Ongoing Conflict Makes Yemen Dark: From the Perspective of Nighttime Light
Abstract
:1. Introduction
2. Materials and Methods
2.1. Study Area
2.2. Data Source
2.2.1. Nighttime Light Imagery
2.2.2. Auxiliary Data
2.3. Nighttime Light Imagery Processing
2.4. Method
2.4.1. Theil-Sen Median Trend Method
2.4.2. Nighttime Light Indexes
3. Results
3.1. Time Series Analysis
3.2. Spatial Pattern Analysis
4. Discussion
5. Conclusions
- (1)
- At the national scale, nighttime light showed a sharp decline from February 2015 to June 2015, and TNL lost 71.60%. The nighttime light in all provinces also showed the decline period. These findings reflect that the Saudi-led airstrikes caused widespread and severe humanitarian crisis in Yemen.
- (2)
- From spatial pattern analysis, the areas of decline were found to be mainly located in Sana’a, Dhamar, Ibb, Ta’izz, ’Adan, Shabwah and Hadramawt. The validation results show that the nighttime light declines in western cities and eastern cities are due to the damage of urban infrastructure and decreased oil exploration, respectively. In addition, a nighttime curfew policy and electrical blackouts are also key factors in the decline of nighttime light in Yemen.
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Parameters | NPP-VIIRS | DMSP-OLS |
---|---|---|
Operator | National Aeronautics and Space Administration (NASA) and National Oceanic and Atmospheric Administration (NOAA) | Department of Defense, United States |
Orbit | Polar orbit satellite | Polar orbit satellite |
Overpass time | 13:30 and 1:30 | 8:30–9:30 and 20:30–21:30 |
Width | 3040 km | 3000 km |
Temporal resolution | 12 h | 12 h |
Spatial resolution | 742 m | 2.7 km |
Wavelength range | 0.5–0.9 µm | 0.4–1.1 µm |
Radiation resolution | 14 bit | 6 bit |
Unit | W·cm−2·sr−1·μm−1 | Relative (0–63 scale) |
On-board calibration | Yes | No |
Pixel saturated | No saturated | Saturated |
Available product | December 2011–now | 1992–2013 |
Product cycle | Month | Year |
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Jiang, W.; He, G.; Long, T.; Liu, H. Ongoing Conflict Makes Yemen Dark: From the Perspective of Nighttime Light. Remote Sens. 2017, 9, 798. https://doi.org/10.3390/rs9080798
Jiang W, He G, Long T, Liu H. Ongoing Conflict Makes Yemen Dark: From the Perspective of Nighttime Light. Remote Sensing. 2017; 9(8):798. https://doi.org/10.3390/rs9080798
Chicago/Turabian StyleJiang, Wei, Guojin He, Tengfei Long, and Huichan Liu. 2017. "Ongoing Conflict Makes Yemen Dark: From the Perspective of Nighttime Light" Remote Sensing 9, no. 8: 798. https://doi.org/10.3390/rs9080798
APA StyleJiang, W., He, G., Long, T., & Liu, H. (2017). Ongoing Conflict Makes Yemen Dark: From the Perspective of Nighttime Light. Remote Sensing, 9(8), 798. https://doi.org/10.3390/rs9080798