Wavelet transform method is applied to measure time-frequency distribution characteristics of digital deformation data and noise. Based on the characteristics of primary modulus and stochastic white noise discriminati...Wavelet transform method is applied to measure time-frequency distribution characteristics of digital deformation data and noise. Based on the characteristics of primary modulus and stochastic white noise discrimination factor of wavelet decomposition, we analyze the variation rule of normal background and noise data from Shandong digital deformation observation data. The research results indicate that: a) 1/4 daily wave, semi-diurnal tide wave, daily wave and half lunar wave and so on quasi-periodic signal exist in the detail decomposing signal of wavelet when scale are equal to 2, 3 and 4; b) The amplitude of detail decomposing signal is the biggest when scale is equal to 3; c) The detail decomposing signal contains mainly noise corresponding to scale 1 and 5, respectively; d) We may trace the abnormal precursory which is related to earthquake by analyzing non-earthquake wavelet decomposing signal whose scale is specified from digital deformation observation data.展开更多
The effort and cost required to convert satellite Earth Observation(EO)data into meaningful geophysical variables has prevented the systematic analysis of all available observations.To overcome these problems,we utili...The effort and cost required to convert satellite Earth Observation(EO)data into meaningful geophysical variables has prevented the systematic analysis of all available observations.To overcome these problems,we utilise an integrated High Performance Computing and Data environment to rapidly process,restructure and analyse the Australian Landsat data archive.In this approach,the EO data are assigned to a common grid framework that spans the full geospatial and temporal extent of the observations–the EO Data Cube.This approach is pixel-based and incorporates geometric and spectral calibration and quality assurance of each Earth surface reflectance measurement.We demonstrate the utility of the approach with rapid time-series mapping of surface water across the entire Australian continent using 27 years of continuous,25 m resolution observations.Our preliminary analysis of the Landsat archive shows how the EO Data Cube can effectively liberate high-resolution EO data from their complex sensor-specific data structures and revolutionise our ability to measure environmental change.展开更多
The technological landscape for managing big Earth observation(EO)data ranges from global solutions on large cloud infrastructures with web-based access to self-hosted implementations.EO data cubes are a leading techn...The technological landscape for managing big Earth observation(EO)data ranges from global solutions on large cloud infrastructures with web-based access to self-hosted implementations.EO data cubes are a leading technology for facilitating big EO data analysis and can be deployed on different spatial scales:local,national,regional,or global.Several EO data cubes with a geographic focus(“local EO data cubes”)have been implemented.However,their alignment with the Digital Earth(DE)vision and the benefits and trade-offs in creating and maintaining them ought to be further examined.We investigate local EO data cubes from five perspectives(science,business and industry,government and policy,education,communities and citizens)and illustrate four examples covering three continents at different geographic scales(Swiss Data Cube,semantic EO data cube for Austria,DE Africa,Virginia Data Cube).A local EO data cube can benefit many stakeholders and players but requires several technical developments.These developments include enabling local EO data cubes based on public,global,and cloud-native EO data streaming and interoperability between local EO data cubes.We argue that blurring the dichotomy between global and local aligns with the DE vision to access the world’s knowledge and explore information about the planet.展开更多
Data Fusion is one of the attractive topic in sonar signal processing. Decision level data fusion of multi-sensor (multi-array) system is described in this paper. The optimum linear data fusion algorithm for N indepen...Data Fusion is one of the attractive topic in sonar signal processing. Decision level data fusion of multi-sensor (multi-array) system is described in this paper. The optimum linear data fusion algorithm for N independent observation data is derived. It is proved that the estimation error of optimum data fusion is not greater than that of individual components. The expression of estimation error and weight coefficients are presented. The results of numerical calculation and some examples are illustrated. The effect of input signal to noise ratio for the data fusion is described.展开更多
Research and application of big data mining,at present,is a hot issue. This paper briefly introduces the basic ideas of big data research, analyses the necessity of big data application in earthquake precursor observa...Research and application of big data mining,at present,is a hot issue. This paper briefly introduces the basic ideas of big data research, analyses the necessity of big data application in earthquake precursor observation,and probes certain issues and solutions when applying this technology to work in the seismic-related domain. By doing so,we hope it can promote the innovative use of big data in earthquake precursor observation data analysis.展开更多
Based on the diurnal consecutively observed data in the offshore area of Jiaonan in 2005, the paper tries to make a preliminary analysis of the specificity of ocean currents, tidal current property and residual curren...Based on the diurnal consecutively observed data in the offshore area of Jiaonan in 2005, the paper tries to make a preliminary analysis of the specificity of ocean currents, tidal current property and residual current property in the area in observing dates. Then on the basis of observed data analysis and by employing the split-step method, the paper conducts a numerical simulation of the tidal current field, which can show the M2 tidal constituent tidal wave system, current ellipse distribution, maximum current velocity distribution and time-dependent current field. The calculated results agree well with the observed data, which can on the one hand reflect the basic specificities of temporal and spatial distribution of the M2 tidal constituent current field to some extent, and, on the other hand, offer more information about the hydrodynamic condition. So the paper would provide a scientific basis for the making of sea environment protection plans in the offshore area of Jiaonan under certain conditions.展开更多
