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[McIDAS #GQK-632247]: WX1 parameter in ptlist.k



Hi Mary Ellen,

re:
> Hi Tom, not sure if you'd remember me but I used to work for Randy
> Alliss years ago and met you a few times.

Yes, of course I remember you.  ...

...

> By the way, thanks for your help with setting up the access to the MTSAT
> and MET-8 data. Here's a new question for you.

No worries.

> I am using the Raw MD data to study the frequency of dust/sand storms
> for the period 1995-present for several points of interest in the middle
> east.  I have been using PTLIST to extract the wx1 and vis data for the
> stations I'm interested in. I have not been able to find in any manual
> the defintions of wx1 values or letters if you will. There does not
> appear to be a direct correlation to the "letters" used in the raw metar
> data.

There is a direct correlation.  McIDAS encodes observations reported in
WMO-standard formats into ones it can use directly.  The source code routines
that do this can be found in the following files:

~mcidas/mcidas2007/src/m0tb4677.for
~mcidas/mcidas2007/src/m0tb4678.for
~mcidas/mcidas2007/src/m0tb4680.for

> Also, there does not appear to be a McIDAS command which lists
> all the options for the wx1 parameter and their definitions.

I can not find one either.  The source code above does, however, have fairly
clear lists of what parameters will be decoded.

> I have come across the following results of wx1 and have provided for
> you what I am guessing they stand for.
> D  = dust?
> DH  = dust/haze?
> BDH = blowing dust and haze?
> BD  = blowing dust?
> WD  no idea
> TD   ""
> TBD  ""

The basic dust reports appear to be 'D' and 'BD'.  The other ones you list
are apparently dust combined with other reports (e.g., BDH is 'BD' with
'H' (haze), etc.).

> So, 1. I want to make sure my python program which extracts all of the
> instances where "sand/dust" occurs in my time period actually gets them
> all by knowing what parameters to search for,

Understood.

> and 2. I want to make sure
> I'm not extracting things that have nothing to do with dust or sand just
> because there is the letter "D" involved.

I believe that all WXn reports that have a 'D' in them refer to dust.  For
instance, I believe that 'TD' is to be interpreted as 'T' (thunder) plus
'D' (dust), and 'TBD' would be interpreted as 'T' plus 'BD'.

> I would really appreciate your help!

Please take a look through the three source routines that McIDAS uses in
encoding METAR reports into McIDAS format for storage in MD files.

Another thing you could do is look at realtime data both in decoded (MDXX)
and raw formats.  Look for instances of 'D' (and any combination that makes
sense) to find stations reporting dust.  Then use SFCRPT to ask for the raw
METAR listings from that/those stations.  It is my impression that you should
get enough reports that you will be able to see the correspondence between
the McIDAS WX1 (and possibly WX2) reports and the encodings in the reports.

More information can be found in the WMO Manual on Codes.  You should be
able to find this through a Google (tm) search.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: GQK-632247
Department: Support McIDAS
Priority: Normal
Status: Closed


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