.
Remote Sensing, 2014, 6(10): 9853-9872
Lin Ma, Jiansheng Wu, Weifeng Li, Jian Peng*, Hao Liu
Abstract: Remotely sensed nighttime lights (NTL) datasets derived from the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) have been identified as a good indicator of the urbanization process and have been widely used to study such demographic and economic variables as population distribution and density, electricity consumption, and carbon emission. However, one issue must be considered in the application of NTL data, i.e., saturation in the bright cores of urban centers. In this study, we evaluate four correction methods in China's cities: the linear regression model and the cubic regression model at the regional level, and the Human Settlement Index (HSI) and the Vegetation Adjusted NTL Urban Index (VANUI) at a pixel level. The results suggest that both correction methods at the regional level improve the correlation between NTL data and socioeconomic variables. However, since the methods can only be used on saturated pixels, the correction effects are limited, as the saturated area in Chinese cities is rather small. HSI and VANUI increase the inter-urban variability within certain cities, especially when their vegetation health and abundance is negatively correlated with NTL. However, the indices may induce bias when applied in a large region with a diverse natural environment and vegetation, and the application of HSI with a relatively high sensitivity of HSI to NDVI may be limited as NTL approaches maximum. Proper methods for reducing saturation effects should thus vary with different study areas and research purposes.
Remote Sensing of Environment, 2013, 134: 111-119
Jiansheng Wu, Zheng Wang*, Weifeng Li, Jian Peng
Abstract: We consider night light as a type of consumer goods and propose a model for factors affecting the relationship between night lights and GDP. It is then decomposed into agricultural and non-agricultural productions. Further, the model is modified to determine how the factors affect residents' propensity to consume lights. Models are tested with time-fixed regression on a set of 15-year panel data of 169 countries globally and regionally. We find that light consumption propensity is affected by GDP per capita, latitude, spatial distribution of human activities and gross saving rate, and that light consumption per capita has an inverted-U relationship with GDP per capita.
17.Intercalibration of DMSP OLS night time light data by the invariant region method
International Journal of Remote Sensing, 2013, 34(20): 7356-7368
Jiansheng Wu, Shengbin He, Jian Peng, Weifeng Li, Xiaohong Zhong
Abstract: DMSP-OLS (Defense Meteorological Satellite Program Operational Linescan System) night-time light data can accurately reflect the scope and intensity of human activities. However, the raw data cannot be used directly for temporal analyses due to the lack of inflight calibration. There are three problems that should be addressed in intercalibration. First, because of differences between sensors, the data are not identical even when obtained in the same year. Second, different acquisition times may lead to random or systematic fluctuations in the data obtained by satellites in different orbits. Third, a pixel saturation phenomenon also exists in the urban centres of the image. Therefore, an invariant region method was used in this article, and the relative radiometric calibration and saturation correction achieved the desired results. In the meantime, intercalibration models for each satellite year of DMSP-OLS night-time light data were produced. Finally, intercalibration accuracy was evaluated, and the intercalibration results were tested with the corresponding gross domestic product (GDP) data.
Ecological Indicators, 2013, 29: 529-537
Jiansheng Wu, Zhe Feng*, Yang Gao, Jian Peng
Abstract: The identification of the relationships between different landscape services is important in social-ecological complex systems, especially in areas with intensive human activities. In this paper, Beijing and its peripheral regions are taken as a case study to calculate and map the intensities of five classic landscape services including material production, carbon storage, soil retention, habitat conservation, and population support based on grid maps. Overlap and correlation analyses were used to identify multiple service hotspots and the relationships between landscape services. The results show that (1) landscape services have spatial heterogeneity: high-intensity area of material production and population support is on the southeast plains of this region and high-intensity area of soil retention and habitat conservation is on the northwest; (2) approximately 96.03% of the region can provide at least one type of landscape services, whereas approximately three-quarters of the area provide multiple services, with the multiple service hotspots surrounding Beijing and Tianjin; (3) correlations exist between all pairs of landscape services, but strong correlations (correlation coefficient >0.5 or <-0.5) exist between four pairs, which are soil retention and habitat conservation (0.672), soil retention and population support (-0.613), habitat conservation and population support (-0.540), and material production and population support (0.529); (4) the services can be divided into two trade-off service bundles: the "natural" bundle, which contains carbon storage, soil retention, and habitat conservation, and the "artificial" bundle, which contains material production and population support. Only 4.19% of the area in this region contains these service bundles simultaneously. Finally, an improved understanding of the relationships between services was illustrated, and the importance of such services was highlighted for decision-makers and stakeholders. (C) 2013 Elsevier Ltd. All rights reserved.
