Center for National Spaceborne Demonstration

Beijing, China

Center for National Spaceborne Demonstration

Beijing, China
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Xiong P.,Beijing Normal University | Xiong P.,University of Chinese Academy of Sciences | Xiong P.,Center for National Spaceborne Demonstration | Xiong P.,China Earthquake Administration | And 7 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

In this paper we present an analysis of DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite data by using the wavelet-based data mining techniques. The analyzed results reveal that the possible anomalous variations exist around the earthquakes. The methods studied in this work include wavelet transformations and spatial/temporal continuity analysis of wavelet maxima. These methods have been used to analyze the singularities of seismic precursors in DEMETER satellite data, which are associated with the two earthquakes of Wenchuan and Pure recently occurred in China. © 2011 Springer-Verlag.


Wan W.,Peking University | Chen X.,Peking University | Zhao L.,University of Chinese Academy of Sciences | Zhao L.,Center for National Spaceborne Demonstration | And 2 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012

The microwave signal of GNSS L band is very sensitive to the electromagnetic property of soil surface, through measuring the reflected electromagnetic energy from soil, the relationship between power of GNSS reflected signals and soil dielectric constant can be built, and then soil moisture can be estimated. In order to improve estimation accuracy, both the direct and reflected GNSS signals need to be calibrated to eliminate the signal error. A soil moisture estimation model utilizing calibrated GNSS L band reflected signals is proposed in this paper, and the estimation accuracy is validated using SMEX02 data. The error of areas with different NDVI is calculated. The error of soil moisture estimation is 7.04% for bare soil condition of the verify areas. It is shown that this model is suitable for bare soil condition or areas with low vegetation coverage. For further research, in the case of soil with high vegetation coverage, the model should be modified through adding the vegetation effect into it. © 2012 IEEE.


Gao H.,Beijing Normal University | Gao H.,University of Chinese Academy of Sciences | Gao H.,Center for National Spaceborne Demonstration | Gu X.,Beijing Normal University | And 11 more authors.
Science China Technological Sciences | Year: 2010

The calibration experiment data at Dunhuang radiometric calibration site in October, 2008 were used to achieve the on-orbit radiometric calibration for HJ-1A hyper spectral imager (HSI). Two other field experiments data were used to validate the Dunhuang calibration results. One field experiment took place in Inner-Mongolia, China in September, 2008, and the other field experiment took place in Lake Frome, Australia in February, 2009. Finally, the 'confidence interval of calibration error' concept was put forward for quantitatively computing the calibration coefficient error confidence interval. The results showed that the Dunhuang calibration results in 2008 had high reliability. The confidence intervals of calibration error for all HSI channels were between 2% to 12%, which could satisfy the requirement of the HSI quantitative applications. © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.


Xu H.,CAS Institute of Remote Sensing Applications | Xu H.,University of Chinese Academy of Sciences | Xu H.,Center for National Spaceborne Demonstration | Yu T.,CAS Institute of Remote Sensing Applications | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

April 8, 2012, the east region of Inner Mongolia out broke a strong sandstorm. Based on the analysis of the spectral characteristics of dust, cloud and surface, this paper propose a duststorm mask algorithm for the identification of dust coverage region by using three infrared channels of FY-3B. By utilizing diurnal variation of brightness temperature of dust aerosol, the bi-temporal thermal dust index was established to represent the intensity of duststorm. Through the analysis we found that BTDI has a high negative correlation with aerosol optical depth which can be used as an effective means to monitor the duststorm. © 2012 SPIE. Downloading of the abstract is permitted for personal use only.


