With such significant advantages as all-day observation, penetrability and all-weather coverage, passive mi-crowave remote sensing technique has been widely applied in the research of global environmental change. As t...With such significant advantages as all-day observation, penetrability and all-weather coverage, passive mi-crowave remote sensing technique has been widely applied in the research of global environmental change. As the sat-ellite-based passive microwave remote sensor, the Advanced Microwave Scanning Radiometer-Earth Observing Sys-tem (AMSR-E) loaded on NASA's (National Aeronautics and Space Administration of USA) Aqua satellite has been popularly used in the field of microwave observation. The Microwave Radiation Imager (MWRI) loaded on the Chi-nese FengYun-3A (FY-3A) satellite is an AMSR-E-like conical scanning microwave sensor, but there are few reports about MWRI data. This paper firstly proposed an optimal spatial position matching algorithm from rough to exact for the position matching between AMSR-E and MWRI data, then taking Northeast China as an example, comparatively analyzed the microwave brightness temperature data derived from AMSR-E and MWRI. The results show that when the antenna footprints of the two sensors are filled with either full water, or full land, or mixed land and water with ap-proximate proportion, the errors of brightness temperature between AMSR-E and MWRI are usually in the range from -10 K to +10 K. In general, the residual values of brightness temperature between the two microwave sensors with the same spatial resolution are in the range of ±3 K. Because the spatial resolution of AMSR-E is three times as high as that of MWRI, the results indicate that the quality of MWRI data is better. The research can provide useful information for the MWRI data application and microwave unmixing method in the future.展开更多
In this paper,a thin cloud removal method was put forward based on the linear relationships between the thin cloud reflectance in the channels from 0.4 μm to 1.0 μm and 1.38 μm.Channels of 0.66 μm,0.86 μm and 1....In this paper,a thin cloud removal method was put forward based on the linear relationships between the thin cloud reflectance in the channels from 0.4 μm to 1.0 μm and 1.38 μm.Channels of 0.66 μm,0.86 μm and 1.38 μm were chosen to extract the water body information under the thin cloud.Two study cases were selected to validate the thin cloud removal method.One case was applied with the Earth Observation System Moderate Resolution Imaging Spectroradiometer(EOS/MODIS) data,and the other with the Medium Resolution Spectral Imager(MERSI) and Visible and Infrared Radiometer(VIRR) data from Fengyun-3A(FY-3A).The test results showed that thin cloud removal method did not change the reflectivity of the ground surface under the clear sky.To the area contaminated by the thin cloud,the reflectance decreased to be closer to the reference reflectance under the clear sky after the thin cloud removal.The spatial distribution of the water body area could not be extracted before the thin cloud removal,while water information could be easily identified by using proper near infrared channel threshold after removing the thin cloud.The thin cloud removal method could improve the image quality and water body extraction precision effectively.展开更多
In this study,the authors evaluated two re-motely sensed surface soil moisture datasets derived from the Advanced Microwave Scanning Radiometer of the Earth Observing System (AMSR-E) over northern China.The soil moist...In this study,the authors evaluated two re-motely sensed surface soil moisture datasets derived from the Advanced Microwave Scanning Radiometer of the Earth Observing System (AMSR-E) over northern China.The soil moisture datasets were derived from algorithms developed by the National Snow and Ice Data Center (NSIDC) and jointly developed by the Vrije Universiteit Amsterdam and NASA Goddard Space Flight Center (VUA-NASA).The NSIDC and VUA-NASA products were compared to in situ soil moisture data from nine enhanced coordinated observation stations.The VUA-NASA dataset presented a strong correlation with top layer in situ soil moisture observations,and the correla-tion coefficients ranged from 0.34 to 0.73 (p<0.01).The correlation coefficients decreased as the observed soil layer depth increased.The correlation coefficients be-tween the NSIDC retrievals and the top layer in situ ob-servations were between 0.10 and 0.62 (p<0.01).Fur-thermore,VUA-NASA soil moisture variations agreed well with in situ soil moisture dynamics and responded sensitively to precipitation events.In contrast,the NSIDC dataset failed to capture signals of soil moisture dynamics.The analyses demonstrated that the VUA-NASA product was capable of representing soil moisture conditions over northern China.展开更多
