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Researchers have developed a novel approach to monitor urban development using satellite imagery, likening the process to tracking a city's "urban pulse." This method, detailed in the journal Proceedings of the National Academy of Sciences, analyzes high-frequency satellite data to detect dynamic changes in cities in near real-time. Unlike traditional methods that rely on infrequent, aggregated data like yearly censuses or decade-long maps, this new technique offers a more nuanced understanding of a metropolis's evolution.

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

Lead study author Zhe Zhu, a professor at the University of Connecticut, explained the inspiration came from the human pulse, which provides more insight into health than simple weight or height measurements. The "urban pulse" can identify early warning signs of economic stress or stagnation before they escalate into full-blown crises. Zhu contrasted this process monitoring with traditional metrics, which he compared to looking at the outcome of a heart attack rather than the lifestyle leading up to it.

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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.

The study highlights that urbanization is not a smooth, steady process. Instead, it is often "spiky," occurring in abrupt bursts, or "cyclical," with boom-and-rest phases unrelated to seasons. Furthermore, different neighborhoods within the same city can develop at uncoordinated times, a phenomenon termed "asynchronous." Senior author Karen Seto, a Yale University professor, noted that for decades, cities were characterized by static maps, failing to capture these complex dynamics.

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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 dense, high-frequency satellite imagery from NASA and the European Space Agency to track physical changes such as new construction, demolition, infrastructure improvements, and expansion into green spaces. They selected cities with diverse political and economic conditions, including Shenzhen's state-led development, Seattle's market-driven growth, Lagos's informal expansion, and Dubai's megaprojects, to test the method's applicability across different urban environments.

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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.