This study presents the utility of remote sensing （RS）, GIS and field observation data to estimate above ground biomass （AGB） and stem volume over tropical forest environment. Application of those data for the mod...This study presents the utility of remote sensing （RS）, GIS and field observation data to estimate above ground biomass （AGB） and stem volume over tropical forest environment. Application of those data for the modeling of forest properties is site specific and highly uncertain, thus further study is encouraged. In this study we used 1460 sampling plots collected in 16 transects measuring tree diameter （DBH） and other forest properties which were useful for the biomass assessment. The study was carded out in tropical forest region in East Kalimantan, Indo- nesia. The AGB density was estimated applying an existing DBH - biomass equation. The estimate was superimposed over the modified GIS map of the study area, and the biomass density of each land cover was calculated. The RS approach was performed using a subset of sample data to develop the AGB and stem volume linear equation models. Pearson correlation statistics test was conducted using ETM bands reflectance, vegetation indices, image transform layers, Principal Component Analysis （PCA） bands, Tasseled Cap （TC）, Grey Level Co-Occurrence Matrix （GLCM） texture features and DEM data as the predictors. Two linear models were generated from the significant RS data. To analyze total biomass and stem volume of each land cover, Landsat ETM images from 2000 and 2003 were preprocessed, classified using maximum likelihood method, and filtered with the majority analysis. We found 158±16 m^3.ha^-1 of stem volume and 168±15 t.ha^-1 of AGB estimated from RS approach, whereas the field measurement and GIS estimated 157±92 m^3.ha^-1 and 167±94 t.ha^-1 of stem volume and AGB, respectively. The dynamics of biomass abundance from 2000 to 2003 were assessed from multi temporal ETM data and we found a slightly declining trend of total biomass over these periods. Remote sensing approach estimated lower biomass abundance than did the GIS and field measurement data. The earlier approach predicted 10.5 Gt and 10.3 Gt of total biomasses in 2000 and 2003, while the later estimated 11.9 Gt and 11.6 Gt of total biomasses, respectively. We found that GLCM mean texture features showed markedly strong correlations with stem volume and biomass.展开更多
The objective,connotations and research issues of big geodata mining were discussed to address its significance to geographical research in this paper.Big geodata may be categorized into two domains:big earth observat...The objective,connotations and research issues of big geodata mining were discussed to address its significance to geographical research in this paper.Big geodata may be categorized into two domains:big earth observation data and big human behavior data.A description of big geodata includes,in addition to the“5Vs”(volume,velocity,value,variety and veracity),a further five features,that is,granularity,scope,density,skewness and precision.Based on this approach,the essence of mining big geodata includes four aspects.First,flow space,where flow replaces points in traditional space,will become the new presentation form for big human behavior data.Second,the objectives for mining big geodata are the spatial patterns and the spatial relationships.Third,the spatiotemporal distributions of big geodata can be viewed as overlays of multiple geographic patterns and the characteristics of the data,namely heterogeneity and homogeneity,may change with scale.Fourth,data mining can be seen as a tool for discovery of geographic patterns and the patterns revealed may be attributed to human-land relationships.The big geodata mining methods may be categorized into two types in view of the mining objective,i.e.,classification mining and relationship mining.Future research will be faced by a number of issues,including the aggregation and connection of big geodata,the effective evaluation of the mining results and the challenge for mining to reveal“non-trivial”knowledge.展开更多
The abilities of typhoon (TC) track prediction by a medium-range forecast model T213L31 at National Meteorological Center are analyzed and its ability to improve its TC forecasts is discussed. The results show that ab...The abilities of typhoon (TC) track prediction by a medium-range forecast model T213L31 at National Meteorological Center are analyzed and its ability to improve its TC forecasts is discussed. The results show that about 57% of the TCs could be predicted by T213L31 but the initial position errors are large. The 43% area without the prediction of TC tracks is concentrated between 13°N and 20°N and east of 120°E and lack of conventional observation data is the main reason for the absence of TC prediction in this area. The adding of bogus TC could improve the ability of TC track prediction when there is no TC vortex in the analysis field, but could only have positive effects on the short-range TC track prediction when there is TC vortex in the T213L31 analysis field.展开更多
Data Center of Xinjiang Astronomical Observatory(XAO-DC)commenced operating in 2015,and provides services including archiving,releasing and retrieving precious astronomical data collected by the Nanshan 26 m Radio Tel...Data Center of Xinjiang Astronomical Observatory(XAO-DC)commenced operating in 2015,and provides services including archiving,releasing and retrieving precious astronomical data collected by the Nanshan 26 m Radio Telescope(NSRT)over the years,and realises the open sharing of astronomical observation data.The observation data from NSRT are transmitted to XAO-DC 100 km away through dedicated fiber for long-term storage.With the continuous increase of data,the static architecture of the current network cannot meet NSRT data-transmission requirements due to limited network bandwidth.To get high-speed data-transmission using the existing static network architecture,a method for reconstruction data-transmission network using Software-Defined Networks(SDN)is proposed.Benefit from the SDN’s data and control plane separation,and open programmable,combined with the Mininet simulation platform for experiments,the TCP throughput(of single thread)was improved by~24.7%,the TCP throughput(of multi threads)was improved by~9.8%,~40.9%,~35.5%and~11.7%.Compared with the current network architecture,the Latency was reduced by~63.2%.展开更多
