[ncl-talk] SPEI (drought index) calculation...

[qudsia zafar]

Hi i am using cru datasets (ts 4.08) for precipitation and potential
evapotranspiration. I have done (precip_minus_pet = prc - pet) and then
I have used the function 'dim_gamfit_n' to estimate shape and scale
parameters for the gamma distribution fitting.

However in the next step of spei calculation I need to do the following:

spei = gmm_transform(precip_minus_pet, shape, scale)

I have now all the three data (precip_minus_pet, shape, scale) but i don't
know if NCL has a gamma transformation function available? I have seen
'cdfgam_p' but I don't know if this corresponds to the gamma transform?.
Kindly advise which function can be used in the final step of spei
calculation. Many Thx..

qudsia
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