Changeset 6320
- Timestamp:
- 2016-02-17T16:24:34+01:00 (8 years ago)
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- trunk/DOC/TexFiles
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trunk/DOC/TexFiles/Biblio/Biblio.bib
r6289 r6320 1262 1262 pages = {1081--1098}, 1263 1263 } 1264 1264 1265 @ARTICLE{Griffies_Hallberg_MWR00, 1265 1266 author = {S.M. Griffies and R.H. Hallberg}, … … 1514 1515 } 1515 1516 1517 @TechReport{Hunter2006, 1518 Title = {Specification for Test Models of Ice Shelf Cavities}, 1519 Author = {J. R. Hunter}, 1520 Institution = {Antarctic Climate \& Ecosystems Cooperative Research Centre Private Bag 80, Hobart, Tasmania 7001}, 1521 Year = {2006}, 1522 } 1523 1516 1524 @TECHREPORT{TEOS10, 1517 1525 author = {IOC and SCOR and IAPSO}, … … 1594 1602 volume = {96}, number = {C11}, 1595 1603 pages = {2298--2312} 1604 } 1605 1606 @ARTICLE{Jenkins2001, 1607 author = {A. Jenkins}, 1608 title = {The Role of Meltwater Advection in the Formulation of Conservative Boundary Conditions at an Ice-Ocean Interface}, 1609 journal = JPO, 1610 year = {2001}, 1611 volume = {31}, 1612 pages = {285--296} 1596 1613 } 1597 1614 -
trunk/DOC/TexFiles/Chapters/Chap_DOM.tex
r6289 r6320 495 495 in each water column is by-passed}. 496 496 If \np{ln\_isfcav}~=~true, an extra file input file describing the ice shelf draft 497 (in meters) (\ifile{isf\_draft\_meter}) is needed and all the location where the isf cavity thinnest 498 than \np{rn\_isfhmin} meters are grounded ($i.e.$ masked). 497 (in meters) (\ifile{isf\_draft\_meter}) is needed. 499 498 500 499 After reading the bathymetry, the algorithm for vertical grid definition differs … … 539 538 domain width at the central latitude. This is meant for the "EEL-R5" configuration, 540 539 a periodic or open boundary channel with a seamount. 541 \item[\np{nn\_bathy} = 1] read a bathymetry . The \ifile{bathy\_meter} file (Netcdf format)542 provides the ocean depth (positive, in meters) at each grid point of the model grid. 543 The bathymetry is usually built by interpolating a standard bathymetry product540 \item[\np{nn\_bathy} = 1] read a bathymetry and ice shelf draft (if needed). 541 The \ifile{bathy\_meter} file (Netcdf format) provides the ocean depth (positive, in meters) 542 at each grid point of the model grid. The bathymetry is usually built by interpolating a standard bathymetry product 544 543 ($e.g.$ ETOPO2) onto the horizontal ocean mesh. Defining the bathymetry also 545 544 defines the coastline: where the bathymetry is zero, no model levels are defined 546 545 (all levels are masked). 546 547 The \ifile{isfdraft\_meter} file (Netcdf format) provides the ice shelf draft (positive, in meters) 548 at each grid point of the model grid. This file is only needed if \np{ln\_isfcav}~=~true. 549 Defining the ice shelf draft will also define the ice shelf edge and the grounding line position. 547 550 \end{description} 548 551 … … 601 604 (Fig.~\ref{Fig_zgr}). 602 605 606 If the ice shelf cavities are opened (\np{ln\_isfcav}=~true~}), the definition of $z_0$ is the same. 607 However, definition of $e_3^0$ at $t$- and $w$-points is respectively changed to: 608 \begin{equation} \label{DOM_zgr_ana} 609 \begin{split} 610 e_3^T(k) &= z_W (k+1) - z_W (k) \\ 611 e_3^W(k) &= z_T (k) - z_T (k-1) \\ 612 \end{split} 613 \end{equation} 614 This formulation decrease the self-generated circulation into the ice shelf cavity 615 (which can, in extreme case, leads to blow up).\\ 616 617 603 618 The most used vertical grid for ORCA2 has $10~m$ ($500~m)$ resolution in the 604 619 surface (bottom) layers and a depth which varies from 0 at the sea surface to a … … 865 880 gives the number of ocean levels ($i.e.$ those that are not masked) at each 866 881 $t$-point. mbathy is computed from the meter bathymetry using the definiton of 867 gdept as the number of $t$-points which gdept $\leq$ bathy. 