It has been observed that low temperature, rainfall, snowfall, frost have never occurred over the past 50 years in the southern China, and weather in this area is very complex, so the monitoring equipments are few. Op...It has been observed that low temperature, rainfall, snowfall, frost have never occurred over the past 50 years in the southern China, and weather in this area is very complex, so the monitoring equipments are few. Optical and thermal infrared remote sensing is influenced much by clouds, so the passive microwave Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) data are the best choice to monitor and analyze the development of disaster. In order to improve estimation accuracy, the dynamic learn- ing neural network was used to retrieve snow depth. The difference of brightness temperatures of TB18.7v and TB36.sv, TBI8.7H and TB36.sH, TB23,sv and TB89v, TBz3.8H and TB89H are made as four main input nodes and the snow depth is the only one output node of neural network. The mean and the standard deviation of retrieval errors are about 4.8 cm and 6.7 cm relative to the test data of ground measurements. The application analysis indicated that the neural network can be utilized to monitor the change of snow intensity distribution through passive microwave data in the complex weather of the southern China.展开更多
By the end of sixties, several satellites were launched to observe the earth; among them the Landsat missions have been important to study natural resources, especially in agriculture. Currently, Landsat 7, with some ...By the end of sixties, several satellites were launched to observe the earth; among them the Landsat missions have been important to study natural resources, especially in agriculture. Currently, Landsat 7, with some problems, and Landsat 5 are useful to evaluate crop development. A project called "Participatory multi-Level EO-assisted tools for Irrigation water management and Agricultural Decision-Support" (PLEIADES) was financed by the European Commission. This project considers eleven countries and 23 research institutions, Mexico being one of the selected countries. Landsat images are a basic tool of this project. Some of the results obtained in this study are presented in this article. By using w^getation indices obtained by the combinations of reflectances in different bands of the electromagnetic spectrum, it has been possible to estimate the behavior of several biophysical parameters of crops which are used to evaluate plant development, water stress, spatial soil variation, and the effect of plagues and crop diseases. To facilitate this process, a visor was developed, named SPIDER (System of Participatory Information Decision support and Expert knowledge for River basin management) whose use in this work is explained.展开更多
Discrete element model was developed to simulate the ellipsoidal particles moving in the moving bed. Multi-element model was used to describe a ellipsoidal particle, the contact detection algorithm of ellipsoidal part...Discrete element model was developed to simulate the ellipsoidal particles moving in the moving bed. Multi-element model was used to describe a ellipsoidal particle, the contact detection algorithm of ellipsoidal particle was developed, and both contact force and gravity force were considered in the models. The simulation results were validated by our experiment. Three algorithms for representing an ellipsoidal particle were compared in macro and micro aspects. The results show that there exists big difference in the microscopic parameters such as kinetic energy, rotational kinetic energy, deformation, contact force and collision number which leads to the difference of macroscopic parameters. The relative error in the discharge rate and tracer particle position is the largest between 3-tangent-element representation and experimental results. The flow pattern is similar for the 5-element and 3-intersection representations. The only difference is the discharge rate of 5-element representation is larger than the experimental value and that of the 3-intersection representation has the contrary result. Finally the 3-intersection- element reoresentation is chosen in the simulation due to less comouting time than that of the 5-element renresentation.展开更多
The Taklamakan Desert in China is one of the major source regions for Asian dust particles.All balloon-borne measurements in this report were carried out in Dunhuang,in the Taklamakan Desert,during calm weather condit...The Taklamakan Desert in China is one of the major source regions for Asian dust particles.All balloon-borne measurements in this report were carried out in Dunhuang,in the Taklamakan Desert,during calm weather conditions.The aerosol number concentration,size distribution,mass concentration,and horizontal mass flux due to westerly wind were investigated.The measurements were performed on 17 August 2001,17 October 2001,11 January 2002,and 30 April 2002.Five channels(0.3,0.5,0.8,1.2,and 3.6μm in diameter)were used in the Optical Particle Counter for particle measurements.The aerosol number concentration in the winter season(11 January 2002)at 3–5 km was very high.Variation of free-tropospheric aerosols on 30 April 2002 was noticeable.A super-micron range was noticeable in the size distribution of all the measurements.Many variations in temperature and aerosol concentration were found at these inversion points.High values of estimated mass concentration of aerosols were frequently observed in the atmosphere near the ground(i.e.,1–2 km);and interestingly,relatively high concentrations were frequently detected above 2 km from the surface.Wind patterns observed using ERA-Interim data at 500 and 850 hPa showed that westerly winds dominated in the Taklamakan Desert during the observation period.The average horizontal mass flux of background Asian dust due to westerly wind was observed to fall within the range of 58.5–1219 tons km?2 d?1.Vertical profiles of aerosol number concentrations showed that significant transport of aerosols dominated in the westerly region(i.e.,4–7 km).展开更多
