Hi guys,

I used that nice script Compute geopotential on model levels to compute the geopotential height on model levels of some ERA5 data. In doing so, I came across some strange behavior: At those locations on Earth where the orography has negative geopotential height values, the geopotential of the model levels decreases (gets more negative) when going upward in the atmosphere (from model level 137 to 0). Did anybody else came across that? Does anybody know how to fix that?

Thanks,

Amelie

5 Comments

  1. XCristian XSimarro2

    Hi Amelie,

    Could you please give us some examples of the behaviour you mention? You can let us know what data you have downloaded from ERA5 and they way you call the script.

    Thanks!

    Cristian

  2. Amelie Mayer

    Hi Cristian,

    I'm sorry, I've just realized that I had a bug in my script analysing the results. It's everything fine with the script! Geopotential height increases everywhere when going upward in the atmosphere. I'm sorry for my mistake. But anyway, thanks for your quick support.

    Cheers,

    Amelie

  3. Ninghui Li

    Hi Cristian,

    I have met an issue that I download the ERA5-pressure-levels data, but I can't find the way to calculate geopotential height in ERA5-pressure-levels. Although there are examples to calculate height in interim and model level, but the single-level is 37 pressure levels, the methods in the documentation seems to be 60 levels. Do you know how to calculate the height in ERA5-single-levels ? I also find some model definitions, but I can't find the definition that suit 37 levels.

    1. Michela Giusti

      Hi,

      you can download the geopotential (m2 s-2) on all the 37 pressure levels and compute the geopotential height (m) dividing the geopotential values by the WMO-defined gravity constant of 9.80665 ms-2, which is constant for all latitudes and all heights.


      Regards

      Michela

      1. Ninghui Li

        Hi, Michela,

        Thank you for your advice, the problem has been solved.

        Best regards

        Thanks!

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