By integrating observational data with dynamic models,data assimilation(DA)refines background state estimates,producing more accurate analysis fields and improving predictive performance.As modern environmental and at...By integrating observational data with dynamic models,data assimilation(DA)refines background state estimates,producing more accurate analysis fields and improving predictive performance.As modern environmental and atmospheric models continue to increase in spatial resolution,the volume of observational data expands accordingly,resulting in substantially higher computational demands for DA.展开更多
In this paper,a quantum-enhanced framework is proposed to optimize observation point selection in environmental data assimilation.The method transforms the task into a QUBO problem,balancing uncertainty reduction and ...In this paper,a quantum-enhanced framework is proposed to optimize observation point selection in environmental data assimilation.The method transforms the task into a QUBO problem,balancing uncertainty reduction and spatial diversity.By leveraging a quantum-inspired optical Ising machine,it avoids the exponential complexity of classical optimization.Tests on the Lorenz-1996 model demonstrate its superiority over traditional methods,enhancing computational efficiency without loss of accuracy.The findings underscore the potential of quantum-inspired optimization for scalable,real-time assimilation in highresolution weather prediction,reducing dimensionality and computational cost.展开更多
To analyze the effects of gas cannons on clouds and precipitation,multisource observational data,including those from National Centers for Environmental Prediction(NCEP)reanalysis,Hangzhou and Huzhou new-generation we...To analyze the effects of gas cannons on clouds and precipitation,multisource observational data,including those from National Centers for Environmental Prediction(NCEP)reanalysis,Hangzhou and Huzhou new-generation weather radars,laser disdrometer,ground-based automatic weather station,wind profiler radar,and Lin'an C-band dualpolarization radar,were adopted in this study.Based on the variational dual-Doppler wind retrieval method and the polarimetric variables obtained by the dual-polarization radar,we analyzed the microphysical processes and the variations in the macro-and microphysical quantities in clouds from the perspective of the synoptic background before precipitation enhancement,the polarization echo characteristics before,during and after enhancement,and the evolution of the fine three-dimensional kinematic structure and the microphysical structure.The results show that the precipitation enhancement operation promoted the development of radar echoes and prolonged their duration,and both the horizontal and vertical wind speeds increased.The dual-polarization radar echo showed that the diameter of the precipitation particles increased,and the concentration of raindrops increased after precipitation enhancement.The raindrops were lifted to a height corresponding to 0 to-20℃due to vertical updrafts.Based on the disdrometer data during precipitation enhancement,the concentration of small raindrops(lgN_(w))showed a significant increase,and the mass-weighted diameter D_(m)value decreased,indicating that the precipitation enhancement operation played a certain“lubricating”effect.After the precipitation enhancement,the concentration of raindrops did not change much compared with that during the enhancement process,while the Dm increased,corresponding to an increase in rain intensity.The results suggest the positive effect of gas cannons on precipitation enhancement.展开更多
We investigate the influence of population density on radio-frequency inter- ference （RFI） affecting radio astronomy. We use a new method to quantify the thresh- old of population density in order to determine the m...We investigate the influence of population density on radio-frequency inter- ference （RFI） affecting radio astronomy. We use a new method to quantify the thresh- old of population density in order to determine the most suitable lower limit for site selection of a radio quiet zone （RQZ）. We found that there is a certain trend in the population density-RFI graph that increases rapidly at lower values and slows down to almost fiat at higher values. We use this trend to identify the thresholds for pop- ulation density that produce RFI. Using this method we found that, for frequencies up to 2.8 GHz, low, medium and high population densities affecting radio astronomy are below 150 ppl km-2, between i50 ppl km-2 and 5125 ppl km-~, and above 5125 ppl km-2 respectively. We also investigate the effect of population density on the environment of RFI in three astronomical windows, namely the deuterium, hydro- gen and hydroxyl lines. We find that a polynomial fitting to the population density produces a similar trend, giving similar thresholds for the effect of population density. We then compare our interference values to the standard threshold levels used by the International Telecommunication Union within these astronomical windows.展开更多
Data assimilation(DA)is a technique that integrates multisource observational data with numerical models to enhance simulation accuracy and optimize data utilization.Its core principle involves correcting biases in mo...Data assimilation(DA)is a technique that integrates multisource observational data with numerical models to enhance simulation accuracy and optimize data utilization.Its core principle involves correcting biases in model simulations using observational data while automatically selecting the most reliable observations.In essence,DA employs mathematical techniques to refine simulations,ensuring they reflect real-world measurements more accurately.展开更多