A validation study of land surface temperature (LST) obtained from the Ka band (37 GHz) vertically polarized brightness temperature over northern China is presented.The remotely sensed LST derived jointly by the Vrije...A validation study of land surface temperature (LST) obtained from the Ka band (37 GHz) vertically polarized brightness temperature over northern China is presented.The remotely sensed LST derived jointly by the Vrije Universiteit Amsterdam and the NASA Goddard Space Flight Center (VUA-NASA) from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) were compared to the daily in-situ top soil temperature/infrared surface temperature observations from eleven/three Enhanced Coordinated Observation stations in arid and semi-arid regions of northern China.The VUA-NASA LST from the descending path exhibited a stronger correspondence to the in-situ infrared surface temperature than soil temperature observations,whereas correlations (R 2) of the latter ranged from 0.41 to 0.86.Meanwhile,the ascending overpass LST was generally warmer than the in-situ soil temperature observations at all stations,and the correlation (R 2) was between 0.07 and 0.72.Furthermore,the correlation of the descending path was generally greater than that of the ascending path at the same station.The descending path VUA-NASA LST was sensitive to precipitation and presented good agreement with ground temperature dynamics.The analyses demonstrated that the descending overpass LST was reliable to reflect reasonable patterns of temperature dynamics for land surface temperature in the region.展开更多
Atmospheric CO2 concentrations from January 2010 to December 2010 were simulated using the GEOS-Chem(Goddard Earth Observing System-Chemistry) model and the results were compared to satellite Gases Observing Satellite...Atmospheric CO2 concentrations from January 2010 to December 2010 were simulated using the GEOS-Chem(Goddard Earth Observing System-Chemistry) model and the results were compared to satellite Gases Observing Satellite(GOSAT) and ground-based the Total Carbon Column Observing Network(TCCON) data. It was found that CO2 concentrations based on GOSAT satellite retrievals were generally higher than those simulated by GEOS-Chem. The differences over the land area in January and April ranged from 1 to 2 ppm, and there were major differences in June and August. At high latitudes in the Northern Hemisphere in June, as well as south of the Sahara, the difference was greater than 5 ppm. In the high latitudes of the Northern Hemisphere the model results were higher than the GOSAT retrievals, while in South America the satellite data were higher. The trend of the difference in the high latitudes of the Northern Hemisphere and the Saharan region in August was opposite to June. Maximum correlation coefficients were found in April, reaching 0.72, but were smaller in June and August. In January, the correlation coefficient was only 0.36. The comparisons between GEOS-Chem data and TCCON observations showed better results than the comparison between GEOS and GOSAT. The correlation coefficients ranged between 0.42(Darwin) and 0.92(Izana). Analysis of the results indicated that the inconsistency between satellite observations and model simulations depended on inversion errors caused by data inaccuracies of the model simulation's inputs, as well as the mismatch of satellite retrieval model input parameters.展开更多
The brokering approach can be successfully used to overcome the crucial question of searching among enormous amount of data (raw and/or processed) produced and stored in different information systems. In this paper,...The brokering approach can be successfully used to overcome the crucial question of searching among enormous amount of data (raw and/or processed) produced and stored in different information systems. In this paper, authors describe the Data Management System the DMS (Data Management System) developed by INGV (Istituto Nazionale di Geofisica e Vulcanologia) to support the brokering system GEOSS (Global Earth Observation System of Systems) adopted for the ARCA (Arctic Present Climate Change and Past Extreme Events) project. This DMS includes heterogeneous data that contributes to the ARCA objective (www.arcaproject.it) focusing on multi-parametric and multi-disciplinary studies on the mechanism (s) behind the release of large volumes of cold and fresh water from melting of ice caps. The DMS is accessible directly at the www.arca.rm.ingv.it, or through the IADC (Italian Arctic Data Center) at http://arcticnode.dta.cnr.it/iadc/gi-portal/index.jsp that interoperates with the GEOSS brokering system (http://www.geoportal.org0 making easy and fast the search of specific data set and its URL.展开更多