15.Soil moisture retrieving using hyperspectral data with the application of wavelet analysis
Environmental Earth Sciences, 2013, 69(1): 279-288
Jian Peng, Hong Shen, San Wei He, Jian Sheng Wu
Abstract: As a powerful tool, the wavelet transform method has been widely used in feature extraction for hyperspectral data, while few studies are focused on soil moisture retrieving. The objective of this study was to evaluate the effectiveness of discrete wavelet transform (DWT) for soil moisture retrieving. In this study, a total of 78 measurements of soil moisture and hyperspectral data were collected through soil sampling as well as laboratory quantitative control. There were 13 different mother wavelets capable of decomposing hyperspectral data that were recommended, along with six decomposition levels from 5 to 10. The performances of two feature extraction methods namely band selection and DWT were compared, using three indexes, i.e., R 2 , R adj and root mean square error (RMSE) introduced to validate soil moisture retrieving results. The experimental results indicated that the wavelet transform method could significantly reduce the dimensionality of hyperspectral data, resulting in a much more effective performance. Among the 78 estimation models using the wavelet transform, there were 42 models superior to band selection, with 24 models yielding good correlations between the predicted soil moisture and the measured ones ( R 2 02≥020.7, RMSE02≤020.050, p 02≤020.05). Furthermore, when the wavelet decomposition level was 9 and the mother wavelets were Daubechies 2, Daubechies 4, Reserve Biorthogonal 3.3 and Biorthogonal 6.8, the retrieving results were optimum. Additionally, the experimental results proved that the wavelet analysis technique was capable of preserving high- and low-frequency spectral information at different decomposition scales, and could correctly reflect the variation of soil moisture. Thus, it would be helpful in further environmental monitoring.
Chinese Geographical Science, 2013, 23(1): 113-128
Qing Chang, Shuangcheng Li, Yanglin Wang, Jiansheng Wu, Miaomiao Xie
Abstract: Through a case study of Shenzhen City,China,this study focused on a quantitative method for analyzing the spatial processes involved in green infrastructure changes associated with rapid urbanization.Based on RS,GIS and SPSS statistics software,the approach includes selection of the square analysis units and representative landscape metrics,quantification of the change types of landscape metrics in all analysis units through two indices and hierarchical cluster analysis of the above analysis units with different landscape metric change types(i.e.spatial attributes).The analyses verify that there is a significant sequence of continuous changes in green infrastructure in Shenzhen.They are the perforation,the segmentation,the fragmentation,the evanescence and the filling-in processes,which have a good spatio-temporal correspondence with urbanization and reflect the synthetic influence of urban planning,government policies and landforms.Compared with other studies on quantifying the spatial pattern,this study provides an alternative probe into linking the spatial pattern to spatial processes and the corresponding ecological processes in the future.These spatio-temporal processes offer many opportunities for identifying,protecting and restoring key elements in an urban green infrastructure network for areas in the early stages of urbanization or for non-urbanized areas.
