Dear Dilip,<br><br>I used to face similar problem. I think this error arise due to convective instability. A common work around is to decrease the time step and restart the model. If run goes well you can stop the model after few days run and restart it with original time step if you want to lose computational time.<br><br>Wish you Happy New Year!<br>Jagadish <br><br><b><i>Dilip Ganguly &lt;dganguly@prl.res.in&gt;</i></b> wrote:<blockquote class="replbq" style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"> Hello everyone,<br><br>My Greetings to you all on Christmas!<br><br>I wanted to run RegCM3 for the year 2004 over the south Asian domain. I <br>choose an initial spin up time of two months. That means I started my <br>simulations from 1st Nov. 2003. Simulations started normally and worked <br>upto 1st February 2004. However after this it started showing problem in <br>calculating 1st and 2nd time deriv of ps and I was getting following
 <br>message on the screen<br><br>     at day =   93.0286, ktau =      12300 :  1st, 2nd time deriv of ps =  <br>NaN        NaN        ,  no. of points w/convection =    0<br> BATS variables written at   2004020203   180.000000000000<br>     at day =   93.1589, ktau =      12350 :  1st, 2nd time deriv of ps =  <br>NaN        NaN        ,  no. of points w/convection =    0<br> OUT-history written date =    2004020206.00000<br> BATS variables written at   2004020206  0.000000000000000E+000<br> Writing rad fields at ktau =        12384  2004020206<br> BCs are ready from   2004020206   to   2004020212<br>     at day =   93.2891, ktau =      12400 :  1st, 2nd time deriv of ps =  <br>NaN        NaN        ,  no. of points w/convection =    0<br><br>---------------------------------------------------------------------<br>At this point I stopped the model and restarted it. However the problem <br>is not solved I am getting following message again<br><br> ******* OPENING NEW OUTPUT
 FILES:  2004020200<br> OPENING NEW OUT FILE: output/ATM.2004020200<br> OPENING NEW BAT FILE: output/SRF.2004020200<br> OPENING NEW RAD FILE: output/RAD.2004020200<br>     at day =   93.0286, ktau =      12300 :  1st, 2nd time deriv of ps =  <br>NaN        NaN        ,  no. of points w/convection =    0<br><br>--------------------------------------------------------------------<br><br>Can anyone tell me why is this problem arising and how to overcome it?<br><br>Thanks in advance.<br><br>Dilip. <br>  <br>     ---------------------------------------------------------------------<br>        DILIP GANGULY                               <br>        Postdoctoral Fellow                     <br>        Space And Atmospheric Sciences Division      <br>        Physical Research Laboratory                <br>        Ahmedabad 380009<br> Gujarat, India<br>        Phone: +91 79 26314558 (Laboratory)    <br>               +91 79 26300505 (Hostel)<br> Fax:   +91 79 26314659<br> Alternate
 Email: ganguly.dilip@gmail.com          <br>            Visit me at   http://www.prl.res.in/~dganguly<br>     ---------------------------------------------------------------------<br><br><br><br><br>_______________________________________________<br>RegCNET mailing list<br>RegCNET@lists.ictp.it<br>https://lists.ictp.it/mailman/listinfo/regcnet<br></blockquote><br><p>&#32;__________________________________________________<br>Do You Yahoo!?<br>Tired of spam?  Yahoo! Mail has the best spam protection around <br>http://mail.yahoo.com