Google Earth Engine（GEE）——ERA5-数据计算逐年全球潜在蒸发量PET

通过ERA5-Land如何在数据文件中汇总潜在蒸发？（pet）数据集（将pet值米转换为mm)

代码：

var geometry = /* color: #d63000 */ee.Geometry.Point([21.021809833554478, -9.078844651504086]);  var aPoint = /* color: #d63000 */geometry; //影像筛选 var era5hourly = ee.ImageCollection("ECMWF/ERA5_LAND/HOURLY").filter(ee.Filter.date('2000-01-01', '2020-12-31')); //添加色度 var classColors = ['FFFFFF','E6E6E6','BEBEBE，969696C4706E','C8B396','FFC775','FFFF54','91FF99','00FF00','40C738']//,'0D9605','05705E003319FF66FF','990099', '3333FF', '000099' ];  // var TOTAL_MONTHLY_PET = "potential_evaporation";  var metersToMillimiters = function( image ){   return ee.Image(          image.select([TOTAL_MONTHLY_PET]).multiply(1000).multiply(-1) // 将m转化为mm