一、数据来源
var geometry = table;var dataset = ee.ImageCollection("UCSB-CHG/CHIRTS/DAILY").filterBounds(geometry).select(["minimum_temperature", "maximum_temperature", "vapor_pressure_deficit", "relative_humidity"]);var yearList = ee.List.sequence(1983, 2016);var yearlyData = yearList.map(function(year) {var startDate = ee.Date.fromYMD(year, 1, 1);var endDate = ee.Date.fromYMD(year, 12, 31);var yearlyCollection = dataset.filterDate(startDate, endDate);var yearlyMean = yearlyCollection.mean().clip(geometry);var Tmean = yearlyMean.expression("(Tmin + Tmax) / 2", {'Tmin': yearlyMean.select('minimum_temperature'),'Tmax': yearlyMean.select('maximum_temperature')}).rename("Tmean");var finalYearly = yearlyMean.addBands(Tmean);var stats = finalYearly.reduceRegion({reducer: ee.Reducer.mean(),geometry: geometry,scale: 5566,maxPixels: 1e13});return ee.Feature(null, {'year': year,'Tmin_mean': stats.get('minimum_temperature'),'Tmax_mean': stats.get('maximum_temperature'),'Tmean_mean': stats.get('Tmean'),'VPD_mean': stats.get('vapor_pressure_deficit'),'RH_mean': stats.get('relative_humidity')});});var yearlyFeatureCollection = ee.FeatureCollection(yearlyData);var chart = ui.Chart.feature.byFeature(yearlyFeatureCollection, 'year', ['Tmin_mean', 'Tmax_mean', 'Tmean_mean', 'VPD_mean', 'RH_mean']).setChartType('LineChart').setOptions({title: 'Annual Mean Tmin, Tmax, Tmean, VPD, RH (1983-2020)',vAxis: {title: 'Temperature (°C), VPD (kPa), RH (%)'},hAxis: {title: 'Year'},lineWidth: 2,pointSize: 3,series: {0: {color: 'blue', lineWidth: 2},1: {color: 'red', lineWidth: 2},2: {color: 'purple', lineWidth: 2},3: {color: 'green', lineWidth: 2},4: {color: 'orange', lineWidth: 2}}});print(chart);
