Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> The Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has a unique capability to detect low levels of visible and near-infrared (VNIR) radiance at night. With the OLS "VIS" band data, it is possible to detect clouds illuminated by moonlight, plus lights from cities, towns, industrial sites, gas pares, and ephemeral events such as fires and lightning illuminated clouds. This paper presents methods which have been developed for detecting and geolocating VNIR emission sources with nighttime DMSP-OLS data and the analysis of image time series to identify spatially stable emissions from cities, towns, and industrial sites. Results are presented for the United States. <s> BIB001 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> Abstract Nightime “city light” footprints derived from DMSP/OLS satellite images were merged with census data and a digital soils map in a continental-scale test of a remote sensing and geographic information system methodology for approximating the extent of built-up land and its potential impact on soil resources in the United States. Using image processing techniques and census data, we generated maps where the “city lights” class represented mean population densities of 947 persons km −2 and 392 housing units km −2 , areas clearly not available to agriculture. By our analysis, such “city lights” representing urban areas accounted for 2.7% of the surface area in the United States, an area approximately equal to the State of Minnesota or one half the size of California. Using the UN/FAO Fertility Capability Classification System to rank soils, results for the United States show that development appears to be following soil resources, with the better agricultural soils being the most urbanized. Some unique soil types appear to be on the verge of being entirely coopted by “urban sprawl.” Urban area figures derived from the DMSP/OLS imagery compare well to those derived from statistical sources. Further testing and refinement of the methodology remain but the technique shows promise for possible extension to global evaluations of urbanization, population and even global productivity. <s> BIB002 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> Abstract A Tresholding technique was used to convert a prototype “city lights” data set from the National Oceanic and Atmospheric Administration's National Geophysical Data Center (NOAAINGDC) into a map of “urban areas” for the continental United States. Thresholding was required to adapt the Defense Meteorological Satellite Program's Operational Linescan System (DMSPIOLS)-based NGDC data set into an urban map because the values reported in the prototype represent a cumulative percentage lighted for each pixel extracted from hundreds of nighttime cloud screened orbits, rather than any suitable land-cover classification. The cumulative percentage lighted data could not be used alone because the very high gain of the OLS nighttime photomultiplier configuration can. lead to a pixel (2.7X2.7 km) appearing “lighted” even with very low intensity, nonurban light sources. We found that a threshold of %89% yielded the best results, removing ephemeral light sources and “blooming” of light onto water when adjacent to cities while still leaving the dense urban core intact. This approach gave very good results when compared with the urban areas as defined by the 1990 U. S. Census; the “urban” area from our analysis being only 5% less than that of the Census. The Census was also used to derive population.- and housing-density statistics for the continent-wide “city lights” analysis; these averaged 1033 persons/km 2 and 426 housing units/ king, respectively. The use of a nighttime sensor to determine the location and estimate the density of population based on light sources has proved feasible in this exploratory effort. However, issues concerning the use of census data as a benchmark for evaluating the accuracy of remotely sensed imagery are discussed, and potential improvements in the sensor regarding spatial resolution, instrument gain, and pointing accuracy are addressed. <s> BIB003 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> The area lit by anthropogenic visible-near infrared emissions (i.e., lights) has been estimated for 21 countries using night-time data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). The area lit is highly correlated to gross domestic product and electric power consumption. Significant outliers exist in the relation between area lit and population. The results indicate that the local level of economic development must be factored into the apportionment of population across the land surface based on DMSP-OLS observed lights. <s> BIB004 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> Abstract Nocturnal lighting is a primary method for enabling human activity. Outdoor lighting is used extensively worldwide in residential, commercial, industrial, public facilities, and roadways. A radiance calibrated nighttime lights image of the United States has been assembled from Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). The satellite observation of the location and intensity of nocturnal lighting provide a unique view of humanities presence and can be used as a spatial indicator for other variables that are more difficult to observe at a global scale. Examples include the modeling of population density and energy related greenhouse gas emissions. <s> BIB005 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> Fire products derived from NOAA-AVHRR channel 3 images and DMSP-OLS are compared to determine the most appropriate AVHRR channel 3 thresholds and methods for operational monitoring of fire in Kalimantan, Indonesia. The results indicate that about 77% of AVHRR fire cells derived from a temperature threshold of 321 deg K applied