882 gdept as the number of $t$-points which gdept $\leq$ bathy. 868 883 869 884 Modifications of the model bathymetry are performed in the \textit{bat\_ctl} … … 871 886 that do not communicate with another ocean point at the same level are eliminated. 872 887 873 From the \textit{mbathy} array, the mask fields are defined as follows: 888 In case of ice shelf cavities, as for the representation of bathymetry, a 2D integer array, misfdep, is created. 889 misfdep defines the level of the first wet $t$-point (ie below the ice-shelf/ocean interface). All the cells between $k=1$ and $misfdep(i,j)-1$ are masked. 890 By default, $misfdep(:,:)=1$ and no cells are masked. 891 Modifications of the model bathymetry and ice shelf draft into 892 the cavities are performed in the \textit{zgr\_isf} routine. The compatibility between ice shelf draft and bathymetry is checked. 893 All the locations where the isf cavity is thinnest than \np{rn\_isfhmin} meters are grounded ($i.e.$ masked). 894 If only one cell on the water column is opened at $t$-, $u$- or $v$-points, the bathymetry or the ice shelf draft is dug to fit this constrain. 895 If the incompatibility is too strong (need to dig more than 1 cell), the cell is masked.\\ 896 897 From the \textit{mbathy} and \textit{misfdep} array, the mask fields are defined as follows: 874 898 \begin{align*} 875 tmask(i,j,k) &= \begin{cases} \; 1& \text{ if $k\leq mbathy(i,j)$ } \\ 876 \; 0& \text{ if $k\leq mbathy(i,j)$ } \end{cases} \\ 899 tmask(i,j,k) &= \begin{cases} \; 0& \text{ if $k < misfdep(i,j) $ } \\ 900 \; 1& \text{ if $misfdep(i,j) \leq k\leq mbathy(i,j)$ } \\ 901 \; 0& \text{ if $k > mbathy(i,j)$ } \end{cases} \\ 877 902 umask(i,j,k) &= \; tmask(i,j,k) \ * \ tmask(i+1,j,k) \\ 878 903 vmask(i,j,k) &= \; tmask(i,j,k) \ * \ tmask(i,j+1,k) \\ 879 904 fmask(i,j,k) &= \; tmask(i,j,k) \ * \ tmask(i+1,j,k) \\ 880 & \ \ \, * tmask(i,j,k) \ * \ tmask(i+1,j,k) 905 & \ \ \, * tmask(i,j,k) \ * \ tmask(i+1,j,k) \\ 906 wmask(i,j,k) &= \; tmask(i,j,k) \ * \ tmask(i,j,k-1) \text{ with } wmask(i,j,1) = tmask(i,j,1) 881 907 \end{align*} 882 908 883 Note that \textit{wmask} is not defined as it is exactly equal to \textit{tmask} with 884 the numerical indexing used (\S~\ref{DOM_Num_Index}). Moreover, the 885 specification of closed lateral boundaries requires that at least the first and last 909 Note, wmask is now defined. It allows, in case of ice shelves, 910 to deal with the top boundary (ice shelf/ocean interface) exactly in the same way as for the bottom boundary. 911 912 The specification of closed lateral boundaries requires that at least the first and last 886 913 rows and columns of the \textit{mbathy} array are set to zero. In the particular 887 914 case of an east-west cyclical boundary condition, \textit{mbathy} has its last -
trunk/DOC/TexFiles/Chapters/Chap_DYN.tex
r6289 r6320 654 654 pressure Jacobian method is used to solve the horizontal pressure gradient. This method can provide 655 655 a more accurate calculation of the horizontal pressure gradient than the standard scheme. 656 657 \subsection{Ice shelf cavity} 658 \label{DYN_hpg_isf} 659 Beneath an ice shelf, the total pressure gradient is the sum of the pressure gradient due to the ice shelf load and 660 the pressure gradient due to the ocean load. If cavity opened (\np{ln\_isfcav}~=~true) these 2 terms can be 661 calculated by setting \np{ln\_dynhpg\_isf}~=~true. No other scheme are working with the ice shelf.\\ 662 663 $\bullet$ The main hypothesis to compute the ice shelf load is that the ice shelf is in an isostatic equilibrium. 664 The top pressure is computed integrating from surface to the base of the ice shelf a reference density profile 665 (prescribed as density of a water at 34.4 PSU and -1.9$\degres C$) and corresponds to the water replaced by the ice shelf. 666 This top pressure is constant over time. A detailed description of this method is described in \citet{Losch2008}.\\ 667 668 $\bullet$ The ocean load is computed using the expression \eqref{Eq_dynhpg_sco} described in \ref{DYN_hpg_sco}. 656 669 657 670 %-------------------------------------------------------------------------------------------------------------- -
