Air Quality Mapping with Sentinel-5P NO2 and DeepSeek

// Define the region of interest (North Morocco)
var roi = ee.Geometry.Rectangle([-6, 32, -2, 36]);

// Define the date range
var startDate = '2023-01-01';
var endDate = '2023-12-31';

// Import the Sentinel-5P NO2 dataset
var no2 = ee.ImageCollection('COPERNICUS/S5P/OFFL/L3_NO2')
  .filterDate(startDate, endDate)
  .filterBounds(roi);

// Function to mask clouds using the QA_value band
var maskClouds = function(image) {
  var qa = image.select('QA_value');
  var cloudMask = qa.gt(0.75);
  return image.updateMask(cloudMask);
};

// Apply cloud masking to the image collection
var no2Masked = no2.map(maskClouds);

// Function to calculate monthly averages
var monthlyAverages = ee.List.sequence(1, 12).map(function(month) {
  var monthString = ee.String(month).format('%02d');
  var monthlyData = no2Masked.filter(ee.Filter.date('2023-' + monthString + '-01', '2023-' + monthString + '-31'))
    .select('tropospheric_NO2_column_number_density')
    .median();
  return monthlyData.set('month', month);
});

// Convert the list of images to an image collection
var monthlyCollection = ee.ImageCollection.fromImages(monthlyAverages);

// Visualization parameters
var visualization = {
  min: 0,
  max: 0.0002,
  palette: ['blue', 'green', 'yellow', 'red']
};

// Add the January average to the map
var januaryAverage = monthlyCollection.filterMetadata('month', 'equals', 1).first();
Map.addLayer(januaryAverage, visualization, 'January 2023 NO2');

// Export the January 2023 average NO2 concentration to Google Drive
Export.image.toDrive({
  image: januaryAverage,
  description: 'January_2023_NO2',
  folder: 'GEE_Exports',
  region: roi,
  scale: 1000, // 1km resolution
  maxPixels: 1e10
});