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revision 1.2 by dimitri, Wed Nov 7 14:38:57 2007 UTC revision 1.6 by mlosch, Tue Jan 15 16:04:50 2008 UTC
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1  \documentclass[12pt]{article}  \documentclass[12pt]{article}
2  \usepackage{epsfig}  
3  \usepackage{graphics}  \usepackage[]{graphicx}
4  \usepackage{subfigure}  \usepackage{subfigure}
5    
6  \usepackage[round,comma]{natbib}  \usepackage[round,comma]{natbib}
# Line 35  Line 35 
35  \newlength{\mediumfigwidth}\setlength{\mediumfigwidth}{39pc}  \newlength{\mediumfigwidth}\setlength{\mediumfigwidth}{39pc}
36  %\newlength{\widefigwidth}\setlength{\widefigwidth}{39pc}  %\newlength{\widefigwidth}\setlength{\widefigwidth}{39pc}
37  \newlength{\widefigwidth}\setlength{\widefigwidth}{\textwidth}  \newlength{\widefigwidth}\setlength{\widefigwidth}{\textwidth}
38  \newcommand{\fpath}{.}  \newcommand{\fpath}{figs}
39    
40    % commenting scheme
41    \newcommand{\ml}[1]{\textsf{\slshape #1}}
42    
43  \title{A Dynamic-Thermodynamic Sea ice Model for Ocean Climate  \title{A Dynamic-Thermodynamic Sea ice Model for Ocean Climate
44    Estimation on an Arakawa C-Grid}    Estimation on an Arakawa C-Grid}
# Line 127  The ice strain rate is given by Line 130  The ice strain rate is given by
130      \frac{\partial{u_{i}}}{\partial{x_{j}}} +      \frac{\partial{u_{i}}}{\partial{x_{j}}} +
131      \frac{\partial{u_{j}}}{\partial{x_{i}}}\right).      \frac{\partial{u_{j}}}{\partial{x_{i}}}\right).
132  \end{equation*}  \end{equation*}
133  The pressure $P$, a measure of ice strength, depends on both thickness  The maximum ice pressure $P_{\max}$, a measure of ice strength, depends on
134  $h$ and compactness (concentration) $c$: \[P =  both thickness $h$ and compactness (concentration) $c$:
135  P^{*}c\,h\,e^{[C^{*}\cdot(1-c)]},\] with the constants $P^{*}$ and  \begin{equation}
136  $C^{*}$. The nonlinear bulk and shear viscosities $\eta$ and $\zeta$    P_{\max} = P^{*}c\,h\,e^{[C^{*}\cdot(1-c)]},
137  are functions of ice strain rate invariants and ice strength such that  \label{icestrength}
138  the principal components of the stress lie on an elliptical yield  \end{equation}
139  curve with the ratio of major to minor axis $e$ equal to $2$; they are  with the constants $P^{*}$ and $C^{*}$. The nonlinear bulk and shear
140  given by:  viscosities $\eta$ and $\zeta$ are functions of ice strain rate
141    invariants and ice strength such that the principal components of the
142    stress lie on an elliptical yield curve with the ratio of major to
143    minor axis $e$ equal to $2$; they are given by:
144  \begin{align*}  \begin{align*}
145    \zeta =& \frac{P}{2\Delta} \\    \zeta =& \min\left(\frac{P_{\max}}{2\max(\Delta,\Delta_{\min})},
146    \eta =& \frac{P}{2\Delta{e}^2} \\     \zeta_{\max}\right) \\
147      \eta =& \frac{\zeta}{e^2} \\
148    \intertext{with the abbreviation}    \intertext{with the abbreviation}
149    \Delta = & \left[    \Delta = & \left[
150      \left(\dot{\epsilon}_{11}^2+\dot{\epsilon}_{22}^2\right)      \left(\dot{\epsilon}_{11}^2+\dot{\epsilon}_{22}^2\right)
# Line 145  given by: Line 152  given by:
152      2\dot{\epsilon}_{11}\dot{\epsilon}_{22} (1-e^{-2})      2\dot{\epsilon}_{11}\dot{\epsilon}_{22} (1-e^{-2})
153    \right]^{-\frac{1}{2}}    \right]^{-\frac{1}{2}}
154  \end{align*}  \end{align*}
155    The bulk viscosities are bounded above by imposing both a minimum
156    $\Delta_{\min}=10^{-11}\text{\,s}^{-1}$ (for numerical reasons) and a
157    maximum $\zeta_{\max} = P_{\max}/\Delta^*$, where
158    $\Delta^*=(5\times10^{12}/2\times10^4)\text{\,s}^{-1}$. For stress
159    tensor compuation the replacement pressure $P = 2\,\Delta\zeta$
160    \citep{hibler95} is used so that the stress state always lies on the
161    elliptic yield curve by definition.