trunk/DOC/TexFiles/Chapters/Chap_SBC.tex
r6289 r6320 51 51 \item the modification of fluxes below ice-covered areas (using observed ice-cover or a sea-ice model) (\np{nn\_ice}~=~0,1, 2 or 3) ; 52 52 \item the addition of river runoffs as surface freshwater fluxes or lateral inflow (\np{ln\_rnf}~=~true) ; 53 \item the addition of isf melting as lateral inflow (parameterisation) (\np{nn\_isf}~=~2 or 3 and \np{ln\_isfcav}~=~false) 54 or as fluxes applied at the land-ice ocean interface (\np{nn\_isf}~=~1 or 4 and \np{ln\_isfcav}~=~true) ; 53 \item the addition of isf melting as lateral inflow (parameterisation) or as fluxes applied at the land-ice ocean interface (\np{ln\_isf}) ; 55 54 \item the addition of a freshwater flux adjustment in order to avoid a mean sea-level drift (\np{nn\_fwb}~=~0,~1~or~2) ; 56 55 \item the transformation of the solar radiation (if provided as daily mean) into a diurnal cycle (\np{ln\_dm2dc}~=~true) ; … … 924 923 \namdisplay{namsbc_isf} 925 924 %-------------------------------------------------------------------------------------------------------- 926 Namelist variable in \ngn{namsbc}, \np{nn\_isf}, control the kind ofice shelf representation used.925 Namelist variable in \ngn{namsbc}, \np{nn\_isf}, controls the ice shelf representation used. 927 926 \begin{description} 928 927 \item[\np{nn\_isf}~=~1] 929 The ice shelf cavity is represented. The fwf and heat flux are computed. 2 bulk formulations are available: 930 the ISOMIP one (\np{nn\_isfblk = 1}) described in (\np{nn\_isfblk = 2}), 931 the 3 equation formulation described in \citet{Jenkins1991}. 932 In addition to this, 3 different ways to compute the exchange coefficient are available. 933 $\gamma\_{T/S}$ is constant (\np{nn\_gammablk = 0}), $\gamma\_{T/S}$ is velocity dependant 934 \citep{Jenkins2010} (\np{nn\_gammablk = 1}) and $\gamma\_{T/S}$ is velocity dependant 935 and stratification dependent \citep{Holland1999} (\np{nn\_gammablk = 2}). 936 For each of them, the thermal/salt exchange coefficient (\np{rn\_gammat0} and \np{rn\_gammas0}) 937 have to be specified (the default values are for the ISOMIP case). 938 Full description, sensitivity and validation in preparation. 928 The ice shelf cavity is represented (\np{ln\_isfcav}~=~true needed). The fwf and heat flux are computed. Two different bulk formula are available: 929 \begin{description} 930 \item[\np{nn\_isfblk}~=~1] 931 The bulk formula used to compute the melt is based the one described in \citet{Hunter2006}. 932 This formulation is based on a balance between the upward ocean heat flux and the latent heat flux at the ice shelf base. 933 934 \item[\np{nn\_isfblk}~=~2] 935 The bulk formula used to compute the melt is based the one described in \citet{Jenkins1991}. 936 This formulation is based on a 3 equations formulation (a heat flux budget, a salt flux budget 937 and a linearised freezing point temperature equation). 938 \end{description} 939 940 For this 2 bulk formulations, there are 3 different ways to compute the exchange coeficient: 941 \begin{description} 942 \item[\np{nn\_gammablk~=~0~}] 943 The salt and heat exchange coefficients are constant and defined by \np{rn\_gammas0} and \np{rn\_gammat0} 944 945 \item[\np{nn\_gammablk~=~1~}] 946 The salt and heat exchange coefficients are velocity dependent and defined as $\np{rn\_gammas0} \times u_{*}$ and $\np{rn\_gammat0} \times u_{*}$ 947 where $u_{*}$ is the friction velocity in the top boundary layer (ie first \np{rn\_hisf\_tbl} meters). 