/[MITgcm]/MITgcm_contrib/articles/ceaice/ceaice_forward.tex

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-revision 1.13 by mlosch,
Fri Mar 14 23:05:34 2008 UTC
+revision 1.14 by mlosch,
Tue Apr 29 14:04:15 2008 UTC
 Line 107 
 The Arctic domain of integration is illu
  boundary conditions from, the global cubed-sphere configuration
  described above.  The horizontal domain size is 420 by 384 grid boxes.
  \begin{figure*}
- \includegraphics*[width=0.44\linewidth]{\fpath/topography}
+ \includegraphics*[width=0.44\linewidth,viewport=139 210 496 606,clip]{\fpath/topography}
+ %\includegraphics*[width=0.44\linewidth,viewport=0 0 496 606,clip]{\fpath/topography}
  \includegraphics*[width=0.46\linewidth]{\fpath/archipelago}
  \caption{Left: Bathymetry and domain boudaries of Arctic
    Domain; the dashed line marks the boundaries of the inset on the
-Line 146 
 conditions:
+Line 147 
 conditions:
  \item[C-LSR-fs:] the LSOR solver on a C-grid with free-slip lateral boundary
    conditions;
  \item[C-EVP-ns:] the EVP solver of \citet{hunke01} on a C-grid with
-   no-slip lateral boundary conditions; and
+   no-slip lateral boundary conditions;
  \item[C-EVP-fs:] the EVP solver on a C-grid with free-slip lateral
-   boundary conditions.
+   boundary conditions;
+ \item[C-LSR-ns adv33:] C-LSR-ns with a third-order flux limited
+   direct-space-time advection scheme \citep{hundsdorfer94};
+ \item[C-LSR-ns TEM:] C-LSR-ns with a truncated
+   ellispe method (TEM) rheology \citep{hibler97};
+ \item[C-LSR-ns HB87:] C-LSR-ns with ocean-ice stress coupling according
+   to \citet{hibler87};
+ \item[C-EVP-ns damp:] C-EVP-ns with additional damping to reduce small
+   scale noise \citep{hunke01}.
  \end{description}
  Both LSOR and EVP solvers solve the same viscous-plastic rheology, so
  that differences between runs B-LSR-ns, C-LSR-ns, and C-EVP-ns can be
  interpreted as pure model error. Lateral boundary conditions on a
  coarse grid (compared to the roughness of the true coast line) are
  unclear, so that comparing the no-slip solutions to the free-slip
- solutions gives another measure of uncertainty in sea ice modeling.
+ solutions gives another measure of uncertainty in sea ice
+ modeling. The remaining experiments explore further
+ sensitivities of the system to different physics (change in rheology,
+ advection and diffusion properties and stress coupling) and numerics
+ (numerical method to damp noise in the EVP solutions).
  A principle difficulty in comparing the solutions obtained with
  different variants of the dynamics solver lies in the non-linear
-Line 179 
 shifted eastwards towards Alaska.
+Line 192 
 shifted eastwards towards Alaska.
  The difference beween runs C-LSR-ns and B-LSR-ns (\reffig{iceveloc}b)
  is most pronounced along the coastlines, where the discretization
  differs most between B and C-grids: On a B-grid the tangential
- velocity lies on the boundary (and thus zero per the no-slip boundary
+ velocity lies on the boundary (and is thus zero through the no-slip
- conditions), whereas on the C-grid the its half a cell width away from
+ boundary conditions), whereas on the C-grid it is half a cell width
- the boundary, thus allowing more flow. The B-LSR-ns solution has less
+ away from the boundary, thus allowing more flow. The B-LSR-ns solution
- ice drift through the Fram Strait and especially the along Greenland's
+ has less ice drift through the Fram Strait and especially the along
- east coast; also, the flow through Baffin Bay and Davis Strait into
+ Greenland's east coast; also, the flow through Baffin Bay and Davis
- the Labrador Sea is reduced with respect the C-LSR-ns solution.
+ Strait into the Labrador Sea is reduced with respect the C-LSR-ns
- \ml{[Do we expect this? Say something about that]}
+ solution.  \ml{[Do we expect this? Say something about that]}
  %
  Compared to the differences between B and C-grid solutions,the
  C-LSR-fs ice drift field differs much less from the C-LSR-ns solution
-Line 197 
 Island.
+Line 210 
 Island.
  \begin{figure}[htbp]
    \centering
    \subfigure[{\footnotesize C-LSR-ns}]
-   {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_lsr_noslip}}
+ %  {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_lsr_noslip}}
+   {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_C-LSR-ns}}
    \subfigure[{\footnotesize B-LSR-ns $-$ C-LSR-ns}]
-   {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_bgrid-lsr_noslip}}\\
+ %  {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_bgrid-lsr_noslip}}\\
+   {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_B-LSR-ns-C-LSR-ns}}\\
    \subfigure[{\footnotesize C-LSR-fs $-$ C-LSR-ns}]
-   {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_lsr_slip-lsr_noslip}}
+ %  {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_lsr_slip-lsr_noslip}}
+   {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_C-LSR-fs-C-LSR-ns}}
    \subfigure[{\footnotesize C-EVP-ns $-$ C-LSR-ns}]
-   {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_evp_noslip-lsr_noslip}}
+ %  {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_evp_noslip-lsr_noslip}}
+   {\includegraphics[width=0.44\textwidth]{\fpath/JFMuv_C-EVP-ns-C-LSR-ns}}
    \caption{(a) Ice drift velocity of the C-LSR-ns solution averaged
      over the first 3 months of integration [cm/s]; (b)-(d) difference
      between B-LSR-ns, C-LSR-fs, C-EVP-ns, and C-LSR-ns solutions
-Line 221 
 biased towards higher values in the EVP
+Line 238 
 biased towards higher values in the EVP
  a histogram of the differences in \reffig{drifthist}.
