# Daily total precipitation from ERA5-land hourly data **URL:** \ **Category:** Other - Software and tools\ **Tags:** c3s, toolbox\ **Created:** [13 June 2020 04:14 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800 "2020-06-13T04:14:53Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Miguel\_Lovino](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/a8b319/32.png) [@Miguel\_Lovino](https://forum.ecmwf.int/u/Miguel_Lovino)\ **Post date:** [13 June 2020 04:14 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/1 "2020-06-13T04:14:53Z")
Dear all, I have a problem with the units of daily total precipitation estimated from hourly data. I do not understand what conversion factor should I use to bring the accumulated daily precipitation to mm / day. Is the output in m / s? Why is the output variable in the following  Toolbox code named "tprate" and what are its units?  I will greatly appreciate your help, Best regards, Miguel Here is the sample Toolbox code: import cdstoolbox as ct @ct.application(title='Download data') @ct.output.download() def download\_application(): total\_prec = ct.catalogue.retrieve( 'reanalysis-era5-land', { 'variable': 'total\_precipitation', 'year': '1981', 'month': '01', 'day': [ '01', '02', '03', '04', '05', '06', '07', '08', '09', '10', '11', '12', '13', '14', '15', '16', '17', '18', '19', '20', '21', '22', '23', '24', '25', '26', '27', '28', '29', '30', '31', ], 'time': [ '00:00', '01:00', '02:00', '03:00', '04:00', '05:00', '06:00', '07:00', '08:00', '09:00', '10:00', '11:00', '12:00', '13:00', '14:00', '15:00', '16:00', '17:00', '18:00', '19:00', '20:00', '21:00', '22:00', '23:00', ], 'area': [ -10, -70, -40, -40, ], } ) # compute daily accumulation of precipitation prec\_daily\_acc = ct.cube.resample(total\_prec, freq='D', how='sum', closed='right') return prec\_daily\_acc ---
**Author:** ![Michela](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/898d66/32.png) [@Michela](https://forum.ecmwf.int/u/Michela)\ **Post date:** [15 June 2020 18:04 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/2 "2020-06-15T18:04:22Z")
Hi, the toolbox converts total precipitation in m/s, please have a look at the following link: [https://cds.climate.copernicus.eu/toolbox/doc/tutorials/3\_create\_a\_climate\_graph\_application\_for\_any\_point\_location/3\_create\_a\_climate\_graph\_application\_for\_any\_point\_location.html#b-retrieve-era5-hourly-data-on-single-levels-total-precipitation](https://cds.climate.copernicus.eu/toolbox/doc/tutorials/3_create_a_climate_graph_application_for_any_point_location/3_create_a_climate_graph_application_for_any_point_location.html#b-retrieve-era5-hourly-data-on-single-levels-total-precipitation) Thanks Michela ---
**Author:** ![Miguel\_Lovino](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/a8b319/32.png) [@Miguel\_Lovino](https://forum.ecmwf.int/u/Miguel_Lovino)\ **Post date:** [15 June 2020 19:53 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/3 "2020-06-15T19:53:32Z")
Hi Michela,  Thank you very much. I saw that total precipitation from ERA5-land exceed observations considerably (by up unit thousand). In contrast, in ERA5 this does not happen. Have you detected any problem with precipitation in ERA5-land? My area of work is southern South America. Thanks in advance, Best regards, Miguel ---
**Author:** ![Michela](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/898d66/32.png) [@Michela](https://forum.ecmwf.int/u/Michela)\ **Post date:** [17 June 2020 15:28 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/4 "2020-06-17T15:28:01Z")
Hi Miguel, did you consider the different accumulation time? Please, note that  **the convention for accumulations used in ERA5-Land differs with that for ERA5**. The accumulations in the short forecasts of ERA5-Land (with hourly steps from 01 to 24) are treated the same as those in ERA-Interim or ERA-Interim/Land, i.e., they are accumulated from the beginning of the forecast to the end of the forecast step. For example, runoff at _day=D_, _step=12_ will provide runoff accumulated from _day=D_, _time=0_ to _day=D, time=12_. The maximum accumulation is over 24 hours, i.e., from _day=D, time=0_ to _day=D+1,time=0_ (_step=24_). Thanks Michela ---