948 See \citet{Jenkins2010} for all the details on this formulation. 949 950 \item[\np{nn\_gammablk~=~2~}] 951 The salt and heat exchange coefficients are velocity and stability dependent and defined as 952 $\gamma_{T,S} = \frac{u_{*}}{\Gamma_{Turb} + \Gamma^{T,S}_{Mole}}$ 953 where $u_{*}$ is the friction velocity in the top boundary layer (ie first \np{rn\_hisf\_tbl} meters), 954 $\Gamma_{Turb}$ the contribution of the ocean stability and 955 $\Gamma^{T,S}_{Mole}$ the contribution of the molecular diffusion. 956 See \citet{Holland1999} for all the details on this formulation. 957 \end{description} 939 958 940 959 \item[\np{nn\_isf}~=~2] … … 942 961 The fwf is distributed along the ice shelf edge between the depth of the average grounding line (GL) 943 962 (\np{sn\_depmax\_isf}) and the base of the ice shelf along the calving front (\np{sn\_depmin\_isf}) as in (\np{nn\_isf}~=~3). 944 Furthermore the fwf is computed using the \citet{Beckmann2003} parameterisation of isf melting. 945 The effective melting length (\np{sn\_Leff\_isf}) is read from a file and the exchange coefficients 946 are set as (\np{rn\_gammat0}) and (\np{rn\_gammas0}). 963 Furthermore the fwf and heat flux are computed using the \citet{Beckmann2003} parameterisation of isf melting. 964 The effective melting length (\np{sn\_Leff\_isf}) is read from a file. 947 965 948 966 \item[\np{nn\_isf}~=~3] 949 967 A simple parameterisation of isf is used. The ice shelf cavity is not represented. 950 The fwf (\np{sn\_rnfisf}) is distributed along the ice shelf edge between the depth of the average grounding line (GL)951 (\np{sn\_depmax\_isf}) and the base of the ice shelf along the calving front (\np{sn\_depmin\_isf}). 952 Full description, sensitivity and validation in preparation.968 The fwf (\np{sn\_rnfisf}) is prescribed and distributed along the ice shelf edge between the depth of the average grounding line (GL) 969 (\np{sn\_depmax\_isf}) and the base of the ice shelf along the calving front (\np{sn\_depmin\_isf}). 970 The heat flux ($Q_h$) is computed as $Q_h = fwf \times L_f$. 953 971 954 972 \item[\np{nn\_isf}~=~4] 955 The ice shelf cavity is represented. However, the fwf (\np{sn\_fwfisf}) and heat flux (\np{sn\_qisf}) are956 not computed but specified from file. 973 The ice shelf cavity is opened (\np{ln\_isfcav}~=~true needed). However, the fwf is not computed but specified from file \np{sn\_fwfisf}). 974 The heat flux ($Q_h$) is computed as $Q_h = fwf \times L_f$.\\ 957 975 \end{description} 958 976 959 \np{nn\_isf}~=~1 and \np{nn\_isf}~=~2 compute a melt rate based on the water masse properties, ocean velocities and depth. 960 This flux is thus highly dependent of the model resolution (horizontal and vertical), realism of the water masse onto the shelf ... 961 962 \np{nn\_isf}~=~3 and \np{nn\_isf}~=~4 read the melt rate and heat flux from a file. You have total control of the fwf scenario. 963 977 978 $\bullet$ \np{nn\_isf}~=~1 and \np{nn\_isf}~=~2 compute a melt rate based on the water mass properties, ocean velocities and depth. 979 This flux is thus highly dependent of the model resolution (horizontal and vertical), realism of the water masses onto the shelf ...\\ 980 981 982 $\bullet$ \np{nn\_isf}~=~3 and \np{nn\_isf}~=~4 read the melt rate from a file. You have total control of the fwf forcing. 964 983 This can be usefull if the water masses on the shelf are not realistic or the resolution (horizontal/vertical) are too 965 coarse to have realistic melting or for sensitivity studies where you want to control your input. 966 Full description, sensitivity and validation in preparation. 