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Signal, Information and Data Processing (ICSIDP), IEEE International Conference on

作者： Chao Wang Heng Sun Xin-Yu Zhang Ran Zhang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing P.R. China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

The missile-borne or airborne synthetic aperture radar (SAR) usually adopts the squint mode and subaperture to satisfy maneuvering and the real-time processing. A realtime imaging algorithm of squint SAR based on SPECAN processing is presented. It has high computational efficiency in low resolution. A unified back-projection algorithm is proposed to solve the problem of fan-shaped distortion and geometric distortion. Simulation results validate the effectiveness of the proposed method.

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Insect wing-beat frequency automatic extraction and experimental verification with a Ku-band insect radar system

Insect wing-beat frequency automatic extraction and experime...

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IET International Radar Conference 2018, IRC 2018

作者： Zhang, Tianran Liu, XiangRong Hu, Cheng Wang, Rui Liu, Changjiang Li, Wenqing Radar Research Laboratory School of Information and Electronics Beijing Institute of Technology Beijing100081 China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China Key Laboratory of Electronic and Information Technology in Satellite Navigation Beijing Institute of Technology Ministry of Education Beijing100081 China

The wing-beat frequency is one of the most important behavioural parameters of migratory insects and is widely used to distinguish insect species due to the diversity of wing-beat frequency among different species. Traditional insect radar has been able to achieve automatic extraction of the wing-beat frequency. However, its low-range resolution and fixed threshold detection may cause false alarms and reduce the precision of wing-beat frequency. The authors' Ku-band insect radar system enables high-resolution, full-polarised detection of insects, but has not achieved automatic extraction of wing-beat frequency yet. The authors propose an insect wing-beat frequency automatic extraction algorithm based on a Ku-band insect radar system. The algorithm adopts the constant false alarm rate detector and tracks the association algorithm to get target echo automatically and combines the amplitude spectrum method and the phase spectrum method to achieve wing-beat frequency extraction. The authors carried out the outfield experiment using the radar system and used the collected data to test the proposed algorithm. The experiment results confirm that the algorithm can extract the wing-beat frequency of insects automatically based on the Ku-band insect radar system, which can improve system efficiency. © 2019 Institution of Engineering and technology. All rights reserved.

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Learning to Infer Weather States Using Partial Observations

Journal of Geophysical Research: Machine Learning and Comput...

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Journal of Geophysical Research: Machine Learning and Computation 2025年第1期2卷

作者： Jie Chao Baoxiang Pan Quanliang Chen Shangshang Yang Jingnan Wang Congyi Nai Yue Zheng Xichen Li Huiling Yuan Xi Chen Bo Lu Ziniu Xiao National Key Laboratory of Earth System Numerical Modeling and Application Institute of Atmospheric Physics Chinese Academy of Science Beijing China School of Atmospheric Sciences Chengdu University of Information Technology Chengdu China Key Laboratory of Mesoscale Severe Weather Ministry of Education and School of Atmospheric Sciences Nanjing University Nanjing China College of Computer National University of Defense Technology Hunan China Clustertech LTD Hong Kong China National Climate Center China Meteorological Administration Beijing China

Accurate state estimation of the high-dimensional, chaotic Earth's atmosphere marks a Sisyphean task, yet is indispensable for initiating weather forecasts and gauging climate variability. While much effort is devoted to assimilating observations and forecasts to infer weather states, the inherent low-dimensional statistical structure in atmospheric circulation, shaped by geophysical laws and geographic boundaries, is underutilized as an informative prior for state inference, or as reference for assessing representative of existing observations and planning new ones. We realize these potential by learning climatological distribution from climate reanalysis/simulation, using a deep generative model. For a case study of estimating 2 m temperature spatial patterns, the learned distribution faithfully reproduces climatology statistics. A combination of the learned climatological prior with few station observations yields strong posterior of spatial pattern estimates, which are spatially coherent, faithful and adaptive to observational constraints, and uncertainty-aware. This allows us to evaluate each observation's value in reducing pattern estimation uncertainty, and guide optimal observation network design by pinpointing the most informative sites. Our study showcases how generative models can extract and utilize information produced in the chaotic evolution of climate system. Deep generative model enables accurate spatial interpolation of weather variables from sparse observations The generative model produces spatially coherent and uncertainty-aware estimates, effectively constrained by observational data The approach provides a framework to quantify observation impact on uncertainty reduction, enabling optimization of observation networks Accurate estimation of weather conditions across a large area is crucial but challenging due to the complex and chaotic nature of the atmosphere. Traditional methods rely on combining observations with forecasts, which can be comp