162    
163    In the so-called truncated ellipse method the shear viscosity $\eta$
164    is capped to suppress any tensile stress \citep{hibler97, geiger98}:
165    \begin{equation}
166      \label{eq:etatem}
167      \eta = \min(\frac{\zeta}{e^2}
168      \frac{\frac{P}{2}-\zeta(\dot{\epsilon}_{11}+\dot{\epsilon}_{22})}
169      {\sqrt{(\dot{\epsilon}_{11}+\dot{\epsilon}_{22})^2
170          +4\dot{\epsilon}_{12}^2}}
171    \end{equation}
172    
173  In the current implementation, the VP-model is integrated with the  In the current implementation, the VP-model is integrated with the
174  semi-implicit line successive over relaxation (LSOR)-solver of  semi-implicit line successive over relaxation (LSOR)-solver of
175  \citet{zhang98}, which allows for long time steps that, in our case,  \citet{zhang98}, which allows for long time steps that, in our case,
# Line 287  the two ice layers and the thickness of Line 312  the two ice layers and the thickness of
312  \section{Funnel Experiments}  \section{Funnel Experiments}
313  \label{sec:funnel}  \label{sec:funnel}
314    
315  \begin{itemize}  For a first/detailed comparison between the different variants of the
316  \item B-grid LSR no-slip  MIT sea ice model an idealized geometry of a periodic channel,
317  \item C-grid LSR no-slip  1000\,km long and 500\,m wide on a non-rotating plane, with converging
318  \item C-grid LSR slip  walls forming a symmetric funnel and a narrow strait of 40\,km width
319  \item C-grid EVP no-slip  is used. The horizontal resolution is 5\,km throughout the domain
320  \item C-grid EVP slip  making the narrow strait 8 grid points wide. The ice model is
321  \end{itemize}  initialized with a complete ice cover of 50\,cm uniform thickness. The
322    ice model is driven by a constant along channel eastward ocean current
323  \subsection{B-grid vs.\ C-grid}  of 25\,cm/s that does not see the walls in the domain. All other
324  Comparison between:  ice-ocean-atmosphere interactions are turned off, in particular there
325  \begin{itemize}  is no feedback of ice dynamics on the ocean current. All thermodynamic
326  \item B-grid, lsr, no-slip  processes are turned off so that ice thickness variations are only
327  \item C-grid, lsr, no-slip  caused by convergent or divergent ice flow. Ice volume (effective
328  \item C-grid, evp, no-slip  thickness) and concentration are advected with a third-order scheme
329  \end{itemize}  with a flux limiter \citep{hundsdorfer94} to avoid undershoots. This
330  all without ice-ocean stress, because ice-ocean stress does not work  scheme is unconditionally stable and does not require additional
331  for B-grid.  diffusion. The time step used here is 1\,h.
332    
333    \reffig{funnelf0} compares the dynamic fields ice concentration $c$,
334    effective thickness $h_{eff} = h\cdot{c}$, and velocities $(u,v)$ for
335    five different cases at steady state (after 10\,years of integration):
336    \begin{description}
337    \item[B-LSRns:] LSR solver with no-slip boundary conditions on a B-grid,
338    \item[C-LSRns:] LSR solver with no-slip boundary conditions on a C-grid,
339    \item[C-LSRfs:] LSR solver with free-slip boundary conditions on a C-grid,
340    \item[C-EVPns:] EVP solver with no-slip boundary conditions on a C-grid,
341    \item[C-EVPfs:] EVP solver with free-slip boundary conditions on a C-grid,
342    \end{description}
343    \ml{[We have not implemented the EVP solver on a B-grid.]}
344    \begin{figure*}[htbp]
345      \includegraphics[width=\widefigwidth]{\fpath/all_086280}
346      \caption{Ice concentration, effective thickness [m], and ice
347        velocities [m/s]
348        for 5 different numerical solutions.}
349      \label{fig:funnelf0}
350    \end{figure*}
351    At a first glance, the solutions look similar. This is encouraging as
352    the details of discretization and numerics should not affect the
353    solutions to first order. In all cases the ice-ocean stress pushes the
354    ice cover eastwards, where it converges in the funnel. In the narrow
355    channel the ice moves quickly (nearly free drift) and leaves the
356    channel as narrow band.
