# Urban green space monitoring with satellite data Satellite images show where a city is green and how its vegetation changes through the year. Vegetation indices such as NDVI, computed from red and near-infrared light, measure greenness and help spot declining plant health across parks, streets and gardens. Single street trees need finer imagery, and a decline seen from space still needs a check on site. ## How it works Vegetation indices compare how strongly a surface reflects red and near-infrared light. The difference shows how green an area is and how that changes over time. The best-known index is the NDVI, calculated from the red and near-infrared bands. It quantifies vegetation greenness and helps to understand vegetation density and to assess changes in plant health [1]. Sentinel-2 provides free data for it: 13 spectral bands, four at 10 m and six at 20 m, including four red-edge bands for vegetation, with a revisit of five days with two satellites [2]. The Copernicus Land Monitoring Service turns these images into ready-made layers: - **Vegetation phenology and productivity** at 10 m, which show where green spaces are and how vegetation changes through the seasons [3]. - **The Urban Atlas Street Tree Layer**, which maps contiguous rows or patches of trees of at least 500 square metres and 10 m width in the urban areas of nearly 800 European cities [4]. It is built from very high resolution imagery [5]. **Figure:** Illustrative map, not real data. Parks, avenues and green cover across a district, as a vegetation layer shows them. Satellite positioning completes the picture on the ground: Earth observation and GNSS are used together to monitor vegetation cover and the health of green spaces and to position green infrastructure precisely [6], for example in a tree inventory. ## What you get Green space monitoring shows where to look and what has changed. The decision on each tree stays with your experts. - **A green cover map** of the whole city, by district or block, as a layer for your GIS. - **Seasonal and yearly trends**, which show where greenness drops earlier or stays lower than in previous years. - **Change maps** of green that has been lost or gained, for example after construction. Losses to sealing are covered in the use case on [land use change](https://leto.space/use-cases/land-use-change/). - **A list of areas to inspect**, where the signal suggests stress, to plan the work of your arborists. ## Limits **Limits** - **Pixel size:** At 10 m, one Sentinel-2 pixel covers 100 square metres and often mixes a tree crown with pavement or lawn. Single street trees need very high resolution imagery or a tree inventory. Even the Copernicus Street Tree Layer, built from such imagery, maps only rows and patches of trees of 500 square metres or more \[4] \[5]. - **Greenness is not a diagnosis:** A falling index shows that the vegetation has changed, not why. Several causes can lower it, so the signal needs a check on site before anyone acts on it. - **Clouds:** Optical sensors are limited by cloud \[7], so a season can have gaps in the record. ## Related use cases - [Mapping urban heat islands](https://leto.space/use-cases/urban-heat-islands/): Where the city overheats, and where green cover is missing. - [Tracking land use change](https://leto.space/use-cases/land-use-change/): Where open land and green have become sealed ground. - [Crop monitoring and precision farming](https://leto.space/use-cases/crop-monitoring/): The same vegetation methods, applied to fields. ## Find providers and get started Providers offer tree inventories, canopy maps and vegetation monitoring as services. The [Spacegraph](https://leto.space/spacegraph/) marketplace has a category for vegetation and crop health. Whether the free Copernicus layers are enough or you need a commercial service depends on the level of detail and how often you need an update. We help you answer that before you buy, starting from your green space goals. [Strategy and use cases](https://leto.space/consulting/strategy/) ## Frequently asked questions ### Which satellite data is used to monitor urban green, and how often is it updated? Sentinel-2 provides free data for this: it records 13 spectral bands, four of them at 10 m, and passes over the same place every five days with two satellites [2]. The Copernicus Land Monitoring Service derives vegetation products from it at 10 m that show green spaces and their seasonal changes [3]. The Urban Atlas Street Tree Layer, built from very high resolution imagery, maps rows and patches of trees for selected reference years [5]. ### Can satellite data show the health of a single tree? Only with very high resolution imagery, and even then as a first signal. At 10 m, one Sentinel-2 pixel covers 100 square metres and usually mixes a tree crown with pavement or lawn. A drop in greenness can have several causes, so it points the arborists to the trees they should inspect first. ### How do we start a pilot for green space monitoring? Start with the question your parks or environment department needs answered, for example where green cover is shrinking, which districts lack shade or which avenues show stress after a dry summer. Then check what your tree inventory already records and which satellite products add to it. ## Sources 1. [Landsat Normalized Difference Vegetation Index, U.S. Geological Survey (USGS), accessed 2026-10-06](https://www.usgs.gov/landsat-missions/landsat-normalized-difference-vegetation-index) 2. [Sentinel-2 mission, European Space Agency (ESA), SentiWiki, accessed 2026-10-06](https://sentiwiki.copernicus.eu/web/s2-mission) 3. [High Resolution Phenology and Productivity data for urban green, Copernicus Land Monitoring Service, accessed 2026-10-06](https://land.copernicus.eu/en/events/high-resolution-phenology-and-productivity-data-for-urban-green) 4. [Urban Atlas Land Cover/Land Use and Street Tree Layer 2012 and 2018: Product User Manual, Copernicus Land Monitoring Service, accessed 2026-10-06](https://library.land.copernicus.eu/products/Urban_Atlas_Land_Cover-Land_Use_and_Street_Tree_Layer_2012_and_2018_PUM_v6.html) 5. [Urban Atlas Street Tree Layer 2021 (vector), Europe, 3-yearly, Copernicus Land Monitoring Service, accessed 2026-10-06](https://land.copernicus.eu/en/products/urban-atlas/street-tree-layer-stl-2021) 6. [EU Space Market Report 2026, Issue 1: Urban development and cultural heritage, EU Agency for the Space Programme (EUSPA), 2026-05-26](https://www.euspa.europa.eu/sites/default/files/documents/EU_Space_Market_Report_2026.pdf) 7. [Recommended Practice: Flood Mapping with Sentinel-1 and Sentinel-2 Imagery and Digital Terrain Models, UN-SPIDER (United Nations Office for Outer Space Affairs), accessed 2026-10-06](https://un-spider.org/advisory-support/recommended-practices/recommended-practice-flood-mapping-sentinel-1-and-sentinel-2) Page: