Urban 'Pulse' Tracked by Satellite Imagery Offers Real-Time City Health Check

Cities behave like living organisms, exhibiting growth, change, and even decay. Now, researchers have developed a novel way to track these "vital signs" using satellite imagery, creating an "urban pulse" to monitor six major global cities in near real-time.

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We got the inspiration from the human pulse, which tells us different information about our health than weight or height.

The "urban pulse" method, inspired by human vital signs, offers a more dynamic understanding of urban development than traditional metrics like yearly censuses or decade-long footprint maps. "We got the inspiration from the human pulse, which tells us different information about our health than weight or height," explained Zhe Zhu, lead author and professor at the University of Connecticut. "The urban pulse measures the high-frequency process of development, and therefore we can spot early warning signs of economic stress or stagnation before they become full-blown crises."

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The urban pulse measures the high-frequency process of development, and therefore we can spot early warning signs of economic stress or stagnation before they become full-blown crises.

This new approach reveals that urbanization is not a steady process. Instead, it happens in "spiky" bursts, moves through "boom-and-rest phases," or occurs "asynchronously" with different neighborhoods developing at uncoordinated times. "For decades, researchers have characterized cities through static maps," said Karen Seto, a Yale University professor and senior author of the study published in Proceedings of the National Academy of Sciences. "This is important because, for decades, researchers have characterized cities through static maps."

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We compare traditional metrics to looking at a heart attack - the outcome - whereas the 'urban pulse' is like monitoring the daily lifestyle and vital signs leading up to that heart attack - the process.

The researchers utilized high-frequency satellite imagery from NASA and the European Space Agency to track physical changes, including new construction, demolition, and infrastructure improvements. They selected cities with diverse political and economic conditions, such as Shenzhen's state-led development, Seattle's market-driven growth, Lagos's informal expansion, and Dubai's megaprojects. This method allows for a more nuanced understanding of how metropolises evolve over time.

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Urbanization is actually 'spiky,' meaning that it happens in abrupt, intense bursts, or 'cyclical,' moving through boom-and-rest phases that don't match annual seasons, or 'asynchronous,' as different neighborhoods in the exact same city develop at completely different, uncoordinated times.