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Influences of the NAO on the North Atlantic CO2 Fluxes in Winter and Summer on the Interannual Scale

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Advances in Atmospheric sciences 2019年第11期36卷 1288-1298页

作者： Yujie JING Yangchun LI Yongfu XU Guangzhou FAN State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China School of Atmospheric Sciences Chengdu University of Information Technology Chengdu 610225 China Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology Qingdao 266237 China Department of Atmospheric Chemistry and Environmental Sciences College of Earth Science University of Chinese Academy of Sciences Beijing 100049 China

The differences in the influences of the North Atlantic Oscillation (NAO) on the air–sea CO2 fluxes (fCO2) in the North Atlantic (NA) between different seasons and between different regions are rarely fully investigated. We used observation-based data of fCO2, surface-ocean CO2 partial pressure (pCO2sea), wind speed and sea surface temperature (SST) to analyze the relationship between the NAO and fCO2 of the subtropical and subpolar NA in winter and summer on the interannual time scale. Based on power spectrum estimation, there are significant interannual signs with a 2–6 year cycle in the NAO indexes and area-averaged fCO2 anomalies in winter and summer from 1980 to 2015. Regression analysis with the 2–6 year filtered data shows that on the interannual scale the response of the fCO2 anomalies to the NAO has an obvious meridional wave-train-like pattern in winter, but a zonal distribution in summer. This seasonal difference is because in winter the fCO2 anomalies are mainly controlled by the NAO-driven wind speed anomalies, which have a meridional distribution pattern, while in summer they are dominated by the NAO-driven SST anomalies, which show distinct zonal difference in the subtropical NA. In addition, in the same season, there are different factors controlling the variation of pCO2sea in different regions. In summer, SST is important to the interannual variation of pCO2sea in the subtropical NA, while some biogeochemical variables probably control the pCO2sea variation in the subpolar NA.

关键词： air-sea CO2 flux North Atlantic Oscillation interannual time scale wind speed surface-ocean CO2 partial pressure

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science and Prediction of Heavy Rainfall over China:Research Progress since the Reform and Opening-Up of New China

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Journal of Meteorological Research 2020年第3期34卷 427-459页

作者： Yali LUO Jisong SUN Ying LI Rudi XIA Yu DU Shuai YANG Yuanchun ZHANG Jing CHEN Kan DAI Xueshun SHEN Haoming CHEN Feifan ZHOU Yimin LIU Shenming FU Mengwen WU Tiangui XIAO Yangruixue CHEN Huiqi LI Mingxin LI State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044 School of Atmospheric Sciences and Guangdong Province Key Laboratory for Climate Change and Natural Disaster StudiesSun Yat-sen UniversityGuangzhou 519082 Key Laboratory of Cloud–Precipitation Physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 National Meteorological Center China Meteorological AdministrationBeijing 100081 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 Zhejiang Institute of Meteorological Sciences Zhejiang Meteorological BureauHangzhou 310008 School of Atmospheric Sciences Chengdu University of Information TechnologyChengdu 610225 Institute of Heavy Rain China Meteorological AdministrationWuhan 43020510 Institute of Tropical and Marine MeteorologyChina Meteorological Administration Guangzhou 510640 Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082 University of Chinese Academy of Sciences Beijing 100049 CAS Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences(CAS)Beijing 100101

This paper reviews the major progress on development of the science and prediction of heavy rainfall over China since the beginning of the reform and opening-up of new China(roughly between 1980 and 2019).The progress of research on the physical mechanisms of heavy rainfall over China is summarized from three perspectives:1)the relevant synoptic weather systems,2)heavy rainfall in major sub-regions of China,and 3)heavy rainfall induced by *** development and application of forecasting techniques for heavy rainfall are summarized in terms of numerical weather prediction techniques and objective forecasting *** aided by the rapid progress in meteorological observing technology and substantial improvement in electronic computing,studies of heavy rainfall in China have advanced to investigating the evolution of heavy-rain-producing storms and observational analysis of the cloud microphysical features.A deeper and more systematic understanding of the synoptic systems of importance to the production of heavy rainfall has also been *** forecast of heavy rainfall in China has changed from subjective weather event forecasts to a combination of both subjective and objective quantitative precipitation forecasts,and is now advancing toward probabilistic quantitative precipitation forecasts with the provision of forecast uncertainty information.

