GEE开发之Modis_LST地表温度数据分析
- 1 MODIS/006/MOD11A1介绍
- 2 遥感影像获取(以LST为例子)
- 3 日遥感数据获取(以LST为例子)
* - 3.1 日数据折线图展现如下（以鹿邑县为例）
- 3.2 日数据tif批量下载（以鹿邑县为例）
- 4 月遥感数据获取(以LST为例)
* - 4.1 月数据折线图展现如下（以鹿邑县为例）
- 4.2 月数据tif批量下载（以鹿邑县为例）
- 5 年遥感数据下载(以LST为例)
前言：这次主要介绍MODIS/006/MOD11A1下的地表温度的数据分析。
1 MODIS/006/MOD11A1介绍
MOD11A1 V6产品提供1200 x 1200公里网格中的每日地表温度（LST）和发射率值。温度值由MOD11_ L2线束乘积导出。在30度纬度以上，某些像素可能具有多个观测值，满足晴空标准。发生这种情况时，像素值是所有合格观测值的平均值。与白天和夜间地表温度带及其质量指示层一起提供的是MODIS波段31和32以及六个观测层。
分辨率：1000ｍ
波段：白天和夜晚的LST都有。
注意：需要什么指数直接select选择就行，本博文以”LST”为例子
var geometry = ee.FeatureCollection('users/www1573979951/luyixian')
Map.centerObject(geometry,7)
var modis = ee.ImageCollection('MODIS/006/MOD11A1');
var modisLST = modis.filterBounds(geometry).filterDate('2021-01-01', '2021-12-31');
print(modisLST)
2 遥感影像获取(以LST为例子)
代码如下（以鹿邑县为例）：
var geometry = ee.FeatureCollection('users/www1573979951/luyixian')
Map.centerObject(geometry,7)
var modis = ee.ImageCollection('MODIS/006/MOD11A1');
var modisLST = modis.filterBounds(geometry).filterDate('2021-01-01', '2021-12-31').select('LST_Day_1km');
modisLST = modisLST.map(function(img){
var date = img.get('system:time_start');
return img.multiply(0.02).subtract(273.15).set('system:time_start', date);
});
print(modisLST)
Map.addLayer(modisLST.mean().clip(geometry), {min: 10, max: 30, palette: ['green','yellow', 'red']},'LST');
遥感图像截图
影像数据截图（364个）
3 日遥感数据获取(以LST为例子)
3.1 日数据折线图展现如下（以鹿邑县为例）
var geometry = ee.FeatureCollection('users/www1573979951/luyixian')
var modis = ee.ImageCollection('MODIS/006/MOD11A1');
var modisLST = modis.filterBounds(geometry).filterDate('2021-01-01', '2021-12-31').select('LST_Day_1km');
modisLST = modisLST.map(function(img){
var date = img.get('system:time_start');
return img.multiply(0.02).subtract(273.15).set('system:time_start', date);
});
print(modisLST)
print(ui.Chart.image.series(modisLST, geometry, ee.Reducer.mean(), 1000));
CSV数据截图：
3.2 日数据tif批量下载（以鹿邑县为例）
var geometry = ee.FeatureCollection('users/www1573979951/luyixian')
Map.centerObject(geometry,7)
var modis = ee.ImageCollection('MODIS/006/MOD11A1');
var modisLST = modis.filterBounds(geometry).filterDate('2021-01-01', '2021-02-01').select('LST_Day_1km');
modisLST = modisLST.map(function(img){
var date = img.get('system:time_start');
return img.multiply(0.02).subtract(273.15).set('system:time_start', date);
});
print(modisLST)
function exportImageCollection(imgCol) {
var indexList = imgCol.reduceColumns(ee.Reducer.toList(), ["system:index"]).get("list");
indexList.evaluate(function(indexs) {
for (var i=0; i<indexs.length; i++) {
var image = imgCol.filter(ee.Filter.eq("system:index", indexs[i])).first();
image = image.clip(geometry);
Map.addLayer(image, {min: 10, max: 30, palette: ['green','yellow', 'red']},'LST'+i);
Export.image.toDrive({
image: image,
description: 'modis_lst_'+indexs[i],
fileNamePrefix: 'modis_lst_'+indexs[i],
folder: 'Modis',
region: geometry,
scale: 1000,
crs: "EPSG:4326",
maxPixels: 1e13
});
}
});
}
exportImageCollection(modisLST);
4 月遥感数据获取(以LST为例)
4.1 月数据折线图展现如下（以鹿邑县为例）
var geometry = ee.FeatureCollection('users/www1573979951/luyixian')
