E-Score_Global_Emissions_Score

// // **************************************************************************************** //
// // ************************** E Global Emissions Score ************************************ //
// // **************************************************************************************** //

// Important! Manually input dates to define dateRangeStart and dateRangeEnd, ensuring they do not fall 
// between 2022-07-26 and 2022-08-31, due to a provider outage during this period. The dates input 
// should correspond exactly to your second (later) monitoring period, or a close time period of
// equivalent length if your second monitoring period falls within the prohibited dates.

//         *** FUNCTIONS ***
//Reclassify the different emissions


// Function to reclassify emissions
var reclassify = function(value, thresholds, classes) {
  var classValue = ee.Image(); // Initialize an empty image 
  for (var i = 0; i < thresholds.length; i++) {
    if (i === 0) {
      classValue = value.lte(thresholds[i]).multiply(0);
    } else {
      classValue = classValue.where(value.gt(thresholds[i - 1]).and(value.lte(thresholds[i])), 0.5);
    }
  }
  return classValue.where(value.gt(thresholds[thresholds.length - 1]), 1).rename('reclassified');
};



//////////////////////////////////////////////////////////
//         *** Definition of emissions classes and thresholds ***
// 
var emissionsClasses = ['low', 'mid', 'high'];
var sulphur_th = [0.001, 0.01];
var methane_th = [1800, 2000];
var nitrogen_th = [0.0002, 0.0005];
var carbon_th = [0.01, 0.05];


// Compute emission within ald
var computeMeanEmission = function(collection) {
  var meanEmission = collection.median();
  return meanEmission.rename('mean_emission');
};

//////////////////////////////////////////////////
//         *** DATES ***


var dateRangeStart = '2022-09-01'; // add your number of weeks (default 4) to the date to the left to calculate the date below
var dateRangeEnd = '2022-10-01'; // check neither date falls within prohibited period

///////////////////////////////////////////////////////////


// Process each Polutant
var pollutants = [
  { name: 'S5P CH4_methane', collectionID: 'COPERNICUS/S5P/OFFL/L3_CH4', band: 'CH4_column_volume_mixing_ratio_dry_air_bias_corrected', thresholds: methane_th },
  { name: 'S5P SO2_sulphur', collectionID: 'COPERNICUS/S5P/OFFL/L3_SO2', band: 'SO2_column_number_density', thresholds: sulphur_th },
  { name: 'S5P N02_nitrogen', collectionID: 'COPERNICUS/S5P/OFFL/L3_NO2', band: 'tropospheric_NO2_column_number_density', thresholds: nitrogen_th },
  { name: 'S5P CO_carbon', collectionID: 'COPERNICUS/S5P/OFFL/L3_CO', band: 'CO_column_number_density', thresholds: carbon_th }
];


// Process each Polutant
pollutants.forEach(function(pollutant) {
  var collection = ee.ImageCollection(pollutant.collectionID)
                    .select(pollutant.band)
                    .filterDate(dateRangeStart, dateRangeEnd);

  collection = collection.map(function(image) {
    return image.clip(ald);
  });

  var meanEmission = computeMeanEmission(collection);
 // print('Mean ' + pollutant.name + ' emission over site:', meanEmission);

  // Reclassify emissions
  var reclassifiedEmission = reclassify(meanEmission, pollutant.thresholds, emissionsClasses);
  Map.addLayer(reclassifiedEmission, {min: 0, max: emissionsClasses.length, palette: ['green', 'yellow', 'red']}, 'Reclassified ' + pollutant.name, false);

  // Add the mean emission layer to the map
  Map.addLayer(meanEmission, {min: pollutant.thresholds[0], max: pollutant.thresholds[pollutant.thresholds.length - 1], palette: ['black', 'blue', 'purple', 'cyan', 'green', 'yellow', 'red']}, 'Median ' + pollutant.name + ' emission', false);

  // Print the mean emission value over the site
  var meanValue = meanEmission.reduceRegion({
    reducer: ee.Reducer.mean(),
    geometry: ald,
    scale: 1000  //1km
  });
  print('Mean ' + pollutant.name + ' emission over site:', meanValue);
});