Sentinel_SAR_China.txt

//collecting Sentinel-1 SAR subset (two polarization) across China in winter season of 2017

//import boundary
var BD = ee.FeatureCollection("users/cyangpkucues/shp_files/CN-sheng-A");
Map.addLayer(BD);
//Map.centerObject(BD,10);
print(BD);

//---------------------------import S1 VV polarization----------------------------
var s1vv1 = ee.ImageCollection('COPERNICUS/S1_GRD')
          .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))
          .filter(ee.Filter.eq('instrumentMode', 'IW'))
          //.filter(ee.Filter.eq('orbitProperties_pass', 'ASCENDING'))
          //.filter(ee.Filter.eq('relativeOrbitNumber_start','69'))
          //.filter(ee.Filter.eq('relativeOrbitNumber_stop','69'))
          .select('VV')
          .filterBounds(BD)
          .filterDate('2017-01-01','2017-03-31');
//print(s1vv1);
var s1vv1_avg = s1vv1.median().clip(BD);
print(s1vv1_avg);


var s1vv2 = ee.ImageCollection('COPERNICUS/S1_GRD')
          .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))
          .filter(ee.Filter.eq('instrumentMode', 'IW'))
          //.filter(ee.Filter.eq('orbitProperties_pass', 'ASCENDING'))
          //.filter(ee.Filter.eq('relativeOrbitNumber_start','69'))
          //.filter(ee.Filter.eq('relativeOrbitNumber_stop','69'))
          .select('VV')
          .filterBounds(BD)
          .filterDate('2017-11-01','2017-12-31');
//print(s1vv2);
var s1vv2_avg = s1vv2.median().clip(BD);
print(s1vv2_avg);

var s1vv = s1vv1_avg.addBands(s1vv2_avg);
var s1vv_avg = s1vv1.median().clip(BD);
print(s1vv);
print(s1vv_avg);
Map.addLayer(s1vv_avg);

Export.image.toDrive({
  image: s1vv_avg.select('VV'),
  description: "s1vv_avg_2017_CN",
  fileNamePrefix: "s1vv_avg_2017_CN",
  scale: 10,
  region: BD,
  crs: "EPSG:4326",
  maxPixels: 1e13
});

//-------------------------import S1 VH polarization--------------------------
var s1vh1 = ee.ImageCollection('COPERNICUS/S1_GRD')
          .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
          .filter(ee.Filter.eq('instrumentMode', 'IW'))
          //.filter(ee.Filter.eq('orbitProperties_pass', 'ASCENDING'))
          //.filter(ee.Filter.eq('relativeOrbitNumber_start','69'))
          //.filter(ee.Filter.eq('relativeOrbitNumber_stop','69'))
          .select('VH')
          .filterBounds(BD)
          .filterDate('2017-01-01','2017-03-31');
//print(s1vv1);
var s1vh1_avg = s1vh1.median().clip(BD);
print(s1vh1_avg);


var s1vh2 = ee.ImageCollection('COPERNICUS/S1_GRD')
          .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
          .filter(ee.Filter.eq('instrumentMode', 'IW'))
          //.filter(ee.Filter.eq('orbitProperties_pass', 'ASCENDING'))
          //.filter(ee.Filter.eq('relativeOrbitNumber_start','69'))
          //.filter(ee.Filter.eq('relativeOrbitNumber_stop','69'))
          .select('VH')
          .filterBounds(BD)
          .filterDate('2017-11-01','2017-12-31');
//print(s1vv2);
var s1vh2_avg = s1vh2.median().clip(BD);
print(s1vh2_avg);

var s1vh = s1vh1_avg.addBands(s1vh2_avg);
var s1vh_avg = s1vh1.median().clip(BD);
print(s1vh);
print(s1vh_avg);
Map.addLayer(s1vh_avg);

Export.image.toDrive({
  image: s1vh_avg.select('VH'),
  description: "s1vh_avg_2017_CN",
  fileNamePrefix: "s1vh_avg_2017_CN",
  scale: 10,
  region: BD,
  crs: "EPSG:4326",
  maxPixels: 1e13
});