357    
358    A close look reveals interesting differences between the B- and C-grid
359    results. The zonal velocity in the narrow channel is nearly the free
360    drift velocity ( = ocean velocity) of 25\,cm/s for the C-grid
361    solutions, regardless of the boundary conditions, while it is just
362    above 20\,cm/s for the B-grid solution. The ice accelerates to
363    25\,cm/s after it exits the channel. Concentrating on the solutions
364    B-LSRns and C-LSRns, the ice volume (effective thickness) along the
365    boundaries in the narrow channel is larger in the B-grid case although
366    the ice concentration is reduces in the C-grid case. The combined
367    effect leads to a larger actual ice thickness at smaller
368    concentrations in the C-grid case. However, since the effective
369    thickness determines the ice strength $P$ in Eq\refeq{icestrength},
370    the ice strength and thus the bulk and shear viscosities are larger in
371    the B-grid case leading to more horizontal friction. This circumstance
372    might explain why the no-slip boundary conditions in the B-grid case
373    appear to be more effective in reducing the flow within the narrow
374    channel, than in the C-grid case. Further, the viscosities are also
375    sensitive to details of the velocity gradients. Via $\Delta$, these
376    gradients enter the viscosities in the denominator so that large
377    gradients tend to reduce the viscosities. This again favors more flow
378    along the boundaries in the C-grid case: larger velocities
379    (\reffig{funnelf0}) on grid points that are closer to the boundary by
380    a factor $\frac{1}{2}$ than in the B-grid case because of the stagger
381    nature of the C-grid lead numerically to larger tangential gradients
382    across the boundary; these in turn make the viscosities smaller for
383    less tangential friction and allow more tangential flow along the
384    boundaries.
385    
386    The above argument can also be invoked to explain the small
387    differences between the free-slip and no-slip solutions on the C-grid.
388    Because of the non-linearities in the ice viscosities, in particular
389    along the boundaries, the no-slip boundary conditions have only a small
390    impact on the solution.
391    
392    The difference between LSR and EVP solutions is largest in the
393    effective thickness and meridional velocity fields. The EVP velocity
394    fields appears to be a little noisy. This noise has been address by
395    \citet{hunke01}. It can be dealt with by reducing EVP's internal time
396    step (increasing the number of iterations along with the computational
397    cost) or by regularizing the bulk and shear viscosities. We revisit
398    the latter option by reproducing some of the results of
399    \citet{hunke01}, namely the experiment described in her section~4, for
400    our C-grid no-slip cases: in a square domain with a few islands the
401    ice model is initialized with constant ice thickness and linearly
402    increasing ice concentration to the east. The model dynamics are
403    forced with a constant anticyclonic ocean gyre and by variable
404    atmospheric wind whose mean direction is diagnonal to the north-east
405    corner of the domain; ice volume and concentration are held constant
406    (no thermodynamics and no advection by ice velocity).
407    \reffig{hunke01} shows the ice velocity field, its divergence, and the
408    bulk viscosity $\zeta$ for the cases C-LRSns and C-EVPns, and for a
409    C-EVPns case, where \citet{hunke01}'s regularization has been
410    implemented; compare to Fig.\,4 in \citet{hunke01}. The regularization
411    contraint limits ice strength and viscosities as a function of damping
412    time scale, resolution and EVP-time step, effectively allowing the
413    elastic waves to damp out more quickly \citep{hunke01}.
414    \begin{figure*}[htbp]
415      \includegraphics[width=\widefigwidth]{\fpath/hun12days}
416      \caption{Ice flow, divergence and bulk viscosities of three
417        experiments with \citet{hunke01}'s test case: C-LSRns (top),
418        C-EVPns (middle), and C-EVPns with damping described in
419        \citet{hunke01} (bottom).}
420      \label{fig:hunke01}
421    \end{figure*}
422    
423    In the far right (``east'') side of the domain the ice concentration
424    is close to one and the ice should be nearly rigid. The applied wind
425    tends to push ice toward the upper right corner. Because the highly
426    compact ice is confined by the boundary, it resists any further
427    compression and exhibits little motion in the rigid region on the
428    right hand side. The C-LSRns solution (top row) allows high
429    viscosities in the rigid region suppressing nearly all flow.
430    \citet{hunke01}'s regularization for the C-EVPns solution (bottom row)
431    clearly suppresses the noise present in $\nabla\cdot\vek{u}$ and
432    $\log_{10}\zeta$ in the
433    unregularized case (middle row), at the cost of reduced viscosities.
