Changeset 11043 for NEMO/trunk/doc/latex/SI3
- Timestamp:
- 2019-05-23T15:51:08+02:00 (5 years ago)
- Location:
- NEMO/trunk/doc/latex/SI3
- Files:
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- 5 edited
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main/SI3_manual.bib (modified) (9 diffs)
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main/SI3_manual.tex (modified) (1 diff)
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subfiles/chap_model_basics.tex (modified) (5 diffs)
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subfiles/chap_ridging_rafting.tex (modified) (3 diffs)
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subfiles/introduction.tex (modified) (1 diff)
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NEMO/trunk/doc/latex/SI3/main/SI3_manual.bib
r11030 r11043 1 1 2 @Article{ 3 author 4 year 5 month 6 pages 7 title 8 volume 9 journal 2 @Article{ assur_1958, 3 author = {Assur, A}, 4 year = {1958}, 5 month = {01}, 6 pages = {106-138}, 7 title = {Composition of sea ice and its tensile strength}, 8 volume = {598}, 9 journal = {Arctic Sea Ice} 10 10 } 11 11 … … 234 234 } 235 235 236 @Article{ h _yland_2002,236 @Article{ hoyland_2002, 237 237 author = {Høyland, Knut V.}, 238 238 title = {Consolidation of first-year sea ice ridges}, … … 308 308 } 309 309 310 @Article{ lepp _ranta_1995,310 @Article{ lepparanta_1995, 311 311 author = {Leppäranta, Matti and Lensu, Mikko and Kosloff, Pekka and 312 312 Veitch, Brian}, … … 324 324 } 325 325 326 @Article{ lepp _ranta_2011,326 @Article{ lepparanta_2011, 327 327 author = {Leppäranta, Matti}, 328 328 title = {Drift ice material}, 329 329 year = 2011, 330 330 pages = {11–63}, 331 doi = {10.1007/978-3-642-04683-4 _2},332 url = {http://dx.doi.org/10.1007/978-3-642-04683-4 _2},331 doi = {10.1007/978-3-642-04683-4\_2}, 332 url = {http://dx.doi.org/10.1007/978-3-642-04683-4\_2}, 333 333 isbn = 9783642046834, 334 334 journal = {The Drift of Sea Ice}, … … 367 367 } 368 368 369 @Article{ massonnet_2018, 370 author = {Massonnet, F. and Barth\'el\'emy, A. and Worou, K. and 371 Fichefet, T. and Vancoppenolle, M. and Rousset, C.}, 372 title = {Insights on the discretization of the ice thickness 373 distribution in large-scale sea ice models}, 374 journal = {submitted}, 375 year = {2018} 376 } 377 369 378 @Article{ maykut_1971, 370 379 author = {Maykut, Gary A. and Untersteiner, Norbert}, … … 383 392 } 384 393 394 @Article{ maykut_1973, 395 author = {Maykut, G. A. and Thorndike, A. S.}, 396 title = {An approach to coupling the dynamics and thermodynamics of 397 Arctic sea ice}, 398 journal = {AIDJEX Bulletin}, 399 year = {1973}, 400 volume = {21}, 401 pages = {23--29} 402 } 403 385 404 @Article{ maykut_1986, 386 405 author = {Maykut, Gary A.}, … … 388 407 year = 1986, 389 408 pages = {395–463}, 390 doi = {10.1007/978-1-4899-5352-0 _6},391 url = {http://dx.doi.org/10.1007/978-1-4899-5352-0 _6},409 doi = {10.1007/978-1-4899-5352-0\_6}, 410 url = {http://dx.doi.org/10.1007/978-1-4899-5352-0\_6}, 392 411 isbn = 9781489953520, 393 412 journal = {The Geophysics of Sea Ice}, … … 546 565 } 547 566 567 @Book{ teos-10_2010, 568 title = {{The international thermodynamic equation of seawater - 569 2010: Calculation and use of thermodynamic properties}}, 570 publisher = {UNESCO (English)}, 571 year = {2010}, 572 author = {{IOC, SCOR and IAPSO}}, 573 series = {Intergovernmental Oceanographic Commission, Manuals and 574 Guides No. 56} 575 } 576 548 577 @Article{ thorndike_1975, 549 578 author = {Thorndike, A. S. and Rothrock, D. A. and Maykut, G. A. and … … 610 639 year = 1992, 611 640 pages = {113–138}, 612 doi = {10.1007/978-94-011-2809-4 _20},613 url = {http://dx.doi.org/10.1007/978-94-011-2809-4 _20},641 doi = {10.1007/978-94-011-2809-4\_20}, 642 url = {http://dx.doi.org/10.1007/978-94-011-2809-4\_20}, 614 643 isbn = 9789401128094, 615 644 journal = {Interactive Dynamics of Convection and Solidification}, -
NEMO/trunk/doc/latex/SI3/main/SI3_manual.tex
r11030 r11043 12 12 %% Custom style (.sty) 13 13 \usepackage{../../NEMO/main/NEMO_manual} 14 \hypersetup{ 15 pdftitle={SI³ – Sea Ice modelling Integrated Initiative – The NEMO Sea Ice engine}, 16 pdfauthor={NEMO Sea Ice Working Group}, 17 colorlinks 18 } 14 19 15 20 %% Include references and index for single subfile compilation -
NEMO/trunk/doc/latex/SI3/subfiles/chap_model_basics.tex