  \begin{figure}[htbp]
    \centering
-   \includegraphics[width=\textwidth]{\fpath/drifthist_evp_noslip-lsr_noslip}
+   \includegraphics[width=\textwidth]{\fpath/drifthist_C-EVP-ns-C-LSR-ns}
    \caption{Histogram of drift velocity differences for C-LSR-ns and
      C-EVP-ns solution [cm/s].}
    \label{fig:drifthist}
-Line 260 
 the ice volume in not larger everywhere:
+Line 277 
 the ice volume in not larger everywhere:
  patches of smaller ice volume in the B-grid solution, most likely
  because the Beaufort Gyre is weaker and hence not as effective in
  transporting ice westwards. There are also dipoles of ice volume
- differences with more ice on the \ml{luv [what is this in English?,
+ differences with more ice on the upstream side of island groups and
-   upstream]} and less ice in the the lee of island groups, such as
+ less ice in their lee, such as Franz-Josef-Land and \ml{IDONTKNOW},
- Franz-Josef-Land and \ml{IDONTKNOW}, because ice tends to flow along
+ because ice tends to flow along coasts less easily in the B-LSR-ns
- coasts less easily in the B-LSR-ns solution.
+ solution.
  Imposing a free-slip boundary condition in C-LSR-fs leads to a much
  smaller differences to C-LSR-ns than the transition from the B-grid to
-Line 284 
 reduced effective ice thickness.
+Line 301 
 reduced effective ice thickness.
  The difference in ice volume and ice drift velocities between the
  different experiments has consequences for the ice transport out of
- the Arctic. Although the most exported ice drifts through the Fram
+ the Arctic. Although by far the most exported ice drifts through the
- Strait (approximately $2300\pm610\text{\,km$^3$\,y$^{-1}$}$), a
+ Fram Strait (approximately $2300\pm610\text{\,km$^3$\,y$^{-1}$}$), a
  considerable amount (order $160\text{\,km$^3$\,y$^{-1}$}$) ice is
  exported through the Canadian Archipelago \citep[and references
  therein]{serreze06}.  \reffig{archipelago} shows a time series of
  \ml{[maybe smooth to different time scales:] daily averaged, smoothed
    with monthly running means,} ice transports through various straits
  in the Canadian Archipelago and the Fram Strait for the different
- model solutions. The export through Fram Strait is too high in all
+ model solutions. The export through Fram Strait agrees with the
- model (annual averages ranges from $3324$ to
+ observations in all model solutions (annual averages range from $2112$
- $3931\text{\,km$^3$\,y$^{-1}$}$) solutions, while the export through
+ to $2425\text{\,km$^3$\,y$^{-1}$}$), while the export through
- Lancaster Sound is lower (annual averages are $41$ to
+ Lancaster Sound is lower (annual averages are $66$ to
- $201\text{\,km$^3$\,y$^{-1}$}$) than compared to observations.
+ $256\text{\,km$^3$\,y$^{-1}$}$) than observed
- Generally, the C-EVP solutions have highest maximum (export out of the
+ \citep[???][]{lancaster}.  Generally, the C-EVP solutions have highest
- Artic) and minimum (import into the Artic) fluxes as the drift
+ maximum (export out of the Artic) and minimum (import into the Artic)
- velocities are largest in this solution. In the extreme, both B- and
+ fluxes as the drift velocities are largest in this solution.  In the
- C-grid LSOR solvers have practically no ice transport through the
+ extreme, both B- and C-grid LSOR solvers have practically no ice
- Nares Strait, which is only a few grid points wide, while the C-EVP
+ transport through the Nares Strait, which is only a few grid points
- solutions allow up to 500\,km$^3$\,y$^{-1}$ in summer.
+ wide, while the C-EVP solutions allow up to
+ $600\text{\,km$^3$\,y$^{-1}$}$ in summer. As as consequence, the
+ import into the Candian Archipelago is overestimated in all EVP
+ solutions (range: $539$ to $773\text{\,km$^3$\,y$^{-1}$}$), while the
+ C-LSR solutions get the order of magnitude right (range: $132$ to
+ $165\text{\,km$^3$\,y$^{-1}$}$); the B-LSR-ns solution grossly
+ underestimates the ice transport with $77\text{\,km$^3$\,y$^{-1}$}$.
  \begin{figure}
  %\centerline{{\includegraphics*[width=0.6\linewidth]{\fpath/Jan1992xport}}}
  \centerline{{\includegraphics*[width=0.6\linewidth]{\fpath/ice_export}}}
  \caption{Transport through Canadian Archipelago for different solver
    flavors. The letters refer to the labels of the sections in
-   \reffig{arctic_topog}; positive values are flux out of the Arctic.
+   \reffig{arctic_topog}; positive values are flux out of the Arctic;
+   legend abbreviations are explained in \reftab{experiments}.
  \label{fig:archipelago}}
  \end{figure}

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