关键词： heavy rainfall reform and opening-up of new China physical mechanisms forecasting techniques

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Direct vegetation response to CO2 rise is critical in projecting seasonal soil moisture droughts in mainland China

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Journal of Hydrology 2025年 661卷

作者： Chen, Sisi Yuan, Xing Ji, Peng Yuan, Shanshui Lu, Chunhui The National Key Laboratory of Water Disaster Prevention Hohai University Nanjing China Key Laboratory of Hydrometeorological Disaster Mechanism and Warning of Ministry of Water Resources Nanjing University of Information Science and Technology Nanjing China State Key Laboratory of Earth System Numerical Modeling and Application Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China College of Hydrology and Water Resources Hohai University Nanjing China Yangtze Institute for Conservation and Development Hohai University Nanjing China

China is a hotspot of vegetation change, accounting for one fourth of the global total vegetation growth. Yet the influence of vegetation change on the future changes of soil moisture drought is two-fold as the response of vegetation physiology (e.g., physiological effects of CO2) and structure (e.g., leaf area index (LAI)) to CO2 rise can either mitigate or exacerbate soil moisture droughts. Here we investigate the net impact of these two factors and their relative importance against the climate change, based on a series of high-resolution land surface simulations. It is found that the direct vegetation response to CO2 rise—encompassing both physiological effects and changes in LAI—will reduce the drought frequency by 15 % in South China but exacerbate the drought severity by 47 % in North China at the 3.0 °C warming level, compared to the reference period (1971–2000). Such an inverse north–south spatial pattern is closely related to the spatial varying impact of vegetation greening, which enhances evapotranspiration and intensifies drought in the water-limited regions (e.g., North China) but has limited effect on evapotranspiration in the energy-limited regions (e.g., South China). Meanwhile, the physiological effects of CO2 mainly mitigate the drought and show small spatial variations. The national mean contribution of climate change, LAI change and CO2 physiological effects to future drought changes are 49 ∼ 54 %, 19 ∼ 27 % and 22 ∼ 28 %, respectively. And the relative importance of ecological factors would increase to >50 % when focusing on the difference among different warming levels. This study highlights the importance of direct vegetation response to CO2 rise in drought projections. © 2025 Elsevier B.V.

关键词： Soil moisture

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Development of Climate and Earth System Models in China: Past Achievements and New CMIP6 Results

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Journal of Meteorological Research 2020年第1期34卷 1-19页

作者： Tianjun ZHOU Ziming CHEN Liwei ZOU Xiaolong CHEN Yongqiang YU Bin WANG Qing BAO Ying BAO Jian CAO Bian HE Shuai HU Lijuan LI Jian LI Yanluan LIN Libin MA Fangli QIAO Xinyao RONG Zhenya SONG Yanli TANG Bo WU Tongwen WU Xiaoge XIN He ZHANG Minghua ZHANG State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049 First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061 School of Atmospheric Science Nanjing University of Information Science&TechnologyNanjing 210044 Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing 100081 Tsinghua University Beijing 100084 National Climate Center China Meteorological AdministrationBeijing 100081 International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029

The Earth–Climate System Model(ECSM)is an important platform for multi-disciplinary and multi-sphere integration research,and its development is at the frontier of international geosciences,especially in the field of global *** research and development(R&D)of ECSM in China began in the 1980 s and have achieved great *** China,ECSMs are now mainly developed at the Chinese Academy of sciences,ministries,and *** a brief review of the development history of Chinese ECSMs,this paper summarized the technical characteristics of nine Chinese ECSMs participating in the Coupled Model Intercomparison Project Phase 6 and preliminarily assessed the basic performances of four Chinese models in simulating the global climate and the climate in East *** projected changes of global precipitation and surface air temperature and the associated relationship with the equilibrium climate sensitivity under four shared socioeconomic path scenarios were also ***,combined with the international situation,from the perspective of further improvement,eight directions were proposed for the future development of Chinese ECSMs.

