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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-SG link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>Hi Jan,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>Thanks! The CFL was happening over the ocean (Malacca Strait) which is quite strange. But is true that maybe the problem was coming from the Time step as I was setting the parent_time_ratio = 1, 2, 3 but the parent_grid ratio = 1, 3, 3 so the CFL errors were coming from domain 2!<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>Just strange that it run till the end and just a couple of this CFL errors were printed….<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>Thanks a lot and all the best for you too!<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>Elena<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext;mso-fareast-language:EN-SG'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext;mso-fareast-language:EN-SG'> Jan Harlass [mailto:jharlass@geomar.de] <br><b>Sent:</b> Friday, 2 November, 2012 4:41 PM<br><b>To:</b> Elena Maria Pison San Pedro<br><b>Cc:</b> wrf-users@ucar.edu<br><b>Subject:</b> Re: [Wrf-users] CFL criterion - general question<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>Hi Elena, <br><br>another thing you could try is to add:<br>smooth_cg_topo = .true.<br>under &domains in the namelist when you run real. This smoothes the model topography to match the low resolution topography that comes with the driving data, if CFL happens along boundary zones. If CFL occurs near complex terrain, you may try to set epssm=0.2 ( up to 0.5) to see if that helps.<br>[from <a href="http://www.mmm.ucar.edu/wrf/users/FAQ.html">http://www.mmm.ucar.edu/wrf/users/FAQ.html</a>]<br><br>Also remember to scale your time step with the maximum map factor of your domain. This value is written out in the log files of real.exe. The time step is then: dt (sec) = 6*dx (km) / (maximum map factor)<br><br>All the best!<br><br> Jan<br><br><br><o:p></o:p></p><div><p class=MsoNormal>Am 01.11.2012 06:51, schrieb Elena Maria Pison San Pedro:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Hello,</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>I’ve remarked that sometimes when I run a simulation (WRF3.4) I got messages saying “ x points exceeded cfl=2 at time…” <u>but the simulation run to completion</u>.</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-SG'><img border=0 width=1037 height=576 id="Picture_x0020_2" src="cid:image001.jpg@01CDB91A.1689F2C0"></span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>How can this affect the results? What can I do to solve this instabilities, run a higher time step?</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Thanks a lot in advance!</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Best regards,</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Elena</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 width=360 style='width:270.0pt'><tr><td colspan=3 valign=top style='padding:0cm 0cm 0cm 0cm'><p class=MsoNormal><span style='font-size:9.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'>Elena Pison San Pedro</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'>M.Sc. in Atmospheric Sciences</span><o:p></o:p></p></td></tr><tr><td colspan=3 valign=top style='padding:0cm 0cm 0cm 0cm'></td></tr><tr style='height:15.0pt'><td colspan=3 valign=top style='padding:0cm 0cm 0cm 0cm;height:15.0pt'><p class=MsoNormal style='line-height:15.0pt'><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'> </span><o:p></o:p></p></td></tr><tr><td colspan=3 valign=top style='padding:0cm 0cm 0cm 0cm'><p class=MsoNormal><span style='font-size:12.0pt'><img border=0 width=150 height=38 id="Picture_x0020_1" src="cid:image002.gif@01CDB91A.1689F2C0" alt="Description: 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style='font-size:8.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'>Tel: </span><o:p></o:p></p></td><td width=5 valign=top style='width:3.75pt;padding:0cm 0cm 0cm 0cm;height:6.0pt'><p class=MsoNormal style='mso-line-height-alt:6.0pt'><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'> </span><o:p></o:p></p></td><td width=305 valign=top style='width:228.75pt;padding:0cm 0cm 0cm 0cm;height:6.0pt'><p class=MsoNormal style='mso-line-height-alt:6.0pt'><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'>+65-6777-6330</span><o:p></o:p></p></td></tr><tr style='height:7.5pt'><td colspan=3 valign=top style='padding:0cm 0cm 0cm 0cm;height:7.5pt'><p class=MsoNormal style='mso-line-height-alt:7.5pt'><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'> </span><o:p></o:p></p></td></tr><tr><td colspan=3 valign=top style='padding:0cm 0cm 0cm 0cm'><p class=MsoNormal><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'><a href="mailto:emp@dhi.com.sg">emp@dhi.com.sg</a></span><o:p></o:p></p></td></tr><tr><td colspan=3 valign=top style='padding:0cm 0cm 0cm 0cm'><p class=MsoNormal><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";mso-fareast-language:EN-SG'><a href="http://www.dhigroup.com/">www.dhigroup.com</a></span><o:p></o:p></p></td></tr></table><p class=MsoNormal><span style='mso-fareast-language:EN-SG'> </span><o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-SG'> </span><o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif";mso-fareast-language:EN-SG'><br><br><br><o:p></o:p></span></p><pre>_______________________________________________<o:p></o:p></pre><pre>Wrf-users mailing list<o:p></o:p></pre><pre><a href="mailto:Wrf-users@ucar.edu">Wrf-users@ucar.edu</a><o:p></o:p></pre><pre><a href="http://mailman.ucar.edu/mailman/listinfo/wrf-users">http://mailman.ucar.edu/mailman/listinfo/wrf-users</a><o:p></o:p></pre></blockquote><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif";mso-fareast-language:EN-SG'><br><br><o:p></o:p></span></p><pre>-- <o:p></o:p></pre><pre>-----------------------------------------------------------<o:p></o:p></pre><pre>Dipl.-Met. Jan Harlaß<o:p></o:p></pre><pre>FB1, FE Maritime Meteorologie, PhD-Student<o:p></o:p></pre><pre>Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR)<o:p></o:p></pre><pre>Düsternbrooker Weg 20<o:p></o:p></pre><pre>Alte Botanik Raum 61<o:p></o:p></pre><pre>24105 Kiel, Germany<o:p></o:p></pre><pre>------------------------------------------------------------<o:p></o:p></pre><pre>Tel. +49-431-600-4034<o:p></o:p></pre><pre>Fax +49-431-600-4052<o:p></o:p></pre><pre><a href="mailto:jharlass@geomar.de">jharlass@geomar.de</a><o:p></o:p></pre><pre><a href="http://www.geomar.de/~jharlass-e">www.geomar.de/~jharlass-e</a><o:p></o:p></pre><pre>-------------------------------------------------------------<o:p></o:p></pre></div></body></html>