Martin Losch Martin.Losch at awi.de
Mon Feb 28 03:39:26 EST 2011

Hi Lian,

the oceanic pressure coordinates are tricky. Please read the corresponding tutorial carefully. Especially here <http://mitgcm.org/public/r2_manual/latest/online_documents/node135.html> you'll find eq. 3.62 which explains the role of the "ploadfile" (\phi'_{-H}^{(0)}). It describes the deviation of the actual pressure field from g*rho0*z at the beginning of the integration. The deviation is caused by your initial vertical profiles of T and S. If you do not specify this \phi'_{-H}^{(0)}, or use a value that does not correspond to your initial T and S, these contributions will end up in p_b, which is OK but will require VERY small time steps during the adjustment process.

Martin

On Feb 27, 2011, at 3:11 PM, lianzhan wrote:

> Hi All
>
> I’m using MITgcm and running an ocean simulation at 1* resolution in pressure coordinates. I got a question about how to
>
> For a climtological run, I should use the annual average T/S to calculate the depth(Pa), and use monthly anomaly of T/S to calculate
> the height anomaly. The monthly height anomaly is the only reason that why we have to use ploadfile. Are these correct or not?
> Moreover, do I need to use ploadfile to adjust the change of depth caused by the discrete vertical levels?
>
> If anyone could shed some light on this, it would be appreciated.
> Regards,
>
> Lian Zhan
>
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