00096_temp_disagg

 
 /*
Tutorial Code by Amirhossein Ahrari
YouTube: https://www.youtube.com/@amirhosseinahrarigee
Tutorial Video: Google Earth Engine Tutorial-101: Temporal Disaggregation

This code is part of a tutorial series on Earth Engine programming techniques
presented on the Amirhossein Ahrari YouTube channel. You are free to use and modify
this code for academic and non-academic purposes. Don't forget to subscribe to
the Amirhossein Ahrari channel and follow the videos to support the instructor!
*/
 
 
var cor = [
  [45.744788721480845,36.683639294666456], 
  [46.305091455855845,36.683639294666456], 
  [46.305091455855845,37.18419233722654], 
  [45.744788721480845,37.18419233722654], 
  [45.744788721480845,36.683639294666456]
  ]

var geometry = ee.Geometry.Polygon(cor)
 
 
var modis = ee.ImageCollection("MODIS/061/MOD13A2")
.select('NDVI')

var time_start = ee.Date('2023')
var time_end = ee.Date('2024')
var time_dif = time_end.difference(time_start, 'days')

print('number of days', time_dif)

var list = ee.List.sequence(0, ee.Number(time_dif).subtract(1), 1).map(function(interval){
  return time_start.advance(interval, 'days')
  })

print(list)

var daily = ee.ImageCollection(list.map(function(date_list){
  var date = ee.Date(date_list)
  
  var before = modis.filterDate(date.advance(-16, 'days'), date)
  .sort('system:time_start', false).first()
  
  var after = modis.filterDate(date, date.advance(16, 'days'))
  .sort('system:time_start', true).first()
  
  var before_time = ee.Date(before.get('system:time_start'))
  var after_time = ee.Date(after.get('system:time_start'))
  
  var coef = date.difference(before_time, 'days').divide(after_time.difference(before_time, 'days'))
  
  var ndvi_daily = before.addBands(after).expression('before + (after - before) * coef', {
    'before': before, 'after': after, 'coef': coef
    }).rename('ndvi_daily')
    
  return ndvi_daily.multiply(0.0001).resample().reproject('EPSG:4326',null, 1000)
  .set('system:time_start', date.millis())
  .set('system:index', date.format('YYYY-MM-dd'))
  
  }))
  

print(modis.filterDate(time_start, time_end))
print(daily)


print(
  ui.Chart.image.series(modis.filterDate(time_start, time_end),
  geometry, ee.Reducer.mean(), 1000, 'system:time_start')
  )

print(
  ui.Chart.image.series(daily, geometry, ee.Reducer.mean(), 1000, 'system:time_start')
  )



Map.addLayer(daily.filterDate('2023-06-01', '2023-07-01').toBands().clip(geometry), [], 'daily_ndvi_clipped', false)

Map.addLayer(daily.filterDate('2023-06-01', '2023-07-01').toBands().clipToBoundsAndScale(geometry, null, null, null, 1000), [], 'daily_ndvi', false)


Export.image.toDrive({
  image: daily.filterDate('2023-06-01', '2023-07-01').toBands().clip(geometry), 
  description: 'daily_ndvi_2023_jun', 
  scale: 1000, 
  region: geometry, 
  maxPixels: 1e13, 
  folder: 'test', 
  crs: 'EPSG:4326'
  
  })