Lightning is one of the most important natural sources of atmospheric NOx.The authors investigate the2000–2050 changes in NOx emissions from lightning using the global three-dimensional Goddard Earth Observing System...Lightning is one of the most important natural sources of atmospheric NOx.The authors investigate the2000–2050 changes in NOx emissions from lightning using the global three-dimensional Goddard Earth Observing System chemical transport model(GEOS-Chem)driven by meteorological fields from the Goddard Institute for Space Studies(GISS)general circulation model(GCM)3.Projected changes in climate over 2000–2050are based on the Intergovernmental Panel on Climate Change(IPCC)A1B scenario.The global NOx emission from lightning is simulated to be 4.8 Tg N in present day and to increase by about 16.7%over 2000–2050 as a result of the future climate change.The largest present-day emissions and climate-induced changes are found in the upper troposphere in the tropics.Regionally in eastern China(20–55 N,98–125 E),NOx emissions from lighting is simulated to be 0.3 Tg N(6.3%of the global total emission)in present day and to increase by 26.7%over2000–2050.The simulated changes in NOx from lightening correspond well with the projected future changes in convective precipitation.展开更多
The observed characteristics of lower atmospheric ducts over the South China Sea(SCS) were analyzed based on Global Position Systerm(GPS) radiosonde data collected four times daily during autumn open cruises from 2006...The observed characteristics of lower atmospheric ducts over the South China Sea(SCS) were analyzed based on Global Position Systerm(GPS) radiosonde data collected four times daily during autumn open cruises from 2006 to 2012.Duct occurrence,thickness,and strength over the SCS were about 40%,150-m thick,and 8 M units,respectively,which were larger than during the summer monsoon period.Most ducts occurred at heights <1 500 m and these ducts easily trap electromagnetic wave clusters with wavelengths <2 m.Diurnal variation of the SCS ducts appeared evident.They occurred more often at midnight at higher altitudes(about 1 100 m),with a thickest layer of about 145 m and less frequently during the evening at lower altitudes(about 800 m),with a thinnest layer of about 125 m.Moreover,ducts during the daytime at a mean height of about 900 m,with the greatest strength of about 10 M units.Furthermore,all duct variables observed over the SCS in autumn decreased from north to south.These findings are useful not only in the design of radar and communication systems,but also for evaluating possible effects of anomalous propagation on meteorological radar and military applications.展开更多
We propose the design of an observation station to establish a reliable datum for displacement and deformation analysis at the first working-face subsidence observation station of Liuzhuang Mine. The design considers ...We propose the design of an observation station to establish a reliable datum for displacement and deformation analysis at the first working-face subsidence observation station of Liuzhuang Mine. The design considers various geologic and mining con-ditions. Having analyzed the aims of the joint survey and the comprehensive survey, we propose design principles, and work modes, for adopting GPS technology as the position measuring technique to be used in these two stages. Baseline vectors and spatial ad-justments of the GPS network were calculated after study of data processing and quality estimation methods. A coordinate system transformation and error estimates of the transformed GPS network data are discussed. The error estimates in all stages show that the GPS control network of the observation station has sufficient accuracy and is highly efficient. The network thus provides a reli-able datum for analyzing the laws of surface displacement and deformation induced by mining.展开更多
The TanDEM-X mission is a scientific and commercial Earth observation mission comprising two satellites flying in close formation. The formation maintenance can be advantageously performed by an onboard autonomous sys...The TanDEM-X mission is a scientific and commercial Earth observation mission comprising two satellites flying in close formation. The formation maintenance can be advantageously performed by an onboard autonomous system, which reduces the operational efforts, provides a shorter reaction time in case of contingencies and increases the control performance. The TanDEM-X Autonomous Formation Flying (TAFF) system has been developed for this purpose and is intended to replace the ground-based formation keeping activities during routine operations. TAFF has been activated for the first time in October 2010 for commissioning, during which the autonomous usage of thrusters was prohibited. Afterwards, a closed-loop campaign was successfully conducted in March 2011, demonstrating the capability of TAFF to maintain autonomously the formation. After a brief technical description of the system, the paper presents the key results gained during the commissioning phase and the closed-loop campaign,展开更多
