Var s2a = ee. ImageCollection('copernicus/S2 sr'). filterBounds(aoi)

var s2a = ee.ImageCollection('COPERNICUS/S2_SR')
.filterBounds(aoi)
.filterDate('2020-06-16', '2020-06-18')
.filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20));
print(s2a, 'aoi');
var s2a = s2a
.max()
.clip(aoi);
print(s2a, 'aoi');
var ndvi = s2a.expression( '(NIR - RED) / (NIR + RED)',
{
'NIR' : s2a.select('B8'),
'RED' : s2a.select('B4')
})
.rename('NDVI');
var evi = s2a.expression( '2.5 * ((NIR-RED) / (NIR + 6 * RED - 7.5* BLUE +1))',
{
'NIR' : s2a.select('B8'),
'RED' : s2a.select('B4'),
'BLUE': s2a.select('B2')
})
.rename('aoi')
print(evi, 'aoi')
var sviParams = {min: -1, max: 0.5, palette: ['red', 'yellow', 'green']};
Map.addLayer(evi, sviParams, 'aoi');
Export.image.toDrive({ image: evi,
description: 'aoi',
scale: 10,
region: aoi,
folder: 'ndvi',
maxPixels: 552296739,
crs: "EPSG:32641" });