/[MITgcm]/MITgcm_contrib/articles/ceaice/ceaice.tex
ViewVC logotype

Diff of /MITgcm_contrib/articles/ceaice/ceaice.tex

Parent Directory Parent Directory | Revision Log Revision Log | View Revision Graph Revision Graph | View Patch Patch

revision 1.13 by dimitri, Mon Feb 25 23:45:46 2008 UTC revision 1.14 by dimitri, Tue Feb 26 00:13:20 2008 UTC
# Line 52  Line 52 
52  \maketitle  \maketitle
53    
54  \begin{abstract}  \begin{abstract}
   
55  As part of ongoing efforts to obtain a best possible synthesis of most  As part of ongoing efforts to obtain a best possible synthesis of most
56  available, global-scale, ocean and sea ice data, a dynamic and thermodynamic  available, global-scale, ocean and sea ice data, a dynamic and thermodynamic
57  sea-ice model has been coupled to the Massachusetts Institute of Technology  sea-ice model has been coupled to the Massachusetts Institute of Technology
# Line 76  example results from coupled ocean and s Line 75  example results from coupled ocean and s
75  \section{Introduction}  \section{Introduction}
76  \label{sec:intro}  \label{sec:intro}
77    
78    The availability of an adjoint model as a powerful research
79    tool complementary to an ocean model was a major design
80    requirement early on in the development of the MIT general
81    circulation model (MITgcm) [Marshall et al. 1997a,
82    Marotzke et al. 1999, Adcroft et al. 2002]. It was recognized
83    that the adjoint permitted very efficient computation
84    of gradients of various scalar-valued model diagnostics,
85    norms or, generally, objective functions with respect
86    to external or independent parameters. Such gradients
87    arise in at least two major contexts. If the objective function
88    is the sum of squared model vs. obervation differences
89    weighted by e.g. the inverse error covariances, the gradient
90    of the objective function can be used to optimize this measure
91    of model vs. data misfit in a least-squares sense. One
92    is then solving a problem of statistical state estimation.
93    If the objective function is a key oceanographic quantity
94    such as meridional heat or volume transport, ocean heat
95    content or mean surface temperature index, the gradient
96    provides a complete set of sensitivities of this quantity
97    with respect to all independent variables simultaneously.
98    
99    References to existing sea-ice adjoint models, explaining that they are either
100    for simplified configurations, for ice-only studies, or for short-duration
101    studies to motivate the present work.
102    
103  Traditionally, probably for historical reasons and the ease of  Traditionally, probably for historical reasons and the ease of
104  treating the Coriolis term, most standard sea-ice models are  treating the Coriolis term, most standard sea-ice models are
105  discretized on Arakawa-B-grids \citep[e.g.,][]{hibler79, harder99,  discretized on Arakawa-B-grids \citep[e.g.,][]{hibler79, harder99,
106    kreyscher00, zhang98, hunke97}. From the perspective of coupling a  kreyscher00, zhang98, hunke97}. From the perspective of coupling a
107  sea ice-model to a C-grid ocean model, the exchange of fluxes of heat  sea ice-model to a C-grid ocean model, the exchange of fluxes of heat
108  and fresh-water pose no difficulty for a B-grid sea-ice model  and fresh-water pose no difficulty for a B-grid sea-ice model
109  \citep[e.g.,][]{timmermann02a}. However, surface stress is defined at  \citep[e.g.,][]{timmermann02a}. However, surface stress is defined at
# Line 95  A further advantage of the C-grid formul Line 119  A further advantage of the C-grid formul
119  straits. In the limit of only one grid cell between coasts there is no  straits. In the limit of only one grid cell between coasts there is no
120  flux allowed for a B-grid (with no-slip lateral boundary counditions),  flux allowed for a B-grid (with no-slip lateral boundary counditions),
121  whereas the C-grid formulation allows a flux of sea-ice through this  whereas the C-grid formulation allows a flux of sea-ice through this
122  passage for all types of lateral boundary conditions. We (will)  passage for all types of lateral boundary conditions. We
123  demonstrate this effect in the Candian archipelago.  demonstrate this effect in the Candian archipelago.
124    
125    Talk about problems that make the sea-ice-ocean code very sensitive and
126    changes in the code that reduce these sensitivities.
127    
128    This paper describes the MITgcm sea ice
129    model; it presents example Arctic and Antarctic results from a realistic,
130    eddy-permitting, global ocean and sea-ice configuration; it compares B-grid
131    and C-grid dynamic solvers in a regional Arctic configuration; and it presents
132    example results from coupled ocean and sea-ice adjoint-model integrations.
133    
134  \section{Model}  \section{Model}
135  \label{sec:model}  \label{sec:model}
136    
Legend:
Removed from v.1.13  
changed lines
  Added in v.1.14
  ViewVC Help
Powered by ViewVC 1.1.22