Given the heightened competition for water in energy,food,and the environment in Africa,it is essential to implement sound integrated plans for basin or regional sustainable development.Zambezi River Basin(ZRB),one of...Given the heightened competition for water in energy,food,and the environment in Africa,it is essential to implement sound integrated plans for basin or regional sustainable development.Zambezi River Basin(ZRB),one of the least developed basins in the world,is under development with great ambition for hydropower and irrigation infrastructure.Here,we proposed a framework to assess different water usage trajectories for agricultural and hydropower development scenarios with data derived from big earth data method.Three future scenarios were set for irrigaiton expansion and development hydropower construction according to current plan,global average and high level,respectively.Using spatial analysis methods,average evapotranspiration(ET)difference before and after irrigation expansion and reservoir construction was used to estimate water usage trajectories.Results show that the total available water resource for ZRB is estimated as 111.8 km3.Due to irrigation and reservoirs construction,additional annual water consumption is estimated to be 0.9 and 14.2 km3 for 2017,respectively.By analyzing the water-energy-food-environment(WEFE)nexus given water availability constraints,we found that the water development boundary in the ZRB could support increases in both irrigation proportion and dam density to global average levels of 20%and 0.56/104 km2,respectively,without degrading the environment.The proposed paradigm for assessing water resources has the potential to endow the ZRB with significant capacity to support the achievement of relevant Sustainable Development Goals(SDGs).展开更多
Fault deformation characteristics in the northern margin of the Tibetan Plateau before the Menyuan Ms6.4 earthquake are investigated through time-series and structural geological analysis based on cross-fault observat...Fault deformation characteristics in the northern margin of the Tibetan Plateau before the Menyuan Ms6.4 earthquake are investigated through time-series and structural geological analysis based on cross-fault observation data from the Qilian Mountain-Haiyuan Fault belt and the West Qinling Fault belt. The results indicate： 1） Group short-term abnormal variations appeared in the Qilian Mountain-Haiyuan Fault belt and the West Qinling Fault belt before the Menyuan Ms6.4 earthquake. 2） More medium and short-term anomalies appear in the middle-eastern segment of the Qilian Mountain Fault belt and the West Qinling Fault belt, suggesting that the faults＇ activities are strong in these areas. The faults＇ activities in the middle-eastern segment of the Qilian Fault belt result from extensional stress, as before the earthquake, whereas those in the West Qinling Fault belt are mainly compressional. 3） In recent years, moderate-strong earthquakes occurred in both the Kunlun Mountain and the Qilian Mountain Fault belts, and some energy was released. It is possible that the seismicity moved eastward under this regime. Therefore, we should pay attention to the West Qinling Mountain area where an Ms6-7 earthquake could occur in future.展开更多
The central Pacific（CP） zonal wind divergence and convergence indices are defined, and the forming mechanism of CP El Nio（La Nia） events is discussed preliminarily. The results show that the divergence and converg...The central Pacific（CP） zonal wind divergence and convergence indices are defined, and the forming mechanism of CP El Nio（La Nia） events is discussed preliminarily. The results show that the divergence and convergence of the zonal wind anomaly（ZWA） are the key process in the forming of CP El Nio（La Nia） events. A correlation analysis between the central Pacific zonal wind divergence and convergence indices and central Pacific El Nio indices indicates that there is a remarkable lag correlation between them. The central Pacific zonal wind divergence and convergence indices can be used to predict the CP events. Based on these results, a linear regression equation is obtained to predict the CP El Nio（La Nia） events 5 months ahead.展开更多
In order to improve the accuracy of free flight conflict detection and reduce the false alarm rate, an improved flight conflict detection algorithm is proposed based on Gauss-Hermite particle filter（GHPF）. The algor...In order to improve the accuracy of free flight conflict detection and reduce the false alarm rate, an improved flight conflict detection algorithm is proposed based on Gauss-Hermite particle filter（GHPF）. The algorithm improves the traditional flight conflict detection method in two aspects：（i） New observation data are integrated into system state transition probability, and Gauss-Hermite Filter（GHF） is used for generating the importance density function.（ii） GHPF is used for flight trajectory prediction and flight conflict probability calculation. The experimental results show that the accuracy of conflict detection and tracing with GHPF is better than that with standard particle filter. The detected conflict probability is more precise with GHPF, and GHPF is suitable for early free flight conflict detection.展开更多
Using the non-hydrostatic meso-scale model MM5v3, dense fog that occurred from March 7 to March 8, 2001 over the Mts. Nanling area was studied. With integrated field experiments and observations, the occurrence, devel...Using the non-hydrostatic meso-scale model MM5v3, dense fog that occurred from March 7 to March 8, 2001 over the Mts. Nanling area was studied. With integrated field experiments and observations, the occurrence, development and lift mechanism of fog were analyzed. The results indicate that before the coming of stratiform clouds, southerly warm and wet air ascended along mountainside and cooling condensation formed mountain fog. Then fog was formed by the stratiform on cloud-contacting mountaintop. A front inversion layer accelerated the development and extended the duration of the lower cloud and fog. The intensity, occurrence time, mass content and the variation of temperature and relative humidity of the fog agreed with those of the observation. It showed that the meso-scale model has the potential to forecast mountain fog.展开更多
基金Natural Science Foundation of Shandong Province (Y2000E08) the bargain item of China Earthquake Administration in the year 2002.