r11031 r11043 28 28 29 29 \subsection{Scales, thermodynamics and dynamics} 30 Because sea ice is much wider -- $\mathcal{O}$(100-1000 km) -- than thick -- $\mathcal{O}$(1 m) -- ice drift can be considered as purely horizontal: vertical motions around the hydrostatic equilibrium position are negligible. The same scaling argument justifies the assumption that heat exchanges are purely vertical\footnote{The latter assumption is probably less valid, because the horizontal scales of temperature variations are $\mathcal{O}$(10-100 m)}. It is on this basis that thermodynamics and dynamics are separated and rely upon different frameworks and sets of hypotheses: thermodynamics use the ice thickness distribution \citep{thorndike_1975} and the mushy-layer \citep{worster_1992} frameworks, whereas dynamics assume continuum mechanics \citep[e.g.,][]{lepp _ranta_2011}. Thermodynamics and dynamics interact by two means: first, advection impacts state variables; second, the horizontal momentum equation depends, among other things, on the ice state.30 Because sea ice is much wider -- $\mathcal{O}$(100-1000 km) -- than thick -- $\mathcal{O}$(1 m) -- ice drift can be considered as purely horizontal: vertical motions around the hydrostatic equilibrium position are negligible. The same scaling argument justifies the assumption that heat exchanges are purely vertical\footnote{The latter assumption is probably less valid, because the horizontal scales of temperature variations are $\mathcal{O}$(10-100 m)}. It is on this basis that thermodynamics and dynamics are separated and rely upon different frameworks and sets of hypotheses: thermodynamics use the ice thickness distribution \citep{thorndike_1975} and the mushy-layer \citep{worster_1992} frameworks, whereas dynamics assume continuum mechanics \citep[e.g.,][]{lepparanta_2011}. Thermodynamics and dynamics interact by two means: first, advection impacts state variables; second, the horizontal momentum equation depends, among other things, on the ice state. 31 31 32 32 \subsection{Subgrid scale variations} … … 70 70 & Description & Value & Units & Ref \\ \hline 71 71 $c_i$ (cpic) & Pure ice specific heat & 2067 & J/kg/K & ? \\ 72 $c_w$ (rcp) & Seawater specific heat & 3991 & J/kg/K & \cite{ TEOS_2010} \\72 $c_w$ (rcp) & Seawater specific heat & 3991 & J/kg/K & \cite{teos-10_2010} \\ 73 73 $L$ (lfus) & Latent heat of fusion (0$^\circ$C) & 334000 & J/kg/K & \cite{bitz_1999} \\ 74 74 $\rho_i$ (rhoic) & Sea ice density & 917 & kg/m$^3$ & \cite{bitz_1999} \\ … … 154 154 \subsection{Dynamic formulation} 155 155 156 The formulation of ice dynamics is based on the continuum approach. The latter holds provided the drift ice particles are much larger than single ice floes, and much smaller than typical gradient scales. This compromise is rarely achieved in practice \citep{lepp _ranta_2011}. Yet the continuum approach generates a convenient momentum equation for the horizontal ice velocity vector $\mathbf{u}=(u,v)$, which can be solved with classical numerical methods (here, finite differences on the NEMO C-grid). The most important term in the momentum equation is internal stress. We follow the viscous-plastic (VP) rheological framework \citep{hibler_1979}, assuming that sea ice has no tensile strength but responds to compressive and shear deformations in a plastic way. In practice, the elastic-viscous-plastic (EVP) technique of \citep{bouillon_2013} is used, more convient numerically than VP. It is well accepted that the VP rheology and its relatives are the minimum complexity to get reasonable ice drift patterns \citep{kreyscher_2000}, but fail at generating the observed deformation patterns \citep{girard_2009}. This is a long-lasting problem: what is the ideal rheological model for sea ice and how it should be applied are still being debated \citep[see, e.g.][]{weiss_2013}.156 The formulation of ice dynamics is based on the continuum approach. The latter holds provided the drift ice particles are much larger than single ice floes, and much smaller than typical gradient scales. This compromise is rarely achieved in practice \citep{lepparanta_2011}. Yet the continuum approach generates a convenient momentum equation for the horizontal ice velocity vector $\mathbf{u}=(u,v)$, which can be solved with classical numerical methods (here, finite differences on the NEMO C-grid). The most important term in the momentum equation is internal stress. We follow the viscous-plastic (VP) rheological framework \citep{hibler_1979}, assuming that sea ice has no tensile strength but responds to compressive and shear deformations in a plastic way. In practice, the elastic-viscous-plastic (EVP) technique of \citep{bouillon_2013} is used, more convient numerically than VP. It is well accepted that the VP rheology and its relatives are the minimum complexity to get reasonable ice drift patterns \citep{kreyscher_2000}, but fail at generating the observed deformation patterns \citep{girard_2009}. This is a long-lasting problem: what is the ideal rheological model for sea ice and how it should be applied are still being debated \citep[see, e.g.][]{weiss_2013}. 