[MITgcm-support] linear growth of runoff

[Dmitri Leonov]

Hi Matthew,

The ssh is growing quadratically, and the rate depends on the timestep 
(inversely proportional) so it looks like some kind of numerical 
instability but I can't see what causes it.

Dmitri.

Matthew Mazloff wrote:
> Hi Dmitri,
>
> If you add runoff constant in time you're ssh should grow linearly; 
> every timestep run-off is added and this will cause linear ssh 
> growth.  There is no problem....or am i missing something.
>
> -Matt
>
>
>
> On Mar 12, 2007, at 9:47 PM, Dmitri Leonov wrote:
>
>> Hello Patrick,
>>
>> Please let me know what exactly it was that you found wrong in my 
>> input files. I've tried setting the runoffperiod to zero as you 
>> suggested but the runoff still seems to be growing linearly - so the 
>> problem is not in the time-interpolation but somewhere else. This is 
>> not architecture or compiler specific as I originally thought it 
>> might be: just got same results on a linux pc using g77.
>>
>> Maybe I'm not allowed to have closed boundaries when I have a 
>> non-zero E-P-R, so it's not a good test? What do you mean by 
>> balancing E-P-R fields? In the actual experiment I have an open 
>> boundary.
>>
>> If there is in fact some kind of bug there I thought some people 
>> other than myself might be interested in looking into it. Otherwise 
>> I'll need to find out what exactly was wrong with my set-up.
>>
>> Regards,
>> Dmitri.
>>
>>
>>> No, you got that wrong.
>>> Time interpolation of runoff is working properly,
>>> assuming you've set values in data.exf correctly.
>>>
>>>> 2) it gets interpolation period wrong so the slope depends on the 
>>>> timestep (as if the period is specified in timesteps rather than in 
>>>> seconds).
>>>
>>> Are your E-P-R fields balanced overall?
>>>
>>> -Patrick
>>>
>>>
>>>> Jean-Michel Campin wrote:
>>>>> Hi Dimitri,
>>>>>
>>>>> I forgot the important thing,
>>>>> apparently, in your set-up, EXF produces a linear increase with 
>>>>> time in run-off, but I don't know precisely what would need to be 
>>>>> changed in data.exf & data.exf_clim to get a constant run-off. May 
>>>>> be someone else will know.
>>>>>
>>>>> Jean-Michel
>>>>>
>>
>> -- 
>> ------------------------------------------------
>> Dmitri A. Leonov
>> Research Associate, Postdoctoral
>> University of Washington, School of Oceanography
>>
>>
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-- 
------------------------------------------------
Dmitri A. Leonov
Research Associate, Postdoctoral
University of Washington, School of Oceanography