[[PageOutline]] Last edited [[Timestamp]] [[BR]] '''Author''' : Mathiot '''ticket''' : #1331 '''Branch''' : [https://forge.ipsl.jussieu.fr/nemo/browser/branches/2014/dev_r4650_UKMO2_ice_shelves dev_r4650_UKMO2_ice_shelves ] ---- === Description === '''Dynamics for the top layer beneath the ice shelves:''' - top partial step - top friction (same option as for the bottom friction) - Correction of the divergence locally (as for runoff fresh water flux) '''Thermodynamics used to compute the melt rate:''' - ISOMIP formulation (2 equation formulation) - 3 equation formulation (Jenkins et al. 1991) - Forcing mode (prescribed melt rate) is available. - Losh top boundary layer (Losch et al., 2008) '''Validation configuration:''' ISOMIP ISOMIP is a closed rectangular basin of uniform depth 900 m, spanning 15° of longitude, and latitudes 80° South to 70° South. The whole basin is covered with an ice shelf, with the ice draft rising linearly from 700 m at 80° South to 200 m at 76° South, and remaining constant at 200 m from 76° South to 70° South. The geometry is uniform in the east-west direction. The vertical coordinates is z . All the model setup and geometry is fully described in J.R. Hunter, 2006. '''Bibliography:''' - Hunter, J.R.: Specification for test models of ice shelf cavities, technical report, Antarctic Climate & Ecosystems Cooperative Research centre, version 7, 2006. - Jenkins, A., Hellmer, H.H. and D.H. Holland: The Role of Meltwater Advection in the Formulation of Conservative Boundary Conditions at an Ice–Ocean Interface, Journal of physical oceanography, 31, 2001. - Losch, M. Modeling ice shelf cavities in a z coordinate ocean general circulation model Journal of Geophysical Research: Oceans, 2008, 113 '''Reviewers:''' - '''System reviewer:''' Andrew Coward - '''Science reviewer:''' Gurvan Madec ---- === Testing === Testing could consider (where appropriate) other configurations in addition to NVTK]. ||NVTK Tested||!'''YES/NO!'''|| ||Other model configurations||!'''YES/NO!'''|| ||Processor configurations tested||'''YES'''|| ||If adding new functionality please confirm that the [[BR]]New code doesn't change results when it is switched off [[BR]]and !''works!'' when switched on||!'''YES/NO/NA!'''|| (Answering UNSURE is likely to generate further questions from reviewers.) 'Please add further summary details here' * Processor configurations tested: 1x8; 8x1; 1x1; 8x4; 4x8; in ISOMIP configuration (12 steps) * Volume conservation test: - configuration ISOMIP vvl after 1 year: volume ssh variation (km3) = ~1e-13 and vol trend (surface forcing (km3)) = 0.0 - configuration ISOMIP novvl after 1 year: volume ssh variation (km3) = ~1e-15 and vol trend (surface forcing (km3)) = 0.0 === Bit Comparability === ||Does this change preserve answers in your tested standard configurations (to the last bit) ?||'''NO'''|| ||Does this change bit compare across various processor configurations. (1xM, Nx1 and MxN are recommended)||'''YES''' in ISOMIP configuration (not yet tested for the other configurations)|| ||Is this change expected to preserve answers in all possible model configurations?||'''NO'''|| ||Is this change expected to preserve all diagnostics? [[BR]]!,,!''Preserving answers in model runs does not necessarily imply preserved diagnostics. !''||'''NO'''|| If you answered !'''NO!''' to any of the above, please provide further details: * Which routine(s) are causing the difference? This have been only tested in GYRE configuration with bump at the bottom and ln_zps activated. - domzgr.F90: For ice shelves, I need to define the the e3t/u/v/w=zt/u/v/w(k+1) - zt/u/v/w(k). If not, dep3w(i,j,k) (could be) .NE. dep3w(i,j+1,k) in the full wet cell beneath the ice shelf. - zpshde.F90 - dynhpg.F90 * Why the changes are not protected by a logical switch or new section-version? * What is needed to achieve regression with the previous model release (e.g. a regression branch, hand-edits etc). If this is not possible, explain why not. - domzgr.F90: Need to replace definition of gdep3w_0, e3uw_0 and e3vw_0, and e3t_1d and e3w_1d by the reference 3.6 version code - zpshde.F90: The easiest thing to do is to keep the header and the variable definition. - dynhpg.F90: The easiest thing to do is to replace this routine by the reference 3.6 version. * What do you expect to see occur in the test harness jobs? * Which diagnostics have you altered and why have they changed?Please add details here........ - sst and sss are now define as the temperature of the first wet cell. In case of ice shelf it is the cell at the ice/ocean interface. ---- === System Changes === || Does your change alter namelists? || '''YES''' || || Does your change require a change in compiler options? || '''NO''' || If any of these apply, please document the changes required here....... Namelist changes: {{{ !----------------------------------------------------------------------- &namsbc ! Surface Boundary Condition (surface module) !----------------------------------------------------------------------- nn_isf = 1 ! 0=no isf / 1 = presence of ISF / 2 = bg03 parametrisation / 3 = rnf file for isf / 4 = prescribed melt rate / !----------------------------------------------------------------------- &namsbc_isf ! Top boundary layer (ISF) !----------------------------------------------------------------------- ! ! file name ! frequency (hours) ! variable ! time interpol. ! clim ! 'yearly'/ ! weights ! rotation ! ! ! ! (if <0 months) ! name ! (logical) ! (T/F) ! 'monthly' ! filename ! pairing ! ! nn_isf == 4 sn_qisf = 'rnfisf' , -12 ,'sohflisf', .false. , .true. , 'yearly' , '' , '' sn_fwfisf = 'rnfisf' , -12 ,'sowflisf', .false. , .true. , 'yearly' , '' , '' ! nn_isf == 3 sn_rnfisf = 'runoffs' , -12 ,'sofwfisf', .false. , .true. , 'yearly' , '' , '' ! nn_isf == 2 and 3 sn_depmax_isf = 'runoffs' , -12 ,'sozisfmax' , .false. , .true. , 'yearly' , '' , '' sn_depmin_isf = 'runoffs' , -12 ,'sozisfmin' , .false. , .true. , 'yearly' , '' , '' ! nn_isf == 2 sn_Leff_isf = 'rnfisf' , 0 ,'Leff' , .false. , .true. , 'yearly' , '' , '' ! for all case ln_divisf = .true. ! apply isf melting as a mass flux or in the salinity trend. (maybe I should remove this option as for runoff?) ! only for nn_isf = 1 or 2 rn_gammat0 = 1.0e-4 ! gammat coefficient used in blk formula rn_gammas0 = 1.0e-4 ! gammas coefficient used in blk formula ! only for nn_isf = 1 nn_isfblk = 1 ! 1 ISOMIP ; 2 conservative (3 equation formulation, Jenkins et al. 1991 ??) rn_hisf_tbl = 30. ! thickness of the top boundary layer (Losh et al. 2008) ! 0 => thickness of the tbl = thickness of the first wet cell ln_conserve = .true. ! conservative case (take into account meltwater advection) nn_gammablk = 0 ! 0 = cst Gammat (= gammat/s) ! 1 = velocity dependend Gamma (u* * gammat/s) (Jenkins et al. 2010) ! if you want to keep the cd as in global config, adjust rn_gammat0 to compensate ! 2 = velocity and stability dependent Gamma Holland et al. 1999 / !----------------------------------------------------------------------- &nambfr ! bottom/top friction !----------------------------------------------------------------------- rn_tfri1 = 4.e-4 ! top drag coefficient (linear case) rn_tfri2 = 2.5e-3 ! top drag coefficient (non linear case). Minimum coeft if ln_loglayer=T rn_tfri2_max = 1.e-1 ! max. top drag coefficient (non linear case and ln_loglayer=T) rn_tfeb2 = 0.0 ! top turbulent kinetic energy background (m2/s2) rn_tfrz0 = 3.e-3 ! top roughness [m] if ln_loglayer=T ln_tfr2d = .false. ! horizontal variation of the top friction coef (read a 2D mask file ) rn_tfrien = 50. ! local multiplying factor of tfr (ln_tfr2d=T) / }}} ---- === Resources === !''Please !''summarize!'' any changes in runtime or memory use caused by this change......!'' ---- === IPR issues === ||Has the code been wholly (100%) produced by NEMO developers staff working exclusively on NEMO?||!'''YES/ NO !'''|| If No: * Identify the collaboration agreement details * Ensure the code routine header is in accordance with the agreement, (Copyright/Redistribution etc).Add further details here if required..........