# Negative volumetric soil water values in ERA5 dataset

**URL:** <https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222>\
**Category:** C3S - Datasets and Usage\
**Tags:** c3s, era5, global\_reanalysis\
**Created:** [14 November 2019 17:19 UTC](https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222 "2019-11-14T17:19:10Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![Neeldip\_Barman](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/n/eb9ed0/32.png) [@Neeldip\_Barman](https://forum.ecmwf.int/u/Neeldip_Barman)\
**Post date:** [14 November 2019 17:19 UTC](https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222/1 "2019-11-14T17:19:10Z")

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The ERA5 surface dataset seems to include negative soil water values, which is practically impossible. It would be helpful if someone could provide some information, is it a model output error?

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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:** [15 November 2019 09:35 UTC](https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222/2 "2019-11-15T09:35:27Z")

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Hi,

Could you please tell me what is the format of the data file?

Regards

Michela

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**Author:** ![Neeldip\_Barman](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/n/eb9ed0/32.png) [@Neeldip\_Barman](https://forum.ecmwf.int/u/Neeldip_Barman)\
**Post date:** [15 November 2019 13:12 UTC](https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222/3 "2019-11-15T13:12:30Z")

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Hi, the format is grib.

Regards,

neeldip

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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:** [19 November 2019 16:59 UTC](https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222/4 "2019-11-19T16:59:24Z")

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Hi,

the problem is with the grib encoding. If a value is very close to zero it could be encoded as a negative value in the grib file, but it should be treated as zero.

Regards

Michela

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**Author:** ![Neeldip\_Barman](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/n/eb9ed0/32.png) [@Neeldip\_Barman](https://forum.ecmwf.int/u/Neeldip_Barman)\
**Post date:** [20 November 2019 03:19 UTC](https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222/5 "2019-11-20T03:19:04Z")

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Hi,

Thanks for the clarification.

Regards

neeldip

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**Author:** ![Miguel\_Segura](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/919ad9/32.png) [@Miguel\_Segura](https://forum.ecmwf.int/u/Miguel_Segura)\
**Post date:** [12 March 2020 16:16 UTC](https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222/6 "2020-03-12T16:16:24Z")

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Hello Neeldip. Would you mind to give me some more information on this issue, such as coordinates and time when this inconsistency has been reported?

Thank you very much.

Miguel

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**Author:** ![Miguel\_Segura](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/919ad9/32.png) [@Miguel\_Segura](https://forum.ecmwf.int/u/Miguel_Segura)\
**Post date:** [18 February 2020 17:18 UTC](https://forum.ecmwf.int/t/negative-volumetric-soil-water-values-in-era5-dataset/1222/7 "2020-02-18T17:18:45Z")

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Hello Neeldip. Would you mind to give me some more information on this issue, such as coordinates and time when this inconsistency has been reported? [Neeldip Barman](https://confluence.ecmwf.int/display/~neeldip7@gmail.com)

Thank you very much.

Miguel