| |
Li, D., Zhao, X., & Li, X. (2016). Remote sensing of human beings – a perspective from nighttime light. Geo-spatial Information Science, 19(1), 69–79.
Abstract: City lights, fishing boats, and oil fields are the major sources of nighttime lights, therefore the nighttime light images provide a unique source to map human beings and their activities from outer space. While most of the scholars focused on application of nighttime light remote sensing in urbanization and regional development, the actual fields are much wider. This paper summarized the applications of nighttime light remote sensing into fields such as the estimation of socioeconomic parameters, monitoring urbanization, evaluation of important events, analyzing light pollution, fishery, etc. For estimation of socioeconomic parameters, the most promising progress is that Gross Domestic Product and its growth rate have been estimated with statistical data and nighttime light data using econometric models. For monitoring urbanization, urban area and its dynamics can be extracted using different classification methods, and spatial analysis has been employed to map urban agglomeration. As sharp changes of nighttime light are associated with important socioeconomic events, the images have been used to evaluate humanitarian disasters, especially in the current Syrian and Iraqi wars. Light pollution is another hotspot of nighttime light application, as the night light is related to some diseases and abnormal behavior of animals, and the nighttime light images can provide light pollution information on large scales so that it is much easier to analyze the effects of light pollutions. In each field, we listed typical cases of the applications. At last, future studies of nighttime light remote sensing have been predicted.
|
|
Li, X., Chen, F., & Chen, X. (2013). Satellite-Observed Nighttime Light Variation as Evidence for Global Armed Conflicts. IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing, 6(5), 2302–2315.
Abstract: The objective of this research is to investigate the potential of nighttime light images, acquired with Defense Meteorological Satellite Program Operational Linescan System (DMSP-OLS), in evaluating global armed conflicts. To achieve this purpose, we assessed the relationship between armed conflicts and the satellite-observed nighttime light variation over 159 countries through annual composites of the nighttime light images. Firstly, a light ratio index was developed to reduce the data inconsistency of annual nighttime light images during 1992-2010. Then 12 countries were selected as examples for a primary investigation, and we found the outbreak of a war can reduce the light and the ceasefire can increase the light from the remote sensing images, which indicates armed conflict events always have significant impact on the nighttime light. Based on this assertion, a nighttime light variation index (NLVI) was developed to quantify the variation of the time series nighttime light. Then using conditional probability analysis, the probability of a country suffering from armed conflicts increases with increase of NLVI. Particularly, when the NLVI value is in a very high level as defined, 80% of the countries have experienced armed conflicts. Furthermore, using correlation analysis, the number of global armed conflicts is highly correlated with the global NLVI in temporal dimension, with a correlation coefficient larger than 0.77. In summary, the potential of nighttime light images in armed conflict evaluation is extended from a regional scale to a global scale by this study.
|
|
Li, X., Zhang, R., Huang, C., & Li, D. (2015). Detecting 2014 Northern Iraq Insurgency using night-time light imagery. International Journal of Remote Sensing, 36(13), 3446–3458.
Abstract: The territory controlled by the Islamic State of Iraq and Syria (ISIS) has grown rapidly since the start of the Syrian Civil War. In 2014, ISIS expanded its control into Northern Iraq, leading to a major humanitarian crisis in the region. This study makes use of night-time light images to detect the ISIS offensive against Iraq in 2014. We developed an algorithm to separate city lights from oilfield lights, based on an urban extent map. The image analysis indicates that all Northern Iraqi provinces experienced a large reduction in city lighting, varying from 16% to 93%. This reduction is especially evident in the three ISIS-controlled provinces, Al-Anbar, Saladin, and Ninawa, where the reduction of city lighting from May to December 2014 was 59%, 50%, and 93%, respectively. Most of the ISIS-controlled cities, including Mosul and Tikrit, experienced a loss of more than 90% in city lighting after being seized by ISIS, while the cities controlled by the Iraqi security forces (ISF) did not lose as much lighting. In contrast, the city lights in Ar Raqqa, Syria, ISIS’s de facto capital, did not show a decline after that region was seized by ISIS. We conclude that the conflict in Northern Iraq has resulted in a major loss of city lighting and that this loss is most likely due to lack of access to the Iraqi electricity supply grid rather than a deliberate ISIS strategy.
|
|
Li, X., & Li, D. (2014). Can night-time light images play a role in evaluating the Syrian Crisis? International Journal of Remote Sensing, 35(18), 6648–6661.
Abstract: This study investigates whether night-time light images acquired from the Defense Meteorological Satellite Program’s Operational Linescan System provide spatial and temporal insight with regard to the humanitarian aspects of the Syrian crisis. Evaluating the ongoing crisis in Syria is challenging since reliable witness reports are hard to gather in a war zone. Therefore satellite images, as one of the few sources of objective information, are potentially of great importance. We used 38 monthly Defense Meteorological Satellite Program’s Operational Linescan System composites covering the period between January 2008 and February 2014. The results indicate that night-time light and lit area in Syria declined by about 74% and 73%, respectively, between March 2011 and February 2014. In 12 of 14 provinces, night-time light declined by >60%. Damascus and Quneitra are the exceptions, with night-time light having declined only by about 35%. Notably, the number of internally displaced persons (IDPs) of each province shows a linear correlation with night-time light loss, with an R2 value of 0.52. Through clustering the time series images, we found that the international border of Syria represents a distinct boundary between regions of differing night-time light spatiotemporal patterns. The contrast across the border increases as the region studied encompasses a wider zone on either side of the border. These findings lend support to the hypothesis that night-time light can be a useful source for monitoring humanitarian crises such as that unfolding in Syria.
|
|
Li, X., Li, D., Xu, H., & Wu, C. (2017). Intercalibration between DMSP/OLS and VIIRS night-time light images to evaluate city light dynamics of Syria’s major human settlement during Syrian Civil War. International Journal of Remote Sensing, 38(21), 5934–5951.
Abstract: Monthly composites of night-time light acquired from the Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) had been used to evaluate socio-economic dynamics and human rights during the Syrian Civil War, which started in March 2011. However, DMSP/OLS monthly composites are not available subsequent to February 2014, and the only available night-time light composites for that period were acquired from the Suomi National Polar-orbiting Partnership satellite’s Visible Infrared Imaging Radiometer Suite (Suomi NPP/VIIRS). This article proposes an intercalibration model to simulate DMSP/OLS composites from the VIIRS day-and-night band (DNB) composites, by using a power function for radiometric degradation and a Gaussian low pass filter for spatial degradation. The DMSP/OLS data and the simulated DMSP/OLS data were combined to estimate the city light dynamics in Syria’s major human settlement between March 2011 and January 2017. Our analysis shows that Syria’s major human settlement lost about 79% of its city light by January 2017, with Aleppo, Daraa, Deir ez-Zor, and Idlib provinces losing 89%, 90%, 96%, and 99% of their light, respectively, indicating that these four provinces were most affected by the war. We also found that the city light in Syria and 12 provinces rebounded from early 2016 to January 2017, possibly as a result of the peace negotiation signed in Geneva.
|
|
|
