[RegCNET] Error in runing RegCM4 from 2009123118 to 2010010100 about CFL VIOLATION

[bixq]

Hi, Duan Wei:

The rule that dt (in second) equals 3*ds (in km) is not absolute !

The computational instability may also be related to the map-factor of 
your domain.

If you use LAMCON, you have to choose the right truelatL and truelatH to 
make the map-factor of your domain as close to 1 as possible.

If you use NORMER and your domain is stretched to 45N, then you have to
use ROTMER instead.

If the wind fields is very strong in your domain, you might also
reduce the timestep.

Regards,
Bi Xunqiang

On Wed, 10 Nov 2010, w d wrote:

> Dear all,
>    I find a new error in in runing RegCM4 from 2009123118 to 20100101 about CFL VIOLATION.
>    I know usually dt< 3ds.
>    I try to some dt and ds parameters,but I failed every test from 2009123118 to 2010010100.
>    these failed  tests about dt&ds:
>        ds=50   dt=150
>        ds=50   dt=100
>        dt=60    dt=150
>        dt=60    dt=120
>        dt=60    dt=90
>   How to solve the error about CFL VIOLATION?
>  
>   Anthers,I try to modify idate1,idate0and idate2,and the same error is found. 
>  
>  
> the failed message is followed.
> BCs are ready from   2009123118   to   2010010100
>      at day =    2.2535, ktau =        650 :  1st, 2nd time deriv of ps =  0.13049E-03 0.13466E-05,  no. of points w/convection =    3987
>  WHUUUUBBBASAAAGASDDWD!!!!!!!!!!!!!!!!
>  No more atmosphere here....
>  CFL violation detected, so model STOP
>  #####################################
>  #            DECREASE DT !!!!       #
>  #####################################
>   -------------- FATAL CALLED ---------------
>   Fatal in file: tend.F90 at line:   2280
>   CFL VIOLATION
>   -------------------------------------------
> forrtl: severe (174): SIGSEGV, segmentation fault occurred
> Image              PC        Routine            Line        Source
> libc.so.6          400D9F00  Unknown               Unknown  Unknown
> regcmSerial        0825867A  Unknown               Unknown  Unknown
> regcmSerial        080EC500  Unknown               Unknown  Unknown
> regcmSerial        081834E9  Unknown               Unknown  Unknown
> regcmSerial        0804A1B1  Unknown               Unknown  Unknown
> libc.so.6          40084F9C  Unknown               Unknown  Unknown
> regcmSerial        0804A0D1  Unknown               Unknown  Unknown
>
>
> Best wishes
> Duan Wei
>  
>  
> 段玮
> Duan Wei
> 云南省气象科学研究所大气成分应用研究室
> Atmospheric Components Laboratory,MIYN
>
> 650034 中国云南.昆明市西昌路77号
> 77 Xichang Road, Kunming, P.R.China
> E-mail: raisest at yahoo.com.cn
> migrant at sohu.com
>
> Tel: 86-871-4189160
> 86-13888741052
>
> Fax: 86-871-4189169
>
> 如有任何疑问,请随时联系.
> If you have any question,
> please feel free to call me.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   Dr. Xunqiang Bi         email:bixq at ictp.it
   Earth System Physics Group
   The Abdus Salam ICTP
   Strada Costiera, 11
   P.O. BOX 586, 34100 Trieste, ITALY
   Tel: +39-040-2240302  Fax: +39-040-2240449
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~