434    These reduced viscosities lead to small but finite ice velocities
435    which in turn can have a strong effect on solutions in the limit of
436    nearly rigid regimes (arching and blocking, not shown).
437    
438  \subsection{C-grid}  \subsection{C-grid}
439  \begin{itemize}  \begin{itemize}
# Line 350  differences between the two main options Line 480  differences between the two main options
480  \subsection{Arctic Domain with Open Boundaries}  \subsection{Arctic Domain with Open Boundaries}
481  \label{sec:arctic}  \label{sec:arctic}
482    
483  The Arctic domain of integration is illustrated in Fig.~\ref{???}.  It is  The Arctic domain of integration is illustrated in Fig.~\ref{???}.  It
484  carved out from, and obtains open boundary conditions from, the global  is carved out from, and obtains open boundary conditions from, the
485  cubed-sphere configuration of the Estimating the Circulation and Climate of  global cubed-sphere configuration of the Estimating the Circulation
486  the Ocean, Phase II (ECCO2) project \cite{men05a}.  The domain size is 420 by  and Climate of the Ocean, Phase II (ECCO2) project
487  384 grid boxes horizontally with mean horizontal grid spacing of 18 km.    \citet{menemenlis05}.  The domain size is 420 by 384 grid boxes
488    horizontally with mean horizontal grid spacing of 18 km.
489    
490  There are 50 vertical levels ranging in thickness from 10 m near the surface  There are 50 vertical levels ranging in thickness from 10 m near the surface
491  to approximately 450 m at a maximum model depth of 6150 m. Bathymetry is from  to approximately 450 m at a maximum model depth of 6150 m. Bathymetry is from
492  the National Geophysical Data Center (NGDC) 2-minute gridded global relief  the National Geophysical Data Center (NGDC) 2-minute gridded global relief
493  data (ETOPO2) and the model employs the partial-cell formulation of  data (ETOPO2) and the model employs the partial-cell formulation of
494  \cite{adc97}, which permits accurate representation of the bathymetry. The  \citet{adcroft97:_shaved_cells}, which permits accurate representation of the bathymetry. The
495  model is integrated in a volume-conserving configuration using a finite volume  model is integrated in a volume-conserving configuration using a finite volume
496  discretization with C-grid staggering of the prognostic variables. In the  discretization with C-grid staggering of the prognostic variables. In the
497  ocean, the non-linear equation of state of \cite{jac95}.  The ocean model is  ocean, the non-linear equation of state of \citet{jackett95}.  The ocean model is
498  coupled to a sea-ice model described hereinabove.    coupled to a sea-ice model described hereinabove.  
499    
500  This particular ECCO2 simulation is initialized from rest using the January  This particular ECCO2 simulation is initialized from rest using the
501  temperature and salinity distribution from the World Ocean Atlas 2001 (WOA01)  January temperature and salinity distribution from the World Ocean
502  [Conkright et al., 2002] and it is integrated for 32 years prior to the  Atlas 2001 (WOA01) [Conkright et al., 2002] and it is integrated for
503  1996-2001 period discussed in the study. Surface boundary conditions are from  32 years prior to the 1996--2001 period discussed in the study. Surface
504  the National Centers for Environmental Prediction and the National Center for  boundary conditions are from the National Centers for Environmental
505  Atmospheric Research (NCEP/NCAR) atmospheric reanalysis [Kistler et al.,  Prediction and the National Center for Atmospheric Research
506  2001]. Six-hourly surface winds, temperature, humidity, downward short- and  (NCEP/NCAR) atmospheric reanalysis [Kistler et al., 2001]. Six-hourly
507  long-wave radiations, and precipitation are converted to heat, freshwater, and  surface winds, temperature, humidity, downward short- and long-wave
508  wind stress fluxes using the Large and Pond [1981, 1982] bulk  radiations, and precipitation are converted to heat, freshwater, and
509  formulae. Shortwave radiation decays exponentially as per Paulson and Simpson  wind stress fluxes using the \citet{large81, large82} bulk formulae.
