I am afraid that you would not get it online and you would have to calculate it for your preferred region using temperature/ evapotranspiration and precipitation data

Dear Daniel, I would suggest calculating daily SPEI manually using the E-OBS data (https://www.ecad.eu/download/ensembles/download.php). I have described the procedure in my paper (https://doi.org/10.1016/j.quascirev.2019.105868) and some R codes are available on GitHub (https://github.com/jernejjevsenak/analysis_european_tree-ring_network/blob/master/SPEI.R).

Hope it helps.

Jernej

In theory, the SPEI can be calculated on a sub-monthly basis, but in practice, this is not recommended. It is highly recommended that the user looks at a minimum averaging window of 4 weeks. One could compute a 1-week SPEI, but the reality is that one will likely encounter many dry day events (0.00 rainfall even in non-arid climates), which makes the SPEI behave erratically, therefore this approach is not recommended. However, updating the SPEI every day or every week for a 1-month up to a 24-month time frame is acceptable. This “moving window” approach does not compromise the program as it is still looking at a minimum of 4 weeks of data each day it moves. Longterm SPEI data from Climate Research (CRU) Unit is available with a 0.5 degrees spatial resolution and a monthly time resolution (https://spei.csic.es/database.html).

Thanks Animesh. I was imagining something like this, but it is to adjust daily dendrometer data. I suppose something similar will happen with PDSI. Regards

So nice question and answers. For me, I have daily data from the weather station. Can we calculate daily SPEI with the package "SPEI" in the R program(especially @Jernej Jevsenak)? It seems that it is just available for monthly data.

Dear Jingshu Wei , dear all,

I have customized the R script used in the SPEI R package, which now allows to calculate SPEI using daily data, considering accumulated drought for the selected time window (argument scale).

The R script with running examples to calculate SPEI using climate data with daily resolution is available from my GitHub account, https://github.com/jernejjevsenak/calculate-daily-SPEI

With best wishes

Jernej