关键词： Earth–Climate System Model(ECSM) Chinese models Coupled Model Intercomparison Project Phase 6(CMIP6) model performance climate prediction and projection outlook

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Performance analysis of one-step prediction-based cognitive jamming in jammer-radar countermeasure model

Performance analysis of one-step prediction-based cognitive ...

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IET International Radar Conference 2018, IRC 2018

作者： Gao, Lu Liu, Li Cao, Yang Wang, Shangyue You, Shixun National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China DFH Satellite Co. Ltd Beijing China Harbin Engineering University 145 Nantong Street Nangang District Harbin China

Strong adaptive radar, such as cognitive radar (CNR), can perform various missions while ensuring its own security in electronic warfare, via detecting environments and changing the radar parameters in real time. Unfortunately, most of the current military countermeasures, such as jamming-based electronic countermeasures, have rarely been related to jamming for CNR. Since the behaviours of radar in the traditional design of the jammer-radar scenario are always static, it is easy to create a subjective or local optimal jamming effect. In order to dynamically analyse the execution process of a complete jamming radar mission, this work establishes an equivalent attack-defence game in which the radar is regarded as a defence decision agent, and the jammer is an attack decision agent. The attributes of the game's players, the rules of the game, and the conditions for the end of the game are set clearly by setting reasonable parameters. After searching for antagonism strategies by exhaustive method, it can be found that the survivability of the predictive cognitive jamming is much stronger than that of the normal jamming based on real-time sampling data of radars. This conclusion is demonstrated through a 1 ms simulation of the game process. © This is an open access article published by the IET under the Creative Commons Attribution License (http://***/licenses/by/3.0/)

关键词： Jamming

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Adaptive feed-forward control for seeker based on the disturbance observer

Adaptive feed-forward control for seeker based on the distur...

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IEEE Advanced Information technology, Electronic and Automation Control Conference (IAEAC)

作者： Xin Liu Zhenhong Niu Yi Shu Lian Xue Mingchao Zhu National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences

In order to improve the tracking and stabilization performance, a control method combining disturbance observer and adaptive feed-forward control using parameterization is proposed for seeker stabilized platforms. The system identification algorithm is used to identify dynamic model of the true plant. Then the discrete-time disturbance observer is designed. The feedback loop controller is designed using pole-placement techniques. The recursive least square (RLS) adaptive filter is used to build the inverse model of the feedback control loop and in this way, the feed-forward control is constructed. The adaptive filter and the feedback loop constitute a control scheme with two degrees-of-freedom (DOF). Tracking experiments conducted on velocity command inputs verify the validity of the adaptive feed-forward controller. Experimental results show that this method responses quickly to commands. For a sinusoidal signal at the frequency of 30Hz, the adaptive feed-forward controller can obtain an amplitude response without attenuation and the phase lag is reduced to 11° in contrast with the feedback control whose phase lag is 60°. This method significantly improves the transient performance and is superior to the feedback control alone.

关键词： Adaptive filters Feedback control Disturbance observers Feedforward systems Low pass filters Tracking loops Stability analysis

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A Direct Position Determination Method for Four-station TDOA Location System

A Direct Position Determination Method for Four-station TDOA...

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Signal, Information and Data Processing (ICSIDP), IEEE International Conference on

作者： Sun-Rui Qi Chen-Shun Yuan Bai-Jin Liang Gao-Lu Li-Hu Sun-Heng BEIJING INSTITUTE OF SPACE LONG MARCH VEHICLE National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

Aiming at the four-station networked TDOA (Time Difference of Arrival) localization system, a direct location method based on electronic elevation map search is proposed, the Geometric Dilution Precision (GDOP) is derived, and the factors affecting the location accuracy are analyzed. The location method under real conditions is also simulated, and its feasibility is demonstrated, which provides a new engineering method for networked TDOA location.

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