510  [1977]. Additionally the time-mean river run-off from Large and Nurser [2001]  Shortwave radiation decays exponentially as per Paulson and Simpson
511  is applied and there is a relaxation to the monthly-mean climatological sea  [1977]. Additionally the time-mean river run-off from Large and Nurser
512  surface salinity values from WOA01 with a relaxation time scale of 3  [2001] is applied and there is a relaxation to the monthly-mean
513  months. Vertical mixing follows Large et al. [1994] with background vertical  climatological sea surface salinity values from WOA01 with a
514  diffusivity of 1.5 × 10-5 m2 s-1 and viscosity of 10-3 m2 s-1. A third order,  relaxation time scale of 3 months. Vertical mixing follows
515  direct-space-time advection scheme with flux limiter is employed and there is  \citet{large94} with background vertical diffusivity of
516  no explicit horizontal diffusivity. Horizontal viscosity follows Leith [1996]  $1.5\times10^{-5}\text{\,m$^{2}$\,s$^{-1}$}$ and viscosity of
517  but modified to sense the divergent flow as per Fox-Kemper and Menemenlis [in  $10^{-3}\text{\,m$^{2}$\,s$^{-1}$}$. A third order, direct-space-time
518  press].  Shortwave radiation decays exponentially as per Paulson and Simpson  advection scheme with flux limiter is employed \citep{hundsdorfer94}
519  [1977].  Additionally, the time-mean runoff of Large and Nurser [2001] is  and there is no explicit horizontal diffusivity. Horizontal viscosity
520  applied near the coastline and, where there is open water, there is a  follows \citet{lei96} but
521  relaxation to monthly-mean WOA01 sea surface salinity with a time constant of  modified to sense the divergent flow as per Fox-Kemper and Menemenlis
522  45 days.  [in press].  Shortwave radiation decays exponentially as per Paulson
523    and Simpson [1977].  Additionally, the time-mean runoff of Large and
524    Nurser [2001] is applied near the coastline and, where there is open
525    water, there is a relaxation to monthly-mean WOA01 sea surface
526    salinity with a time constant of 45 days.
527    
528  Open water, dry  Open water, dry
529  ice, wet ice, dry snow, and wet snow albedo are, respectively, 0.15, 0.85,  ice, wet ice, dry snow, and wet snow albedo are, respectively, 0.15, 0.85,
# Line 417  ice, wet ice, dry snow, and wet snow alb Line 552  ice, wet ice, dry snow, and wet snow alb
552  \item C-grid LSR slip  \item C-grid LSR slip
553  \item C-grid EVP no-slip  \item C-grid EVP no-slip
554  \item C-grid EVP slip  \item C-grid EVP slip
555    \item C-grid LSR + TEM (truncated ellipse method, no tensile stress, new flag)
556  \item C-grid LSR no-slip + Winton  \item C-grid LSR no-slip + Winton
557  \item  speed-performance-accuracy (small)  \item  speed-performance-accuracy (small)
558    ice transport through Canadian Archipelago differences    ice transport through Canadian Archipelago differences
# Line 428  We anticipate small differences between Line 564  We anticipate small differences between
564  \begin{itemize}  \begin{itemize}
565  \item advection schemes: along the ice-edge and regions with large  \item advection schemes: along the ice-edge and regions with large
566    gradients    gradients
567  \item C-grid: more transport through narrow straits for no slip  \item C-grid: less transport through narrow straits for no slip
568    conditons, less for free slip    conditons, more for free slip
569  \item VP vs.\ EVP: speed performance, accuracy?  \item VP vs.\ EVP: speed performance, accuracy?
570  \item ocean stress: different water mass properties beneath the ice  \item ocean stress: different water mass properties beneath the ice
571  \end{itemize}  \end{itemize}
572    
 \section{Adjoint sensitivity experiment}  
 \label{sec:adjoint}  
   
 Adjoint sensitivity experiment on 1/2-res setup  
  Sensitivity of sea ice volume flow through Fram Strait  
   
573  \section{Adjoint sensiivities of the MITsim}  \section{Adjoint sensiivities of the MITsim}
574    
575  \subsection{The adjoint of MITsim}  \subsection{The adjoint of MITsim}
# Line 516  storing vs. recomputation of the model s Line 646  storing vs. recomputation of the model s
646  checkpointing loop.  checkpointing loop.
647  Again, an initial code adjustment is required to support TAFs  Again, an initial code adjustment is required to support TAFs
648  checkpointing capability.  checkpointing capability.
649  The code adjustments are sufficiently simply so as not to cause  The code adjustments are sufficiently simple so as not to cause
650  major limitations to the full nonlinear parent model.  major limitations to the full nonlinear parent model.
651  Once in place, an adjoint model of a new model configuration  Once in place, an adjoint model of a new model configuration
652  may be derived in about 10 minutes.  may be derived in about 10 minutes.
