Vegetation

Indices such as the Normalized Difference Vegetation Index (NDVI) can be utilized to observe the intensity and seasonality of vegetation. NDVI values ranging from -1 to 1, that quantify vegetation by measuring the difference between near-infrared (which vegetation strongly reflects) and red light (which vegetation absorbs) can be found in Earth Map for vegetation related analysis. Several Earth observation sensors (e.g. Sentinel 2 MSI, Landsat 5 TM/7 ETM+/8OLI, CBERS 2/2B/4/4A, MODIS Aqua/ Terra, AVHRR) feature spectral resolution covering the near-infrared and the red wavelengths. For the moment, the Earth Map user will have the opportunity to display NDVI average, change and anomalies maps derived from processing MOD13A1 Vegetation Indices time series available from 2000 to present and to generate statistics in any area of interest thanks to MODIS Aqua/ Terra, Landsat 5 TM/7 ETM+/8OLI and Sentinel 2 MSI sensors. 

The user should pay attention to the spatial resolution of the Earth observation sensors (500m per pixel for MODIS to 10m per pixel for Sentinel-2), for analysis in limited (agricultural/ forest plantation level) or wider (provincial or country level) areas of interest. NDVI is undoubtedly the most widely used vegetation indicator due to its simplicity of usage and flexibility, that is why it is the first vegetation parameter that was included in Earth Map. Nevertheless, other vegetation indices such as the Enhanced Vegetation Index (EVI) or the Modified Soil-Adjusted Vegetation Index (MSAVI) can help assessing vegetation patterns in lands where the use of NDVI has been shown to not perform optimally and might be included in Earth Map in the future.