Hi,<div><br></div><div>Just to fill in some details:</div><div><br></div><div>In the situation Elena described, the first GFS data set gets interpolated over space to give initial conditions to the WRF grids. This data is in the wrfinput files produced by real.exe. Then the first two data sets get interpolated over space AND time to provide values but only for the outside edges of your WRF grid, not inside the WRF grid. This data is in the wrfbdy file produced by real.exe. After the second data set is used up, the boundary conditions are interpolated in time and space between the second and third GFS data set. And so on. You can NOT forecast beyond the last GFS data set because real.exe does not have a next data set to use for interpolation. Without boundary conditions, the forecast can not continue because no new weather can enter your WRF grid because it is not provided. The GFS program is global so it has no boundaries (wraps around to itself). GFS could continue on indefinitely. WRF, unless run as a global grid, has to stop when there are no more boundary conditions to specify new weather along its outside grid border.</div>
<div><br></div><div>If some of that was already obvious, sorry. Just trying to be complete and of course, I don't know what you do or do not already know.</div><div>Kevin<br><br><div class="gmail_quote">On Tue, Jul 3, 2012 at 4:57 PM, Oleksandr Huziy <span dir="ltr"><<a href="mailto:guziy.sasha@gmail.com" target="_blank">guziy.sasha@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br><br>I can only tell you this as a guess, because I don't remember how it is done in wrf:<br><br>1) The 6h data is used on each time step as a boundary condition. They could linearly interpolate it in time to the time steps or just take the closest field to the current time step (or something more sophisticated). <br>
<br>2) You probably could do it for 6 more hours but then you would be using the same boundary conditions from the last 6 hourly forecast on each time step. In general I would say that this is not a good idea.<br><br>Cheers<br>
--<br>Oleksandr (Sasha) Huziy<br><br><div class="gmail_quote"><div><div class="h5">2012/7/2 Elena Maria Pison San Pedro <span dir="ltr"><<a href="mailto:emp@dhi.com.sg" target="_blank">emp@dhi.com.sg</a>></span><br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
<div link="blue" vlink="purple" lang="EN-SG"><div><p class="MsoNormal">Hello,<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">My question is regarding the capability of WRF to do forecasting. The common utilization of WRF is using GFS (ex. 6hourly) with analysis or forecasts files. Anyhow, WRF is running by itself between 2 GFS files, and we can say, it is preforming a forecast of 6 hours. Am I right? <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p><u></u><span>-<span style="font:7.0pt "Times New Roman""> </span></span><u></u>when the model arrives to the time step of the new GFS file (time+ 6h), <u>how it integrates the information of the already atmospheric situation and the info from the GFS new file</u>?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p><u></u><span>-<span style="font:7.0pt "Times New Roman""> </span></span><u></u>Is it then <u>possible to run WRF beyond the last GFS analysis</u> or longer than this intervals? <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Thanks a lot in advance!<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Cheers,<u></u><u></u></p>
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