Zhao L.,Beijing Normal University | Zhao L.,Center for National Spaceborne Demonstration | Gu X.,Beijing Normal University | Gu X.,Center for National Spaceborne Demonstration | And 10 more authors.
Science China Technological Sciences | Year: 2012

Modeling and analyzing dynamic changes of land thermal radiance scenes play an important role in thermal remote sensing. In this paper, the diurnal variation of ground surface thermal scene is mainly discussed. Firstly, based on the land surface energy balance equation, the diurnal variation of land surface temperatures (LSTs) over bare land covers were simulated by an analytical thermal model with second harmonic terms, and the diurnal LST variation of vegetation canopy was simulated using the Cupid model. Secondly, normalized difference vegetation index (NDVI), normalized difference water index (NDWI), and ratio resident-area index (RRI) were used to evaluate the endmember abundance of four land cover types including vegetation, bare soil, impervious and water area, which were calculated from IKONOS visible and near infrared (VNIR) bands. Finally, the thermal radiance scenes at various times and view angles were modeled based on the linear-energy-mixing hypothesis. The results showed that the simulated daily LST variations for vegetated and bare surfaces are correlated with the measured values with a maximum standard deviation of 2.7°C, that land thermal radiant textures with high-resolution are restored from the linear-energy-mixing method, and that the information abundance of the scene are related to the distribution of land cover, the imaging time, and the view angle. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.


Liu L.,CAS Institute of Remote Sensing Applications | Liu L.,University of Chinese Academy of Sciences | Liu L.,Center for National Spaceborne Demonstration | Gu X.-F.,CAS Institute of Remote Sensing Applications | And 11 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The absolute calibration of HJ-1B thermal infrared channel is achieved by 7 times cross-calibration of Qinghai Lake in 2010, between the HJ-1B thermal infrared channel and MODIS 31, 32 channels. At the same time, the intercept of calibration coefficients is calculated. First, the spatial match are completed between the HJ-1B IRS image and MODIS 31, 32 channels image. Then, the spectral response of HJ-1B IRS thermal channel and MODIS 31, 32 channels are used for the spectral match. Based on the SST algorithms of MODIS, the MODTRAN4.0 is used to simulate the radiative transfer results under the condition of variety surface temperature of the Qinghai Lake, the atmospheric profile, observational geometry combined with the spectral response functions of the remote sensors. The quantitative linear relationship can be established with the simulation results. The gain and offset of cross-calibration are 52.7788 1/(W/ (m2•sr•μm)), -55.4137. The result needs further validation of longer sequence. © 2011 SPIE.


Gao H.,CAS Institute of Remote Sensing Applications | Gao H.,University of Chinese Academy of Sciences | Gao H.,Center for National Spaceborne Demonstration | Gu X.,CAS Institute of Remote Sensing Applications | And 14 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The first 20 channel images of Hyper Spectral Image (HSI) have obvious stripe noise, which seriously affects the application of the HSI data. This paper summarized and analyzed the existed destriping methods. Based on the image characteristics of HSI, a new stripe noise removal method was proposed by using spline interpolation function to re-sample. Taking the HSI image of Guangzhou area as an example, the Fourier transform method, moment matching method and the new method proposed in this paper were used to remove the stripe noise. The results showed that the Fourier transform method couldn't remove the image stripe noise effectively; the moment matching method could remove the image stripe noise, but it also forced the image mean column value to 1, which would destroy the differences of image features information; The new method proposed in this paper was able to retain the differences of image surface features while removing the image stripe noise. The destriping efficiency of the new method was better than the other methods. © 2011 SPIE.


Hu X.,University of Chinese Academy of Sciences | Hu X.,CAS Institute of Remote Sensing | Hu X.,National Satellite Meteorological Center | Hu X.,Center for National Spaceborne Demonstration | And 10 more authors.
Canadian Journal of Remote Sensing | Year: 2010

The Dunhuang test site, one of the China Radiometric Calibration Sites (CRCS) for the vicarious calibration (VC) of Chinese spaceborne sensors, was selected in 2008 by the Working Group on Calibration and Validation (WGCV) of the Committee on Earth Observation Satellites (CEOS) as one of the instrumented reference sites. The site is spatially uniform with a coefficient of variation (CV) (standard deviation / mean) less than 2% of spectral reflectance over the 10 km × 10 km central region, based on the imagery of the Medium Resolution Spectral Imager (MERSI) onboard the Fengyun 3A (FY-3A) satellite. This result is also proven by several ground truth measurements. The surface spectral reflectance is temporally stable with a CV of about 3% from 7-year Moderate Resolution Imaging Spectroradiometer (MODIS) surface albedo product and has been validated using the ground-based measurement eight times in 10 years. Several calibration/validation (Cal/Val) field campaigns for the site evaluation and VC have been conducted since 1999, and a database including atmospheric and surface characteristics has been established. The aerosol optical depth (AOD) at the Dunhuang site is low (τ550 is about 0.2), except for the dusty spring season from March to May. The surface reflectance of this site is about 15%-30% from the visible to near-infrared spectral region. The site surface is not Lambertian, with clearly direction-dependent reflectance variation especially at the large solar or observation zenith angles. The CRCS VC was the baseline operational calibration approach from 2002 for the Multichannel Visible and Infrared Scanning Radiometer (MVISR) onboard the FY-1C and FY-1D satellites. The approach is inherited by the optical imaging sensors (Visible and Infrared Radiometer (VIRR) and MERSI) of the Chinese second-generation polar-orbiting satellite FY-3A. The CRCS VC is used not only to correct the significant bias of preflight calibration in some bands of these sensors but also to monitor the sensor radiometric degradation. The Dunhuang site can also be used as the earth target in the cross-calibration for the FY satellite sensors. © 2010 CASI.


Zhao L.,University of Chinese Academy of Sciences | Zhao L.,Center for National Spaceborne Demonstration | Gu X.,University of Chinese Academy of Sciences | Gu X.,Center for National Spaceborne Demonstration | And 4 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012

One of the significant factors for improving the accuracy of Land Surface Temperature (LST) retrieval is the correct understanding of the directional anisotropy for thermal radiance. In this paper, the multiple scattering effect between heterogeneous non-isothermal surfaces is described rigorously according to the concept of configuration factor, based on which a directional thermal radiance model is built, and the directional radiant character for urban canopy is analyzed. The model is applied to a simple urban canopy with row structure to simulate the change of Directional Brightness Temperature (DBT). The results show that the DBT is aggrandized because of the multiple scattering effects, whereas the change range of DBT is smoothed. The temperature difference, spatial distribution, emissivity of the components can all lead to the change of DBT. The 'hot spot' phenomenon occurs when the proportion of high temperature component in the vision field came to a head. On the other hand, the 'cool spot' phenomena occur when low temperature proportion came to the head. The 'spot' effect disappears only when the proportion of every component keeps invariability. The model built in this paper can be used for the study of directional effect on emissivity, the LST retrieval over urban areas and the adjacency effect of thermal remote sensing pixels. © 2012 IEEE.


Xu J.,CAS Institute of Remote Sensing Applications | Xu J.,Center for National Spaceborne Demonstration | Gu X.,CAS Institute of Remote Sensing Applications | Gu X.,Center for National Spaceborne Demonstration | And 6 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2010

In remote chlorophyll-a (Chla) retrieval in Case-II waters, the uncertainties from Chla specific absorption coefficient a * ph has a significant effect on the retrieving accuracy. In this paper, we presented newly improved three-band model and four-band model by a case study in Shitoukoumen Reservoir. The proposed three-band model can be expressed as [R rs -1(λ 1-R rs -1(λ 2)]×R rs(λ 3)×a * ph -1(λ 1), while the improved four-band model is [R rs -1(λ 1-R rs -1(λ 2)]×[R rs -1(λ 4)-R rs -1(λ 3)] -1×a * ph -1(λ 1) Results showed that the latter one was slightly superior to the former one. Comparison with original models without correction of a * ph, the improved models achieved higher precision and stability. The findings underlined the rationale behind the proposed models and demonstrated a potentially use for assessing Chla in Case-II waters. © 2010 IEEE.

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