I don’t know the answer, but I find that searching JuliaHub is good way to find packages. You can search both docs and source code for all registered packages.
Indeed, it is not implemented in ClimateTools. We have the “Drought Index” (
drought_dc function). ClimateTools.jl/indicators.jl at e48a9ec46b673dd9101527beb690ab50fabf9863 · JuliaClimate/ClimateTools.jl · GitHub
Back then, I simply used GitHub - monocongo/climate_indices: Climate indices for drought monitoring, community reference implementations in Python for my need as I did not had enough time to code it in Julia.