Remote sensing, which came into being at the first International Symposium on Remote Sensing of Environment (ISRSE) 50 years ago, has enabled people to obtain objecive and realistic spatial and temporal information th...Remote sensing, which came into being at the first International Symposium on Remote Sensing of Environment (ISRSE) 50 years ago, has enabled people to obtain objecive and realistic spatial and temporal information through the application of Earth observation technologies and analyze and understand the macro-level changes of the Earth system from a spaial view. The technology of Earth observaion from space has incomparable advantages in the study of the Earth. This aricle introduces the 50-year development of Earth observaion in the world and the 30-year development of Earth observaion in China and reflects on the building of China's Earth observaion system.展开更多
基金Under the auspices of National Natural Science Foundation of China (No. 40971189)Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-340)China Postdoctoral Science Foundation (No. 20100471276)
文摘With such significant advantages as all-day observation, penetrability and all-weather coverage, passive mi-crowave remote sensing technique has been widely applied in the research of global environmental change. As the sat-ellite-based passive microwave remote sensor, the Advanced Microwave Scanning Radiometer-Earth Observing Sys-tem (AMSR-E) loaded on NASA's (National Aeronautics and Space Administration of USA) Aqua satellite has been popularly used in the field of microwave observation. The Microwave Radiation Imager (MWRI) loaded on the Chi-nese FengYun-3A (FY-3A) satellite is an AMSR-E-like conical scanning microwave sensor, but there are few reports about MWRI data. This paper firstly proposed an optimal spatial position matching algorithm from rough to exact for the position matching between AMSR-E and MWRI data, then taking Northeast China as an example, comparatively analyzed the microwave brightness temperature data derived from AMSR-E and MWRI. The results show that when the antenna footprints of the two sensors are filled with either full water, or full land, or mixed land and water with ap-proximate proportion, the errors of brightness temperature between AMSR-E and MWRI are usually in the range from -10 K to +10 K. In general, the residual values of brightness temperature between the two microwave sensors with the same spatial resolution are in the range of ±3 K. Because the spatial resolution of AMSR-E is three times as high as that of MWRI, the results indicate that the quality of MWRI data is better. The research can provide useful information for the MWRI data application and microwave unmixing method in the future.
基金Under the auspices of National Nature Science Foundation of China(No.40901231,41101517)
文摘In this paper,a thin cloud removal method was put forward based on the linear relationships between the thin cloud reflectance in the channels from 0.4 μm to 1.0 μm and 1.38 μm.Channels of 0.66 μm,0.86 μm and 1.38 μm were chosen to extract the water body information under the thin cloud.Two study cases were selected to validate the thin cloud removal method.One case was applied with the Earth Observation System Moderate Resolution Imaging Spectroradiometer(EOS/MODIS) data,and the other with the Medium Resolution Spectral Imager(MERSI) and Visible and Infrared Radiometer(VIRR) data from Fengyun-3A(FY-3A).The test results showed that thin cloud removal method did not change the reflectivity of the ground surface under the clear sky.To the area contaminated by the thin cloud,the reflectance decreased to be closer to the reference reflectance under the clear sky after the thin cloud removal.The spatial distribution of the water body area could not be extracted before the thin cloud removal,while water information could be easily identified by using proper near infrared channel threshold after removing the thin cloud.The thin cloud removal method could improve the image quality and water body extraction precision effectively.
基金supported by the National Basic Research Program of China (Grant No.2009CB723904)
文摘In this study,the authors evaluated two re-motely sensed surface soil moisture datasets derived from the Advanced Microwave Scanning Radiometer of the Earth Observing System (AMSR-E) over northern China.The soil moisture datasets were derived from algorithms developed by the National Snow and Ice Data Center (NSIDC) and jointly developed by the Vrije Universiteit Amsterdam and NASA Goddard Space Flight Center (VUA-NASA).The NSIDC and VUA-NASA products were compared to in situ soil moisture data from nine enhanced coordinated observation stations.The VUA-NASA dataset presented a strong correlation with top layer in situ soil moisture observations,and the correla-tion coefficients ranged from 0.34 to 0.73 (p<0.01).The correlation coefficients decreased as the observed soil layer depth increased.The correlation coefficients be-tween the NSIDC retrievals and the top layer in situ ob-servations were between 0.10 and 0.62 (p<0.01).Fur-thermore,VUA-NASA soil moisture variations agreed well with in situ soil moisture dynamics and responded sensitively to precipitation events.In contrast,the NSIDC dataset failed to capture signals of soil moisture dynamics.The analyses demonstrated that the VUA-NASA product was capable of representing soil moisture conditions over northern China.
