# NetCDF items change when downloading more variables

**URL:** <https://forum.ecmwf.int/t/netcdf-items-change-when-downloading-more-variables/2538>\
**Category:** C3S - Datasets and Usage\
**Tags:** era5\
**Created:** [19 April 2024 13:23 UTC](https://forum.ecmwf.int/t/netcdf-items-change-when-downloading-more-variables/2538 "2024-04-19T13:23:35Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Wessel\_Kruin](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/w/779978/32.png) [@Wessel\_Kruin](https://forum.ecmwf.int/u/Wessel_Kruin)\
**Post date:** [19 April 2024 13:23 UTC](https://forum.ecmwf.int/t/netcdf-items-change-when-downloading-more-variables/2538/1 "2024-04-19T13:23:35Z")

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Hi,

Today (19th of April) I downloaded a NetCDF from “ERA5 hourly data on pressure levels from 1940 to present”. I noticed that the values for a variable change when I download more variables. E.g., the mean temperature of my NetCDF was 219 K when I only downloaded the temperature variable. When I downloaded the same NetCDF, but now also with geopotential, the mean became 217 K. Things got even worse when I added more variables (mean temp = 5.8e-7 K).

I am positive that I only took the mean of the temperature, inspecting the individual values of temperature confirmed that they changed too.

Could the NetCDF data still be corrupted?

Best regards,

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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:** [22 April 2024 17:20 UTC](https://forum.ecmwf.int/t/netcdf-items-change-when-downloading-more-variables/2538/2 "2024-04-22T17:20:40Z")

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Hi,  
please refer to the announcement posted here: [You may need to re-download data from the CDS](https://prod.ecmwf-forum-prod.compute.cci2.ecmwf.int/t/you-may-need-to-re-download-data-from-the-cds/2548)

Apologies for the inconvenience caused.