[IDV #JMC-417505]: Plotting METAR cigc cc1 cc2 fields with IDV

Hi Hans-

> I see, thanks for clarifying that. A bit confusing to have different 
> encodings for the same type of parameter

I agree.  Unfortunately, at this point, it's the only dataset
we have easy access to.

> What made me believe the ccx fields where WMO encoded was that a variable 
> with the name "CC" is described in the parameter alias table as "WMO Cloud 
> cover code". So I just assumed...

Yes, it is confusing.
 
> So the METAR plot model does not really work with METAR obs, with regards to 
> cloud cover?

Not with that dataset.  When we eventually move to the netCDF based
surface datasets, the cloud cover will be stored as octets.  It does
work with the synoptic datasets now from the existing chooser.

Don
> -----Original Message-----
> From: Unidata IDV Support [mailto:address@hidden]
> Sent: Sunday, October 12, 2008 3:48 PM
> To: address@hidden
> Cc: address@hidden
> Subject: [IDV #JMC-417505]: Plotting METAR cigc cc1 cc2 fields with IDV
> 
> Hi Hans-
> 
> In the METAR dataset from the point obs chooser, the CIGC, CC1 and
> CC2 values are not the WMO cloud cover values as one would think.
> They are a McIDAS specific code as follows:
> 
> 0 - clear
> 1 - scattered
> 2 - broken
> 3 - overcast
> 
> So, when used with the METAR station model, you will end
> up with bad values.  If you use the Synoptic data, the
> CA value gets used for the cloud cover which is the WMO
> code.
> 
> Unfortunately, we have no way of distinguishing the values without
> some ugly hardcoded hack which we don't want to do.
> 
> Hope that helps explain what you are seeing.
> 
> BTW, feedback on the new analysis functionality is appreciated!
> 
> Don Murray
> 
> > With the new Barnes objective analysis of point data, I have been looking at
> > plotting the cloud cover information contained in METAR code (cigc, cc1 and
> > cc2 fields).
> >
> >
> >
> > However, I can't really understand how IDV interprets that info in the METAR
> > code. Plotting station plots with the standard IDV METAR plot model results
> > in cloud cover symbols that I think do not match the actual info in the
> > METAR code. For example, most of today, IDV have plotted cloud cover symbols
> > equaling a cloud cover of 1/8 where I live. However, checking the relevant
> > METAR code manually reveals a cloud cover of up to 7/8 for the same station.
> > Checking what actual values the cloud cover fields have in IDV, it appears
> > those lie in the interval 0-3 (?), though I cannot understand how to
> > interpret that. As far as I know, METAR's express cloud cover with, at
> > least, five different codes (Sky Clear, Few, Scattered, Broken, Overcast).
> >
> >
> >
> > So, am I doing something wrong here?
> >
> >
> >
> > Using the latest and greatest nightly build.
> >
> >
> >
> > Regards,
> >
> > Hans
> >
> >
> >
> 
> 
> Ticket Details
> ===================
> Ticket ID: JMC-417505
> Department: Support IDV
> Priority: Normal
> Status: Open
> 
> 


Ticket Details
===================
Ticket ID: JMC-417505
Department: Support IDV
Priority: Normal
Status: Open