Normalized Burn Ratio

NBR to capture of disturbance events

Step 1: get the collection and area of interest.

// get annual collection
var annualSRcollection = ee.ImageCollection("projects/servir-mekong/yearlyComposites")

// set the area of interest
var chl = ee.FeatureCollection("users/servirmekong/Vietnam/CHL_Boundary").geometry();

Step 2: add the function to calculate the nbr

// define function to calculate a spectral index to segment with LT
var nbr = function(img) {

    var index = img.normalizedDifference(['nir', 'swir1'])
                   .select([0], ['NBR'])
                   .set('system:time_start', img.get('system:time_start'));
    return img.addBands(index) ;
}

Step 3: apply the function to the image collection

var ltCollection = annualSRcollection.map(nbr)

Step 4: Display the results

/*
 0.66	High-severity burn*/

Map.addLayer(y2010.clip(chl),{min:0,max:3000,bands:"red,green,blue"},"2010 rgb")
Map.addLayer(y2010.clip(chl),{min:-0.2,max:0.5,bands:"NBR",palette:"red,orange,yellow,green,darkgreen"},"2010 nbr")

Map.addLayer(y2010.clip(chl),{min:0,max:3000,bands:"red,green,blue"},"2017 rgb")
Map.addLayer(y2017.clip(chl),{min:-0.2,max:0.5,bands:"NBR",palette:"red,orange,yellow,green,darkgreen"},"2017 nbr")

 

example