文摘Wavelet transform method is applied to measure time-frequency distribution characteristics of digital deformation data and noise. Based on the characteristics of primary modulus and stochastic white noise discrimination factor of wavelet decomposition, we analyze the variation rule of normal background and noise data from Shandong digital deformation observation data. The research results indicate that: a) 1/4 daily wave, semi-diurnal tide wave, daily wave and half lunar wave and so on quasi-periodic signal exist in the detail decomposing signal of wavelet when scale are equal to 2, 3 and 4; b) The amplitude of detail decomposing signal is the biggest when scale is equal to 3; c) The detail decomposing signal contains mainly noise corresponding to scale 1 and 5, respectively; d) We may trace the abnormal precursory which is related to earthquake by analyzing non-earthquake wavelet decomposing signal whose scale is specified from digital deformation observation data.
文摘The effort and cost required to convert satellite Earth Observation(EO)data into meaningful geophysical variables has prevented the systematic analysis of all available observations.To overcome these problems,we utilise an integrated High Performance Computing and Data environment to rapidly process,restructure and analyse the Australian Landsat data archive.In this approach,the EO data are assigned to a common grid framework that spans the full geospatial and temporal extent of the observations–the EO Data Cube.This approach is pixel-based and incorporates geometric and spectral calibration and quality assurance of each Earth surface reflectance measurement.We demonstrate the utility of the approach with rapid time-series mapping of surface water across the entire Australian continent using 27 years of continuous,25 m resolution observations.Our preliminary analysis of the Landsat archive shows how the EO Data Cube can effectively liberate high-resolution EO data from their complex sensor-specific data structures and revolutionise our ability to measure environmental change.
基金the Austrian Research Promotion Agency(FFG)under the Austrian Space Application Programme(ASAP)within the projects Sen2Cube.at(project no.:866016)SemantiX(project no.:878939)SIMS(project no.:885365).
文摘The technological landscape for managing big Earth observation(EO)data ranges from global solutions on large cloud infrastructures with web-based access to self-hosted implementations.EO data cubes are a leading technology for facilitating big EO data analysis and can be deployed on different spatial scales:local,national,regional,or global.Several EO data cubes with a geographic focus(“local EO data cubes”)have been implemented.However,their alignment with the Digital Earth(DE)vision and the benefits and trade-offs in creating and maintaining them ought to be further examined.We investigate local EO data cubes from five perspectives(science,business and industry,government and policy,education,communities and citizens)and illustrate four examples covering three continents at different geographic scales(Swiss Data Cube,semantic EO data cube for Austria,DE Africa,Virginia Data Cube).A local EO data cube can benefit many stakeholders and players but requires several technical developments.These developments include enabling local EO data cubes based on public,global,and cloud-native EO data streaming and interoperability between local EO data cubes.We argue that blurring the dichotomy between global and local aligns with the DE vision to access the world’s knowledge and explore information about the planet.
文摘Data Fusion is one of the attractive topic in sonar signal processing. Decision level data fusion of multi-sensor (multi-array) system is described in this paper. The optimum linear data fusion algorithm for N independent observation data is derived. It is proved that the estimation error of optimum data fusion is not greater than that of individual components. The expression of estimation error and weight coefficients are presented. The results of numerical calculation and some examples are illustrated. The effect of input signal to noise ratio for the data fusion is described.
基金sponsored by the Earthquake Monitoring Special Project of "Precursor Observation Data Mining",Key Laboratory of Crustal Dynamics,Institute of Crustal Dynamics,China Earthquake Administration
文摘Research and application of big data mining,at present,is a hot issue. This paper briefly introduces the basic ideas of big data research, analyses the necessity of big data application in earthquake precursor observation,and probes certain issues and solutions when applying this technology to work in the seismic-related domain. By doing so,we hope it can promote the innovative use of big data in earthquake precursor observation data analysis.
文摘Based on the diurnal consecutively observed data in the offshore area of Jiaonan in 2005, the paper tries to make a preliminary analysis of the specificity of ocean currents, tidal current property and residual current property in the area in observing dates. Then on the basis of observed data analysis and by employing the split-step method, the paper conducts a numerical simulation of the tidal current field, which can show the M2 tidal constituent tidal wave system, current ellipse distribution, maximum current velocity distribution and time-dependent current field. The calculated results agree well with the observed data, which can on the one hand reflect the basic specificities of temporal and spatial distribution of the M2 tidal constituent current field to some extent, and, on the other hand, offer more information about the hydrodynamic condition. So the paper would provide a scientific basis for the making of sea environment protection plans in the offshore area of Jiaonan under certain conditions.