# Line 539  may be derived in about 10 minutes. Line 669  may be derived in about 10 minutes.
669  We demonstrate the power of the adjoint method  We demonstrate the power of the adjoint method
670  in the context of investigating sea-ice export sensitivities through Fram Strait  in the context of investigating sea-ice export sensitivities through Fram Strait
671  (for details of this study see Heimbach et al., 2007).  (for details of this study see Heimbach et al., 2007).
672    %\citep[for details of this study see][]{heimbach07}. %Heimbach et al., 2007).
673  The domain chosen is a coarsened version of the Arctic face of the  The domain chosen is a coarsened version of the Arctic face of the
674  high-resolution cubed-sphere configuration of the ECCO2 project  high-resolution cubed-sphere configuration of the ECCO2 project
675  (see Menemenlis et al. 2005). It covers the entire Arctic,  \citep[see][]{menemenlis05}. It covers the entire Arctic,
676  extends into the North Pacific such as to cover the entire  extends into the North Pacific such as to cover the entire
677  ice-covered regions, and comprises parts of the North Atlantic  ice-covered regions, and comprises parts of the North Atlantic
678  down to XXN to enable analysis of remote influences of the  down to XXN to enable analysis of remote influences of the
# Line 552  The adjoint models run efficiently on 80 Line 683  The adjoint models run efficiently on 80
683  (benchmarks have been performed both on an SGI Altix as well as an  (benchmarks have been performed both on an SGI Altix as well as an
684  IBM SP5 at NASA/ARC).  IBM SP5 at NASA/ARC).
685    
686  Following a 1-year spinup, the model has been integrated for four years  Following a 1-year spinup, the model has been integrated for four
687  between 1992 and 1995.  years between 1992 and 1995. It is forced using realistic 6-hourly
688  It is forced using realistic 6-hourly NCEP/NCAR atmospheric state variables.  NCEP/NCAR atmospheric state variables. Over the open ocean these are
689  Over the open ocean these are converted into  converted into air-sea fluxes via the bulk formulae of
690  air-sea fluxes via the bulk formulae of Large and Yeager (2004).  \citet{large04}.  Derivation of air-sea fluxes in the presence of
691  Derivation of air-sea fluxes in the presence of sea-ice is handled  sea-ice is handled by the ice model as described in \refsec{model}.
 by the ice model as described in Section XXX.  
692  The objective function chosen is sea-ice export through Fram Strait  The objective function chosen is sea-ice export through Fram Strait
693  computed for December 1995  computed for December 1995.  The adjoint model computes sensitivities
694  The adjoint model computes sensitivities to sea-ice export back in time  to sea-ice export back in time from 1995 to 1992 along this
695  from 1995 to 1992 along this trajectory.  trajectory.  In principle all adjoint model variable (i.e., Lagrange
696  In principle all adjoint model variable (i.e. Lagrange multipliers)  multipliers) of the coupled ocean/sea-ice model are available to
697  of the coupled ocean/sea-ice model  analyze the transient sensitivity behaviour of the ocean and sea-ice
698  are available to analyze the transient sensitivity behaviour  state.  Over the open ocean, the adjoint of the bulk formula scheme
699  of the ocean and sea-ice state.  computes sensitivities to the time-varying atmospheric state.  Over
700  Over the open ocean, the adjoint of the bulk formula scheme  ice-covered parts, the sea-ice adjoint converts surface ocean
701  computes sensitivities to the time-varying atmospheric state.  sensitivities to atmospheric sensitivities.
702  Over ice-covered parts, the sea-ice adjoint converts  
703  surface ocean sensitivities to atmospheric sensitivities.  \reffig{4yradjheff}(a--d) depict sensitivities of sea-ice export
704    through Fram Strait in December 1995 to changes in sea-ice thickness
705  Fig. XXX(a--d) depict sensitivities of sea-ice export through Fram Strait  12, 24, 36, 48 months back in time. Corresponding sensitivities to
706  in December 1995 to changes in sea-ice thickness  ocean surface temperature are depicted in
707  12, 24, 36, 48 months back in time.  \reffig{4yradjthetalev1}(a--d).  The main characteristics is
708  Corresponding sensitivities to ocean surface temperature are  consistency with expected advection of sea-ice over the relevant time
709  depicted in Fig. XXX(a--d).  scales considered.  The general positive pattern means that an
710  The main characteristics is consistency with expected advection  increase in sea-ice thickness at location $(x,y)$ and time $t$ will
711  of sea-ice over the relevant time scales considered.  increase sea-ice export through Fram Strait at time $T_e$.  Largest
712  The general positive pattern means that an increase in  distances from Fram Strait indicate fastest sea-ice advection over the
713  sea-ice thickness at location $(x,y)$ and time $t$ will increase  time span considered.  The ice thickness sensitivities are in close
714  sea-ice export through Fram Strait at time $T_e$.  correspondence to ocean surface sentivitites, but of opposite sign.
