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I'm trying to get albedo for my study area but my values are not coming good. I need values in range of 0-1 but these values are out of this range. I don't know when I multiply scale value, its not working yet. My code is

//cloud mask
function maskL8sr(col) {
  // Bits 3 and 5 are cloud shadow and cloud, respectively.
  var cloudShadowBitMask = (1 << 3);
  var cloudsBitMask = (1 << 5);
  // Get the pixel QA band.
  var qa = col.select('pixel_qa');
  // Both flags should be set to zero, indicating clear conditions.
  var mask = qa.bitwiseAnd(cloudShadowBitMask).eq(0)
                .and(qa.bitwiseAnd(cloudsBitMask).eq(0));
  return col.updateMask(mask);
}


var albedo = function(image){
  var alb = image.expression(
  "((0.356*blue)+(0.130*red)+(0.373*nir)+(0.085*swir)+(0.072*swir2)- 0.018)/ 1.016",
  {
    'red': image.select('B3'),
    'blue':  image.select('B1'),
    'nir':  image.select('B4'),
    'swir':  image.select('B5'),
    'swir2':  image.select('B7')
  });
  return(image.addBands(alb.rename("albedo"))).multiply(0.0001);
};

var dataset = ee.ImageCollection('LANDSAT/LC08/C01/T1_SR')
                  .filterDate('2016-01-01', '2020-12-31')
                  .filterBounds(geometry)
                  .map(albedo)
                  .map(maskL8sr);

// print("dataset",dataset);

var myAlbedo = dataset.select("albedo").mosaic(); 
// print("myAlbedo",myAlbedo);

Map.addLayer(myAlbedo, Albedo_pallete, "Albedo" )

The script is given: https://code.earthengine.google.com/0da82ade43f03592f22233123d40a67a

1 Answer 1

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The LANDSAT/LC08/C01/T1_SR image collection has a scale of 0.0001, i.e, values are between 0 and 10,000 instead of 0 and 1 as the albedo function expects. Multiply the bands with 0.0001 before doing the calculation.

https://code.earthengine.google.com/c50c68a9e55f951fd7f44f75b6a5078c

Note that this image collection is deprecated, so might want to switch to LANDSAT/LC08/C02/T1_L2. To get these values between 0 and 1 you have to multiply with 2.75e-05 and subtract 0.2. Band names have also changed and you have to tweak your cloud masking function.

https://code.earthengine.google.com/85db598d7343fcb7588ce0f7c46e8055

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