Sentinel-2 is the multispectral optical component of Europe’s Copernicus programme. Its twin satellites in orbit since June 2015 and March 2017 are tasked with acquiring continuous high-resolution multispectral imagery in 13 frequency bands of Earth’s land surfaces with short revisit cycles.
Continuity of observations is required to complement the multispectral imagery acquired by the SPOT and Landsat satellites.
Through Copernicus, Sentinel-2 delivers raw data that are processed into products for mapping land cover, urban growth, forests, wetlands and vegetation, glaciers and coasts. The satellites’ Earth-observation missions fall into four main categories:
- Plant health and phenology: Sentinel-2 is collecting key data at its 3 red/near-infrared frequencies on vegetation, wetland cover, chlorophyll and crops.
- Land monitoring: the ability to observe changing land use and land cover over time is vital to manage natural resources, keep track of deforestation and its impacts and promote sustainable land stewardship.
- Water resources: observing water quality by measuring its clarity and pollution, proliferation of dangerous algae and human-induced impacts on coasts.
- Emergency and risk mapping: through the Copernicus Emergency Management Services (CEMS) programme, Sentinel-2 is supporting analysis of natural disasters (hurricanes, wildfires, etc.) as they unfold, forecasting and tracking floods and supplying precious data for monitoring outbreaks of malaria by precisely identifying conditions on the ground where epidemics are likely to occur.
The Sentinel-2 mission is systematically acquiring data over land and coastal areas in a band of latitude extending from 56° South (Isla Hornos, Cape Horn, South America) to 83° North (above Greenland). Data collection within this region will include:
- all islands larger than 100 sq.km
- all EU islands
- all coastal waters and lands up to 20 km from the shore
- the Mediterranean Sea
- all lakes and closed seas
Orbit of sentinel-2
Sentinel-2A and Sentinel-2B are in a circular sun-synchronous orbit at a mean altitude of 786 km, inclined 98.62°. This means that any point on the globe is viewed every 5 days in the same illumination conditions and from the same angle. Observed changes in the landscape are therefore more easily attributable to seasonal or natural factors than to varying measuring conditions. The satellites fly over the same regions of the globe at the same mean local solar time (MLST) of 10:30 a.m., thus minimizing shadows and cloud cover. Sentinel-2A and Sentinel-2B’s overpass times are also designed to ensure compatibility with imagery from SPOT 5 and Landsat, enabling integration of Sentinel-2 data with these 2 legacy missions.