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Wang Y.,CAS Institute of Remote Sensing | Wang Y.,University of Chinese Academy of Sciences | Liu L.,CAS Institute of Remote Sensing | Hu Y.,Chongqing Institute of Surveying and Planning for Land Resources and Housing | And 4 more authors.
International Journal of Remote Sensing | Year: 2016

Landsat satellites have the longest history of making global-scale Earth observations at medium spatial resolution of any series of satellites and have been widely used in various remote-sensing fields. However, many remote-sensing applications, including large-area or long-term land-cover monitoring, need Landsat reflectance data that have had accurate atmospheric correction carried out. In this research, a MODIS-based per-pixel atmospheric correction procedure was developed and employed to produce the surface reflectance (SR) product. A total of 510 Landsat-8 Operational Land Imager (OLI) scenes covering the whole of China in 2013 were collected and processed. The mean relative differences between the surface and top-of-atmosphere (TOA) reflectance for China, composited and expressed as percentages, were found to be 67, 47, 18, 13, 4, 4, and 7% for Landsat-8 OLI bands 1, 2, 3, 4, 5, 6, and 7, respectively. Then, the accuracy of MODIS atmospheric products was validated using ground-based sun-radiometer observation network data, including Sun/sky-radiometer Observation Network (SONET) and Aerosol Robotic Network (AERONET) data collected from 14 SONET/AERONET stations. The validation results showed that the MODIS atmospheric products are reliable for China, with an R2 value of 0.78 and a root mean square error (RMSE) value of 0.12 for aerosols, and an R2 value of 0.98 and an RMSE of 0.25 for water vapour. Third, the SR product using our per-pixel atmospheric correction method was evaluated by comparison with the MODIS daily surface reflectance product (MOD09GA) and the United States Geological Survey (USGS) provisional Landsat-8 SR product, with a mean R2 of 0.93 and an RMSE of 0.02 for MOD09GA; and with a mean R2 of 0.97 and an RMSE of 0.01 for the USGS SR product. Finally, the advantage of our per-pixel atmospheric correction method over the per-scene method was investigated by analysis of the spatial variation of the atmospheric parameters within one Landsat scene (about 1.5 (Formula presented.) 1.5 (Formula presented.)), with a mean standard deviation value of 0.03–0.09 for aerosol. When such aerosol variation was omitted as the per-scene atmospheric correction method, the SR absolute error due to aerosol optical thickness (AOT) spatial variation was about 0.027, 0.018, 0.005, 0.003, 0.002, 0.0007, and 0.003 for the seven reflectance bands of Landsat-8. Therefore, use of Landsat-8 SR products over China with our per-pixel atmospheric correction was proved reliable, and more promising than the per-scene method, especially for the short-wavelength bands. © 2016 Taylor & Francis. Source


Peng D.,CAS Institute of Remote Sensing | Hu Y.,Chongqing Institute of Surveying and Planning for Land Resources and Housing | Li Z.,Chinese Academy of Agricultural Sciences
Journal of Applied Spectroscopy | Year: 2016

It is important to detect and quantify deforestation to guide strategic decisions regarding environment, socioeconomic development, and climate change. In the present study, we conducted a field experiment to examine spectral reflectance and vegetation index changes in poplar and locust tree foliage with different leaf area indices over the course of three sunny days, following tree removal from the canopy. The spectral reflectance of foliage from harvested trees was measured using an ASD FieldSpec Pro spectroradiometer; synchronous meteorological data were also obtained. We found that reflectance in short-wave infrared and red-edge reflectance was more time sensitive after tree removal than reflectance in other spectral regions, and that the normalized difference water index (NDWI) and the red-edge chlorophyll index (CIRE) were the preferred indicators of these changes from several indices evaluated. Synthesized meteorological environments were found to influence water and chlorophyll contents after tree removal, and this subsequently changed the spectral canopy reflectance. Our results indicate the potential for such tree removal to be detected with NDWI or CIRE from the second day of a deforestation event. © 2016 Springer Science+Business Media New York. Source


