How are T2MIN, T2MEAN, and T2MAX calculated?

[jds485]

I am wondering how the daily min, mean, and max air temperature at 2 m (T2) are computed. The wrfxtrm file has these computed daily T2MIN, T2MEAN, and T2MAX timeseries, and the values are different than computing the daily min, mean and max of the raw data T2 time series. Was a time zone shift applied to the T2MIN, T2MEAN, and T2MAX data? Or some other adjustment?

This is for CONUS404 data. I'm not sure if this also applies to CONUS404 PGW data (I have not checked).

[amsnyder]

@jds485 - this is for CONUS404 bias adjusted data right?

@aubreyd can you help answer this one or tag in someone at NCAR who can?

@mirizarry-ortiz - tagging you for awareness

[mirizarry-ortiz]

Jared,
The issue has been elevated to the CONUS404 developers by Aubrey. For background, we would like to understand how you planned to use those variables and whether you were trying to compute daily Tmax and Tmin from hourly or 15-min data based on local time as opposed to UTC time.

[jds485]

I am working from the data described here for CONUS404 (not bias adjusted as far as I can tell). https://www.sciencebase.gov/catalog/item/6372cd09d34ed907bf6c6ab1.

whether you were trying to compute daily Tmax and Tmin from hourly or 15-min data based on local time as opposed to UTC time.

I would like to have daily min, mean, and max temperatures for local time, but I am not sure what time zone was used to create the T2MIN, T2MEAN, and T2MAX variables in the above wrfxstrm dataset. It is not stated in the metadata.

[mirizarry-ortiz]

Thanks Jared! That would help NCAR folks better understand your question and what you are trying to accomplish.

[aubreyd]

I checked with the WRF team and two notes on what might be driving the difference: (1) the wrfxstrm values are calculated between 00Z (UTC) times, (2) the summarized values in the wrfxtrm files are based on the values calculated on the internal WRF timestep (i.e., seconds), so we would expect them to be different from what you can calculate with, say, hourly WRF outputs.

[jds485]

Thanks! What do you mean by "calculated between UTC times?" Are the timeseries shifted?

[aubreyd]

So the "daily" values are UTC days (not local time zone days).