The technology behind Syria's lights out campaign

Dramatic satellite images of Syria’s steady loss of night-time light during its four-year civil war have been released by human rights groups pushing for both a stronger humanitarian response to the crisis and increased efforts towards a political resolution.

The two most striking things about the images distributed by the #WithSyria coalition of rights groups are that they showed that war had led 83 percent of Syria’s lights  - 97 percent in Aleppo province - to go out, and that the data behind the research cost just $300.

Xi Li, an assistant professor at State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing at Wuhana University in China, and currently a visiting scholar at Maryland University, US, conducted the night-time imagery research on Syria.

Li has researched fluctuating light patterns in almost 160 countries, but nowhere else has he seen such a dramatic decline in night-time light, except during the genocide in Rwanda where 80 percent of lights went out in just a few months – rather than years as in Syria’s case.

Li sees tremendous benefit in measuring night-time light, a low-budget addition to a hi-tech conflict-monitoring toolbox increasingly used by humanitarian agencies and rights groups that includes high-resolution imagery and unmanned aerial vehicles – or drones.

“These night-time light images are very cheap, almost free, compared to the very high price of high-resolution images. They also have incredibly large cover, and they can record the earth nearly every day, unlike the higher resolutions,” said Li.

Li’s budget does not cover humanitarian work such as this Syria project, which he said was motivated by “personal interest” and a desire “to focus on issues that can help people.”

It involved two sets of data: the first – costing the $300 – consisted of 2.8km/pixel images from the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS), whose extensive archives allowed Li to study conflict patterns in 159 countries going back to 1992.

The second, much higher-resolution infra-red images (740m/pixel), came from the National Polar-orbiting Partnership (NPP), and were downloaded for free.

Although researchers have long used night-time light imaging in studies of urbanization, population growth and the like, its use in monitoring conflict and the large-scale movement of displaced people is a relatively new trend that is only starting to gather momentum, says Frank Witmer, computer science professor at the University of Alaska Anchorage, US.

Witmer, who conducted his own research on fluctuations in night-time light during the separatist conflicts in Chechnya and Georgia/South Ossetia in 2011, found that many aspects of war such as individual explosions and deaths were not detectable, but that other phenomena such as refugee movements, power grid damage and fires could show up. “Combining multiple sources of satellite imagery with the often partial and biased media reports can help provide a more accurate picture of the spatial and temporal distribution of violence, even in the “fog of war”, he concluded in his research.

The science is far from perfect and many other components are required to corroborate the imagery evidence, including witness reports on the ground and other hi-tech information sources, Witmer explained.

Lack of light doesn’t necessarily mean people have moved out. In very underdeveloped countries, millions live without electricity in regions that show up as vast areas of black. Usually, year-on-year images of such countries show a steady increase in electricity, in tandem with development and economic growth.

But research Li conducted on Zimbabwe showed a steady loss of light that corresponded directly with the country’s slide into economic collapse. Light patterns there showed a decline in the agricultural industry but a boom near the South African border.

The benefits of night-time light imaging are clear – low cost and a long-term record – and efforts are underway to digitize older, analogue night-time light imagery. But there are obstacles too: cloud cover, bright moons and summer months in the far northern hemisphere where nights are short, can all inhibit good data.

Li has now started research on the socio-economic situation in ISIS-controlled territory in Iraq and Syria. He wants to know whether the coalition airstrikes are really having an impact on ISIS.

“Are areas no longer controlled by ISIS now brighter than they were before? How effectively is ISIS managing the land? Some media reports say that it is not just brutal but that it is also very effective in managing land and people. I want to know what kind of access they have to electricity in these areas,” he says.