How is Landsat 7 NDWI calculated?
- For Landsat 7 data, NDWI = (Band 4 – Band 5) / (Band 4 + Band 5)
- For Landsat 8 data, NDWI = (Band 5 – Band 6) / (Band 5 + Band 6)
- For Landsat 7 data, NDWI = (Band 2 – Band 5) / (Band 2 + Band 5)
- For Landsat 8 data, NDWI = (Band 3 – Band 6) / (Band 3 + Band 6)
What does NDWI indicate?
The Normalized Difference Water Index (NDWI) is known to be strongly related to the plant water content. It is therefore a very good proxy for plant water stress. The Normalized Difference Water Index (NDWI) (Gao, 1996) is a satellite-derived index from the Near-Infrared (NIR) and Short Wave Infrared (SWIR) channels.
How is ndwi calculated in Google Earth Engine?
The confusion here derives from the fact that there are two definition of NDWI, and both from 1996! One is by Gao (1996) where NDWI is defined as the normalized difference between NIR and SWIR. This is used to monitor changes in water content of leaves in plants.
How are Landsat 7 collection 1 Tier 1 composites calculated?
The product description says: These Landsat 7 Collection 1 Tier 1 composites are made from Tier 1 orthorectified scenes, using the computed top-of-atmosphere (TOA) reflectance. It is derived from the Near-IR band and a second IR band, ≈1.24μm when available and the nearest available IR band otherwise.
What are the sensor IDs of Landsat 7 and 8?
Set the property manually to avoid that. The sensor IDs of Landsat 5, 7 and 8 are ‘TM’, ‘ETM+’ and ‘OLI_TIRS’, respectively. For creating simple cloud-free Landsat composites, Earth Engine provides the ee.Algorithms.Landsat.simpleComposite () method.
How does Google Earth Engine create Landsat composites?
For creating simple cloud-free Landsat composites, Earth Engine provides the ee.Algorithms.Landsat.simpleComposite () method. This method selects a subset of scenes at each location, converts to TOA reflectance, applies the simple cloud score and takes the median of the least cloudy pixels.