[gradsusr] NAM and APCPSFC data

[Jeff Duda]

Mark,
Why do you not think it works the way you described in (1)? That's the way
I've always used it, and I've never had a problem. The particular t-index
value you use in grads depends on how you setup the control file. If you
didn't start the time index at forecast hour 0, then there will be a phase
difference between what you think and what actually works.

Jeff Duda

On Fri, Oct 14, 2016 at 10:55 AM, Mark Sponsler <msponsler at comcast.net>
wrote:

> Hi,
> I'm trying to display variable 'apcpsfc' from the 3 hr and 1 hr NAM.  The
> resulting images appear to pulsate/accumulate precip every few images then
> reset only to accumulate again.
>
> I've seen the threads in the archive on this issue with HD GFS data, but
> I'm trying to understand 2 things:
>
> 1) What is the accumulation period for NAM 1 hr and 3 hr data.  I was
> thinking it was every 3 time steps (i.e. excluding time step 1 / 00 hr), it
> is 2, 3, 4 then reset and start accumulating again for the next 3 time
> steps 5, 6 and 7).  But that doesnt seem to be the case.
>
> 2) What does it mean to 'normalize' the data? Westly did something in
> wgrib2 for HD GFS data to normalize it and I was wondering if that was also
> applicable to NAM data.  What is done to mathmatically to get the data to
> be valid for just a single timestep?.  Can I write something in GRDADS to
> perform the normalization rather than having to use WGRIB2.
>
> Assuming the accumulation theory is correct (that apcpsfc accumulates
> every three time steps), I've been trying to write code to remove the
> accumulation by:
>
> Display Time = 2
> Time 3 = Time 3 - Time 2
> Display Time 3
> Time 4 = Time 4 - Time 3
> Display Time 4
>
> But it doesnt work.
>
> Any help would be appreciated.
>
> Thanks,
> Mark
> Thanks,
> Mark
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
>
>


-- 
Jeff Duda
Post-doctoral research associate
University of Oklahoma School of Meteorology
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20161014/b675c476/attachment.html