<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: arial,helvetica,sans-serif; font-size: 12pt; color: #000000'>Dmitry,<div><br></div><div>The base state value of 290 should not be changed. It's a parameter in WRF's hypothetical mean temperature profile. To get total potential temperature, it is equal to T + 300 (T is the perturbation potential temperature). Then use Poisson's equation to calculate temperature from potential temperature and pressure (pressure is also split into base and perturbation values).</div><div><br></div><div>Best regards,<br><br><div><span name="x"></span>Eric L. Altshuler<br>Research Scientist<br>Center for Ocean-Land-Atmosphere Studies<br>4041 Powder Mill Road, Suite 302<br>Calverton, MD 20705-3106<br>USA<br><br>E-mail: ela@cola.iges.org<br>Phone: (301) 902-1257<br>Fax: (301) 595-9793<span name="x"></span><br></div><br><hr id="zwchr"><b>From: </b>"Dmitry Khvorostyanov" <dmitry.khvorostyanov@lmd.polytechnique.fr><br><b>To: </b>wrf-users@ucar.edu<br><b>Sent: </b>Tuesday, June 11, 2013 1:28:22 PM<br><b>Subject: </b>[Wrf-users] Base-state potential temperature: 300 or 290 K?<br><br>Dear WRF Users,<br><br>I have a question concerning the value of the base-state potential <br>temperature (the T00 variable in the WRF outputs).<br><br>In the WRF Users' Guide, p. 5-79 (v 3.4) the total potential temperature <br>is defined as T + 300. At the same time the namelist variable <br>'base_temp' equals 290.<br><br>Quickly looking through the code, it seems that the namelist value 290K <br>is used for calculations, e.g., for the T2 field.<br><br>However, in some parts of the code (apparently post-processing) the <br>value of 300 is explicitly set.<br><br>Also, trying to set 'base_temp' to 300 results in the eta levels <br>definition error "dz (m) above fixed eta levels".<br><br>Has anybody had to deal with this point? What value do you use to <br>reconstruct the total potential temperature field?<br><br>With best wishes,<br>Dmitry<br><br><br>-- <br>Dmitry Khvorostyanov<br>Laboratoire de Météorologie Dynamique IPSL<br>Ecole Polytechnique 91128 Palaiseau Cedex<br>France<br><br><br>_______________________________________________<br>Wrf-users mailing list<br>Wrf-users@ucar.edu<br>http://mailman.ucar.edu/mailman/listinfo/wrf-users<br></div></div></body></html>