DMSP-OLS Nighttime Light Data Research Articles

Research on spatial characteristics of metropolis development using nighttime light data: NTL based spatial characteristics of Beijing.

As the capital and one of the metropolises in China, Beijing has met with a number of serious so-called "urban diseases" in the process of rapid urbanization such as blind expansion of urban areas, explosion of population and the increase of urban heat island effect. To treat these “urban diseases” and make the metropolis develop healthful and sustainable in Beijing in the future, the spatial characteristics of metropolis developments in Beijing are explored in this paper. The urban built-up areas in Beijing are extracted using the DMSP-OLS nighttime light data from 1992 to 2013. The characteristics of the urban developments of Beijing are studied, including spatial and temporal scales of urban developments, urban barycenter of Beijing and its transfer trajectory, variations of urban spatial forms and the differences of urban internal developments. The results have shown that the built-up areas had been increasing and circling extending from the central urban areas to the outer spaces in the last 21 years. The built-up area had expanded by 878km2 in 1992–2013, and the built-up area in 2013 had expanded to three times comparing to that of 1992. The expanding area of the built-up area in the northeast is the largest. The expansion of the urban had mainly occurred in 1996–2007, and the expanded area had accounted for 92% of the total research period. During the whole research period, the urban barycenter of Beijing had moved 5000.71 meters towards Northeast 28° of its original place from Dongcheng District to Chaoyang District. The development level of each municipal district had been increasing year by year, and the development differences among the municipal districts had been gradually reduced; the spatial forms of Beijing had been alternately changed between extensive and intensive expansion. The results of this study can help to plan urban land use and people migration of Beijing.

A New Fusion Approach for Extracting Urban Built-up Areas from Multisource Remotely Sensed Data

Recent advances in the fusion technology of remotely sensed data have led to an increased availability of extracted urban information from multiple spatial resolutions and multi-temporal acquisitions. Despite the existing extraction methods, there remains the challenging task of fully exploiting the characteristics of multisource remote sensing data, each of which has its own advantages. In this paper, a new fusion approach for accurately extracting urban built-up areas based on the use of multisource remotely sensed data, i.e., the DMSP-OLS nighttime light data, the MODIS land cover product (MCD12Q1) and Landsat 7 ETM+ images, was proposed. The proposed method mainly consists of two components: (1) the multi-level data fusion, including the initial sample selection, unified pixel resolution and feature weighted calculation at the feature level, as well as pixel attribution determination at decision level; and (2) the optimized sample selection with multi-factor constraints, which indicates that an iterative optimization with the normalized difference vegetation index (NDVI), the modified normalized difference water index (MNDWI), and the bare soil index (BSI), along with the sample training of the support vector machine (SVM) and the extraction of urban built-up areas, produces results with high credibility. Nine Chinese provincial capitals along the Silk Road Economic Belt, such as Chengdu, Chongqing, Kunming, Xining, and Nanning, were selected to test the proposed method with data from 2001 to 2010. Compared with the results obtained by the traditional threshold dichotomy and the improved neighborhood focal statistics (NFS) method, the following could be concluded. (1) The proposed approach achieved high accuracy and eliminated natural elements to a great extent while obtaining extraction results very consistent to those of the more precise improved NFS approach at a fine scale. The average overall accuracy (OA) and average Kappa values of the extracted urban built-up areas were 95% and 0.83, respectively. (2) The proposed method not only identified the characteristics of the urban built-up area from the nighttime light data and other daylight images at the feature level but also optimized the samples of the urban built-up area category at the decision level, making it possible to provide valuable information for urban planning, construction, and management with high accuracy.

Assessing the Impacts of Urban Expansion on Bundles of Ecosystem Services by Dmsp-Ols Nighttime Light Data

