00023_smap_soil_moisture

/*
Tutorial Code by Amirhossein Ahrari
YouTube: https://www.youtube.com/@amirhosseinahrarigee

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 fao = ee.FeatureCollection("FAO/GAUL/2015/level0")


var cor1 = [52.57063162600449,34.17766271003876]

var cor2 = [49.67024100100449,37.28054901678059]


var roi1 = fao.filterBounds(ee.Geometry.Point(cor1));

var roi2 = ee.Geometry.Point(cor2)

var sm = ee.ImageCollection("NASA/SMAP/SPL3SMP_E/005")
.select(['soil_moisture_am'])
.filterDate('2020','2024');

var sm_mean = sm.median();

Map.addLayer(sm_mean.clip(roi1),{palette: ['0300ff', '418504', 'efff07', 'efff07', 'ff0303']},
        'sm_mean',false)

Export.image.toDrive({
  image: sm_mean, 
  description: 'soil_moisture_mean', 
  scale: 9000,
  region: roi1,
  crs: sm_mean.getInfo().crs,
  maxPixels: 1e13,
  folder: 'soil_moisture'
  })
  

print(
  ui.Chart.image.series(sm, roi2, ee.Reducer.first(), 9000, 'system:time_start')
  )
  
  
  
function temporal_collection(collection, start, count, interval, unit){
  var seq = ee.List.sequence(0, ee.Number(count).subtract(1));
  var origin_date = ee.Date(start);
  return ee.ImageCollection(seq.map(function(i){
    var start_date = origin_date.advance(ee.Number(interval).multiply(i), unit)
    var end_date = origin_date.advance(ee.Number(interval).multiply(ee.Number(i).add(1)), unit)
    return collection.filterDate(start_date, end_date).mean()
    .set('system:time_start', start_date.millis())
    .set('system:time_end', end_date.millis())
    }))
  }  
  
  
var weekly = temporal_collection(sm, '2020', 208, 1, 'week')

print(
  ui.Chart.image.series(weekly, roi2, ee.Reducer.first(), 9000, 'system:time_start')
  )

// year = 52 weeks, 4 * 52 = 208
// year = 12 months, 4 * 12 = 48

var monthly = temporal_collection(sm, '2020', 48, 1, 'month');


print(
  ui.Chart.image.series(monthly, roi2, ee.Reducer.first(), 9000, 'system:time_start')
  )


var annual = temporal_collection(sm, '2020', 4, 1, 'year');


print(
  ui.Chart.image.series(annual, roi2, ee.Reducer.first(), 9000, 'system:time_start')
  )