715  Largest distances from Fram Strait indicate fastest sea-ice advection  An increase in temperature will incur ice melting, decrease in ice
716  over the time span considered.  thickness, and therefore decrease in sea-ice export at time $T_e$.
 The ice thickness sensitivities are in close correspondence to  
 ocean surface sentivitites, but of opposite sign.  
 An increase in temperature will incur ice melting, decrease in ice thickness,  
 and therefore decrease in sea-ice export at time $T_e$.  
717    
718  The picture is fundamentally different and much more complex  The picture is fundamentally different and much more complex
719  for sensitivities to ocean temperatures away from the surface.  for sensitivities to ocean temperatures away from the surface.
720  Fig. XXX (a--d) depicts ice export sensitivities to  \reffig{4yradjthetalev10??}(a--d) depicts ice export sensitivities to
721  temperatures at roughly 400 m depth.  temperatures at roughly 400 m depth.
722  Primary features are the effect of the heat transport of the North  Primary features are the effect of the heat transport of the North
723  Atlantic current which feeds into the West Spitsbergen current,  Atlantic current which feeds into the West Spitsbergen current,
# Line 600  the circulation around Svalbard, and ... Line 726  the circulation around Svalbard, and ...
726  \begin{figure}[t!]  \begin{figure}[t!]
727  \centerline{  \centerline{
728  \subfigure[{\footnotesize -12 months}]  \subfigure[{\footnotesize -12 months}]
729  {\includegraphics*[width=0.44\linewidth]{figs/run_4yr_ADJheff_arc_lev1_tim072_cmax2.0E+02.eps}}  {\includegraphics*[width=0.44\linewidth]{\fpath/run_4yr_ADJheff_arc_lev1_tim072_cmax2.0E+02.eps}}
730  %\includegraphics*[width=.3\textwidth]{H_c.bin_res_100_lev1.pdf}  %\includegraphics*[width=.3\textwidth]{H_c.bin_res_100_lev1.pdf}
731  %  %
732  \subfigure[{\footnotesize -24 months}]  \subfigure[{\footnotesize -24 months}]
733  {\includegraphics*[width=0.44\linewidth]{figs/run_4yr_ADJheff_arc_lev1_tim145_cmax2.0E+02.eps}}  {\includegraphics*[width=0.44\linewidth]{\fpath/run_4yr_ADJheff_arc_lev1_tim145_cmax2.0E+02.eps}}
734  }  }
735    
736  \centerline{  \centerline{
737  \subfigure[{\footnotesize  \subfigure[{\footnotesize
738  -36 months}]  -36 months}]
739  {\includegraphics*[width=0.44\linewidth]{figs/run_4yr_ADJheff_arc_lev1_tim218_cmax2.0E+02.eps}}  {\includegraphics*[width=0.44\linewidth]{\fpath/run_4yr_ADJheff_arc_lev1_tim218_cmax2.0E+02.eps}}
740  %  %
741  \subfigure[{\footnotesize  \subfigure[{\footnotesize
742  -48 months}]  -48 months}]
743  {\includegraphics*[width=0.44\linewidth]{figs/run_4yr_ADJheff_arc_lev1_tim292_cmax2.0E+02.eps}}  {\includegraphics*[width=0.44\linewidth]{\fpath/run_4yr_ADJheff_arc_lev1_tim292_cmax2.0E+02.eps}}
744  }  }
745  \caption{Sensitivity of sea-ice export through Fram Strait in December 2005 to  \caption{Sensitivity of sea-ice export through Fram Strait in December 2005 to
746  sea-ice thickness at various prior times.  sea-ice thickness at various prior times.
# Line 625  sea-ice thickness at various prior times Line 751  sea-ice thickness at various prior times
751  \begin{figure}[t!]  \begin{figure}[t!]