to channel 3 daytime images corresponded with DMSP-OLS fire cells at monthly or longer time scales. However, lower temperature thresholds produced slightly greater correspondence between the two sensors on the same date. By contrast, a contextual algorithm produced a lower correspondence (approximately 50%) between fire products from the two sensors. Although the number and extent of DMSP-OLS fire cells was much greater than fire-cells derived from AVHRR channel 3, the spatial distribution of the two products was broadly similar in the study area. <s> BIB006 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> Abstract Night-time satellite imagery acquired between October 1994 and March 1995 is here exploited to derive economic and energy-related global maps. By considering the lit area of a city, and combining this with ancillary statistical information, an analysis was performed designed to investigate the potential of night-time imagery for quantitative estimation of global socioeconomic parameters. An attempt to estimate global urban population using correlations of lit area and urban populations to derive country-level relationships accounted for over 90% of the quoted total. Furthermore, the total lit area of a country has a statistically significant high correlation value with other parameters, specifically Gross Domestic Product (GDP) and total carbon dioxide (CO2) emission. The new technique is limited by the spatial resolution of the sensor and the poorer correlation using night-time lights for centrally-planned economies. These findings offer great potential for synoptic global mapping of such parame... <s> BIB007 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> ABSTRA C T We present the first World Atlas of the zenith artificial night sky brightness at sea level. Based on radiance-calibrated high-resolution DMSP satellite data and on accurate modelling of light propagation in the atmosphere, it provides a nearly global picture of how mankind is proceeding to envelop itself in a luminous fog. Comparing the Atlas with the United States Department of Energy (DOE) population density data base, we determined the fraction of population who are living under a sky of given brightness. About two-thirds of the World population and 99 per cent of the population in the United States (excluding Alaska and Hawaii) and European Union live in areas where the night sky is above the threshold set for polluted status. Assuming average eye functionality, about one-fifth of the World population, more than two-thirds of the United States population and more than one half of the European Union population have already lost naked eye visibility of the Milky Way. Finally, about onetenth of the World population, more than 40 per cent of the United States population and one sixth of the European Union population no longer view the heavens with the eye adapted to night vision, because of the sky brightness. <s> BIB008 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> Night-time satellite imagery provided by the Defense Meteorological Satellite Program' s Operational Linescan System (DMSP OLS) is evaluated as a means of estimating the population of all the cities of the world based on their areal extent in the image. A global night-time image product was registered to a dataset of 2000 known city locations with known populations. A relationship between areal extent and city population discovered by Tobler and Nordbeck is identie ed on a nation by nation basis to estimate the population of the 22920 urban clusters that exist in the night-time satellite image. The relationship between city population and city areal extent was derived from 1597 city point locations with known population that landed in a ' lit' area of the image. Due to conurbation, these 1597 cities resulted in only 1383 points of analysis for performing regression. When several cities fell into one ' lit' area their populations were summed. The results of this analysis allow for an estimate of the urban population of every nation of the world. By using the known percent of population in urban areas for every nation a total national population was also estimated. The sum of these estimates is a total estimate of the global human population, which in this case was 6.3 billion. This is fairly close to the generally accepted contemporaneous (1997) estimate of the global population which stood at approximately 5.9 billion. <s> BIB009 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> Abstract The Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has a unique low-light imaging capability developed for the detection of clouds using moonlight. In addition to moonlit clouds, the OLS also detects lights from human settlements, fires, gas flares, heavily lit fishing boats, lightning and the aurora. By analysing the location, frequency, and appearance of lights observed in an image time series, it is possible to distinguish four primary types of lights present at the earth's surface: human settlements, gas flares, fires, and fishing boats. We have produced a global map of the four types of light sources as observed during a 6-month time period in 1994–1995. We review a number of environmental applications that have been developed or proposed based on the night-time light data. We examine the relationship between area of lighting, population, economic activity, electric power consumption, and energy related carbon emissions for 200 nations, representing 99% of the world's population. <s> BIB010 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> We estimated global marketed and non-marketed economic value from two classified satellite images with global coverage at 1 km2 resolution. GDP (a measure of marketed economic output) is correlated with the amount of light energy (LE) emitted by that nation as measured by nighttime satellite