基金Under the auspices of National Program on Key Basic Research Project(No.2010CB951503)National Key Technology R&D Program of China(No.2013BAC03B00)National High Technology Research and Development Program of China(No.2012AA120905)
文摘It has been observed that low temperature, rainfall, snowfall, frost have never occurred over the past 50 years in the southern China, and weather in this area is very complex, so the monitoring equipments are few. Optical and thermal infrared remote sensing is influenced much by clouds, so the passive microwave Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) data are the best choice to monitor and analyze the development of disaster. In order to improve estimation accuracy, the dynamic learn- ing neural network was used to retrieve snow depth. The difference of brightness temperatures of TB18.7v and TB36.sv, TBI8.7H and TB36.sH, TB23,sv and TB89v, TBz3.8H and TB89H are made as four main input nodes and the snow depth is the only one output node of neural network. The mean and the standard deviation of retrieval errors are about 4.8 cm and 6.7 cm relative to the test data of ground measurements. The application analysis indicated that the neural network can be utilized to monitor the change of snow intensity distribution through passive microwave data in the complex weather of the southern China.
文摘By the end of sixties, several satellites were launched to observe the earth; among them the Landsat missions have been important to study natural resources, especially in agriculture. Currently, Landsat 7, with some problems, and Landsat 5 are useful to evaluate crop development. A project called "Participatory multi-Level EO-assisted tools for Irrigation water management and Agricultural Decision-Support" (PLEIADES) was financed by the European Commission. This project considers eleven countries and 23 research institutions, Mexico being one of the selected countries. Landsat images are a basic tool of this project. Some of the results obtained in this study are presented in this article. By using w^getation indices obtained by the combinations of reflectances in different bands of the electromagnetic spectrum, it has been possible to estimate the behavior of several biophysical parameters of crops which are used to evaluate plant development, water stress, spatial soil variation, and the effect of plagues and crop diseases. To facilitate this process, a visor was developed, named SPIDER (System of Participatory Information Decision support and Expert knowledge for River basin management) whose use in this work is explained.
基金Supported by the Major State Basic Research Development Program of China (2011CB201505), the National Natural Science Foundation of China (50976025) and the Key Proj ect.of Science and Technology of Henan Province (12B610012).
文摘Discrete element model was developed to simulate the ellipsoidal particles moving in the moving bed. Multi-element model was used to describe a ellipsoidal particle, the contact detection algorithm of ellipsoidal particle was developed, and both contact force and gravity force were considered in the models. The simulation results were validated by our experiment. Three algorithms for representing an ellipsoidal particle were compared in macro and micro aspects. The results show that there exists big difference in the microscopic parameters such as kinetic energy, rotational kinetic energy, deformation, contact force and collision number which leads to the difference of macroscopic parameters. The relative error in the discharge rate and tracer particle position is the largest between 3-tangent-element representation and experimental results. The flow pattern is similar for the 5-element and 3-intersection representations. The only difference is the discharge rate of 5-element representation is larger than the experimental value and that of the 3-intersection representation has the contrary result. Finally the 3-intersection- element reoresentation is chosen in the simulation due to less comouting time than that of the 5-element renresentation.
基金supported by the National Natural Science Foundations of China [grant numbers 41590871 and 41475136]the International Science&Technology Cooperation Program of China [grant number 2013DFG22820]
文摘The Taklamakan Desert in China is one of the major source regions for Asian dust particles.All balloon-borne measurements in this report were carried out in Dunhuang,in the Taklamakan Desert,during calm weather conditions.The aerosol number concentration,size distribution,mass concentration,and horizontal mass flux due to westerly wind were investigated.The measurements were performed on 17 August 2001,17 October 2001,11 January 2002,and 30 April 2002.Five channels(0.3,0.5,0.8,1.2,and 3.6μm in diameter)were used in the Optical Particle Counter for particle measurements.The aerosol number concentration in the winter season(11 January 2002)at 3–5 km was very high.Variation of free-tropospheric aerosols on 30 April 2002 was noticeable.A super-micron range was noticeable in the size distribution of all the measurements.Many variations in temperature and aerosol concentration were found at these inversion points.High values of estimated mass concentration of aerosols were frequently observed in the atmosphere near the ground(i.e.,1–2 km);and interestingly,relatively high concentrations were frequently detected above 2 km from the surface.Wind patterns observed using ERA-Interim data at 500 and 850 hPa showed that westerly winds dominated in the Taklamakan Desert during the observation period.The average horizontal mass flux of background Asian dust due to westerly wind was observed to fall within the range of 58.5–1219 tons km?2 d?1.Vertical profiles of aerosol number concentrations showed that significant transport of aerosols dominated in the westerly region(i.e.,4–7 km).