157 157 158 158 %------------------------------------------------------------------------------------------------------------------------- … … 296 296 $C$ (rn\_crhg) & ice strength concentration param. & 20 & - & \citep{hibler_1979} \\ 297 297 $H^*$ (rn\_hstar) & maximum ridged ice thickness param. & 25 & m & \citep{lipscomb_2007} \\ 298 $p$ (rn\_por\_rdg) & porosity of new ridges & 0.3 & - & \citep{lepp _ranta_1995} \\298 $p$ (rn\_por\_rdg) & porosity of new ridges & 0.3 & - & \citep{lepparanta_1995} \\ 299 299 $amax$ (rn\_amax) & maximum ice concentration & 0.999 & - & -\\ 300 300 $h_0$ (rn\_hnewice) & thickness of newly formed ice & 0.1 & m & - \\ … … 313 313 Transport connects the horizontal velocity fields and the rest of the ice properties. LIM assumes that the ice properties in the different thickness categories are transported at the same velocity. The scheme of \cite{prather_1986}, based on the conservation of 0, 1$^{st}$ and 2$^{nd}$ order moments in $x-$ and $y-$directions, is used, with some numerical diffusion if desired. Whereas this scheme is accurate, nearly conservative, it is also quite expensive since, for each advected field, five moments need to be advected, which proves CPU consuming, in particular when multiple categories are used. Other solutions are currently explored. 314 314 315 The dissipation of energy associated with plastic failure under convergence and shear is accomplished by rafting (overriding of two ice plates) and ridging (breaking of an ice plate and subsequent piling of the broken ice blocks into pressure ridges). Thin ice preferentially rafts whereas thick ice preferentially ridges \citep{tuhkuri_2002}. Because observations of these processes are limited, their representation in LIM is rather heuristic. The amount of ice that rafts/ridges depends on the strain rate tensor invariants (shear and divergence) as in \citep{flato_1995}, while the ice categories involved are determined by a participation function favouring thin ice \citep{lipscomb_2007}. The thickness of ice being deformed ($h'$) determines whether ice rafts ($h'<$ 0.75 m) or ridges ($h'>$ 0.75 m), following \cite{haapala_2000}. The deformed ice thickness is $2h'$ after rafting, and is distributed between $2h'$ and $2 \sqrt{H^*h'}$ after ridging, where $H^* = 25$ m \citep{lipscomb_2007}. Newly ridged ice is highly porous, effectively trapping seawater. To represent this, a prescribed volume fraction (30\%) of newly ridged ice \citep{lepp _ranta_1995} incorporates mass, salt and heat are extracted from the ocean. Hence, in contrast with other models, the net thermodynamic ice production during convergence is not zero in LIM, since mass is added to sea ice during ridging. Consequently, simulated new ridges have high temperature and salinity as observed \citep{h_yland_2002}. A fraction of snow (50 \%) falls into the ocean during deformation.315 The dissipation of energy associated with plastic failure under convergence and shear is accomplished by rafting (overriding of two ice plates) and ridging (breaking of an ice plate and subsequent piling of the broken ice blocks into pressure ridges). Thin ice preferentially rafts whereas thick ice preferentially ridges \citep{tuhkuri_2002}. Because observations of these processes are limited, their representation in LIM is rather heuristic. The amount of ice that rafts/ridges depends on the strain rate tensor invariants (shear and divergence) as in \citep{flato_1995}, while the ice categories involved are determined by a participation function favouring thin ice \citep{lipscomb_2007}. The thickness of ice being deformed ($h'$) determines whether ice rafts ($h'<$ 0.75 m) or ridges ($h'>$ 0.75 m), following \cite{haapala_2000}. The deformed ice thickness is $2h'$ after rafting, and is distributed between $2h'$ and $2 \sqrt{H^*h'}$ after ridging, where $H^* = 25$ m \citep{lipscomb_2007}. Newly ridged ice is highly porous, effectively trapping seawater. To represent this, a prescribed volume fraction (30\%) of newly ridged ice \citep{lepparanta_1995} incorporates mass, salt and heat are extracted from the ocean. Hence, in contrast with other models, the net thermodynamic ice production during convergence is not zero in LIM, since mass is added to sea ice during ridging. Consequently, simulated new ridges have high temperature and salinity as observed \citep{hoyland_2002}. A fraction of snow (50 \%) falls into the ocean during deformation. 316 316 317 317 \section{Ice thermodynamics} -
