[Met_help] [RAL-IT #103502] History for concerns about MODE-TD percentiles

[Julie Prestopnik via RT]

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  Initial Request
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Dear MET help team,

I am writing to in concerns of the computation of the intensity 
percentiles in MODE-TD.

When applying a threshold to precipitation rate of 5mm/hour (see 
attached files) I yield the following intensity percentiles for object 
F026: [p10,p25,p50,p75,p90,p99] = [0.01,0.41,3.77,15.57,33.43,79.34]

I am a bit surprised that the small percentiles are <5mm/hour, as I had 
assumed that MODE-TD computes the percentiles from the object's 
convolved field, which would be all greater 5mm/hour. I now see that 
MODE-TD computes the percentiles from the raw field, but I find this 
unfortunate, since then it is integrated over grid cells that actually 
don't show precipitation at all. Eventually I'd like to compute the mean 
precipitation rate or integrated rain volume of an object, and I, just 
like MODE-TD, do this by integrating the original/raw field over the 
objects identified cells, which I fear of being in-accurate.

Well, I would just like to raise some concerns about this. I guess to 
compute percentiles from the convolved field would be the better solution.

Best regards
Sebastian


-- 
*********************************************************************
Sebastian K. Müller
Earth System Physics Section
The Abdus Salam International Centre for Theoretical Physics
Strada Costiera 11
34100 Trieste, ITALY
phone: + 39 040 2240 438
email: smueller at ictp.it


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  Complete Ticket History
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Subject: concerns about MODE-TD percentiles
From: Julie Prestopnik
Time: Thu Mar 31 08:55:01 2022

Hi,

We switched from providing support through this email address to
providing
support through GitHub Discussions. You will need to create a free
GitHub
account if you don't have one already and post your questions to the
METplus Discussion Forum:

https://github.com/dtcenter/METplus/discussions/new

Thanks!

On Thu, Mar 31, 2022 at 8:52 AM Sebastian K. Müller via RT <
met_help at ucar.edu> wrote:

>
> Thu Mar 31 08:51:57 2022: Request 103502 was acted upon.
> Transaction: Ticket created by smueller at ictp.it
>        Queue: met_help
>      Subject: concerns about MODE-TD percentiles
>        Owner: Nobody
>   Requestors: smueller at ictp.it
>       Status: new
>  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=103502 >
>
>
> Dear MET help team,
>
> I am writing to in concerns of the computation of the intensity
> percentiles in MODE-TD.
>
> When applying a threshold to precipitation rate of 5mm/hour (see
> attached files) I yield the following intensity percentiles for
object
> F026: [p10,p25,p50,p75,p90,p99] = [0.01,0.41,3.77,15.57,33.43,79.34]
>
> I am a bit surprised that the small percentiles are <5mm/hour, as I
had
> assumed that MODE-TD computes the percentiles from the object's
> convolved field, which would be all greater 5mm/hour. I now see that
> MODE-TD computes the percentiles from the raw field, but I find this
> unfortunate, since then it is integrated over grid cells that
actually
> don't show precipitation at all. Eventually I'd like to compute the
mean
> precipitation rate or integrated rain volume of an object, and I,
just
> like MODE-TD, do this by integrating the original/raw field over the
> objects identified cells, which I fear of being in-accurate.
>
> Well, I would just like to raise some concerns about this. I guess
to
> compute percentiles from the convolved field would be the better
solution.
>
> Best regards
> Sebastian
>
>
> --
>
*********************************************************************
> Sebastian K. Müller
> Earth System Physics Section
> The Abdus Salam International Centre for Theoretical Physics
> Strada Costiera 11
> 34100 Trieste, ITALY
> phone: + 39 040 2240 438
> email: smueller at ictp.it
>
>

--
Julie Prestopnik (she/her)
Software Engineer
National Center for Atmospheric Research
Research Applications Laboratory
Email: jpresto at ucar.edu

My working day may not be your working day.  Please do not feel
obliged to
reply to this email outside of your normal working hours.

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