images. LE emitted is more spatially explicit than whole country GDP, may (for some nations or regions) be a more accurate indicator of economic activity than GDP itself, can be directly observed, and can be easily updated on an annual basis. As far as we know, this is the first global map of estimated economic activity produced at this high spatial resolution (1 km2). Ecosystem services product (ESP) is an important type of non-marketed value. ESP at 1 km2 resolution was estimated using the IGBP land-cover dataset and unit ecosystem service values estimated by Costanza et al. [Valuing Ecosystem Services with Efficiency, Fairness and Sustainability as Goals. Nature's Services, Island Press, Washington DC, pp. 49–70]. The sum of these two (GDP+ESP)=SEP is a measure of the subtotal ecological–economic product (marketed plus a significant portion of the non-marketed). The ratio: (ESP/SEP)×100=%ESP is a measure of proportion of the SEP from ecosystem services. Both SEP and %ESP were calculated and mapped for each 1 km2 pixel on the earth's surface, and aggregated by country. Results show the detailed spatial patterns of GDP, ESP, and SEP (also available at: http://www.du.edu/∼psutton/esiindexisee/EcolEconESI.htm). Globally, while GDP is concentrated in the northern industrialized countries, ESP is concentrated in tropical regions and in wetlands and other coastal systems. %ESP ranges from 1% for Belgium and Luxembourg to 3% for the Netherlands, 18% for India, 22% for the United States, 49% for Costa Rica, 57% for Chile, 73% for Brazil, and 92% for Russia. While GDP per capita has the usual northern industrialized countries at the top of the list, SEP per capita shows a quite different picture, with a mixture of countries with either high GDP/capita, high ESP/capita, or a combination near the top of the list. Finally, we compare our results with two other indices: (1) The 2001 Environmental Sustainability Index (ESI) derived as an initiative of the Global Leaders of Tomorrow Environment Task Force, World Economic Forum, and (2) Ecological Footprints of Nations: How much Nature do they use? How much Nature do they have? developed by Mathis Wackernagel and others. While both of these indices purport to measure sustainability, the ESI is actually mainly a measure of economic activity (and is correlated with GDP), while the Eco-Footprint index is a measure of environmental impact. The related eco-deficit (national ecological capacity minus national footprint) correlates well with %ESP. <s> BIB011 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> On many occasions over the centuries, mariners have reported witnessing surreal nocturnal displays where the surface of the sea produces an intense, uniform, and sustained glow that extends to the horizon in all directions. Although such emissions cannot be fully reconciled with the known features of any light-emitting organism, these so-called “milky seas” are hypothesized to be manifestations of unusually strong bioluminescence produced by colonies of bacteria in association with a microalgal bloom in the surface waters. Because of their ephemeral nature and the paucity of scientific observations, an explanation of milky seas has remained elusive. Here, we report the first satellite observations of the phenomenon. An ≈15,400-km2 area of the northwestern Indian Ocean, roughly the size of the state of Connecticut, was observed to glow over 3 consecutive nights, corroborated on the first night by a ship-based account. This unanticipated application of satellite remote-sensing technology provides insights pertaining to the formation and scale of these poorly understood events. <s> BIB012 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> Measles epidemics in West Africa cause a significant proportion of vaccine-preventable childhood mortality. Epidemics are strongly seasonal, but the drivers of these fluctuations are poorly understood, which limits the predictability of outbreaks and the dynamic response to immunization. We show that measles seasonality can be explained by spatiotemporal changes in population density, which we measure by quantifying anthropogenic light from satellite imagery. We find that measles transmission and population density are highly correlated for three cities in Niger. With dynamic epidemic models, we demonstrate that measures of population density are essential for predicting epidemic progression at the city level and improving intervention strategies. In addition to epidemiological applications, the ability to measure fine-scale changes in population density has implications for public health, crisis management, and economic development. <s> BIB013 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Research Trends Based on Selected Publications <s> A pervasive issue in social and environmental research has been how to improve the quality of socioeconomic data in developing countries. Given the shortcomings of standard sources, the present study examines luminosity (measures of nighttime lights visible from space) as a proxy for standard measures of output (gross domestic product). We compare output and luminosity at the country level and at the 1° latitude × 1° longitude grid-cell level for the period 1992–2008. We find that luminosity has informational value for countries with low-quality statistical systems, particularly for those countries with no recent population or economic censuses. <s> BIB014