NEMO/trunk/doc/latex/SI3/subfiles/chap_ridging_rafting.tex
r11031 r11043 70 70 \textbf{Rafting} is the piling of two ice sheets on top of each other. Rafting doubles the participating ice thickness and is a volume-conserving process. \cite{babko_2002} concluded that rafting plays a significant role during initial ice growth in fall, therefore we included it into the model. 71 71 72 \textbf{Ridging} is the piling of a series of broken ice blocks into pressure ridges. Ridging redistributes participating ice on a various range of thicknesses. Ridging does not conserve ice volume, as pressure ridges are porous. Therefore, the volume of ridged ice is larger than the volume of new ice being ridged. In the model, newly ridged is has a prescribed porosity $p=30\%$ (\textit{ridge\_por} in \textit{namelist\_ice}), following observations \citep{lepp _ranta_1995,h_yland_2002}. The importance of ridging is now since the early works of \citep{thorndike_1975}.72 \textbf{Ridging} is the piling of a series of broken ice blocks into pressure ridges. Ridging redistributes participating ice on a various range of thicknesses. Ridging does not conserve ice volume, as pressure ridges are porous. Therefore, the volume of ridged ice is larger than the volume of new ice being ridged. In the model, newly ridged is has a prescribed porosity $p=30\%$ (\textit{ridge\_por} in \textit{namelist\_ice}), following observations \citep{lepparanta_1995,hoyland_2002}. The importance of ridging is now since the early works of \citep{thorndike_1975}. 73 73 74 74 The deformation modes are formulated using \textbf{participation} and \textbf{transfer} functions with specific contributions from ridging and rafting: … … 115 115 \label{eq:nri} 116 116 \end{equation} 117 The redistributor $\gamma(h',h)$ specifies how area of thickness $h'$ is redistributed on area of thickness $h$. We follow \citep{hibler_1980} who constructed a rule, based on observations, that forces all ice participating in ridging with thickness $h'$ to be linearly distributed between ice that is between $2h'$ and $2\sqrt{H^*h'}$ thick, where $H^\star=100$ m (\textit{Hstar} in \textit{namelist\_ice}). This in turn determines how to construct the ice volume redistribution function $\Psi^v$. Volumes equal to participating area times thickness are removed from thin ice. They are redistributed following Hibler's rule. The factor $(1+p)$ accounts for initial ridge porosity $p$ (\textit{ridge\_por} in \textit{namelist\_ice}, defined as the fractional volume of seawater initially included into ridges. In many previous models, the initial ridge porosity has been assumed to be 0, which is not the case in reality since newly formed ridges are porous, as indicated by in-situ observations \citep{lepp _ranta_1995,h_yland_2002}. In other words, LIM3 creates a higher volume of ridged ice with the same participating ice.117 The redistributor $\gamma(h',h)$ specifies how area of thickness $h'$ is redistributed on area of thickness $h$. We follow \citep{hibler_1980} who constructed a rule, based on observations, that forces all ice participating in ridging with thickness $h'$ to be linearly distributed between ice that is between $2h'$ and $2\sqrt{H^*h'}$ thick, where $H^\star=100$ m (\textit{Hstar} in \textit{namelist\_ice}). This in turn determines how to construct the ice volume redistribution function $\Psi^v$. Volumes equal to participating area times thickness are removed from thin ice. They are redistributed following Hibler's rule. The factor $(1+p)$ accounts for initial ridge porosity $p$ (\textit{ridge\_por} in \textit{namelist\_ice}, defined as the fractional volume of seawater initially included into ridges. In many previous models, the initial ridge porosity has been assumed to be 0, which is not the case in reality since newly formed ridges are porous, as indicated by in-situ observations \citep{lepparanta_1995,hoyland_2002}. In other words, LIM3 creates a higher volume of ridged ice with the same participating ice. 118 118 119 119 For the numerical computation of the integrals, we have to compute several temporary values: … … 152 