Abstract
Nighttime light imagery offers a unique view of the Earth’s surface. In the past, the nighttime light data collected by the DMSP-OLS sensors have been used as an efficient means to correlate regional and global socio-economic activities. With the launch of the Suomi National Polar-orbiting Partnership (Suomi-NPP) satellite in 2011, the day-night band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard represents a major advancement in nighttime imaging capabilities, because it surpasses its predecessor DMSP-OLS in radiometric accuracy, spatial resolution and geometric quality. In this paper, four variables (total night light, light area, average night light and log average night light) are extracted from nighttime radiance data observed by the VIIRS-DNB composite in 2013 and nighttime digital number (DN) data from the DMSP-OLS stable dataset in 2012, respectively, and correlated with 12 socio-economic parameters at the provincial level in mainland China during the corresponding period. Background noise of DNB composite data is removed using either a masking method or an optimal threshold method. In general, the correlation of these socio-economic data with the total night light and light area of VIIRS-DNB composite data is better than with the DMSP-OLS stable data. The correlations between total night light of denoised DNB composite data and built-up area, gross regional product (GRP) and power consumption are higher than 0.9 and so are the correlations between the light area of denoised DNB composite data and city and town population, built-up area, GRP, power consumption and waste water discharge. However, the correlations of socio-economic data with the average night light and log average night light of VIIRS-DNB composite data are not as good as with the DMSP-OLS stable data. To quantitatively analyze the reasons for the correlation difference, a cubic regression method is developed to correct the saturation effect of the DMSP stable data, and we artificially convert the pixel value of the DNB composite into six bits to match the DMSP stable data format. The correlation results between the processed data and socio-economic data show that the effects of saturation and quantization are two of the reasons for the correlation difference. Additionally, on this basis, we estimate the total night light ratio between saturation-corrected DMSP stable data and finite quantization DNB composite data, and it is found that the ratio is ~11.28 ± 4.02 for China. Therefore, it appears that a different acquisition time is the other reason for the correlation difference.
Highlights
Remote sensing of the environment provides great opportunities to understand links between human and nature and global socio-economic changes
China to compare the performance of Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS)/day-night band (DNB) composite data and DMSP-OLS stable data in correlating with regional socio-economic parameters
The noise masking method and optimal threshold method have been used to remove the background noise of DNB composite data that is not related to economic activities before calculating the correlations
Summary
Remote sensing of the environment provides great opportunities to understand links between human and nature and global socio-economic changes. With rapid advances in remote sensing technology and its applications, it becomes increasingly more desirable to use remote sensing data to study and monitor the socio-economic environment. The presence of lighting across the globe is mostly due to some form of human activity, such as human settlements, shipping fleets, gas flaring or fire associated with swidden agriculture [1,2]. Satellite sensors, such as OLS on DMSP, have been acquiring day/night images since the early
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