[RegCNET] Time step problem or something else ?
Dilip Ganguly
dganguly at prl.res.in
Mon Jan 8 10:38:19 CET 2007
Dear Sara,
Thanks for your help. It seems my problem is solved for the time being as
I have completed my previous simulation which was crashing again and
again. I tried to restart my simulation with reduced time step in regcm.in
file and adding proper link for the files of the type SAVTMP.2004111800
saved in my run directory in the regcm.x file. However, the model was
crashing even with reduced time step. My problem was solved only when I
restarted the model with reduced time step and from the first date of the
particular month and giving link to the file of the type SAV.2004110100
saved in the output directory inside the run directory.
Many thanks to Jagadish and Sara for your help suggestions.
By the way my name is 'Dilip' and not 'Dipil'. I think Jagadish
misspelled it in his last email.
Anyway Cheers,
Dilip.
On Mon, 8 Jan 2007, Rauscher Sara A wrote:
> Hi Dipil,
>
> During a long run this can sometimes happen. Usually I restart (before
> the time of the crash) using a shorter time step in regcm.in. When the
> simulation moves past the time of the crash, I then stop the simulation
> and restart with the original time step. This is a way for dealing with
> one or two crashes in a long simulation.
>
> If you are experiencing lots of crashes, this is NOT an appropriate way
> to handle it - you should follow Jagadish's suggestions regarding
> checking the time step, location and boundaries of the domain, model
> resolution, and the physical parameterizations etc. and do further tests
> before beginning a long simulation.
>
> Let me know if you require further information.
>
> cheers,
> sara
>
> jagadish karmacharya wrote:
> > Dear Dipil,
> >
> > You shouldn't change parameters at the middle of an experiments. My
> > suggestion was to make the changes if you are starting new experiments.
> >
> > Have you checked the ICBC file for that date/month in grads?
> >
> > One thing you can do is to run new identical simulation begining from
> > the 1st date of the month where you are getting problem just to
> > check if the problem persist or not. You may also try to restart the
> > experiment with different convection scheme just for the purpose of
> > checking. Obviously these will not be part of you long simulation.
> >
> > All the best
> >
> > Jagadish
> >
> > */Dilip Ganguly <dganguly at prl.res.in>/* wrote:
> >
> > Dear Jagadish,
> >
> > As you are suggesting that changing domain boundary, convective
> > scheme,
> > increasing resolution etc. might help in avoiding this kind of
> > situation.
> > But my problem is that I am already in the middle of a long
> > simulation and
> > this problem due to convective instability is occuring towards the
> > end of
> > my simulation. At this stage how can I introduce changes which you
> > want me
> > to try ? Is there any other way to get out of this problem at this
> > stage ?
> >
> > Regards,
> >
> > Dilip.
> >
> >
> > > Dear Dilip,
> > >
> > > You have tried all the way down to dt=1 sec but as you have seen
> > > decreasing time step doesn't always solve the problem. I generally
> > > decrease dt upto 1.5*resolution in km (instead of dt=3*res) to
> > check if
> > > if overcome the problem.
> > > When the problem persists with decreased timestep as well it is
> > difficult
> > > to figure out a solution.
> > >
> > > Changing domain boundary, convective scheme, increasing
> > resolution may
> > > help but if one has already completed long simulation then it
> > become a
> > > problem. One possibility is that your ICBC or driving data file
> > for that
> > > month may be corrupt but its less likely.
> > >
> > > Can anyone give some suggestion?
> > >
> > > Regards
> > > Jagadish
> > >
> > >
> > > Dilip Ganguly wrote: Dear all,
> > >
> > > I am facing problem in running RegCM3. The program hangs and
> > does not seem
> > > to work after a particular time and I am getting messages on the
> > screen
> > > like the following.
> > >
> > > BATS variables written at 2004120121 180.000000000000
> > > at day = 396.8762, ktau = 210200 : 1st, 2nd time deriv of ps =
> > > 0.10915E-02 0.49528E-05, no. of points w/convection = 81
> > > at day = 396.8849, ktau = 210250 : 1st, 2nd time deriv of ps =
> > > 0.97549E-03 0.41641E-05, no. of points w/convection = 71
> > > at day = 396.8936, ktau = 210300 : 1st, 2nd time deriv of ps =
> > > NaN NaN , no. of points w/convection = 0
> > >
> > >
> > -------------------------------------------------------------------------
> > >
> > > It do not know if it is due to improper choice of time steps. I have
> > > restarted the program several times with lower and lower values
> > of time
> > > step dt but every time the program hangs around a certain period
> > of time
> > > and not able to cross this period. I have tried with numerous
> > combinations
> > > of gradually decreasing time steps. Some are given below.
> > >
> > > radfrq= 30 30 30 30 15 15 15
> > > abemh = 18 18 18 18 9 9 9
> > > abatm = 300 120 90 45 30 9 3
> > > dt = 100 60 30 15 10 3 1
> > >
> > > But none of them worked. Everytime it shows the same problem
> > possibly due
> > > to convective instability as told by Jagadish. I am using a 90 km
> > > horizontal resolution in my simulation.
> > >
> > > Can anyone suggest a way to solve this problem ?
> > >
> > > Thanking you in advance.
> > >
> > > Dilip.
> > >
> > >
> > ---------------------------------------------------------------------
> > > DILIP GANGULY
> > > Postdoctoral Fellow
> > > Space And Atmospheric Sciences Division
> > > Physical Research Laboratory
> > > Ahmedabad 380009
> > > Gujarat, India
> > > Phone: +91 79 26314558 (Laboratory)
> > > +91 79 26300505 (Hostel)
> > > Fax: +91 79 26314659
> > > Alternate Email: ganguly.dilip at gmail.com
> > > Visit me at http://www.prl.res.in/~dganguly
> > >
> > ---------------------------------------------------------------------
> > >
> > >
> > > _______________________________________________
> > > RegCNET mailing list
> > > RegCNET at lists.ictp.it
> > > https://lists.ictp.it/mailman/listinfo/regcnet
> > >
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
> > > Tired of spam? Yahoo! Mail has the best spam protection around
> > > http://mail.yahoo.com
> >
> >
> > --
> > Dilip Ganguly
> > Postdoctoral Fellow
> > Space and Atmospheric Sciences Division
> > Physical Research Laboratory
> > Navrangpura
> > Ahmedabad-380009
> > Gujarat, India
> > Phone:+91 79 26314558, Fax: +91 79 26314659
> > Alternate Email: ganguly.dilip at gmail.com
> > visit me at: http://www.prl.res.in/~dganguly
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam? Yahoo! Mail has the best spam protection around
> > http://mail.yahoo.com
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > RegCNET mailing list
> > RegCNET at lists.ictp.it
> > https://lists.ictp.it/mailman/listinfo/regcnet
> >
>
> --
>
> Dr. Sara A. Rauscher
> Earth System Physics Section
> The Abdus Salam International Centre for Theoretical Physics
> Strada Costiera 11
> 34014 Trieste ITALY
> ph: +39 040 2240 225 fax: +39 040 2240 449
> email: srausche at ictp.it
>
>
Dilip.
---------------------------------------------------------------------
DILIP GANGULY
Postdoctoral Fellow
Space And Atmospheric Sciences Division
Physical Research Laboratory
Ahmedabad 380009
Gujarat, India
Phone: +91 79 26314558 (Laboratory)
+91 79 26300505 (Hostel)
Fax: +91 79 26314659
Alternate Email: ganguly.dilip at gmail.com
Visit me at http://www.prl.res.in/~dganguly
---------------------------------------------------------------------
More information about the RegCNET
mailing list