{"id":539306,"date":"2026-06-17T05:17:15","date_gmt":"2026-06-17T05:17:15","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/539306\/"},"modified":"2026-06-17T05:17:15","modified_gmt":"2026-06-17T05:17:15","slug":"satellites-can-now-detect-a-citys-hidden-vital-signs-before-humans-notice","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/539306\/","title":{"rendered":"Satellites Can Now Detect a City\u2019s Hidden Vital Signs Before Humans Notice"},"content":{"rendered":"

\"Network<\/a>By analyzing decades of satellite observations, researchers uncovered surprising similarities in how very different cities change over time. Credit: Shutterstock<\/p>\n

A new satellite-based framework allows scientists to measure the changing rhythms of cities in near real time.<\/strong><\/p>\n

Cities are often described as living systems, but until now that idea has mostly been a metaphor. Roads, buildings, parks, and neighborhoods change constantly, yet much of that activity is hard to see as it happens. By the time a pattern becomes obvious from the ground, a neighborhood may already be booming, declining, or spreading into nearby green space.<\/p>\n

Researchers now say satellites can reveal those changes much earlier. In a study published in the Proceedings of the National Academy of Sciences (PNAS), scientists introduced a framework called the \u201cUrban Pulse,\u201d which uses frequent satellite observations to track how cities physically change over time.<\/p>\n

The idea is similar to an electrocardiogram (EKG), which helps doctors detect hidden signals from the heart. Instead of measuring electrical activity in the body, Urban Pulse monitors the visible signs of construction, demolition, repairs, infrastructure upgrades, and expansion across urban landscapes.<\/p>\n

Zhe Zhu, director of the Global Environmental Remote Sensing (GERS) Laboratory and associate professor of natural resources and the environment in the College of Agriculture, Health and Natural Resources (CAHNR), was the study\u2019s first author. He worked with senior author Karen C. Seto, the Frederick C. Hixon Professor of Geography and Urbanization Science at the Yale School of the Environment, along with Michail Fragkias of Boise State University and a multi-institutional research team.<\/p>\n

\u201cFor decades, we had just been capturing the outcome of urbanization \u2013 a house that\u2019s been built, or a road expansion,\u201d Zhu says. \u201cBut you don\u2019t really see the dynamics within an urban area.\u201d<\/p>\n

Measuring a City\u2019s Heartbeat<\/p>\n

Urban growth is usually studied after the fact. Planners may count new buildings, review zoning changes, analyze census data, or compare older satellite images with newer ones. Those methods can be useful, but they often miss the timing and rhythm of change.<\/p>\n

Urban Pulse is designed to capture that rhythm. It analyzes decades of dense time series data from NASA\u2019s Harmonized Landsat and Sentinel-2 (HLS) datasets, which combine observations from major Earth observing satellite missions. This allows researchers to examine repeated views of the same places and identify when physical changes occur.<\/p>\n

\"Urban<\/a>This figure visualizes Dubai\u2019s rapid expansion as a glowing \u201curban pulse.\u201d Mapping monthly construction data from the city\u2019s top 65 most active locations, the ridge plot reveals how distinct neighborhoods grow through spiky, cyclical, and asynchronous bursts. Rather than a steady wave, urbanization unfolds as dynamic, localized heartbeats, exposing the complex rhythms driving a modern metropolis. Credit: Zhe Zhu\/GERS Lab<\/p>\n

The framework uses CAPES, a deep learning and time series analysis method developed by former UConn postdoctoral researcher Ji Won Suh. Suh is now a tenure-track assistant professor at the University of Victoria in Canada. With this approach, the team can detect neighborhood-level transformations such as new construction, demolition, and infrastructure improvements.<\/p>\n

Three Vital Signs of a City<\/p>\n

To develop and test the framework, Zhu\u2019s team examined many cities and several types of satellite inputs. The study highlights six cities: Seattle, Shenzhen, Lagos, Mumbai, Dubai, and Mexico City. They differ sharply in geography, wealth, governance, climate, and development history, yet they shared three major patterns.<\/p>\n

The first pattern is that urbanization is spiky. Cities do not grow at a smooth, constant rate. Construction often arrives in bursts, with intense periods of activity followed by quieter intervals.<\/p>\n

The second pattern is that urbanization is cyclical. Neighborhoods can move through boom and rest phases, but those cycles do not necessarily follow seasons or predictable annual schedules.<\/p>\n

The third pattern is that urbanization is asynchronous. A city does not develop all at once. One district may surge while another slows down, creating an uneven pattern across the urban landscape. The researchers suggest this lack of synchronization may help keep infrastructure systems and labor markets from overheating.<\/p>\n

What COVID Revealed About Cities<\/p>\n

The framework also captured how cities responded to the COVID-19 pandemic. According to the researchers, the data showed a widespread, synchronized slowdown in urban development, a pattern they describe as a global \u201ccardiac arrest\u201d in construction activity.<\/p>\n

But the recovery was not the same everywhere. Shenzhen showed coordinated declines followed by rapid, policy-driven rebounds. Mumbai and Mexico City had more muted responses, suggesting that the pandemic\u2019s urban effects varied widely depending on local conditions, policies, economies, and development systems.<\/p>\n

\u201cIt\u2019s like in human beings,\u201d Zhu notes. \u201cWhen you get a disease, it\u2019s not going to show up exactly the same in different people.\u201d<\/p>\n

A Possible Early Warning System<\/p>\n

The researchers say Urban Pulse could eventually help governments detect problems before they become entrenched. If a neighborhood\u2019s activity drops sharply or if development begins pushing rapidly into green space, planners may have a chance to respond sooner.<\/p>\n

Public access to this kind of data could also affect everyday decisions. A person considering a move, or a business owner choosing where to open a new location, could use a neighborhood\u2019s pulse as one signal of local activity and economic vitality.<\/p>\n

\u201cThis is going to be a very impactful tool influencing not only top-down policy decisions from governments but also bottom-up decisions from everyday people navigating their cities,\u201d Zhu says.<\/p>\n

Reference: \u201cThe Urban Pulse: Diagnosing the urbanization process as spiky, cyclical, and asynchronous\u201d by Zhe Zhu, Michail Fragkias, Ji Won Suh, Ella McCoshan, Lelin Chen, Kexin Song, Juwon Kong, Tian Li and Karen C. Seto, 8 June 2026, Proceedings of the National Academy of Sciences.
DOI: 10.1073\/pnas.2537770123<\/a><\/p>\n

Zhu completed this work while on sabbatical at Yale University alongside his collaborator Karen Seto.<\/p>\n

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