Dust Storm Detection with MODIS and DeepSeek

// Define the region of interest (North Morocco).
var roi = ee.Geometry.Rectangle([-6, 32, -2, 35]);

// Define the date range.
var startDate = '2023-07-01';
var endDate = '2023-07-31';

// Load the MODIS surface reflectance dataset.
var modis = ee.ImageCollection('MODIS/061/MOD09GA')
    .filterDate(startDate, endDate)
    .filterBounds(roi);

// Function to calculate NDVI.
var calculateNDVI = function(image) {
  return image.normalizedDifference(['sur_refl_b02', 'sur_refl_b01']).rename('NDVI');
};

// Apply the NDVI calculation to the MODIS collection.
var modisWithNDVI = modis.map(calculateNDVI);

// Composite the MODIS collection to a single image (median).
var modisImage = modisWithNDVI.median().clip(roi);

// Define a threshold for NDVI to identify potential dust areas.
var ndviThreshold = 0.1;

// Create a mask for dust storms based on the NDVI threshold.
var dustMask = modisImage.select('NDVI').lt(ndviThreshold);

// Create a false-color composite for visualization.
var falseColor = modisImage.select(['sur_refl_b04', 'sur_refl_b03', 'sur_refl_b01']).multiply(0.0001);

// Display the false-color composite on the map.
Map.addLayer(falseColor, {min: 0, max: 0.3}, 'False Color Composite');

// Display the dust storm mask on the map.
Map.addLayer(dustMask.updateMask(dustMask), {palette: 'red'}, 'Dust Storms');

// Export the dust storm mask to Google Drive.
Export.image.toDrive({
  image: dustMask,
  description: 'Dust_Storm_Mask',
  folder: 'GEE_Exports',
  region: roi,
  scale: 1000,
  maxPixels: 1e13
});