I try to apply an expression to the satellite image and then try to chart the mean of the series of images but I'm getting this error:
"Error generating chart: No features contain non-null values of
"system:time_start"
Link to the code:
https://code.earthengine.google.com/c977a6ea5b61ec830b15835036e64c97
Code:
var app = function (image)
{
var conv = image.expression(
'band/(4.4615*10**-4)', //formula for coverting mol/m2 to DU(Dobson)
{
band: image.select('SO2_column_number_density'),
});
return conv;
};
// Load the sentinel data
var sentinel = ee.ImageCollection('COPERNICUS/S5P/NRTI/L3_SO2')
.filterDate('2019-04-01', '2019-04-21')
.map(app)
//Identify country
var region = ee.FeatureCollection("ft:1p_3AqEj1T9fG0BNu6pGqmP6_HdDOalruzpk54Ne8");
Map.addLayer(region);
Map.addLayer(sentinel)
var TS5 = Chart.image.series(sentinel, region, ee.Reducer.mean(),1000, 'system:time_start').setOptions({
title: 'pollutants Full Time Series',
vAxis: {title: 'mol/m2'},
});
print(TS5);
Best Answer
using an image expression, the image will losse it's original properties. Copy the properties of the source (image) to the new image (conv):