967 968 \np{rn\_hisf\_tbl} is the top boundary layer (tbl) thickness used by the Losch parametrisation \citep{Losch2008} to compute the melt. if 0, temperature/salt/velocity in the top cell is used to compute the melt. 969 Otherwise, NEMO used the mean value into the tbl. 984 coarse to have realistic melting or for studies where you need to control your heat and fw input.\\ 985 986 A namelist parameters control over how many meters the heat and fw fluxes are spread. 987 \np{rn\_hisf\_tbl}] is the top boundary layer thickness as defined in \citet{Losch2008}. 988 This parameter is only used if \np{nn\_isf}~=~1 or \np{nn\_isf}~=~4 989 990 If \np{rn\_hisf\_tbl} = 0.0, the fluxes are put in the top level whatever is its tickness. 991 992 If \np{rn\_hisf\_tbl} $>$ 0.0, the fluxes are spread over the first \np{rn\_hisf\_tbl} m (ie over one or several cells).\\ 993 994 The ice shelf melt is implemented as a volume flux with in the same way as for the runoff. 995 The fw addition due to the ice shelf melting is, at each relevant depth level, added to the horizontal divergence 996 (\textit{hdivn}) in the subroutine \rou{sbc\_isf\_div}, called from \mdl{divcur}. 997 See the runoff section \ref{SBC_rnf} for all the details about the divergence correction. 998 970 999 971 1000 \section{ Ice sheet coupling} -
trunk/DOC/TexFiles/Chapters/Chap_TRA.tex
r6289 r6320 734 734 (see \S\ref{SBC_rnf} for further detail of how it acts on temperature and salinity tendencies) 735 735 736 $\bullet$ \textit{fwfisf}, the mass flux associated with ice shelf melt, (see \S\ref{SBC_isf} for further details 737 on how the ice shelf melt is computed and applied). 738 736 739 The surface boundary condition on temperature and salinity is applied as follows: 737 740 \begin{equation} \label{Eq_tra_sbc} … … 1382 1385 I've changed "derivative" to "difference" and "mean" to "average"} 1383 1386 1384 With partial bottom cells (\np{ln\_zps}=true), in general, tracers in horizontally1387 With partial cells (\np{ln\_zps}=true) at bottom and top (\np{ln\_isfcav}=true), in general, tracers in horizontally 1385 1388 adjacent cells live at different depths. Horizontal gradients of tracers are needed 1386 1389 for horizontal diffusion (\mdl{traldf} module) and for the hydrostatic pressure 1387 gradient (\mdl{dynhpg} module) to be active. 1390 gradient (\mdl{dynhpg} module) to be active. The partial cell properties 1391 at the top (\np{ln\_isfcav}=true) are computed in the same way as for the bottom. So, only the bottom interpolation is shown. 1388 1392 \gmcomment{STEVEN from gm : question: not sure of what -to be active- means} 1393 1389 1394 Before taking horizontal gradients between the tracers next to the bottom, a linear 1390 1395 interpolation in the vertical is used to approximate the deeper tracer as if it actually -
trunk/DOC/TexFiles/Chapters/Chap_ZDF.tex
r6289 r6320 842 842 % Bottom Friction 843 843 % ================================================================ 844 \section [Bottom and top Friction (\textit{zdfbfr})] {BottomFriction (\mdl{zdfbfr} module)}844 \section [Bottom and Top Friction (\textit{zdfbfr})] {Bottom and Top Friction (\mdl{zdfbfr} module)} 845 845 \label{ZDF_bfr} 846 846 … … 850 850 851 851 Options to define the top and bottom friction are defined through the \ngn{nambfr} namelist variables. 852 The top friction is activated only if the ice shelf cavities are opened (\np{ln\_isfcav}~=~true). 853 As the friction processes at the top and bottom are the represented similarly, only the bottom friction is described in detail. 852 The bottom friction represents the friction generated by the bathymetry. 853 The top friction represents the friction generated by the ice shelf/ocean interface. 854 As the friction processes at the top and bottom are represented similarly, only the bottom friction is described in detail below.\\ 855 854 856 855 857 Both the surface momentum flux (wind stress) and the bottom momentum
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