Cloud cover percentage in Google Earth Engine for Sentinel-2

Question

I'm trying to obtain the cloud cover percentage of my ROI in a specific time interval using Sentinel-2.

//Sentinel collection
var sentinel2 = ee.ImageCollection("COPERNICUS/S2")
.filterBounds(ROI)
.filterDate('2017-06-01','2018-06-01');

//Add a cloud cover band
var cloud = function(sentinel2) {
return sentinel2.addBands(sentinel2.metadata('CLOUD_COVERAGE_ASSESSMENT')); };
print(sentinel2.map(cloud));

var getCloudScores = function(sentinel2){
var value = ee.Image(sentinel2).get('CLOUD_COVERAGE_ASSESSMENT');
return ee.Feature(null, {'score': value})
};

var s2 = sentinel2.filterBounds(ROI);
var results = s2.map(getCloudScores);
var chart = ui.Chart.feature.byFeature(results)
    .setChartType('LineChart')
    .setOptions({
      title: 'Cloud cover',
      hAxis: {
        title: 'Date',},
      vAxis: {
        title: 'Clouds'
      },
      lineWidth: 1,
      pointSize: 0
});

print(chart);

So far this code has worked, but I was wondering if there is another way to get it?

Answer 1

You can use the image collection as it is, and chart the CLOUD_COVERAGE_ASSESSMENT property directly:

var ROI = Map.getBounds(true)

var sentinel2 = ee.ImageCollection("COPERNICUS/S2")
.filterBounds(ROI)
.filterDate('2017-06-01','2018-06-01')

var chart = ui.Chart.feature.byFeature({
    features: sentinel2, 
    yProperties: ['CLOUD_COVERAGE_ASSESSMENT']
  })
  .setChartType('LineChart')
  .setOptions({
    title: 'Cloud cover',
    hAxis: {title: 'Date'},
    vAxis: {title: 'Clouds'},
    lineWidth: 1,
    pointSize: 0
  })

print(chart)

https://code.earthengine.google.com/e8cfe7fd4bef84bdacc11a6c9ab22afb