Changeset 6317 for branches/2015
- Timestamp:
- 2016-02-15T16:21:15+01:00 (8 years ago)
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- branches/2015/nemo_v3_6_STABLE/DOC/TexFiles
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branches/2015/nemo_v3_6_STABLE/DOC/TexFiles/Biblio/Biblio.bib
r6303 r6317 1514 1514 } 1515 1515 1516 @TechReport{Hunter2006, 1517 Title = {Specification for Test Models of Ice Shelf Cavities}, 1518 Author = {J. R. Hunter}, 1519 Institution = {Antarctic Climate \& Ecosystems Cooperative Research Centre Private Bag 80, Hobart, Tasmania 7001}, 1520 Year = {2006}, 1521 } 1522 1516 1523 @TECHREPORT{TEOS10, 1517 1524 author = {IOC and SCOR and IAPSO}, … … 1594 1601 volume = {96}, number = {C11}, 1595 1602 pages = {2298--2312} 1603 } 1604 1605 @ARTICLE{Jenkins2001, 1606 author = {A. Jenkins}, 1607 title = {The Role of Meltwater Advection in the Formulation of Conservative Boundary Conditions at an Ice-Ocean Interface}, 1608 journal = JPO, 1609 year = {2001}, 1610 volume = {31}, 1611 pages = {285--296} 1596 1612 } 1597 1613 -
branches/2015/nemo_v3_6_STABLE/DOC/TexFiles/Chapters/Chap_DOM.tex
r6275 r6317 494 494 bathymetry or $s$-coordinate (hybrid and partial step coordinates have not 495 495 yet been tested in NEMO v2.3). If using $z$-coordinate with partial step bathymetry 496 (\np{ln\_zps}~=~true), ocean cavity beneath ice shelves can be open (\np{ln\_isfcav}~=~true). 496 (\np{ln\_zps}~=~true), ocean cavity beneath ice shelves can be open (\np{ln\_isfcav}~=~true) 497 and partial step are also applied at the ocean/ice shelf interface. 497 498 498 499 Contrary to the horizontal grid, the vertical grid is computed in the code and no … … 548 549 domain width at the central latitude. This is meant for the "EEL-R5" configuration, 549 550 a periodic or open boundary channel with a seamount. 550 \item[\np{nn\_bathy} = 1] read a bathymetry . The \ifile{bathy\_meter} file (Netcdf format)551 provides the ocean depth (positive, in meters) at each grid point of the model grid. 552 The bathymetry is usually built by interpolating a standard bathymetry product551 \item[\np{nn\_bathy} = 1] read a bathymetry and ice shelf draft (if needed). 552 The \ifile{bathy\_meter} file (Netcdf format) provides the ocean depth (positive, in meters) 553 at each grid point of the model grid. The bathymetry is usually built by interpolating a standard bathymetry product 553 554 ($e.g.$ ETOPO2) onto the horizontal ocean mesh. Defining the bathymetry also 554 555 defines the coastline: where the bathymetry is zero, no model levels are defined 555 556 (all levels are masked). 557 558 The \ifile{isfdraft\_meter} file (Netcdf format) provides the ice shelf draft (positive, in meters) 559 at each grid point of the model grid. This file is only needed if \np{ln\_isfcav}~=~true. 560 Defining the ice shelf draft will also define the ice shelf edge and the grounding line position. 556 561 \end{description} 557 562 … … 610 615 (Fig.~\ref{Fig_zgr}). 611 616 617 If the ice shelf cavities are opened (\np{ln\_isfcav}=~true~}), the definition of $z_0$ is the same. 618 However, definition of $e_3^0$ at $t$- and $w$-points is respectively changed to: 619 \begin{equation} \label{DOM_zgr_ana} 620 \begin{split} 621 e_3^T(k) &= z_W (k+1) - z_W (k) \\ 622 e_3^W(k) &= z_T (k) - z_T (k-1) \\ 623 \end{split} 624 \end{equation} 625 This formulation decrease the self-generated circulation into the ice shelf cavity 626 (which can, in extreme case, leads to blow up).\\ 627 628 612 629 The most used vertical grid for ORCA2 has $10~m$ ($500~m)$ resolution in the 613 630 surface (bottom) layers and a depth which varies from 0 at the sea surface to a … … 860 877 gives the number of ocean levels ($i.e.$ those that are not masked) at each 861 878 $t$-point. mbathy is computed from the meter bathymetry using the definiton of 862 gdept as the number of $t$-points which gdept $\leq$ bathy. 879 gdept as the number of $t$-points which gdept $\leq$ bathy. 863 880 864 881 Modifications of the model bathymetry are performed in the \textit{bat\_ctl} 865 882 routine (see \mdl{domzgr} module) after mbathy is computed. Isolated grid points 866 that do not communicate with another ocean point at the same level are eliminated. 883 that do not communicate with another ocean point at the same level are eliminated.\\ 884 885 As for the representation of bathymetry, a 2D integer array, misfdep, is created. 