I have calculated from Landsat images monthly maximum NDVI values for a period of time. Now I want to calculate the seasonal values for this same variable but I don't know how to do it since I want it to be winter December - February, spring March - May, summer June - August and summer September - November.
var mycollection = ee.ImageCollection('LANDSAT/LC08/C02/T1_L2')
.filterBounds(geometry)
.filter(ee.Filter.date('2014-12-01', '2021-11-30'))
.map(calcularNDVI)
print(mycollection, 'NDVI 2015 2022');
//NDVI
function calcularNDVI(image) {
var ndvi = image.normalizedDifference(['SR_B5','SR_B4']).rename('NDVI')
return image.addBands(ndvi);
}
// monthly NDVI calculation
var start = ee.Date('2014-12-01');
var end = ee.Date('2021-11-30');
var numbmonthly = end.difference(start, 'month').divide(1).ceil();
// make a composite image for every month
var monthlyImages = ee.ImageCollection.fromImages(
ee.List.sequence(1, numbmonthly).map(
function(monthly){
var startTemp = start.advance(
ee.Number(monthly).subtract(1).multiply(1), 'month');
var endTemp = start.advance(ee.Number(monthly).multiply(1), 'month');
var image = mycollection.filterDate(startTemp, endTemp)
.filterBounds(geometry)
.mean()
.clip(geometry)
.select('NDVI');
return image.set('system:time_start', startTemp.millis(),
'system:time_end', endTemp.millis());
}));
print(monthlyImages, "Monthly Images");
Map.addLayer(monthlyImages.first());