Hu Y.,CAS Institute of Remote Sensing | Hu Y.,Chongqing Institute of Surveying and Planning for Land Resources and Housing | Liu L.,CAS Institute of Remote Sensing | Caccetta P.,CSIRO | Jiao Q.,CAS Institute of Remote Sensing
Journal of Remote Sensing | Year: 2015

Time-series remote sensing images were previously employed to detect land use and land-cover changes and to analyze related trends. However, land-cover change mapping using time-series remote sensing data, especially medium-resolution imagery, was often constrained by a lack of high-quality training and validation data, especially for historical satellite images. In this study, we tested and evaluated a generalized classifier for time series Landsat Thematic Mapper (TM) imagery based on spectral signature extension. First, a new atmospheric correction procedure and a robust relative normalization method were performed on time-series images to eliminate the radiometric differences between them and to retrieve the surface reflectance. Second, we selected one surface reflectance image from the time series as a source image based on the availability of reliable ground truth data. The spectral signature was then extracted from the training data and the source image. Third, the spectral signature was extended to all the corrected time-series images to build a generalized classifier. This method was tested on a time series consisting of five Landsat TM images of the Tibetan Plateau, and the results showed that the corrected time-series images could be classified effectively from the reference image using the generalized classifier. The overall accuracy achieved was between 88.35% and 94.25%, which is comparable with the results obtained using traditional scene-by-scene supervised classification. Results also showed that the performance of the extension method was affected by the difference in acquisition times of the source image and target image. ©, 2015, Journal of Remote Sensing. All right reserved. Source


Guo H.,Beijing Normal University | Guo H.,Chongqing Institute of Surveying and Planning for Land Resources and Housing | Guo H.,Chongqing Research Center | Li B.,Beijing Normal University | And 4 more authors.
Forest Policy and Economics | Year: 2014

The Grain for Green program (GGP) is one of the most ambitious forestry projects in China. The GGP uses a public payment scheme to propel the participation of rural households in order to make the program acceptable and sustainable. The modification of the GGP for its long-term effectiveness has raised interest from researchers. However, few researchers have realized the role that rural households play in adjusting the GGP. By building an econometric model, we found that the decision making of rural households is optimal when the sum of the marginal benefit from residual farmland and the marginal benefit from agricultural labor time equals the sum of the subsidies for retired farmland, benefits from the increased forest/grassland and the opportunity cost rate of the rural household engaged in agricultural labor divided by agricultural labor efficiency. The results derived by a Logit regression method indicate that the economic benefit and non-monetary values stimulate households' willingness to participate, and households' attitudes have significant effects on their willingness. Our attempt to comprehensively explore the influencing factors concerning households' attitudes, the environment benefits and benefits from the GGP proves to be promising as a reference for future studies and for decision making regarding GGP. © 2014 Elsevier B.V. Source


Zheng C.,Southwest University | Zheng C.,Chongqing Institute of Surveying and Planning for Land Resources and Housing
WIT Transactions on Information and Communication Technologies | Year: 2014

This paper makes a research on the urgency problems and overall idea of establishing cultivated land protection fund which aims to provide policy reference to the establishing Chongqing cultivated land protection fund. Methods of documentary data approach and comparative analysis approach are applied. The result of the study indicates that (i) it is urgent to establish cultivated land protection fund in Chongqing; (ii) funding gap of cultivated land protection is much bigger; (iii) the subsidy standard of cultivated land protection is hard to be unified; (iv) the square measure of cultivated land protection subsidy ascertains difficult; (v) the subsidy way of cultivated land protection is difficult to be unified; (vi) it is hard to coordinate establishing of cultivated land protection; (vii) the supervision and control of cultivated land protection funds is troublesome. The conclusion of this paper shows that (i) building up other classifications and levels of subsidy standards; (ii) expanding source channel of cultivated land protection fund; (iii) perfecting statistics and registering of cultivated land; (iv) granting subsidy of cultivated land protection by various forms; (v) establishing corporation responsibility of cultivated land protection funds; (vi) building up strict fund supervision and administration management. © 2014 WIT Press. Source

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