Use data from 'UCSB-CHG/CHIRPS/DAILY' to calculate total precipitation

Question

The total amount of precipitation for the same days using data from 'UCSB-CHG/CHIRPS/DAILY' gave almost identical amounts of precipitation for a large country and for a city in the country.

How can I find the total precipitation accurately?

var countries=ee.FeatureCollection('FAO/GAUL/2015/level2');
var Turkey=countries.filter(ee.Filter.eq('ADM0_NAME','Turkey'));

var city= countries.filter(ee.Filter.eq('ADM1_NAME','Istanbul'));


var chirps = ee.ImageCollection("UCSB-CHG/CHIRPS/DAILY").select('precipitation')
.filterDate('2001-01-01','2001-02-01')


print(
  ui.Chart.image.series({
    imageCollection: chirps,
    region: Turkey,
    reducer: ee.Reducer.mean(),
    scale: 1000
  }).setOptions({title: 'Total Rainfall at Country'})
);

print(
  ui.Chart.image.series({
    imageCollection: chirps,
    region: city,
    reducer: ee.Reducer.mean(),
    scale: 1000
  }).setOptions({title: 'Total Rainfall at City'})
);

Answer 1

The reducer mean() is the issue. Change it to sum() and you will get the total precipitation value.

print(
  ui.Chart.image.series({
    imageCollection: chirps,
    region: Turkey,
    reducer: ee.Reducer.sum(),
    scale: 1000
  }).setOptions({title: 'Total Rainfall at Country'})
);