var modis = ee.ImageCollection('MODIS/006/MOD11A1');
var modisLST = modis.filterBounds(geometry).filterDate('2021-01-01', '2021-12-31').select('LST_Day_1km');
modisLST = modisLST.map(function(img){
var date = img.get('system:time_start');
return img.multiply(0.02).subtract(273.15).set('system:time_start', date);
});
var MODISproj = ee.Image(modisLST.first()).projection();
var monthList = ee.List.sequence({start:1,end:12,step:1});
var createMonthTS = function(month){
var start = ee.Date.fromYMD(2021, month, 1);
var end = start.advance(1, 'month');
var monthColl = modisLST.filterDate(start, end);
var monthMean = monthColl.mean();
var meanVal = monthMean.reduceRegion({
reducer: ee.Reducer.mean(),
geometry: geometry,
crs: MODISproj});
var ft = ee.Feature(null, {
'system:time_start': ee.Image(monthColl.first()).get('system:time_start'),
'date': start.format('Y/M/d'),
'value': meanVal.get('LST_Day_1km')
});
return ft;
};
var monthTS = ee.FeatureCollection(monthList.map(createMonthTS));
print('monthTS:', monthTS);
var monthGraph = ui.Chart.feature.byFeature({
features:monthTS,
xProperty:'system:time_start',
yProperties: 'value'});
print(monthGraph.setChartType("ColumnChart").setOptions({vAxis: {title: 'LST [deg. C]'},hAxis: {title: 'Date'}}));
4.2 月数据tif批量下载（以鹿邑县为例）
var geometry = ee.FeatureCollection('users/www1573979951/luyixian');
Map.centerObject(geometry,6);
var modisLST =ee.ImageCollection("MODIS/006/MOD11A1");
for(var i=2018;i2020;i++){
for(var j=1;j12;j++){
var data_collection = null;
switch(j){
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
data_collection = modisLST.filterDate(i+'-'+j+'-01',i+'-'+j+'-31').select('LST_Day_1km');
break;
case 4:
case 6:
case 9:
case 11:
data_collection = modisLST.filterDate(i+'-'+j+'-01',i+'-'+j+'-30').select('LST_Day_1km');
break;
case 2:
data_collection = modisLST.filterDate(i+'-'+j+'-01',i+'-'+j+'-28').select('LST_Day_1km');
break;
}
data_collection = data_collection.map(function(img){
var date = img.get('system:time_start');
return img.multiply(0.02).subtract(273.15).set('system:time_start', date);
});
var YR_collection = data_collection.mean().clip(geometry);
Export.image.toDrive({
image: YR_collection,
description: i+'-'+j,
fileNamePrefix: i+'-'+j,
scale: 1000,
region: geometry,
maxPixels: 1e13,
folder: 'Modis'
})
}
}
5 年遥感数据下载(以LST为例)
var geometry = ee.FeatureCollection('users/www1573979951/luyixian');
Map.centerObject(geometry,6);
var modisLST =ee.ImageCollection("MODIS/006/MOD11A1");
for(var i=2018;i2020;i++){
var data_collection = modisLST.filterDate(i+'-01-01',i+'-12-31').select('LST_Day_1km');
data_collection = data_collection.map(function(img){
var date = img.get('system:time_start');
return img.multiply(0.02).subtract(273.15).set('system:time_start', date);
});
var YR_collection = data_collection.mean().clip(geometry);
Export.image.toDrive({
image: YR_collection,
description: i,
fileNamePrefix: i,
scale: 1000,
region: geometry,
maxPixels: 1e13,
folder: 'Modis'
});
}
Original: https://blog.csdn.net/qq_32306361/article/details/126221654
Author: 等待着冬天的风
Title: GEE开发之Modis_LST地表温度数据分析
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