can make them more likely to participate in ***,it introduces a local control vector and a global control vector to predict the local gradient direction and global gradient direction,respectively,and calculates the gradient correction vector to correct the gradient direction to reduce the cumulative deviationof the local gradient causedby *** experiments to verify the validity of FedChoice on CIFAR-10,CINIC-10,MNIST,EMNITS,and FEMNIST datasets,and the results show that the convergence of FedChoice is significantly improved,compared with FedAvg,FedProx,and FedNova.

关键词： Federated learning model aggregation Non-IID

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Attributing climate and weather extremes to Northern Hemisphere sea ice and terrestrial snow: progress, challenges and ways forward

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npj Climate and Atmospheric Science 2025年第1期8卷 1-22页

作者： Ye, Kunhui Cohen, Judah Chen, Hans W. Zhang, Shiyue Luo, Dehai Hamouda, Mostafa Essam Atmospheric Oceanic and Planetary Physics University of Oxford Oxford United Kingdom Atmospheric and Environmental Research Lexington United States Department of Civil and Environmental Engineering Massachusetts Institute of Technology Cambridge United States Department of Space Earth and Environment Chalmers University of Technology Gothenburg Sweden Key Laboratory of Meteorological Disaster Ministry of Education Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Joint International Research Laboratory of Climate and Environment Change Nanjing University of Information Science and Technology Nanjing China Key Laboratory of Earth System Numerical Modeling and Application and Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China and University of Chinese Academy of Sciences Beijing China Astronomy and Meteorology Department Faculty of Science Cairo University Cairo Al Giza Egypt

Sea ice and snow are crucial components of the cryosphere and the climate system. Both sea ice and spring snow in the Northern Hemisphere (NH) have been decreasing at an alarming rate in a changing climate. Changes in NH sea ice and snow have been linked with a variety of climate and weather extremes including cold spells, heatwaves, droughts and wildfires. Understanding of these linkages will benefit the predictions of climate and weather extremes. However, existing work on this has been largely fragmented and is subject to large uncertainties in physical pathways and methodologies. This has prevented further substantial progress in attributing climate and weather extremes to sea ice and snow change, and will potentially risk the loss of a critical window for effective climate change mitigation. In this review, we synthesize the current progress in attributing climate and weather extremes to sea ice and snow change by evaluating the observed linkages, their physical pathways and uncertainties in these pathways, and suggesting ways forward for future research efforts. By adopting the same framework for both sea ice and snow, we highlight their combined influence and the cryospheric feedback to the climate system. We suggest that future research will benefit from improving observational networks, addressing the causality and complexity of the linkages using multiple lines of evidence, adopting large-ensemble approaches and artificial intelligence, achieving synergy between different methodologies/disciplines, widening the context, and coordinated international collaboration. © The Author(s) 2025.

关键词： Atmospheric dynamics Climate change Cryospheric science

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Cross-sectional rainfall observation on the central-western Tibetan Plateau in the warm season:system design and preliminary results

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Science China Earth Sciences 2023年第5期66卷 1015-1030页

作者： Kun YANG Yingying CHEN Lazhu Changhui ZHAN Xiaoyan LING Xu ZHOU Yaozhi JIANG Xiangnan YAO Hui LU Xiaogang MA Lin OUYANG Weihao PAN Yanghang REN Changkun SHAO Jiaxin TIAN Yan WANG Hua YANG Siyu YUE Ke ZHANG Dingchi ZHAO Long ZHAO Jianhong ZHOU Mijun ZOU Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceInstitute for Global Change StudiesTsinghua UniversityBeijing100084China National Tibetan Plateau Data Center State Key Laboratory of Tibetan Plateau Earth System and Resource EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing100101China Research Center for Ecology College of ScienceTibet UniversityLhasa850011China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Science and Natural Resources ResearchChinese Academy of SciencesBeijing100101China Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station School of Geographical SciencesSouthwest UniversityChongqing400715China

The central and western Tibetan Plateau(CWTP)is characterized by harsh environment and strong interactions among the spheres of earth as well as significant changes in climate and water cycles over the past four *** lack of precipitation observations is a bottleneck for the study of land surface processes in this *** the past six years,we have designed and established two observation transects across the south-north and the west-east in this region to obtain hourly rainfall data during the warm season(May-September).The south-north transect extends from Yadong Valley on the southern slope of the Himalayas to Shuanghu County in the hinterland of the plateau,with a total of 31stations;the west-east transect extends from Shiquanhe in the west to Naqu in the central TP,with a total of 22 *** observation dataset has been applied to clarify the spatiotemporal characteristics of precipitation in the CWTP,to evaluate the quality of typical gridded precipitation products,to support the development of regional climate models,and to reveal the processes of summertime lake-air *** observation dataset has been released in the National Tibetan Plateau Data center.