13.Trend analysis of vegetation dynamics in Qinghai–Tibet Plateau using Hurst Exponent
Ecological Indicators, 2012, 14(1): 28-39
Jian Peng, Zhenhuan Liu, Yinghui Liu*, Jiansheng Wu, Yinan Han
Abstract: As one of the most sensitive areas responding to global environmental change, especially global climate change, Qinghai–Tibet Plateau has been recognized as a hotspot for coupled studies on global terrestrial ecosystem change and global climate change. As an important component of terrestrial ecosystems, vegetation dynamic has become one of the key issues in global environmental change, and numerous case studies have been conducted on vegetation dynamic trend in different study periods. However, few are focused on the quantitative analysis of the consistency of vegetation dynamic trends after the study periods. In the study, taking Qinghai–Tibet Plateau as a case, vegetation dynamic trend during 1982–2003 were analyzed, with the application of the method of linear regression analysis. The results showed that, vegetation dynamics in Qinghai–Tibet Plateau experienced a significant increasing as a whole, with nearly 50% forest degradation in the study period. And among the 7 kinds of vegetation types, the change of forest was the most fluctuant with desert the least one. Furthermore, the consistency of vegetation dynamic trends after the study period, was quantified using Hurst Exponent and the method of R/S analysis. The results showed high consistency of future vegetation dynamic trends for the whole plateau, and inconsistent areas were mainly meadow and steppe distributed in the middle or east of the plateau. It was also convinced that, vegetation dynamic trends in the study area were significantly influenced by topography, especially the elevation.
Environmental Earth Sciences, 2011, 64(1): 151-156
Maokun Zheng, Yanglin Wang, Jing Xie, Jiansheng Wu, Junjie Li, Jian Peng, Jing Song
Abstract: Fifty-two surface soil samples from agricultural, forest, and grassland sites were collected from the Shenzhen municipal area for determination of copper and lead levels. The spatial dependence of the measured results was quantified using semivariogram modeling, and structural changes in copper and lead in Shenzhen surface soil were analyzed during the past 20years from the late 1980s to 2009. The resulting semivariogram direction of copper was from northwest to southwest, while that of lead was from east to northwest. KeywordsStructural change–Surface soil–Shenzhen.
11.Research Progress on Evaluation Frameworks of Regional Ecological Sustainability
Chinese Geographical Science, 2011, 21(4): 496-510
Jian Peng, Yanglin Wang, Jiansheng Wu, Hong Shen, Yajing Pan
Abstract: As natural ecosystems provide the material basis and fundamental support for regional sustainable devel-opment,the sustainability of natural ecosystems is an important prerequisite and a viable approach for the achievement of regional sustainable development.It is also the final criteria to assess whether sustainable development paradigm is successful.Along with the increasing impacts of human activities on natural ecosystems,the evaluation of regional ecological sustainability has become one of the key issues for research on macro ecology and sustainable development.Based on different unit of indicators,this study firstly groups the evaluation frameworks of regional ecological sus-tainability into three major types:comprehensive index evaluation with dimensionless unit,monetary valuation,and biophysical quantity measurement.We then discuss and compare these types in terms of basic principles,scope of ap-plications,advantages and shortcomings.Finally,drawn on the discussion about characteristics of ecological sustain-ability,we outline the current trend and future directions of regional ecological sustainability evaluation,for instance,transition from sustainable development evaluation to sustainability science,integration of goal-oriented and problem-solving approaches,combination of spatial pattern analysis and ecological sustainability evaluation,and en-hancement of ecological sustainability evaluation at landscape scale.
10.Housing Migrant Workers in Rapidly Urbanizing Regions A Study of the Chinese Model in Shenzhen
Housing Studies, 2010, 25(1): 83-100.
Ya Ping Wang, Yanglin Wang, Jiansheng Wu
Abstract: China has experienced a huge wave of rural to urban migration over the last 25 years; however, Chinese cities do not have the large-scale slum settlements found in other developing countries. Has China found a new way to solve the housing problems of migrants and the urban poor? This paper addresses this question and reports the findings of a recent research project carried out in Shenzhen City. In general, Chinese migrants are poor in comparison with official urban residents. The majority of them live in shared rooms or small apartments in the so-called urban villages. Housing poverty, especially overcrowding, is a serious problem. This paper also highlights the positive contributions made by urban villages and private landlords in housing the large number of migrants in cities.
90-100 80-89 70-79 60-69 50-59 40-49 30-39 20-29 10-19 1-9
注：如PDF文件无法打开，请刷新页面或退出后重试。