752  \centerline{  \centerline{
753  \subfigure[{\footnotesize -12 months}]  \subfigure[{\footnotesize -12 months}]
754  {\includegraphics*[width=0.44\linewidth]{figs/run_4yr_ADJtheta_arc_lev1_tim072_cmax5.0E+01.eps}}  {\includegraphics*[width=0.44\linewidth]{\fpath/run_4yr_ADJtheta_arc_lev1_tim072_cmax5.0E+01.eps}}
755  %\includegraphics*[width=.3\textwidth]{H_c.bin_res_100_lev1.pdf}  %\includegraphics*[width=.3\textwidth]{H_c.bin_res_100_lev1.pdf}
756  %  %
757  \subfigure[{\footnotesize -24 months}]  \subfigure[{\footnotesize -24 months}]
758  {\includegraphics*[width=0.44\linewidth]{figs/run_4yr_ADJtheta_arc_lev1_tim145_cmax5.0E+01.eps}}  {\includegraphics*[width=0.44\linewidth]{\fpath/run_4yr_ADJtheta_arc_lev1_tim145_cmax5.0E+01.eps}}
759  }  }
760    
761  \centerline{  \centerline{
762  \subfigure[{\footnotesize  \subfigure[{\footnotesize
763  -36 months}]  -36 months}]
764  {\includegraphics*[width=0.44\linewidth]{figs/run_4yr_ADJtheta_arc_lev1_tim218_cmax5.0E+01.eps}}  {\includegraphics*[width=0.44\linewidth]{\fpath/run_4yr_ADJtheta_arc_lev1_tim218_cmax5.0E+01.eps}}
765  %  %
766  \subfigure[{\footnotesize  \subfigure[{\footnotesize
767  -48 months}]  -48 months}]
768  {\includegraphics*[width=0.44\linewidth]{figs/run_4yr_ADJtheta_arc_lev1_tim292_cmax5.0E+01.eps}}  {\includegraphics*[width=0.44\linewidth]{\fpath/run_4yr_ADJtheta_arc_lev1_tim292_cmax5.0E+01.eps}}
769  }  }
770  \caption{Same as Fig. XXX but for sea surface temperature  \caption{Same as \reffig{4yradjheff} but for sea surface temperature
771  \label{fig:4yradjthetalev1}}  \label{fig:4yradjthetalev1}}
772  \end{figure}  \end{figure}
773    
# Line 666  parameters that we use here. What about Line 792  parameters that we use here. What about
792    
793  \paragraph{Acknowledgements}  \paragraph{Acknowledgements}
794  We thank Jinlun Zhang for providing the original B-grid code and many  We thank Jinlun Zhang for providing the original B-grid code and many
795  helpful discussions.  helpful discussions. ML thanks Elizabeth Hunke for multiple explanations.
796    
797  \bibliography{bib/journal_abrvs,bib/seaice,bib/genocean,bib/maths,bib/mitgcmuv,bib/fram}  %\bibliography{bib/journal_abrvs,bib/seaice,bib/genocean,bib/maths,bib/mitgcmuv,bib/fram}
798    \bibliography{journal_abrvs,seaice,genocean,maths,mixing,mitgcmuv,bib/fram}
799    
800  \end{document}  \end{document}
801    
# Line 676  helpful discussions. Line 803  helpful discussions.
803  %%% mode: latex  %%% mode: latex
804  %%% TeX-master: t  %%% TeX-master: t
805  %%% End:  %%% End:
806    
807    
808    A Dynamic-Thermodynamic Sea ice Model for Ocean Climate
809      Estimation on an Arakawa C-Grid
810    
811    Introduction
812    
813    Ice Model:
814     Dynamics formulation.
815      B-C, LSR, EVP, no-slip, slip
816      parallellization
817     Thermodynamics formulation.
818      0-layer Hibler salinity + snow
819      3-layer Winton
820    
821    Idealized tests
822     Funnel Experiments
823     Downstream Island tests
824      B-grid LSR no-slip
825      C-grid LSR no-slip
826      C-grid LSR slip
827      C-grid EVP no-slip
828      C-grid EVP slip
829    
830    Arctic Setup
831     Configuration
832     OBCS from cube
833     forcing
834     1/2 and full resolution
835     with a few JFM figs from C-grid LSR no slip
836      ice transport through Canadian Archipelago
837      thickness distribution
838      ice velocity and transport
839    
840    Arctic forward sensitivity experiments
841     B-grid LSR no-slip
842     C-grid LSR no-slip
843     C-grid LSR slip
844     C-grid EVP no-slip
845     C-grid EVP slip
846     C-grid LSR no-slip + Winton
847      speed-performance-accuracy (small)
848      ice transport through Canadian Archipelago differences
849      thickness distribution differences
850      ice velocity and transport differences
851    
852    Adjoint sensitivity experiment on 1/2-res setup
853     Sensitivity of sea ice volume flow through Fram Strait
854    *** Sensitivity of sea ice volume flow through Canadian Archipelago
855    
856    Summary and conluding remarks

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