关键词： Central and western Tibetan Plateau Rainfall observation transects Observation uncertainty Spatiotemporal characteristics of precipitation Precipitation data evaluation

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Adaptive Statistical Spatial Downscaling of Precipitation Supported by High-Resolution Atmospheric simulation Data for Mountainous Areas of Nepal

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Journal of Meteorological research 2023年第4期37卷 508-520页

作者： Hua YANG Kun YANG Jun QIN Baohong DING Yaozhi JIANG Yingying CHEN Xu ZHOU Yan WANG Shankar SHARMA National Tibetan Plateau Data Center State Key Laboratory of Tibetan Plateau Earth SystemEnvironment and ResourcesInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101 University of Chinese Academy of Sciences Beijing 100049 Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceInstitute for Global Change StudiesTsinghua UniversityBeijing 100084 State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101 Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101

In complex terrain regions, it is very challenging to obtain high accuracy and resolution precipitation data that are required in land hydrological studies. In this study, an adaptive precipitation downscaling method is proposed based on the statistical downscaling model MicroMet. A key input parameter in the MicroMet is the precipitation adjustment factor(PAF) that shows the elevation dependence of precipitation. Its value is estimated conventionally based on station observations and suffers sparse stations in high altitudes. This study proposes to estimate the PAF value and its spatial variability with precipitation data from high-resolution atmospheric simulations and tests the idea in Nepal of South Himalayas, where rainfall stations are relatively dense. The result shows that MicroMet performs the best with the PAF value estimated from the simulation data at the scale of approximately 1.5 degrees. Not only the value at this scale is qualitatively consistent with early knowledge obtained from intensive observations, but also the downscaling performance with this value is better than or comparable to that with the PAF estimated from dense station data. Finally, it is shown that the PAF estimation, although critical, cannot replace the importance of increasing input station density for downscaling.

关键词： precipitation statistical downscaling precipitation adjustment factor adaptive estimation high resolution dynamical downscaling

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Contribution of Winter SSTA in the Tropical Eastern Pacific to Changes of Tropical Cyclone Precipitation over Southeast China

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Journal of Meteorological research 2022年第2期36卷 282-291页

作者： Xianghua WU Qihao ZHU Chao WANG Yue ZHOU Yiqi CHEN Xintong TIAN Yajie HUA School of Mathematics and Statistics Nanjing University of Information Science&TechnologyNanjing 210044 Key Laboratory of Meteorological Disaster of Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters and Earth System Modeling Center Nanjing University of Information Science&TechnologyNanjing 210044 Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research Institute of Heavy RainChina Meteorological AdministrationWuhan 430074

Tropical cyclone precipitation(TCP)accounts for 10%-40%of the boreal summer precipitation that occurs over Southeast China(SEC),causing flood disasters and serious *** the decadal scale,TCP increases significantly in SEC while TC frequency decreases in the western North Pacific(WNP)during ***,variations in TCP and the corresponding physical mechanism are investigated in this ***,an empirical statistical method is introduced to quantify the TCP amount based on accumulated cyclone energy(ACE)and TC frequency with the TCP anomaly decomposed into three items(rainfall frequency,rainfall intensity,and nonlinear item).ACE,as the integration of TC intensity and frequency,is a more effective index than TC frequency for depicting the characteristics of TCP because the contribution of rainfall frequency represented by ACE is higher than that of TC ***,the physical mechanism affecting the WNP TC activities and TCP in SEC are *** sea surface temperature anomaly(SSTA)over the tropical eastern Pacific(TEP)in winter can trigger variations of air-sea interaction over the tropical Pacific,including low-level divergent winds,mid-tropospheric descent flows,high-level convergent winds coupled with negative anomalies of vorticity and humidity over the tropical western Pacific(TWP)in the next *** dynamic conditions provide unfavorable environments for TC activities in the WNP and constrain TCP in ***,more significantly negative SSTA events in the TEP facilitate enhanced ACE along with positive relative vorticity,relative humidity,and upwelling vertical winds anomalies over the coast of SEC after 1998,which is a reasonable explanation for the increasing TCP in SEC.

关键词： tropical cyclone precipitation accumulated cyclone energy sea surface temperature anomaly air–sea interaction

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