基于 GEE ERA5 数据集监测不同土壤层水分和温度变化

目录

1 数据介绍

2 完整代码

3 运行结果

1 数据介绍

2 完整代码

// 定义研究区域
var geometry = table;

// 加载 ERA5 数据集
var era5Dataset = ee.ImageCollection("ECMWF/ERA5_LAND/MONTHLY_AGGR");

// 筛选土壤水分和土壤温度相关波段
var soilMoistureBands = [
  'volumetric_soil_water_layer_1',  // 0-7 cm
  'volumetric_soil_water_layer_2',  // 7-28 cm
  'volumetric_soil_water_layer_3',  // 28-100 cm
  'volumetric_soil_water_layer_4'   // 100-289 cm
];

var soilTemperatureBands = [
  'soil_temperature_level_1',  // 0-7 cm
  'soil_temperature_level_2',  // 7-28 cm
  'soil_temperature_level_3',  // 28-100 cm
  'soil_temperature_level_4'   // 100-289 cm
];

// 定义年份范围
var years = ee.List.sequence(1951, 2023);

// 计算年度均值
function calculateAnnualMean(year, bands) {
  var startDate = ee.Date.fromYMD(year, 1, 1);
  var endDate = startDate.advance(1, 'year');

  // 筛选对应年份的数据并计算均值
  var annualMean = era5Dataset.filterDate(startDate, endDate)
    .select(bands)
    .mean()
    .reduceRegion({
      reducer: ee.Reducer.mean(),
      geometry: geometry,
      scale: 11132, // 数据分辨率
      maxPixels: 1e13
    });

  return ee.Feature(null, annualMean).set('year', year);
}

// 生成年度土壤水分的统计数据
var soilMoistureStats = years.map(function(year) {
  return calculateAnnualMean(year, soilMoistureBands);
});

// 生成年度土壤温度的统计数据
var soilTemperatureStats = years.map(function(year) {
  return calculateAnnualMean(year, soilTemperatureBands);
});

// 转换为 FeatureCollection
var soilMoistureFC = ee.FeatureCollection(soilMoistureStats);
var soilTemperatureFC = ee.FeatureCollection(soilTemperatureStats);

// 可视化折线图
// 土壤水分折线图
var soilMoistureChart = ui.Chart.feature.byFeature(soilMoistureFC, 'year', soilMoistureBands)
  .setChartType('LineChart')
  .setOptions({
    title: 'Annual Soil Water (2000-2023)',
    hAxis: { title: 'Year' },
    vAxis: { title: 'Soil Water (m³/m³)' },
    lineWidth: 2,
    pointSize: 4,
    series: {
      0: { color: 'blue', label: 'Layer 1 (0-7 cm)' },
      1: { color: 'green', label: 'Layer 2 (7-28 cm)' },
      2: { color: 'orange', label: 'Layer 3 (28-100 cm)' },
      3: { color: 'red', label: 'Layer 4 (100-289 cm)' }
    }
  });

// 土壤温度折线图
var soilTemperatureChart = ui.Chart.feature.byFeature(soilTemperatureFC, 'year', soilTemperatureBands)
  .setChartType('LineChart')
  .setOptions({
    title: 'Annual Soil Temperature (2000-2023)',
    hAxis: { title: 'Year' },
    vAxis: { title: 'Soil Temperature (K)' },
    lineWidth: 2,
    pointSize: 4,
    series: {
      0: { color: 'blue', label: 'Layer 1 (0-7 cm)' },
      1: { color: 'green', label: 'Layer 2 (7-28 cm)' },
      2: { color: 'orange', label: 'Layer 3 (28-100 cm)' },
      3: { color: 'red', label: 'Layer 4 (100-289 cm)' }
    }
  });

// 打印折线图
print(soilMoistureChart);
print(soilTemperatureChart);

// 导出年度土壤水分统计数据为 CSV
Export.table.toDrive({
  collection: soilMoistureFC,
  description: 'Annual_Soil_Moisture_Stats',
  fileNamePrefix: 'Annual_Soil_Moisture',
  fileFormat: 'CSV',
  folder: 'ERA5_Stats'
});

// 导出年度土壤温度统计数据为 CSV
Export.table.toDrive({
  collection: soilTemperatureFC,
  description: 'Annual_Soil_Temperature_Stats',
  fileNamePrefix: 'Annual_Soil_Temperature',
  fileFormat: 'CSV',
  folder: 'ERA5_Stats'
});

3 运行结果