文摘This study presents the utility of remote sensing （RS）, GIS and field observation data to estimate above ground biomass （AGB） and stem volume over tropical forest environment. Application of those data for the modeling of forest properties is site specific and highly uncertain, thus further study is encouraged. In this study we used 1460 sampling plots collected in 16 transects measuring tree diameter （DBH） and other forest properties which were useful for the biomass assessment. The study was carded out in tropical forest region in East Kalimantan, Indo- nesia. The AGB density was estimated applying an existing DBH - biomass equation. The estimate was superimposed over the modified GIS map of the study area, and the biomass density of each land cover was calculated. The RS approach was performed using a subset of sample data to develop the AGB and stem volume linear equation models. Pearson correlation statistics test was conducted using ETM bands reflectance, vegetation indices, image transform layers, Principal Component Analysis （PCA） bands, Tasseled Cap （TC）, Grey Level Co-Occurrence Matrix （GLCM） texture features and DEM data as the predictors. Two linear models were generated from the significant RS data. To analyze total biomass and stem volume of each land cover, Landsat ETM images from 2000 and 2003 were preprocessed, classified using maximum likelihood method, and filtered with the majority analysis. We found 158±16 m^3.ha^-1 of stem volume and 168±15 t.ha^-1 of AGB estimated from RS approach, whereas the field measurement and GIS estimated 157±92 m^3.ha^-1 and 167±94 t.ha^-1 of stem volume and AGB, respectively. The dynamics of biomass abundance from 2000 to 2003 were assessed from multi temporal ETM data and we found a slightly declining trend of total biomass over these periods. Remote sensing approach estimated lower biomass abundance than did the GIS and field measurement data. The earlier approach predicted 10.5 Gt and 10.3 Gt of total biomasses in 2000 and 2003, while the later estimated 11.9 Gt and 11.6 Gt of total biomasses, respectively. We found that GLCM mean texture features showed markedly strong correlations with stem volume and biomass.
基金National Natural Science Foundation of China,No.41525004,No.41421001。
文摘The objective,connotations and research issues of big geodata mining were discussed to address its significance to geographical research in this paper.Big geodata may be categorized into two domains:big earth observation data and big human behavior data.A description of big geodata includes,in addition to the“5Vs”(volume,velocity,value,variety and veracity),a further five features,that is,granularity,scope,density,skewness and precision.Based on this approach,the essence of mining big geodata includes four aspects.First,flow space,where flow replaces points in traditional space,will become the new presentation form for big human behavior data.Second,the objectives for mining big geodata are the spatial patterns and the spatial relationships.Third,the spatiotemporal distributions of big geodata can be viewed as overlays of multiple geographic patterns and the characteristics of the data,namely heterogeneity and homogeneity,may change with scale.Fourth,data mining can be seen as a tool for discovery of geographic patterns and the patterns revealed may be attributed to human-land relationships.The big geodata mining methods may be categorized into two types in view of the mining objective,i.e.,classification mining and relationship mining.Future research will be faced by a number of issues,including the aggregation and connection of big geodata,the effective evaluation of the mining results and the challenge for mining to reveal“non-trivial”knowledge.
文摘The abilities of typhoon (TC) track prediction by a medium-range forecast model T213L31 at National Meteorological Center are analyzed and its ability to improve its TC forecasts is discussed. The results show that about 57% of the TCs could be predicted by T213L31 but the initial position errors are large. The 43% area without the prediction of TC tracks is concentrated between 13°N and 20°N and east of 120°E and lack of conventional observation data is the main reason for the absence of TC prediction in this area. The adding of bogus TC could improve the ability of TC track prediction when there is no TC vortex in the analysis field, but could only have positive effects on the short-range TC track prediction when there is TC vortex in the T213L31 analysis field.
基金the National Natural Science Foundation of China(NSFC,Grant Nos.11803080,11873082 and 12003062)the National Key Research and Development Program of China(2018YFA0404704)+3 种基金the Youth Innovation Promotion Association,Chinese Academy of Sciences(CAS)the program of the Light in China’s Western Region(2019-XBQNXZ-B-018)supported by China National Astronomical Data Center(NADC)supported by Astronomical Big Data Joint Research Center,co-founded by National Astronomical Observatories,CAS。
文摘Data Center of Xinjiang Astronomical Observatory(XAO-DC)commenced operating in 2015,and provides services including archiving,releasing and retrieving precious astronomical data collected by the Nanshan 26 m Radio Telescope(NSRT)over the years,and realises the open sharing of astronomical observation data.The observation data from NSRT are transmitted to XAO-DC 100 km away through dedicated fiber for long-term storage.With the continuous increase of data,the static architecture of the current network cannot meet NSRT data-transmission requirements due to limited network bandwidth.To get high-speed data-transmission using the existing static network architecture,a method for reconstruction data-transmission network using Software-Defined Networks(SDN)is proposed.Benefit from the SDN’s data and control plane separation,and open programmable,combined with the Mininet simulation platform for experiments,the TCP throughput(of single thread)was improved by~24.7%,the TCP throughput(of multi threads)was improved by~9.8%,~40.9%,~35.5%and~11.7%.Compared with the current network architecture,the Latency was reduced by~63.2%.
