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Correction to Daymet Monthly Climate Summaries

Daymet precipitation in January 2000

Daymet V3 total precipitation for January 2000 for a subset of the Daymet domain in eastern North America.

A correction to data in “Daymet Monthly Climate Summaries on a 1-km Grid for North America, Version 3” has been released. This correction affects Daymet monthly summaries for years that are not leap years. The other Daymet datasets, such as the daily surface weather data, are NOT affected. Only the monthly climatologies are affected. If you are using this monthly climatology data product, please download and use the corrected version, particularly if you are working with the precipitation data.

Daymet: Monthly Climate Summaries on a 1-km Grid for North America, Version 3. Updated data are available at: https://doi.org/10.3334/ORNLDAAC/1345

Error details:
The error that was discovered is that monthly summaries always used 29 days for February, rather than doing that for just leap years. As a result, for a non-leap year, the March climatologies would be for March 2 through April 1, rather than March 1 through March 31. This can have a small, but significant effect, particularly where there is an unusually high or low value on the first of the month. Please note that Daymet currently always has 365 days in a year, as noted in the dataset documentation. For leap years, the Daymet dataset includes the leap day (February 29) and the value for December 31 is discarded from leap years to maintain a 365-day year.

If you have any questions or concerns regarding this matter, please contact the ORNL DAAC user services at uso@daac.ornl.gov. We apologize for any inconvenience this update may cause.