BBlue.
The Sentinel Water Mask (SWM) is a water spectral index intended for multispectral sensing. It was introduced in 2017; its source is cited as Marta Milczarek, Anna Robak, & Alicja Gadawska (2017). Sentinel Water Mask (SWM) - new index for water detection on Sentinel-2 images. 7th Advanced Training Course on Land Remote Sensing, Szent István University, Gödöllő, Hungary 4-9 September 2017. https://eoscience.esa.int/landtraining2017/files/posters/MILCZAREK.pdf .
(B + G)/(N + S1)BBlue.
GGreen.
NNear-Infrared (NIR).
S1Short-wave Infrared (SWIR) 1.