Order of operations & necessity of attenuation correction

[DavidQ]

Hi all,

I am working with a SRI (Surface Rainfall Intensity). The product comes in dBZ from an Iris radar which seems to work with Z in mm**6/mm**3. In their doc they write

dBZ = 10 log(Z); with Z in mm**6/mm**3,

so I get Z in mm**6/m**3 to convert it to Marshall-Palmer with

data = (1e6)*10**(data/10)

Since it seems that my data has clutters, I apply the Gabella filter now:

data = wrl.clutter.filter_gabella(data, wsize=5, thrsnorain=0., tr1=6., n_p=8, tr2=1.3)

And now I finally obtain the rainfall intensity with the Marshall-Palmer:

data = wrl.zr.z_to_r(data, a=200.0, b=1.6)

My questions are:

1) is this order of operations correct? Should I perhaps apply the filter even before the conversion to m**3?

2) Should I apply some attenuation correction for SRI? If so, where in the process should I apply it? In this recipe https://debug-docs.readthedocs.io/en/test/notebooks/workflow/recipe1.html the attenuation correction is applied just before the Marshall-Palmer correction, in my case would that be after the "filter_gabella"?

Thx.

[Syed Hamid Ali]

First of all dBZ = 10log10(Z), so use
wradlib.trafo.idecibel function of wradlib to convert dBZ to Z(mm⁶/m³)or simply 10**(data/10)

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[David Quintero]

Ok, thx. I was confused because I saw mm**6/mm**3 somewhere. (Anyway, the conversion should be with 10**9 as factor), but yes, your conversion was the right one.

On the other hand, it seems SRI comes with some preprocessing in iris sigmet radar and I don't think attenuation correction and cluttering are necessary.

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