886 misfdep defines the level of the first wet $t$-point. All the cells between $k=1$ and $misfdep(i,j)-1$ are masked. 887 By default, misfdep(:,:)=1 and no cells are masked. 888 889 In case of ice shelf cavities, modifications of the model bathymetry and ice shelf draft into 890 the cavities are performed in the \textit{zgr\_isf} routine. The compatibility between ice shelf draft and bathymetry is checked. 891 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. 892 If the incompatibility is too strong (need to dig more than 1 cell), the cell is masked.\\ 867 893 868 894 From the \textit{mbathy} array, the mask fields are defined as follows: 869 895 \begin{align*} 870 tmask(i,j,k) &= \begin{cases} \; 1& \text{ if $k\leq mbathy(i,j)$ } \\ 871 \; 0& \text{ if $k\leq mbathy(i,j)$ } \end{cases} \\ 896 tmask(i,j,k) &= \begin{cases} \; 0& \text{ if $k < misfdep(i,j) $ } \\ 897 \; 1& \text{ if $misfdep(i,j) \leq k\leq mbathy(i,j)$ } \\ 898 \; 0& \text{ if $k > mbathy(i,j)$ } \end{cases} \\ 872 899 umask(i,j,k) &= \; tmask(i,j,k) \ * \ tmask(i+1,j,k) \\ 873 900 vmask(i,j,k) &= \; tmask(i,j,k) \ * \ tmask(i,j+1,k) \\ 874 901 fmask(i,j,k) &= \; tmask(i,j,k) \ * \ tmask(i+1,j,k) \\ 875 & \ \ \, * tmask(i,j,k) \ * \ tmask(i+1,j,k) 902 & \ \ \, * tmask(i,j,k) \ * \ tmask(i+1,j,k) \\ 903 wmask(i,j,k) &= \; tmask(i,j,k) \ * \ tmask(i,j,k-1) \text{ with } wmask(i,j,1) = tmask(i,j,1) 876 904 \end{align*} 877 905 878 Note that \textit{wmask} is not defined as it is exactly equal to \textit{tmask} with 879 the numerical indexing used (\S~\ref{DOM_Num_Index}). Moreover, the 880 specification of closed lateral boundaries requires that at least the first and last 906 Note, wmask is now defined. It allows, in case of ice shelves, 907 to deal with the top boundary (ice shelf/ocean interface) exactly in the same way as for the bottom boundary. 908 909 The specification of closed lateral boundaries requires that at least the first and last 881 910 rows and columns of the \textit{mbathy} array are set to zero. In the particular 882 911 case of an east-west cyclical boundary condition, \textit{mbathy} has its last -
branches/2015/nemo_v3_6_STABLE/DOC/TexFiles/Chapters/Chap_DYN.tex
r6275 r6317 637 637 ($e_{3w}$). 638 638 639 $\bullet$ Traditional coding with adaptation for ice shelf cavities (\np{ln\_hpg\_isf}=true).640 This scheme need the activation of ice shelf cavities (\np{ln\_isfcav}=true).641 642 639 $\bullet$ Pressure Jacobian scheme (prj) (a research paper in preparation) (\np{ln\_dynhpg\_prj}=true) 643 640 … … 654 651 pressure Jacobian method is used to solve the horizontal pressure gradient. This method can provide 655 652 a more accurate calculation of the horizontal pressure gradient than the standard scheme. 653 654 \subsection{Ice shelf cavity} 655 \label{DYN_hpg_isf} 656 Beneath an ice shelf, the total pressure gradient is the sum of the pressure gradient due to the ice shelf load and 657 the pressure gradient due to the ocean load. If cavity opened (\np{ln\_isfcav}~=~true) these 2 terms can be 658 calculated by setting \np{ln\_dynhpg\_isf}~=~true. No other scheme are working with the ice shelf.\\ 659 660 $\bullet$ The main hypothesis to compute the ice shelf load is that the ice shelf is in an isostatic equilibrium. 661 The top pressure is computed integrating from surface to the base of the ice shelf a reference density profile 662 (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. 663 This top pressure is constant over time. A detailed description of this method is described in \citet{Losch2008}.\\ 664 665 $\bullet$ The ocean load is computed using the expression \eqref{Eq_dynhpg_sco} described in \ref{DYN_hpg_sco}. 666 A treatment of the partial cell for top and bottom similar to the one described in \ref{DYN_hpg_zps} is done 667 to reduce the residual circulation generated by the top partial cell. 656 668 657 669 %-------------------------------------------------------------------------------------------------------------- -
branches/2015/nemo_v3_6_STABLE/DOC/TexFiles/Chapters/Chap_SBC.tex
