I'd like to copy the time:start property from dataset2021 collection to ndvi2021 and further to difference which is 2021-2020. How can I do it?
//point
var point = ee.Geometry.Point(-122.082, 37.42).buffer(50);
//Dataset
var dataset2021 = ee.ImageCollection('COPERNICUS/S2_SR')
.filterDate('2021-04-15', '2021-09-30')
.filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 5))
.filterBounds(point)
.select(['B4', 'B8']);
var dataset2020 = ee.ImageCollection('COPERNICUS/S2_SR')
.filterDate('2020-04-15', '2020-09-30')
.filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 5))
.filterBounds(point)
.select(['B4, 'B8']);
Map.centerObject(point, 14);
// NDVI 2021
var med2021 = dataset2021.median();
var result2021 = med2021.select('B4', 'B8');
var ndvi2021 = result2021.normalizedDifference(['B8', 'B4']).rename('ndvi');
// NDVI 2020
var med2020 = dataset2020.median();
var result2020 = med2020.select('B4', 'B8');
var ndvi2020 = result2020.normalizedDifference(['B8', 'B4']).rename('ndvi');
// difference
var diff2019 = ndvi2021.subtract(ndvi2020);
// CHART with properties
var chart = ui.Chart.image.series({
imageCollection: ndvi2021.select('ndvi'),
region: point,
reducer: ee.Reducer.median(),
scale: 10
}).setOptions({
title: 'NDVI over time',
hAxis: {title: 'Date'},
vAxis: {title: 'NDVI'}
});
print(chart);
var chart = ui.Chart.image.series({
imageCollection: diff2019.select('ndvi'),
region: point,
reducer: ee.Reducer.median(),
scale: 10
}).setOptions({
title: 'ZNDVI over time',
hAxis: {title: 'Date'},
vAxis: {title: 'difference'}
});
print(chart);