[Met_help] [rt.rap.ucar.edu #93155] History for Plotting dilemma

Fri Jan 17 14:35:04 MST 2020

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  Initial Request
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Hi there,

I'm trying to plot up some MTD output, specifically the output from the 2d text file, to show where the centroids were.

But, I have a problem. I'm looking at ocean data and the output is giving me (apparently) centroids over land. Now, plotting this in R can be a tricky business but I'm a little bit concerned. Is this because it could be merging objects which fall either side of the UK, so that the centroid ends up being not enclosed in either object but somewhere in the middle, i.e. over land?!

Can you shed any light on what is going on here? I've tried an x-y plot 9:42, and a lat-lon plot 9:56... but it's not a project problem, which was my first thought.

Ta
Marion

--
Dr Marion Mittermaier     Manager: Model diagnostics and novel verification

Met Office   FitzRoy Road   Exeter   EX1 3PB   United Kingdom
Tel:  +44 (0) 330 135 1604
E-mail: marion.mittermaier at metoffice.gov.uk<mailto:marion.mittermaier at metoffice.gov.uk>  http://www.metoffice.gov.uk<http://www.metoffice.gov.uk/>

http://www.metoffice.gov.uk/research/people/marion-mittermaier

I am co-chair of the WMO WWRP Joint Working Group on Forecast Verification Research (JWGFVR) http://www.wmo.int/pages/prog/arep/wwrp/new/Forecast_Verification.html

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  Complete Ticket History
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Subject: Plotting dilemma
From: John Halley Gotway
Time: Mon Nov 18 10:28:45 2019

Hi Marion,

I see you have some questions about the x,y and lat,lon centroid
locations
of object reported by MTD.  I also saw your other email to met_help,
and I
merged that one into this ticket.  So please respond to this email for
both
issues.

I looked at some MTD output from our nightly build and found a bug
which
explains some of this behavior right away.

MTD is incorrectly reporting longitudes in degrees west, when it
should be
following the MET convention of reporting them in degrees east.  That
explains the reflection of longitudes about Greenwich that was evident
in
the plots you sent.  This is a bug that we will fix in met-9.0.  We
did a
met-8.1.2 bugfix release a couple of weeks ago which included many
bugfixes.  Would it be useful to get this included in a met-8.1.3
bugfix
release or is met-9.0 sufficient?

Regarding centroids over land, I think we need to clarify this issue a
bit
more.  First, be aware that MTD reports multiple centroid locations in
its
output.  The CENTROID_X/Y and CENTROID_LAT/LON output columns appear
in:
- mtd_YYYYMMDD_HHMMSSV_2d.txt for each individual 2-dimensional time-
slice
of the 3D time/space object.
- mtd_YYYYMMDD_HHMMSSV_3D_single_simple.txt for each simple 3D object.
- mtd_YYYYMMDD_HHMMSSV_3D_single_cluster.txt for each cluster 3D
object
(e.g. one or more simple objects grouped together and matching a
cluster
object in the other field).

Which of these centroids are you plotting, the 2D ones, 3D simple, or
3D
cluster?  I think that trying to diagnose what's going on in a
specific
case would be very helpful.

Thanks,
John

On Mon, Nov 18, 2019 at 3:01 AM marion.mittermaier at metoffice.gov.uk
via RT <
met_help at ucar.edu> wrote:

>
> Mon Nov 18 03:01:10 2019: Request 93155 was acted upon.
> Transaction: Ticket created by marion.mittermaier at metoffice.gov.uk
>        Queue: met_help
>      Subject: Plotting dilemma
>        Owner: Nobody
>   Requestors: marion.mittermaier at metoffice.gov.uk
>       Status: new
>  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=93155 >
>
>
> Hi there,
>
> I'm trying to plot up some MTD output, specifically the output from
the 2d
> text file, to show where the centroids were.
>
> But, I have a problem. I'm looking at ocean data and the output is
giving
> me (apparently) centroids over land. Now, plotting this in R can be
a
> tricky business but I'm a little bit concerned. Is this because it
could be
> merging objects which fall either side of the UK, so that the
centroid ends
> up being not enclosed in either object but somewhere in the middle,
i.e.
> over land?!
>
> Can you shed any light on what is going on here? I've tried an x-y
plot
> 9:42, and a lat-lon plot 9:56... but it's not a project problem,
which was
> my first thought.
>
> Ta
> Marion
>
> --
> Dr Marion Mittermaier     Manager: Model diagnostics and novel
verification
>
> Met Office   FitzRoy Road   Exeter   EX1 3PB   United Kingdom
> Tel:  +44 (0) 330 135 1604
> E-mail: marion.mittermaier at metoffice.gov.uk<mailto:
> marion.mittermaier at metoffice.gov.uk>  http://www.metoffice.gov.uk<
> http://www.metoffice.gov.uk/>
>
> http://www.metoffice.gov.uk/research/people/marion-mittermaier
>
> I am co-chair of the WMO WWRP Joint Working Group on Forecast
Verification
> Research (JWGFVR)
>
http://www.wmo.int/pages/prog/arep/wwrp/new/Forecast_Verification.html
>
>
>

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Subject: Plotting dilemma
From: John Halley Gotway
Time: Fri Jan 17 14:34:37 2020

Marion,

I'm following up on this older met-help ticket. The MTD longitude bug
was fixed and included in met-8.1.1:
https://github.com/NCAR/MET/issues/1128

Thanks for finding this issue!  I'll go ahead and resolve this ticket.

John

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