r6275 r6317 924 924 \namdisplay{namsbc_isf} 925 925 %-------------------------------------------------------------------------------------------------------- 926 Namelist variable in \ngn{namsbc}, \np{nn\_isf}, control the kind ofice shelf representation used.926 Namelist variable in \ngn{namsbc}, \np{nn\_isf}, controls the ice shelf representation used. 927 927 \begin{description} 928 928 \item[\np{nn\_isf}~=~1] 929 The ice shelf cavity is represented. The fwf and heat flux are computed. 930 Full description, sensitivity and validation in preparation. 929 The ice shelf cavity is represented. The fwf and heat flux are computed. Two different bulk formula are available: 930 \begin{description} 931 \item[\np{nn\_isfblk}~=~1] 932 The bulk formula used to compute the melt is based the one described in \citet{Hunter2006}. 933 This formulation is based on a balance between the upward ocean heat flux and the latent heat flux at the ice shelf base. 934 935 \item[\np{nn\_isfblk}~=~2] 936 The bulk formula used to compute the melt is based the one described in \citet{Jenkins1991}. 937 This formulation is based on a 3 equations formulation (a heat flux budget, a salt flux budget 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} 931 958 932 959 \item[\np{nn\_isf}~=~2] … … 934 961 The fwf is distributed along the ice shelf edge between the depth of the average grounding line (GL) 935 962 (\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). 936 Furthermore the fwf iscomputed using the \citet{Beckmann2003} parameterisation of isf melting.963 Furthermore the fwf and heat flux are computed using the \citet{Beckmann2003} parameterisation of isf melting. 937 964 The effective melting length (\np{sn\_Leff\_isf}) is read from a file. 938 965 939 966 \item[\np{nn\_isf}~=~3] 940 967 A simple parameterisation of isf is used. The ice shelf cavity is not represented. 941 The fwf (\np{sn\_rnfisf}) is distributed along the ice shelf edge between the depth of the average grounding line (GL)942 (\np{sn\_depmax\_isf}) and the base of the ice shelf along the calving front (\np{sn\_depmin\_isf}). 943 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 $Q_h = fwf \times L_f$. 944 971 945 972 \item[\np{nn\_isf}~=~4] 946 The ice shelf cavity is represented. However, the fwf (\np{sn\_fwfisf}) and heat flux (\np{sn\_qisf}) are947 not computed but specified from file. 973 The ice shelf cavity is opened. However, the fwf is not computed but specified from file \np{sn\_fwfisf}). 974 The heat flux ($Q_h$) is computed as $Q_h = fwf \times L_f$.\\ 948 975 \end{description} 949 976 950 \np{nn\_isf}~=~1 and \np{nn\_isf}~=~2 compute a melt rate based on the water masse properties, ocean velocities and depth. 951 This flux is thus highly dependent of the model resolution (horizontal and vertical), realism of the water masse onto the shelf ... 952 953 \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. 954 977 978 $\bullet$ \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. 955 983 This can be usefull if the water masses on the shelf are not realistic or the resolution (horizontal/vertical) are too 956 coarse to have realistic melting or for sensitivity studies where you want to control your input. 957 Full description, sensitivity and validation in preparation. 958 959 There is 2 ways to apply the fwf to NEMO. The first possibility (\np{ln\_divisf}~=~false) applied the fwf 960 and heat flux directly on the salinity and temperature tendancy. The second possibility (\np{ln\_divisf}~=~true) 961 apply the fwf as for the runoff fwf (see \S\ref{SBC_rnf}). The mass/volume addition due to the ice shelf melting is, 962 at each relevant depth level, added to the horizontal divergence (\textit{hdivn}) in the subroutine \rou{sbc\_isf\_div} 963 (called from \mdl{divcur}). 984 coarse to have realistic melting or for studies where you need to control your heat and fw input.\\ 985 986 Two namelist parameters control how the heat and fw fluxes are passed to NEMO: \np{rn\_hisf\_tbl} and \np{ln\_divisf} 987 \begin{description} 988 \item[\np{rn\_hisf\_tbl}] is the top boundary layer thickness as defined in \citet{Losch2008}. 989 This parameter is only used if \np{nn\_isf}~=~1 or \np{nn\_isf}~=~4 990 It allows you to control over which depth you want to spread the heat and fw fluxes. 991 992 If \np{rn\_hisf\_tbl} = 0.0, the fluxes are put in the top level whatever is its tickness. 993 994 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). 995 996 \item[\np{ln\_divisf}] is a flag to apply the fw flux as a volume flux or as a salt flux. 997 998 \np{ln\_divisf}~=~true applies the fwf as a volume flux. This volume flux is implemented with in the same way as for the runoff. 