Prague also uses the view from space to monitor vegetation and summer heat. Key outputs are maps of vegetation index, surface temperature and vulnerability index. The documents are created by analyzing freely available satellite images. More frequent use is limited by their relatively low accuracy.

Map of the Normalized Difference Vegetation Index (NDVI)

NDVI is a standardized indicator of the condition and quantity of green vegetation. Values between -1 and 1 are represented by a color scale, where greener shades represent more healthy vegetation in a given 10x10 m square. The data were collected from the Sentinel satellites of the European Copernicus program during the summer months of 2019 and 2020.

Sample map of NDVI

Surface temperature map

The map shows the measured surface temperature in degrees Celsius on an intuitive color scale on a 30x30 m raster. The data used was collected by Landsat satellites (NASA/USGS) during the summer months of 2019 and 2020.

Sample surface temperature display

Vulnerability index map (HVI)

HVI values represent the relative vulnerability of an area during a heat wave in a 100x100 m square. This is calculated from the satellite data mentioned above and other additional information about the area. The data was collected during extremely hot days between 2015 and 2019. Each square has an index value from -1 to 1. The cumulative value for the whole square is determined by the combination of surface temperature and the occurrence of blue-green infrastructure.

Sample HVI map