# Mismatch between instantaneous and accumulations validity time

**URL:** <https://forum.ecmwf.int/t/mismatch-between-instantaneous-and-accumulations-validity-time/1024>\
**Category:** C3S - Datasets and Usage\
**Tags:** c3s, file\_format, era5\
**Created:** [9 March 2021 15:07 UTC](https://forum.ecmwf.int/t/mismatch-between-instantaneous-and-accumulations-validity-time/1024 "2021-03-09T15:07:35Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Taina\_Martins](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/t/b2d939/32.png) [@Taina\_Martins](https://forum.ecmwf.int/u/Taina_Martins)\
**Post date:** [9 March 2021 15:07 UTC](https://forum.ecmwf.int/t/mismatch-between-instantaneous-and-accumulations-validity-time/1024/1 "2021-03-09T15:07:35Z")

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Dear all,  
  
I'm part of a team which is using ERA5 data to estimate the power production of wind and solar plants. To do that, we use U and V wind components, surface temperature, and radiation (SSRD and TISR).  
  
While wind components and temperature are instantaneous parameters (valid at the specified time), radiation is an accumulation over the hour ending at the validity date/time. Therefore, as far as I understand, there is a mismatch between the validity time of the data. So, to fix this mismatch, we should "delay" the radiation series by one hour.  
  
Does anyone come across this same issue before? Am I missing something? Is there any way to download the data for the same validity time?  
  
Thanks in advance,  
  
Taina

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**Author:** ![Michela](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/898d66/32.png) [@Michela](https://forum.ecmwf.int/u/Michela)\
**Post date:** [29 March 2021 13:42 UTC](https://forum.ecmwf.int/t/mismatch-between-instantaneous-and-accumulations-validity-time/1024/2 "2021-03-29T13:42:07Z")

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Hi,

please have a look at the following definitions:

ERA5 terminology: analysis and forecast; time and steps; instantaneous and accumulated and mean rates and min/max parameters - Copernicus Knowledge Base - ECMWF Confluence Wiki

Best regards

Michela

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**Author:** ![Taina\_Martins](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/t/b2d939/32.png) [@Taina\_Martins](https://forum.ecmwf.int/u/Taina_Martins)\
**Post date:** [15 April 2021 20:43 UTC](https://forum.ecmwf.int/t/mismatch-between-instantaneous-and-accumulations-validity-time/1024/3 "2021-04-15T20:43:55Z")

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Hi Michela,

I had already checked the definitions and the reason of the mismatch is explained:&nbsp;While wind components and temperature are instantaneous parameters (valid **at** the specified time), radiation is an accumulation over the hour **ending** at the validity date/time.

The problem is the mismatch between radiation and wind time series. When working with both of them,&nbsp;to fix this mismatch, we should "delay" the radiation series by one hour.&nbsp;

I just wanted to confirm my understanding. Thank you!

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**Author:** ![Alina\_Burmester](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/a/f9ae1b/32.png) [@Alina\_Burmester](https://forum.ecmwf.int/u/Alina_Burmester)\
**Post date:** [8 August 2022 10:45 UTC](https://forum.ecmwf.int/t/mismatch-between-instantaneous-and-accumulations-validity-time/1024/4 "2022-08-08T10:45:49Z")

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Hi Taina,&nbsp;

did you receive any feedback how to combine instantaneous timeseries with accumulation over an hour?

Best regards,

Alina

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**Author:** ![Taina\_Martins](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/t/b2d939/32.png) [@Taina\_Martins](https://forum.ecmwf.int/u/Taina_Martins)\
**Post date:** [8 August 2022 13:49 UTC](https://forum.ecmwf.int/t/mismatch-between-instantaneous-and-accumulations-validity-time/1024/5 "2022-08-08T13:49:28Z")

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Hi Alina,

The only answer I got was from Michela Giusti, you can see it here in the thread.

Best,

Tainá