基金supported by the National Basic Research Program of China (Grant No.2009CB723904)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA05090201)
文摘A validation study of land surface temperature (LST) obtained from the Ka band (37 GHz) vertically polarized brightness temperature over northern China is presented.The remotely sensed LST derived jointly by the Vrije Universiteit Amsterdam and the NASA Goddard Space Flight Center (VUA-NASA) from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) were compared to the daily in-situ top soil temperature/infrared surface temperature observations from eleven/three Enhanced Coordinated Observation stations in arid and semi-arid regions of northern China.The VUA-NASA LST from the descending path exhibited a stronger correspondence to the in-situ infrared surface temperature than soil temperature observations,whereas correlations (R 2) of the latter ranged from 0.41 to 0.86.Meanwhile,the ascending overpass LST was generally warmer than the in-situ soil temperature observations at all stations,and the correlation (R 2) was between 0.07 and 0.72.Furthermore,the correlation of the descending path was generally greater than that of the ascending path at the same station.The descending path VUA-NASA LST was sensitive to precipitation and presented good agreement with ground temperature dynamics.The analyses demonstrated that the descending overpass LST was reliable to reflect reasonable patterns of temperature dynamics for land surface temperature in the region.
基金supported by the National High Technology Research and Development Program of China (Grant No. 2013AA122002)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-EW-QN207)the National Basic Research Program of China (Grant Nos. 2010CB428403 and 2009CB421407)
文摘Atmospheric CO2 concentrations from January 2010 to December 2010 were simulated using the GEOS-Chem(Goddard Earth Observing System-Chemistry) model and the results were compared to satellite Gases Observing Satellite(GOSAT) and ground-based the Total Carbon Column Observing Network(TCCON) data. It was found that CO2 concentrations based on GOSAT satellite retrievals were generally higher than those simulated by GEOS-Chem. The differences over the land area in January and April ranged from 1 to 2 ppm, and there were major differences in June and August. At high latitudes in the Northern Hemisphere in June, as well as south of the Sahara, the difference was greater than 5 ppm. In the high latitudes of the Northern Hemisphere the model results were higher than the GOSAT retrievals, while in South America the satellite data were higher. The trend of the difference in the high latitudes of the Northern Hemisphere and the Saharan region in August was opposite to June. Maximum correlation coefficients were found in April, reaching 0.72, but were smaller in June and August. In January, the correlation coefficient was only 0.36. The comparisons between GEOS-Chem data and TCCON observations showed better results than the comparison between GEOS and GOSAT. The correlation coefficients ranged between 0.42(Darwin) and 0.92(Izana). Analysis of the results indicated that the inconsistency between satellite observations and model simulations depended on inversion errors caused by data inaccuracies of the model simulation's inputs, as well as the mismatch of satellite retrieval model input parameters.
