GEE Code to generate TCT.txt

var shapefile = ee.FeatureCollection("users/stLuciashp"),

//Import study area shapefile
var shp= ee.FeatureCollection(shapefile);

//Import Sentinel-2 MSI: MultiSpectral Instrument, Level-1C
//from GEE cloud 
var dataset = ee.ImageCollection("COPERNICUS/S2")
    .filterBounds(shp)
    .filterDate('2021-06-01', '2022-12-31')
    ;
//Display the study area shapefile
Map.addLayer (shapefile, {color: 'blue'}, 'Study Area')

//Display the sentinel image
Map.addLayer(dataset, {bands:['B4', 'B3', 'B2'], min:0, max:3000}, 'Sentinel 2021')

//clip the sentinel image to study area shapefile
//and select the median composite
var clip = dataset.median().clip(shp);
Map.addLayer(clip, {bands:['B4', 'B3', 'B2'], min:0, max:3000}, 'Clip 2020')


// Define an Array of Tasseled Cap coefficients for bands 2,3,4 and 8.
var coefficients = ee.Array([
  [0.0822,0.1360,0.2611, 0.3895],
  [-0.1128,-0.1680,-0.3480,0.3165],
  [0.1363,0.2802,0.3072 ,-0.0807],
  
]);

//select the four bands from the sentinel image 
//where the coefficients will be applied.
var image = clip.select(['B2', 'B3', 'B4', 'B8']);

// Make an Array Image, with a 1-D Array per pixel.
var arrayImage1D = image.toArray();

// Make an Array Image with a 2-D Array per pixel, 6x1.
var arrayImage2D = arrayImage1D.toArray(1);

// Do a matrix multiplication: 6x6 times 6x1.
var componentsImage = ee.Image(coefficients)
  .matrixMultiply(arrayImage2D)
  // Get rid of the extra dimensions.
  .arrayProject([0])
  .arrayFlatten(
    [['brightness', 'greenness', 'wetness']]);

// Display the first three bands of the result and the input imagery.
var vizParams = {
  bands: ['brightness', 'greenness', 'wetness'],
  min: 0.5, max: [0.5,0.1,0.1]
};

//Display the TCT images
Map.addLayer(clip, {bands: ['B5', 'B4', 'B3'], min: 0, max: 3000}, 'TCT');
Map.addLayer(componentsImage, vizParams, 'Components');

//Export to google drive folder
Export.image.toDrive({
  image: componentsImage,
  description: 'Sentinel_TCT_STLucia',
  folder: 'GEE',
  region: shapefile,
  scale: 10,
  maxPixels: 1e10
});