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\section{Model Formulation} |
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\label{sec:model} |
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|
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The MITgcm sea ice model (MITsim) is based on a variant of the |
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viscous-plastic (VP) dynamic-thermodynamic sea ice model |
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\citep{zhang97} first introduced by \citet{hibler79, hibler80}. In |
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order to adapt this model to the requirements of coupled |
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ice-ocean state estimation, many important aspects of the original code have |
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been modified and improved: |
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\begin{itemize} |
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\item the code has been rewritten for an Arakawa C-grid, both B- and |
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C-grid variants are available; the C-grid code allows for no-slip |
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and free-slip lateral boundary conditions; |
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\item two different solution methods for solving the nonlinear |
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momentum equations have been adopted: LSOR \citep{zhang97}, and EVP |
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\citep{hunke97}; |
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\item ice-ocean stress can be formulated as in \citet{hibler87} or as in \citet{cam08}; |
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\item ice variables \ml{can be} advected by sophisticated, \ml{conservative} |
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advection schemes \ml{with flux limiting}; |
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\item growth and melt parameterizations have been refined and extended |
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in order to allow for more stable automatic differentiation of the code. |
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\end{itemize} |
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|
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The sea ice model is tightly coupled to the ocean compontent of the MITgcm |
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\citep{mar97a}. Heat, fresh water fluxes and surface stresses are computed |
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from the atmospheric state and modified by the ice model at every time step. |
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The model equations and details of their numerical realization are summarized |
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in the appendix. Further documentation and model code can be found at |
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\url{http://mitgcm.org}. |
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|
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%\subsection{C-grid} |
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%\begin{itemize} |
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%\item no-slip vs. free-slip for both lsr and evp; |
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% "diagnostics" to look at and use for comparison |
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% \begin{itemize} |
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% \item ice transport through Fram Strait/Denmark Strait/Davis |
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% Strait/Bering strait (these are general) |
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% \item ice transport through narrow passages, e.g.\ Nares-Strait |
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% \end{itemize} |
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%\item compare different advection schemes (if lsr turns out to be more |
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% effective, then with lsr otherwise I prefer evp), eg. |
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% \begin{itemize} |
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% \item default 2nd-order with diff1=0.002 |
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% \item 1st-order upwind with diff1=0. |
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% \item DST3FL (SEAICEadvScheme=33 with diff1=0., should work, works for me) |
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% \item 2nd-order wit flux limiter (SEAICEadvScheme=77 with diff1=0.) |
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% \end{itemize} |
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% That should be enough. Here, total ice mass and location of ice edge |
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% is interesting. However, this comparison can be done in an idealized |
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% domain, may not require full Arctic Domain? |
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%\item |
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%Do a little study on the parameters of LSR and EVP |
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%\begin{enumerate} |
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%\item convergence of LSR, how many iterations do you need to get a |
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% true elliptic yield curve |
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%\item vary deltaTevp and the relaxation parameter for EVP and see when |
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% the EVP solution breaks down (relative to the forcing time scale). |
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% For this, it is essential that the evp solver gives use "stripeless" |
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% solutions, that is your dtevp = 1sec solutions/or 10sec solutions |
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% with SEAICE\_evpDampC = 615. |
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%\end{enumerate} |
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|
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%\end{itemize} |
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|
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%%% Local Variables: |
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%%% mode: latex |
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%%% TeX-master: "ceaice" |
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%%% End: |
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