<div dir="ltr"><div><div>Mark,<br></div>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.<br><br></div>Jeff Duda<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Oct 14, 2016 at 10:55 AM, Mark Sponsler <span dir="ltr"><<a href="mailto:msponsler@comcast.net" target="_blank">msponsler@comcast.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Hi,<br>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.<br><br>I've seen the threads in the archive on this issue with HD GFS data, but I'm trying to understand 2 things:<br><br>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. <br><br>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. <br><br>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:<br><br>Display Time = 2<br>Time 3 = Time 3 - Time 2<br>Display Time 3<br>Time 4 = Time 4 - Time 3<br>Display Time 4<br><br>But it doesnt work. <br><br>Any help would be appreciated.<br><br>Thanks,<br>Mark </div>
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<div><span style="font-size:small">Thanks,<br>Mark</span></div><br>______________________________<wbr>_________________<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>Jeff Duda<br>Post-doctoral research associate<br>University of Oklahoma School of Meteorology<br></div></div></div>
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