152 \section{Mechanical redistribution for other global ice variables} 153 153 154 The other global ice state variables redistribution functions $\Psi^X$ are computed based on $\Psi^g$ for the ice age content and on $\Psi^{v^i}$ for the remainder (ice enthalpy and salt content, snow volume and enthalpy). The general principles behind this derivation are described in Appendix A of \cite{bitz_2001}. A fraction $f_s=0.5$ (\textit{fsnowrdg} and \textit{fsnowrft} in \textit{namelist\_ice}) of the snow volume and enthalpy is assumed to be lost during ridging and rafting and transferred to the ocean. The contribution of the seawater trapped into the porous ridges is included in the computation of the redistribution of ice enthalpy and salt content (i.e., $\Psi^{e^i}$ and $\Psi^{M^s}$). During this computation, seawater is supposed to be in thermal equilibrium with the surrounding ice blocks. Ridged ice desalination induces an implicit decrease in internal brine volume, and heat supply to the ocean, which accounts for ridge consolidation as described by \cite{h _yland_2002}. The inclusion of seawater in ridges does not imply any net change in ocean salinity. The energy used to cool down the seawater trapped in porous ridges until the seawater freezing point is rejected into the ocean.154 The other global ice state variables redistribution functions $\Psi^X$ are computed based on $\Psi^g$ for the ice age content and on $\Psi^{v^i}$ for the remainder (ice enthalpy and salt content, snow volume and enthalpy). The general principles behind this derivation are described in Appendix A of \cite{bitz_2001}. A fraction $f_s=0.5$ (\textit{fsnowrdg} and \textit{fsnowrft} in \textit{namelist\_ice}) of the snow volume and enthalpy is assumed to be lost during ridging and rafting and transferred to the ocean. The contribution of the seawater trapped into the porous ridges is included in the computation of the redistribution of ice enthalpy and salt content (i.e., $\Psi^{e^i}$ and $\Psi^{M^s}$). During this computation, seawater is supposed to be in thermal equilibrium with the surrounding ice blocks. Ridged ice desalination induces an implicit decrease in internal brine volume, and heat supply to the ocean, which accounts for ridge consolidation as described by \cite{hoyland_2002}. The inclusion of seawater in ridges does not imply any net change in ocean salinity. The energy used to cool down the seawater trapped in porous ridges until the seawater freezing point is rejected into the ocean. 155 155 156 156 \end{document} -
NEMO/trunk/doc/latex/SI3/subfiles/introduction.tex
r11031 r11043 15 15 16 16 % Limitations & scope 17 %There are limitations to the applicability of models such as SI$^3$. The continuum approach is not invalid for grid cell size above at least 1 km, below which sea ice particles may include just a few floes, which is not sufficient \citep{lepp _ranta_2011}. Second, one must remember that our current knowledge of sea ice is not as complete as for the ocean: there are no fundamental equations such as Navier Stokes equations for sea ice. Besides, important features and processes span widely different scales, such as brine inclusions (1 $\mu$m-1 mm) \citep{perovich_1996}, horizontal thickness variations (1 m-100 km) \citep{percival_2008}, deformation and fracturing (10 m-1000 km) \citep{marsan_2004}. These impose complicated and often subjective subgrid-scale treatments. All in all, there is more empirism in sea ice models than in ocean models.17 %There are limitations to the applicability of models such as SI$^3$. The continuum approach is not invalid for grid cell size above at least 1 km, below which sea ice particles may include just a few floes, which is not sufficient \citep{lepparanta_2011}. Second, one must remember that our current knowledge of sea ice is not as complete as for the ocean: there are no fundamental equations such as Navier Stokes equations for sea ice. Besides, important features and processes span widely different scales, such as brine inclusions (1 $\mu$m-1 mm) \citep{perovich_1996}, horizontal thickness variations (1 m-100 km) \citep{percival_2008}, deformation and fracturing (10 m-1000 km) \citep{marsan_2004}. These impose complicated and often subjective subgrid-scale treatments. All in all, there is more empirism in sea ice models than in ocean models. 18 18 19 19 In order to handle all the subsequent required subjective choices, we applied the following guidelines or principles:
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