ERA5-land daily maximum outputs hourly data?

Datasets and Usage
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1

Hi ,
I am using the API and the web GUI to download 2m temperature daily maximum using the daily statistics (ERA5-Land post-processed daily statistics from 1950 to present) but it is giving hourly values… when I use daily_mean instead of daily_maximum, I do obtain daily values as expected.

I wonder if this is a known behaviour in ERA5-land or how to solve it?

See an example API request that gives me hourly data instead of daily maximum:

import cdsapi

dataset = "derived-era5-land-daily-statistics"
request = {
    "variable": ["2m_temperature"],
    "year": "2021",
    "month": "02",
    "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"
    ],
    "daily_statistic": "daily_maximum",
    "time_zone": "utc+00:00",
    "frequency": "1_hourly"
}

client = cdsapi.Client()
client.retrieve(dataset, request).download()
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2

I also received hourly data. When you select either daily maximum or daily minimum, the downloaded data remains the same—they are hourly data. Users can obtain the maximum and minimum values from these 24 hourly data points.

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3

I am having the same problem. This should be raised as a ticket - the daily temperature minimum/maximum values right now are the only ones I have encountered which have this issue. (I am not sure if other daily maximum/minimum for other variables are also experiencing this issue.)

Edit: I’ve just submitted a ticket: https://jira.ecmwf.int/plugins/servlet/desk/portal/4/SD-101079

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4

I read the hourly data and found that each month contains 24 extra values. For example, January has 24X32 data points, February has 24X29 values, and April has 24X31 values. Does anyone know what these extra values represent?

5

Hi,
the issue has been fixed.
Please try to request the data again.
Thanks

3 Likes
6

Hi Michela,
Thank you for such a prompt response. Without having checked the data itself yet, I can at least confirm that the download size for one month makes more sense.

7

Thanks to the support team for their hard work. I downloaded some data and compared them. All the problems we mentioned have now been fixed. That’s great!

1 Like