Google Earth Engine进行去云处理并逐月计算ndvi并获取时间序列的代码

以下是Google Earth Engine进行去云处理并逐月计算ndvi并获取时间序列的代码：

// Load Landsat 8 surface reflectance data.
var collection = ee.ImageCollection('LANDSAT/LC08/C01/T1_SR')
  .filterDate('2013-01-01', '2021-12-31')
  .filterBounds(geometry)
  .map(function(image) {
    var qa = image.select('pixel_qa');
    // Bits 3 and 5 are cloud and cloud shadow, respectively.
    var cloud = qa.bitwiseAnd(1 << 3)
                    .or(qa.bitwiseAnd(1 << 5));
    // Remove cloud and cloud shadow pixels.
    var masked = image.updateMask(cloud.not());
    // Compute NDVI.
    var ndvi = masked.normalizedDifference(['B5', 'B4'])
                    .rename('NDVI');
    // Add time band.
    var time = image.metadata('system:time_start')
                    .divide(1000 * 60 * 60 * 24 * 30)
                    .floor()
                    .int()
                    .rename('time');
    return masked.addBands(ndvi).addBands(time);
  });

// Create monthly composites and reduce to mean.
var monthlyComposites = ee.ImageCollection.fromImages(
  ee.List.sequence(0, 103).map(function(month) {
    var filtered = collection.filter(ee.Filter.eq('time', month));
    var composite = filtered.mean();
    return composite.set('month', month);
  })
);

// Get NDVI time series.
var ndviTimeSeries = monthlyComposites.select('NDVI')
                                       .reduceRegions({
                                         collection: geometry,
                                         reducer: ee.Reducer.mean(),
                                         scale: 30
                                       })
                                       .get('groups')
                                       .map(function(group) {
                                         return ee.Feature(geometry)
                                                  .set('NDVI', group.mean)
                                                  .set('month', group.month);
                                       });
print(ndviTimeSeries);

该代码首先加载了Landsat 8表面反射数据，并根据日期和地理位置筛选出需要的数据。然后，代码对每个图像进行去云处理，计算NDVI，并添加时间带。接下来，代码从每个月的图像集合中创建月度组合，并将其减少为平均值。最后，代码从NDVI时间序列中获取数据，并按月份和位置进行分组。最终，代码输出ndviTimeSeries。