999 The fw addition due to the ice shelf melting is, at each relevant depth level, added to the horizontal divergence 1000 (\textit{hdivn}) in the subroutine \rou{sbc\_isf\_div}, called from \mdl{divcur}. 1001 See the runoff section \ref{SBC_rnf} for all the details about the divergence correction. 1002 1003 \np{ln\_divisf}~=~false applies the fwf and heat flux directly on the salinity and temperature tendancy. 1004 1005 \item[\np{ln\_conserve}] is a flag for \np{nn\_isf}~=~1. A conservative boundary layer scheme as described in \citet{Jenkins2001} 1006 is used if \np{ln\_conserve}=true. It takes into account the fact that the melt water is at freezing T and needs to be warm up to ocean temperature. 1007 It is only relevant for \np{ln\_divisf}~=~false. 1008 If \np{ln\_divisf}~=~true, \np{ln\_conserve} has to be set to false to avoid a double counting of the contribution. 1009 1010 \end{description} 964 1011 % 965 1012 % ================================================================ -
branches/2015/nemo_v3_6_STABLE/DOC/TexFiles/Chapters/Chap_TRA.tex
r6275 r6317 641 641 $\bullet$ \textit{rnf}, the mass flux associated with runoff 642 642 (see \S\ref{SBC_rnf} for further detail of how it acts on temperature and salinity tendencies) 643 644 $\bullet$ \textit{fwfisf}, the mass flux associated with ice shelf melt, (see \S\ref{SBC_isf} for further details 645 on how the ice shelf melt is computed and applied).\\ 643 646 644 647 In the non-linear free surface case (\key{vvl} is defined), the surface boundary condition … … 1280 1283 I've changed "derivative" to "difference" and "mean" to "average"} 1281 1284 1282 With partial bottom cells (\np{ln\_zps}=true), in general, tracers in horizontally1285 With partial cells (\np{ln\_zps}=true) at bottom and top (\np{ln\_isfcav}=true), in general, tracers in horizontally 1283 1286 adjacent cells live at different depths. Horizontal gradients of tracers are needed 1284 1287 for horizontal diffusion (\mdl{traldf} module) and for the hydrostatic pressure 1285 1288 gradient (\mdl{dynhpg} module) to be active. 1286 1289 \gmcomment{STEVEN from gm : question: not sure of what -to be active- means} 1290 1287 1291 Before taking horizontal gradients between the tracers next to the bottom, a linear 1288 1292 interpolation in the vertical is used to approximate the deeper tracer as if it actually … … 1360 1364 \gmcomment{gm : this last remark has to be done} 1361 1365 %%% 1366 1367 If under ice shelf seas opened (\np{ln\_isfcav}=true), the partial cell properties 1368 at the top are computed in the same way as for the bottom. Some extra variables are, 1369 however, computed to reduce the flow generated at the top and bottom if $z*$ coordinates activated. 1370 The extra variables calculated and used by \S\ref{DYN_hpg_isf} are: 1371 1372 $\bullet$ $\overline{T}_k^{\,i+1/2}$ as described in \eqref{Eq_zps_hde} 1373 1374 $\bullet$ $\delta _{i+1/2} Z_{T_k} = \widetilde {Z}^{\,i}_{T_k}-Z^{\,i}_{T_k}$ to compute 1375 the pressure gradient correction term used by \eqref{Eq_dynhpg_sco} in \S\ref{DYN_hpg_isf}, 1376 with $\widetilde {Z}_{T_k}$ the depth of the point $\widetilde {T}_{k}$ in case of $z^*$ coordinates 1377 (this term = 0 in z-coordinates) -
branches/2015/nemo_v3_6_STABLE/DOC/TexFiles/Chapters/Chap_ZDF.tex
r6306 r6317 857 857 % Bottom Friction 858 858 % ================================================================ 859 \section [Bottom and top Friction (\textit{zdfbfr})] {BottomFriction (\mdl{zdfbfr} module)}859 \section [Bottom and Top Friction (\textit{zdfbfr})] {Bottom and Top Friction (\mdl{zdfbfr} module)} 860 860 \label{ZDF_bfr} 861 861 … … 865 865 866 866 Options to define the top and bottom friction are defined through the \ngn{nambfr} namelist variables. 867 The top friction is activated only if the ice shelf cavities are opened (\np{ln\_isfcav}~=~true). 868 As the friction processes at the top and bottom are the represented similarly, only the bottom friction is described in detail. 867 The bottom friction represents the friction generated by the bathymetry. 868 The top friction represents the friction generated by the ice shelf/ocean interface. 869 As the friction processes at the top and bottom are represented similarly, only the bottom friction is described in detail below.\\ 870 869 871 870 872 Both the surface momentum flux (wind stress) and the bottom momentum
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