文摘The brokering approach can be successfully used to overcome the crucial question of searching among enormous amount of data (raw and/or processed) produced and stored in different information systems. In this paper, authors describe the Data Management System the DMS (Data Management System) developed by INGV (Istituto Nazionale di Geofisica e Vulcanologia) to support the brokering system GEOSS (Global Earth Observation System of Systems) adopted for the ARCA (Arctic Present Climate Change and Past Extreme Events) project. This DMS includes heterogeneous data that contributes to the ARCA objective (www.arcaproject.it) focusing on multi-parametric and multi-disciplinary studies on the mechanism (s) behind the release of large volumes of cold and fresh water from melting of ice caps. The DMS is accessible directly at the www.arca.rm.ingv.it, or through the IADC (Italian Arctic Data Center) at http://arcticnode.dta.cnr.it/iadc/gi-portal/index.jsp that interoperates with the GEOSS brokering system (http://www.geoportal.org0 making easy and fast the search of specific data set and its URL.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05100503)the National Natural Science Foundation of China(Grant Nos.40775083,40825016,and 41021004)the China Meteorological Administration special funding inatmospheric science(Grant No.GYHY200906020)
文摘Lightning is one of the most important natural sources of atmospheric NOx.The authors investigate the2000–2050 changes in NOx emissions from lightning using the global three-dimensional Goddard Earth Observing System chemical transport model(GEOS-Chem)driven by meteorological fields from the Goddard Institute for Space Studies(GISS)general circulation model(GCM)3.Projected changes in climate over 2000–2050are based on the Intergovernmental Panel on Climate Change(IPCC)A1B scenario.The global NOx emission from lightning is simulated to be 4.8 Tg N in present day and to increase by about 16.7%over 2000–2050 as a result of the future climate change.The largest present-day emissions and climate-induced changes are found in the upper troposphere in the tropics.Regionally in eastern China(20–55 N,98–125 E),NOx emissions from lighting is simulated to be 0.3 Tg N(6.3%of the global total emission)in present day and to increase by 26.7%over2000–2050.The simulated changes in NOx from lightening correspond well with the projected future changes in convective precipitation.
基金Supported by the National Natural Science Foundation of China(Nos.41106011,41176027)the National Basic Research Program of China(973 Program)(No.2011CB403504)
文摘The observed characteristics of lower atmospheric ducts over the South China Sea(SCS) were analyzed based on Global Position Systerm(GPS) radiosonde data collected four times daily during autumn open cruises from 2006 to 2012.Duct occurrence,thickness,and strength over the SCS were about 40%,150-m thick,and 8 M units,respectively,which were larger than during the summer monsoon period.Most ducts occurred at heights <1 500 m and these ducts easily trap electromagnetic wave clusters with wavelengths <2 m.Diurnal variation of the SCS ducts appeared evident.They occurred more often at midnight at higher altitudes(about 1 100 m),with a thickest layer of about 145 m and less frequently during the evening at lower altitudes(about 800 m),with a thinnest layer of about 125 m.Moreover,ducts during the daytime at a mean height of about 900 m,with the greatest strength of about 10 M units.Furthermore,all duct variables observed over the SCS in autumn decreased from north to south.These findings are useful not only in the design of radar and communication systems,but also for evaluating possible effects of anomalous propagation on meteorological radar and military applications.
文摘We propose the design of an observation station to establish a reliable datum for displacement and deformation analysis at the first working-face subsidence observation station of Liuzhuang Mine. The design considers various geologic and mining con-ditions. Having analyzed the aims of the joint survey and the comprehensive survey, we propose design principles, and work modes, for adopting GPS technology as the position measuring technique to be used in these two stages. Baseline vectors and spatial ad-justments of the GPS network were calculated after study of data processing and quality estimation methods. A coordinate system transformation and error estimates of the transformed GPS network data are discussed. The error estimates in all stages show that the GPS control network of the observation station has sufficient accuracy and is highly efficient. The network thus provides a reli-able datum for analyzing the laws of surface displacement and deformation induced by mining.
文摘The TanDEM-X mission is a scientific and commercial Earth observation mission comprising two satellites flying in close formation. The formation maintenance can be advantageously performed by an onboard autonomous system, which reduces the operational efforts, provides a shorter reaction time in case of contingencies and increases the control performance. The TanDEM-X Autonomous Formation Flying (TAFF) system has been developed for this purpose and is intended to replace the ground-based formation keeping activities during routine operations. TAFF has been activated for the first time in October 2010 for commissioning, during which the autonomous usage of thrusters was prohibited. Afterwards, a closed-loop campaign was successfully conducted in March 2011, demonstrating the capability of TAFF to maintain autonomously the formation. After a brief technical description of the system, the paper presents the key results gained during the commissioning phase and the closed-loop campaign,
文摘Remote sensing, which came into being at the first International Symposium on Remote Sensing of Environment (ISRSE) 50 years ago, has enabled people to obtain objecive and realistic spatial and temporal information through the application of Earth observation technologies and analyze and understand the macro-level changes of the Earth system from a spaial view. The technology of Earth observaion from space has incomparable advantages in the study of the Earth. This aricle introduces the 50-year development of Earth observaion in the world and the 30-year development of Earth observaion in China and reflects on the building of China's Earth observaion system.