**Author:** ![Miguel\_Lovino](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/a8b319/32.png) [@Miguel\_Lovino](https://forum.ecmwf.int/u/Miguel_Lovino)\ **Post date:** [17 June 2020 17:32 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/5 "2020-06-17T17:32:01Z")
Hi Michela,  Thank you very much. If I understood correctly, then D + 1 (step 24) is the daily precipitation? Does this step include the accumulated precipitation in the previous 24 hours? Best regards, Miguel ---
**Author:** ![Michela](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/898d66/32.png) [@Michela](https://forum.ecmwf.int/u/Michela)\ **Post date:** [18 June 2020 17:29 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/6 "2020-06-18T17:29:05Z")
Hi Miguel, yes, the time step _d_+1 is the daily precipitation and it contains the accumulated total precipitation over the previous 24 hours. Best regards, Michela ---
**Author:** ![xiangyi\_wang](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/x/bbe5ce/32.png) [@xiangyi\_wang](https://forum.ecmwf.int/u/xiangyi_wang)\ **Post date:** [3 July 2020 03:10 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/7 "2020-07-03T03:10:14Z")
Hi Michela,  When I use the following code, how='mean'（total\_precipitation-snowfall）the daily precipitation curve is basically correct, but the  precipitation is half of the actual value tp\_hourly = ct.geo.extract\_point(data[0], lon=lon, lat=lat) tp\_hourly\_column = tp\_hourly \* 3600 \* 1000 tp\_hourly\_column = ct.cdm.update\_attributes(tp\_hourly\_column, {'units': 'mm'}) tp\_daily\_sums = ct.cube.resample(tp\_hourly\_column, freq='day', dim='time', how='mean',closed='right') sf\_hourly = ct.geo.extract\_point(data[1], lon=lon, lat=lat) sf\_hourly\_column = sf\_hourly \* 3600 \* 1000 sf\_hourly\_column = ct.cdm.update\_attributes(sf\_hourly\_column, {'units': 'mm'}) sf\_daily\_sums = ct.cube.resample(sf\_hourly\_column, freq='day', dim='time',how='mean', closed='right') precp = (tp\_daily\_sums-sf\_daily\_sums)\*2 Regards, Xiangyi Wang ---
**Author:** ![zhao\_chn](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/z/87869e/32.png) [@zhao\_chn](https://forum.ecmwf.int/u/zhao_chn)\ **Post date:** [28 January 2022 12:55 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/8 "2022-01-28T12:55:42Z")
Hi，Miguel, In datasets 'ERA5-Land hourly data from 1950 to present', for example, if i want the total precipitation in 1st, January, I can download the total precipitation in 0:00, 2nd, January, because that represents the previous 24 hours, am i right? ---
**Author:** ![Giovanni\_Battista\_Ch](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/g/a183cd/32.png) [@Giovanni\_Battista\_Ch](https://forum.ecmwf.int/u/Giovanni_Battista_Ch)\ **Post date:** [14 September 2020 22:05 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/9 "2020-09-14T22:05:47Z")
Hi Miguel  I am experiencing the same issue in retrieving daily total precipitation from hourly data. Did you solve it? ---
**Author:** ![Miguel\_Lovino](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/a8b319/32.png) [@Miguel\_Lovino](https://forum.ecmwf.int/u/Miguel_Lovino)\ **Post date:** [17 September 2020 16:17 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/10 "2020-09-17T16:17:35Z")
Hi Giovanni, I finally switched to ERA5. But I was able to check that the daily accumulated of ERA5-land is per hour and differs from that of ERA5. Please take a look at Michela's previous comment. If you do the comparison in a grid point of both databases, you will see it and you may find the solution to the accumulation factor. Successes with that. Best regards, Miguel ---
**Author:** ![Puri\_Amrish](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/p/eada6e/32.png) [@Puri\_Amrish](https://forum.ecmwf.int/u/Puri_Amrish)\ **Post date:** [13 April 2021 19:28 UTC](https://forum.ecmwf.int/t/daily-total-precipitation-from-era5-land-hourly-data/1800/11 "2021-04-13T19:28:54Z")
Hi, I would like to know if my time zone is UTC+8, and the data is UTC0, then how to transfer the time to the correct regional time by cdo? Best,