文摘By integrating observational data with dynamic models,data assimilation(DA)refines background state estimates,producing more accurate analysis fields and improving predictive performance.As modern environmental and atmospheric models continue to increase in spatial resolution,the volume of observational data expands accordingly,resulting in substantially higher computational demands for DA.
基金supported by the National Natural Science Foundation of China(Grant No.62471058)the State Key Laboratory of Information Photonics and Optical Communications,Beijing University of Posts and Telecommunications,China(Grant No.IPOC2022ZT10)。
文摘In this paper,a quantum-enhanced framework is proposed to optimize observation point selection in environmental data assimilation.The method transforms the task into a QUBO problem,balancing uncertainty reduction and spatial diversity.By leveraging a quantum-inspired optical Ising machine,it avoids the exponential complexity of classical optimization.Tests on the Lorenz-1996 model demonstrate its superiority over traditional methods,enhancing computational efficiency without loss of accuracy.The findings underscore the potential of quantum-inspired optimization for scalable,real-time assimilation in highresolution weather prediction,reducing dimensionality and computational cost.
基金National Natural Science Foundation of China(41675029)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX18_0998)+1 种基金Science and Technology Program of Huzhou(2021GZ14,2020GZ31)Science and Technology(Key)Program of Zhejiang Meteorological Service(2021ZD27)。
文摘To analyze the effects of gas cannons on clouds and precipitation,multisource observational data,including those from National Centers for Environmental Prediction(NCEP)reanalysis,Hangzhou and Huzhou new-generation weather radars,laser disdrometer,ground-based automatic weather station,wind profiler radar,and Lin'an C-band dualpolarization radar,were adopted in this study.Based on the variational dual-Doppler wind retrieval method and the polarimetric variables obtained by the dual-polarization radar,we analyzed the microphysical processes and the variations in the macro-and microphysical quantities in clouds from the perspective of the synoptic background before precipitation enhancement,the polarization echo characteristics before,during and after enhancement,and the evolution of the fine three-dimensional kinematic structure and the microphysical structure.The results show that the precipitation enhancement operation promoted the development of radar echoes and prolonged their duration,and both the horizontal and vertical wind speeds increased.The dual-polarization radar echo showed that the diameter of the precipitation particles increased,and the concentration of raindrops increased after precipitation enhancement.The raindrops were lifted to a height corresponding to 0 to-20℃due to vertical updrafts.Based on the disdrometer data during precipitation enhancement,the concentration of small raindrops(lgN_(w))showed a significant increase,and the mass-weighted diameter D_(m)value decreased,indicating that the precipitation enhancement operation played a certain“lubricating”effect.After the precipitation enhancement,the concentration of raindrops did not change much compared with that during the enhancement process,while the Dm increased,corresponding to an increase in rain intensity.The results suggest the positive effect of gas cannons on precipitation enhancement.
基金made possible by the usage of the University of Malaya’s grants UMRG(RG118-10AFR),IPPP(PV025-2011A)and HIR(H-21001-F000028)Universiti Sultan Zainal Abidin(UniSZA)and the Ministry of Higher Education(MOHE)for their sponsorship
文摘We investigate the influence of population density on radio-frequency inter- ference （RFI） affecting radio astronomy. We use a new method to quantify the thresh- old of population density in order to determine the most suitable lower limit for site selection of a radio quiet zone （RQZ）. We found that there is a certain trend in the population density-RFI graph that increases rapidly at lower values and slows down to almost fiat at higher values. We use this trend to identify the thresholds for pop- ulation density that produce RFI. Using this method we found that, for frequencies up to 2.8 GHz, low, medium and high population densities affecting radio astronomy are below 150 ppl km-2, between i50 ppl km-2 and 5125 ppl km-~, and above 5125 ppl km-2 respectively. We also investigate the effect of population density on the environment of RFI in three astronomical windows, namely the deuterium, hydro- gen and hydroxyl lines. We find that a polynomial fitting to the population density produces a similar trend, giving similar thresholds for the effect of population density. We then compare our interference values to the standard threshold levels used by the International Telecommunication Union within these astronomical windows.
基金supported by the National Natural Science Foundation of China(Grant No.42125502)the National Key Research and Development Program of China(Grant No.2024YFF0807903)。
文摘Data assimilation(DA)is a technique that integrates multisource observational data with numerical models to enhance simulation accuracy and optimize data utilization.Its core principle involves correcting biases in model simulations using observational data while automatically selecting the most reliable observations.In essence,DA employs mathematical techniques to refine simulations,ensuring they reflect real-world measurements more accurately.
