Changeset 6006 for branches/2015/dev_MetOffice_merge_2015/DOC

Timestamp:

2015-12-04T17:56:07+01:00 (9 years ago)

Author:

mathiot

Message:

Merged ice sheet coupling branch

Location:

branches/2015/dev_MetOffice_merge_2015/DOC/TexFiles

Files:

• Chapters/Chap_DOM.tex (modified) (1 diff)
• Chapters/Chap_SBC.tex (modified) (1 diff)
• Namelist/namdom (modified) (1 diff)
• Namelist/namrun (modified) (1 diff)
• Namelist/namsbc_iscpl (copied) (copied from branches/NERC/dev_r5589_is_oce_cpl/DOC/TexFiles/Namelist/namsbc_iscpl)

branches/2015/dev_MetOffice_merge_2015/DOC/TexFiles/Chapters/Chap_DOM.tex

@@ -498 +498 @@
 Contrary to the horizontal grid, the vertical grid is computed in the code and no 
 provision is made for reading it from a file. The only input file is the bathymetry 
-(in meters) (\ifile{bathy\_meter}) 
+(in meters) (\ifile{bathy\_meter}). 
 \footnote{N.B. in full step $z$-coordinate, a \ifile{bathy\_level} file can replace the 
 \ifile{bathy\_meter} file, so that the computation of the number of wet ocean point 
 in each water column is by-passed}. 
+If \np{ln\_isfcav}~=~true, an extra file input file describing the ice shelf draft 
+(in meters) (\ifile{isf\_draft\_meter}) is needed and all the location where the isf cavity thinnest
+ than \np{rn\_isfhmin} meters are grounded (ie masked). 
+
 After reading the bathymetry, the algorithm for vertical grid definition differs 
 between the different options:

branches/2015/dev_MetOffice_merge_2015/DOC/TexFiles/Chapters/Chap_SBC.tex

@@ -996 +996 @@
  at each relevant depth level, added to the horizontal divergence (\textit{hdivn}) in the subroutine \rou{sbc\_isf\_div} 
 (called from \mdl{divcur}). 
+
+\section{ Ice sheet coupling}
+\label{SBC_iscpl}
+%------------------------------------------namsbc_iscpl----------------------------------------------------
+\namdisplay{namsbc_iscpl}
+%--------------------------------------------------------------------------------------------------------
+Ice sheet/ocean coupling is done through file exchange at the restart step. NEMO, at each restart step, 
+read the bathymetry and ice shelf draft variable in a netcdf file. 
+If \np{ln\_iscpl = ~true}, the isf draft is assume to be different at each restart step 
+with potentially some new wet/dry cells due to the ice sheet dynamics/thermodynamics.
+The wetting and drying scheme applied on the restart is very simple and described below for the 6 different cases:
+\begin{description}
+\item[Thin a cell down:]
+   T/S/ssh are unchanged and U/V in the top cell are corrected to keep the barotropic transport (bt) constant ($bt_b=bt_n$).
+\item[Enlarge  a cell:]
+   See case "Thin a cell down"
+\item[Dry a cell:]
+   mask, T/S, U/V and ssh are set to 0. Furthermore, U/V into the water column are modified to satisfy ($bt_b=bt_n$).
+\item[Wet a cell:] 
+   mask is set to 1, T/S is extrapolated from neighbours, $ssh_n = ssh_b$ and U/V set to 0. If no neighbours along i,j and k, T/S/U/V and mask are set to 0.
+\item[Dry a column:]
+   mask, T/S, U/V are set to 0 everywhere in the column and ssh set to 0.
+\item[Wet a column:]
+   set mask to 1, T/S is extrapolated from neighbours, ssh is extrapolated from neighbours and U/V set to 0. If no neighbour, T/S/U/V and mask set to 0.
+\end{description}
+The extrapolation is call \np{nn\_drown} times. It means that if the grounding line retreat by more than \np{nn\_drown} cells between 2 coupling steps,
+ the code will be unable to fill all the new wet cells properly. The default number is set up for the MISOMIP idealised experiments.\\
+This coupling procedure is able to take into account grounding line and calving front migration. However, it is a non-conservative processe. 
+This could lead to a trend in heat/salt content and volume. In order to remove the trend and keep the conservation level as close to 0 as possible,
+ a simple conservation scheme is available with \np{ln\_hsb = ~true}. The heat/salt/vol. gain/loss is diagnose, as well as the location. 
+Based on what is done on sbcrnf to prescribed a source of heat/salt/vol., the heat/salt/vol. gain/loss is removed/added,
+ over a period of \np{rn\_fiscpl} time step, into the system. 
+So after \np{rn\_fiscpl} time step, all the heat/salt/vol. gain/loss due to extrapolation process is canceled.\\
+
+As the before and now fields are not compatible (modification of the geometry), the restart time step is prescribed to be an euler time step instead of a leap frog and $fields_b = fields_n$.
 %
 % ================================================================

branches/2015/dev_MetOffice_merge_2015/DOC/TexFiles/Namelist/namdom

@@ -6 +6 @@
    nn_msh      =    0      !  create (=1) a mesh file or not (=0)
    rn_hmin     =   -3.     !  min depth of the ocean (>0) or min number of ocean level (<0)
+   rn_isfhmin  =    1.00   !  treshold (m) to discriminate grounding ice to floating ice
    rn_e3zps_min=   20.     !  partial step thickness is set larger than the minimum of
    rn_e3zps_rat=    0.1    !  rn_e3zps_min and rn_e3zps_rat*e3t, with 0<rn_e3zps_rat<1

branches/2015/dev_MetOffice_merge_2015/DOC/TexFiles/Namelist/namrun

@@ -15 +15 @@
    cn_ocerst_in  = "restart"   !  suffix of ocean restart name (input)
    cn_ocerst_out = "restart"   !  suffix of ocean restart name (output)
+   ln_iscpl    = .false.   !  cavity evolution forcing or coupling to ice sheet model (ln_iscpl = T => namsbc_iscpl)
    nn_istate   =       0   !  output the initial state (1) or not (0)
    nn_stock    =    5475   !  frequency of creation of a restart file (modulo referenced to 1)