Problems plotting precipitation and 2m temperature data from seasonal models

Datasets and Usage C3S - Datasets and Usage
, ,
1

Hello, I am not able to plot the data correctly because I did not find any documentation where I could objectively explain how to do this.

In the seasonal data of precipitation the minimum values are in the order of 10^-12 and maximum values in the order of 10^-7, how do I change this to millimeters?

In the temperature variable at 2 meters the minimum values are in the order of 0.23354 and maximum in the order of 7.6154, in which unit is this? And how do I convert to degrees celsius?

I am working with the data for "Seasonal forecast anomalies on single levels" and the variables used are: "Total precipitation anomalous rate of accumulation" and "2m temperature anomaly" and the type of product selected was only "Ensemble mean".

https://cds.climate.copernicus.eu/cdsapp#!/dataset/seasonal-postprocessed-single-levels?tab=form

Please, if you can help me with how to do this I would be very grateful.


Best regards,

2

Olá Gabriel,


As you can see from the names of the variables you are trying to plot ("Total precipitation anomalous rate of accumulation" and "2m temperature anomaly") and from the name of the dataset you are querying ("Seasonal forecast anomalies on single levels"), the variables you are looking at are "anomalies" in the sense they tell you how different the forecast is from the mean model climate, and that's a good thing in the sense that by construction it implies the mean model bias has been removed, which is something one would expect to be done when dealing with this long range forecasts.

Regarding the units in which these variables are expressed, you can find that information in the table describing the variables included in the "overview" tab of the CDS dataset you are interested in, specifically, I mean here: https://cds.climate.copernicus.eu/cdsapp#!/dataset/seasonal-postprocessed-single-levels?tab=overview 

So, in the case of the two variables you mentioned:

  • "2m temperature anomaly": this is expressed in Kelvin, so being it an anomaly (i.e. the difference between two temperatures) it means it's completely equivalent to the value in degrees Celsius
  • "Total precipitation anomalous rate of accumulation": expressed in m/s
    • As precipitation is an accumulated variable, its anomaly is expressed as the anomaly of a rate of accumulation (and hence the seconds in the units denominator), so to obtain the absolute anomaly for a given month, you'd need to multiply the value by the number of seconds in that month, i.e. multiply by 86400 * number_of_days
    • To convert that absolute anomaly in meters to milimetres, you will need to multiply it by 1000.
    • In your example that would mean the range 10-12 to 10-7 m/s will be approximately 0.002 to 260 mm 


I hope that makes sense to you!

Regards,

Eduardo Penabad
C3S Seasonal Forecast

3

Eduardo, one last question, which anomalies maps of the C3S models are anomalies calculated for which period? 1979 to 2019?

4

Thank you for clarifying my question!

Just one more question, on which day and time approximately does the seasonal forecast update of the models that make up the C3S occur?

5

From https://climate.copernicus.eu/seasonal-forecasts

"The seasonal forecasts include data as well as graphical products, and are updated every month – currently on the 13th day at 12 UTC. They cover a time period of six months."


Additionally I would recommend you to "watch" (subscribe to) the following seasonal forecast documentation page (and the C3S user's forum announcements), so you get warned when something is announced in them:

Summary of available data

Announcements

C3S Announcements


Regards,

Eduardo Penabad
C3S Seasonal Forecast