基金Under the auspices of National Natural Science Foundation of China(No.41861144019,W2412015,42301409)。
文摘Given the heightened competition for water in energy,food,and the environment in Africa,it is essential to implement sound integrated plans for basin or regional sustainable development.Zambezi River Basin(ZRB),one of the least developed basins in the world,is under development with great ambition for hydropower and irrigation infrastructure.Here,we proposed a framework to assess different water usage trajectories for agricultural and hydropower development scenarios with data derived from big earth data method.Three future scenarios were set for irrigaiton expansion and development hydropower construction according to current plan,global average and high level,respectively.Using spatial analysis methods,average evapotranspiration(ET)difference before and after irrigation expansion and reservoir construction was used to estimate water usage trajectories.Results show that the total available water resource for ZRB is estimated as 111.8 km3.Due to irrigation and reservoirs construction,additional annual water consumption is estimated to be 0.9 and 14.2 km3 for 2017,respectively.By analyzing the water-energy-food-environment(WEFE)nexus given water availability constraints,we found that the water development boundary in the ZRB could support increases in both irrigation proportion and dam density to global average levels of 20%and 0.56/104 km2,respectively,without degrading the environment.The proposed paradigm for assessing water resources has the potential to endow the ZRB with significant capacity to support the achievement of relevant Sustainable Development Goals(SDGs).
基金funded by the Special Project of Basic Work of Science and Technology“Compilation and dataprocessing of modern vertical deformation Atlas of Chinese mainland”(2015FY210400)the Science and Technology Innovation Fund(FMC2015013)of the First Crust Monitoring and Application Center,China Earthquake Administration
文摘Fault deformation characteristics in the northern margin of the Tibetan Plateau before the Menyuan Ms6.4 earthquake are investigated through time-series and structural geological analysis based on cross-fault observation data from the Qilian Mountain-Haiyuan Fault belt and the West Qinling Fault belt. The results indicate： 1） Group short-term abnormal variations appeared in the Qilian Mountain-Haiyuan Fault belt and the West Qinling Fault belt before the Menyuan Ms6.4 earthquake. 2） More medium and short-term anomalies appear in the middle-eastern segment of the Qilian Mountain Fault belt and the West Qinling Fault belt, suggesting that the faults＇ activities are strong in these areas. The faults＇ activities in the middle-eastern segment of the Qilian Fault belt result from extensional stress, as before the earthquake, whereas those in the West Qinling Fault belt are mainly compressional. 3） In recent years, moderate-strong earthquakes occurred in both the Kunlun Mountain and the Qilian Mountain Fault belts, and some energy was released. It is possible that the seismicity moved eastward under this regime. Therefore, we should pay attention to the West Qinling Mountain area where an Ms6-7 earthquake could occur in future.
基金The National Basic Research Program(973 Program)of China under contract No.2012CB417402the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA11010102
文摘The central Pacific（CP） zonal wind divergence and convergence indices are defined, and the forming mechanism of CP El Nio（La Nia） events is discussed preliminarily. The results show that the divergence and convergence of the zonal wind anomaly（ZWA） are the key process in the forming of CP El Nio（La Nia） events. A correlation analysis between the central Pacific zonal wind divergence and convergence indices and central Pacific El Nio indices indicates that there is a remarkable lag correlation between them. The central Pacific zonal wind divergence and convergence indices can be used to predict the CP events. Based on these results, a linear regression equation is obtained to predict the CP El Nio（La Nia） events 5 months ahead.
基金Supported by the Joint Project of National Natural Science Foundation of ChinaCivil Aviation Administration of China(U1333116)
文摘In order to improve the accuracy of free flight conflict detection and reduce the false alarm rate, an improved flight conflict detection algorithm is proposed based on Gauss-Hermite particle filter（GHPF）. The algorithm improves the traditional flight conflict detection method in two aspects：（i） New observation data are integrated into system state transition probability, and Gauss-Hermite Filter（GHF） is used for generating the importance density function.（ii） GHPF is used for flight trajectory prediction and flight conflict probability calculation. The experimental results show that the accuracy of conflict detection and tracing with GHPF is better than that with standard particle filter. The detected conflict probability is more precise with GHPF, and GHPF is suitable for early free flight conflict detection.
基金Project "973" (2006CB403701)Natural Science Foundation of GuangdongProvince(033029)+1 种基金Key Project for Science and Technology of Guangdong Province (2004A30401002,2005B32601011)Project for Applied Foundation Research of Guangzhou (2004J1-0021)
文摘Using the non-hydrostatic meso-scale model MM5v3, dense fog that occurred from March 7 to March 8, 2001 over the Mts. Nanling area was studied. With integrated field experiments and observations, the occurrence, development and lift mechanism of fog were analyzed. The results indicate that before the coming of stratiform clouds, southerly warm and wet air ascended along mountainside and cooling condensation formed mountain fog. Then fog was formed by the stratiform on cloud-contacting mountaintop. A front inversion layer accelerated the development and extended the duration of the lower cloud and fog. The intensity, occurrence time, mass content and the variation of temperature and relative humidity of the fog agreed with those of the observation. It showed that the meso-scale model has the potential to forecast mountain fog.