In this section, we present the research trends that emerged from the 144 articles, which were published in 61 journals between 1992 and 2013. Although the analyses based on these selected publications may not support a rigorous statistical conclusion, we believe that the trends found among these SCI/SSCI papers present a general picture of the research trends. We analyzed trends for the following aspects: publication and reference trends, published journals, author and institution productivity, and the top 10 most cited articles. The number of publications showed an increasing trend from 1995 onward (Figure 1 ). There was a significant emergence of publications in 1997, which marked a new era of applications based on the newly assembled digital archived records of DMSP/OLS data. The number of publications continued to grow, from one added to the literature in 1998 to ten added in 2010. In the last 3 years of the time period considered, the number of publications increased more quickly, with BIB006 Studies based on DMSP/OLS nighttime images appeared in comprehensive journals that cover a wide variety of research areas (e.g., Science BIB013 and Proceedings of the National Academy of Sciences BIB012 BIB014 ) as well as professional journals that serve a more narrow research community (e.g., Remote Sensing of Environment, Monthly Notices of the Royal Astronomical Society, and Landscape and Urban Planning). Among the 62 journals, 9 published more than 3 research articles on DMSP/OLS data. A total of 75 articles were published by the 9 journals, accounting for nearly 70% of total citations. Two major publication outlets for research based on DMSP/OLS data were the International Journal of Remote Sensing and Remote Sensing of Environment; however, the top three most cited journals (measured by citation per paper, Table 2 Consistent with observations in other fields, a small number of authors and institutions contributed to a significant share of publications. A total of 344 authors were listed on the 144 published manuscripts, and among them, 14 authors were listed more than five times (Table 3) . A total of 67 publications included at least 1 of these 14 authors. In other words, 4.1% of all authors included in this sample of articles produced 46.5% of all publications. Prolific authors will accordingly promote the productivity of their institutions, and as such, the trends at the institutional level were similar. There were 154 different institutions listed among the 144 manuscripts, and 9 published more than 6 papers in this research field (Table 4) . A total of 75 publications included at least one of these institutions, meaning that 5.8% of all institutions included in the sample accounted for 52.1% of all publications. The relative concentration of productive authors and institutions was due to two main factors. First, the accessibility of DMSP/OLS nighttime images was largely limited before the free online release of Version 4 data in 2010. The original products were processed at NOAA/NGDC by a group of researchers led by Professor Christopher Elvidge, the most productive institution and author (measured by total publications, Tables 3 and 4), respectively. Second, the range of applications based on DMSP/OLS nighttime light images was relatively narrow, mainly focusing on urban socioeconomic parameters. Some institutions that have access to this database need spatially and temporally matched statistical data or ground observation data to validate the DMSP/OLS data when applied to certain topics. These include studies on urban dynamics and populations from Beijing Normal University and the Chinese Academy of Science, and research on forest fires and aerosol properties from the Department of Space, Government of India. The top 10 most-cited articles BIB011 BIB007 BIB005 BIB001 BIB002 BIB003 BIB008 BIB004 BIB009 BIB010 share several similarities. First, all were published prior to 2002 (Table 5 ). This is not surprising, as citations increase over time. Four top 10 articles were published in 1997, which marked a new era of research using nighttime images. The top 10 articles could be classified into three categories. The first category included papers describing the data processing methods that produced composites of nighttime images, which have great potential for observing human activities. For instance, the second ranked paper provided the method for developing a stable light image from 236 orbits between 1994 and 1995 BIB001 . In addition, the third ranked paper provided the earliest radiance-calibrated light image between 1996 and 1997 BIB005 . These two datasets were widely used by other researchers among following publication. The second category was review papers that summarized the progress of research and offered critical perspectives on research development; for example, the eighth ranked paper offered a relatively comprehensive review of environmental applications of the stable light dataset and discussed their potential advantages and disadvantages BIB008 . The third category of papers represented the early adoption of DMSP/OLS nighttime images in specific application areas. All of the remaining 7 papers in the top 10 list belong to this category; these include the first ranked paper, which mapped socioeconomic parameters and greenhouse gas emissions BIB007 , and the fourth ranked paper, which mapped urban areas BIB003 . In summary, the number of publications on this research topic has increased steadily over the past two decades. Although a number of journals, authors, and institutions have dominated the number and influence of publications, increasing numbers of journals, authors, and institutions around the world have recognized the research potential of DMSP/OLS nighttime images and have attempted to fully explore these datasets. The growing trend of publications was fueled by the release of different datasets and their application to different research areas. Therefore, we encoded the 144 publications by dataset (daily and monthly, stable light, radiance-calibrated, Version 4 time series, and Asia light datasets) and research area (e.g., urban extent, demographic features, socioeconomic parameters, fire detection) to further analyze how the DMSP/OLS database of images has been utilized. 