strange problem in cclm – in #9: CCLM

in #9: CCLM

<p> Dear Iya </p> <p> actually, I have no explanation for the error. <br/> At a frist glance, it seems to be a system ( <span class="caps"> MPI </span> ?) error. <br/> But who knows. <br/> Nevertheless, here are a few comments on your setup: </p> <p> 1. the timestep dt: you are using dt=120 (sec) together with a spatial resolution of about 12 km. <br/> dt=120 is, to my opinion, much too high. There is a large danger for violations of the <span class="caps"> CFL </span> -criterion. <br/> I would use dt=75 </p> <p> 2. if I understand your setup correctly, you want to perform a 30 day simulation, starting 2009120100 and ending 2009123100. <br/> This is a simulation duration of 720 hours (30 days * 24 hours/day) which should be the value for the namelist parameter “hstop”. <br/> But you are using “hstop=30*720” (see your cclm-setup) <br/> This could be corrected in your setup file by defining <br/> NHOURS=24 <br/> instead of <br/> NHOURS=720 </p> <p> 3. the triple of values for namelist parameter “nhour_restart” should be <br/> nhour_restart=120,$HSTOP,120 <br/> and not <br/> nhour_restart=0,$HSTOP,120 <br/> where the values are given in hours. <br/> However, this mistake (the first value of the triple) is corrected by <span class="caps"> CCLM </span> (see cclm.exe.out) </p> <p> 4. Can someone else comment on Iya’s choices of Tuning parameters (see cclm.exe.out and <span class="caps"> YUSPECIF </span> ). They seem to be rather “extreme”. </p> <p> Best regards <br/> Hans-Juergen </p>

  @hans-jürgenpanitz in #205868c

<p> Dear Iya </p> <p> actually, I have no explanation for the error. <br/> At a frist glance, it seems to be a system ( <span class="caps"> MPI </span> ?) error. <br/> But who knows. <br/> Nevertheless, here are a few comments on your setup: </p> <p> 1. the timestep dt: you are using dt=120 (sec) together with a spatial resolution of about 12 km. <br/> dt=120 is, to my opinion, much too high. There is a large danger for violations of the <span class="caps"> CFL </span> -criterion. <br/> I would use dt=75 </p> <p> 2. if I understand your setup correctly, you want to perform a 30 day simulation, starting 2009120100 and ending 2009123100. <br/> This is a simulation duration of 720 hours (30 days * 24 hours/day) which should be the value for the namelist parameter “hstop”. <br/> But you are using “hstop=30*720” (see your cclm-setup) <br/> This could be corrected in your setup file by defining <br/> NHOURS=24 <br/> instead of <br/> NHOURS=720 </p> <p> 3. the triple of values for namelist parameter “nhour_restart” should be <br/> nhour_restart=120,$HSTOP,120 <br/> and not <br/> nhour_restart=0,$HSTOP,120 <br/> where the values are given in hours. <br/> However, this mistake (the first value of the triple) is corrected by <span class="caps"> CCLM </span> (see cclm.exe.out) </p> <p> 4. Can someone else comment on Iya’s choices of Tuning parameters (see cclm.exe.out and <span class="caps"> YUSPECIF </span> ). They seem to be rather “extreme”. </p> <p> Best regards <br/> Hans-Juergen </p>
HP replied

Dear Iya

actually, I have no explanation for the error.
At a frist glance, it seems to be a system ( MPI ?) error.
But who knows.
Nevertheless, here are a few comments on your setup:

1. the timestep dt: you are using dt=120 (sec) together with a spatial resolution of about 12 km.
dt=120 is, to my opinion, much too high. There is a large danger for violations of the CFL -criterion.
I would use dt=75

2. if I understand your setup correctly, you want to perform a 30 day simulation, starting 2009120100 and ending 2009123100.
This is a simulation duration of 720 hours (30 days * 24 hours/day) which should be the value for the namelist parameter “hstop”.
But you are using “hstop=30*720” (see your cclm-setup)
This could be corrected in your setup file by defining
NHOURS=24
instead of
NHOURS=720

3. the triple of values for namelist parameter “nhour_restart” should be
nhour_restart=120,$HSTOP,120
and not
nhour_restart=0,$HSTOP,120
where the values are given in hours.
However, this mistake (the first value of the triple) is corrected by CCLM (see cclm.exe.out)

4. Can someone else comment on Iya’s choices of Tuning parameters (see cclm.exe.out and YUSPECIF ). They seem to be rather “extreme”.

Best regards
Hans-Juergen

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