Urban expansion poses severe threats to ecosystems. It is therefore important we better understand the impact of different urban expansion level on ecosystems for developing regionally differentiated ecological protection policies. Here, we proposed a conceptual framework to describe the impacts of urbanization on bundles of ecosystem services. Referred to as the concept of land use degree by nighttime light data, we put forward and verified an urban expansion level model. According to this model, study area was divided into a slow increase zone, increase zone, and rapid increase zone. Then, taking Taihu Lake Basin in China as a case, we used Zonal-statistics and Pearson correlation coefficients to reveal the impact in different zones of urban expansion level on multiple ecosystem services: crop production, freshwater supply, aquatic production, net primary productivity, soil conservation, water retention, flood regulation, and forest recreation index. Our results revealed that urban expansion levels significantly impacted all ecosystem services. In either increase zone or rapid increase zone, we found lowered values of crop production, net primary productivity, soil conservation, water retention, and flood regulation, while both aquatic production and forest recreation index increased in all zones from 1990 to 2010. Across the levels of urbanization, urban expansion level was always negatively correlated with provisioning services. This result suggests local governors should improve crop production per unit area and increase the cultivated land area to guarantee food security. In addition, urban expansion level had positive correlations with the trade-offs between flood regulation and forest recreation index, and those among crop production, freshwater supply, and net primary productivity. Therefore, policy-makers should effectively maintain the land use balance among ecological protection, agriculture development, and urban expansion to better coordinate relationships between development and protection. In acquiring quantitative knowledge of how urban expansion level drives ecosystem changes, our findings may help guide future sustainable urban planning with respect to ecosystem services, urban development, and human welfare benefits.

Measurement of blooming effect of DMSP-OLS nighttime light data based on NPP-VIIRS data

ABSTRACTNighttime light (NTL) imagery offers important data for socio-economic research since it depicts human activities at night. Blooming effect is one of the main problems of DMSP-OLS NTL data, but the problem has been largely mitigated in NPP-VIIRS data. Blooming effect smooths light intensity through diffusing the brightness from the bright area to the dark areas. This effect could be quantified by the alteration of spatial heterogeneity in light intensity which can be represented by spatial texture indices. Taking NPP-VIIRS data as the standard, this study calculates relative difference of spatial texture indices between NPP-VIIRS and DMSP-OLS images to measure the blooming effect of DMSP-OLS data at pixel scale in mainland China. Results show that within the real urban area, spatial texture indices of DMSP-OLS pixels are generally smaller than that of NPP-VIIRS, suggesting that blooming effect underestimates spatial heterogeneity and it is more serious towards to urban centres where nighttime light is stronger. DMSP-OLS underestimates 90% spatial heterogeneity when NPP-VIIRS value >10. On the contrary, in the region outside real urban area, spatial texture indices of DMSP-OLS data are greater than that of NPP-VIIRS, suggesting that blooming effect introduces fake spatial heterogeneity outside the real urban area.Abbreviations: NTL: Nighttime light; DMSP: Defense Meteorological Satellite Program; OLS: Operational Linescan System; NPP: National Polar-orbiting Partnership; VIIRS: Visible Infrared Imaging Radiometer Suite; NOAA: The National Oceanic and Atmospheric Administration; NGDC: The National Geophysical Data Center; NCV: Normalized coefficient of variation; DN: Digital number

Analysis of Spatial Pattern of Urban System along the Overland Silk Road Economic Belt Using DMSP-OLS Nighttime Light Data

As China promotes the Belt and Road (BAR) initiative, the overland SREB development is widely concerned. The cities (including towns), population centers, of urban system are the cores of the economy along the SREB. Therefore, it is necessary to monitoring the urbanization of the belt so that the new growing points of urban development and the valid coupling mechanism between human and nature will be explored to promote the regional socio-economic sustainable development and effectively implement the BAR initiative. Using the DMSP-OLS stable nighttime lights (NTL) data in 1992, 2003, and 2014, in this paper we studied the urbanized spatial patterns of and the urbanized characteristics and trends of the main city system along the SREB in the view of the whole regionalized economic zone and typical cities and settlements (towns). The results showed that in general the NTL intensities in the SREB’s city system had the obvious geographical differentiation characteristics where there was maximum brightness of NTLs over the western European countries as well as being gradually decreasing from west to east. There were obvious increases of the NTL digital number (DN) values and NTL covering areas in 2003 and 2013 comparatively with that of 1992, which indicates the great urbanization development during this period. As for the four types of urban development process, there was an apparent consistency in a certain local area but a large heterogeneity among different areas. By analyzing the 273 pivot cities and the most pivot 26 cities, we found the number of the relatively small cities being decreasing but that of the large and medium-sized cities increasing. This study would provide the scientific support for the related researches and decision making of urbanization and urban economic development to promote the socio-economic comprehensive development of the overland SREB.