tindex.rst - pism - [fork] customized build of PISM, the parallel ice sheet model (tillflux branch) (HTM) git clone git://src.adamsgaard.dk/pism (DIR) Log (DIR) Files (DIR) Refs (DIR) LICENSE --- tindex.rst (3843B) --- 1 .. include:: ../../global.txt 2 3 .. _sec-simp: 4 5 Simplified geometry experiments 6 =============================== 7 8 There have been three stages of ice sheet model intercomparisons based on simplified 9 geometry experiments since the early 1990s :cite:`BuelerSpray`. 10 11 EISMINT I (European Ice Sheet Modeling INiTiative) :cite:`EISMINT96`\ [#]_ was the first of 12 these and involved only the isothermal shallow ice approximation (SIA). Both fixed margin 13 and moving margin experiments were performed in EISMINT I, and various conclusions were 14 drawn about the several numerical schemes used in the intercomparison. EISMINT I is 15 superceded, however, by verification using the full variety of known exact solutions to 16 the isothermal SIA :cite:`BLKCB`. The "rediscovery", since EISMINT I, of the Halfar similarity 17 solution with zero accumulation :cite:`Halfar83`, and verification runs using that solution, 18 already suffices to measure the isothermal SIA performance of PISM more precisely than 19 would be allowed by comparison to EISMINT I results. 20 21 EISMINT II :cite:`EISMINT00` pointed out interesting and surprising properties of the 22 thermocoupled SIA. References :cite:`BBL`, :cite:`Hindmarsh04`, :cite:`Hindmarsh06`, 23 :cite:`PayneBaldwin`, :cite:`SaitoEISMINT`, :cite:`BBssasliding` each interpret the 24 EISMINT II experiments and/or describe attempts to add more complete physical models to 25 "fix" the (perceived and real) shortfalls of ice sheet model behavior on EISMINT II 26 experiments. We believe that the discussion in :cite:`PayneDongelmans`, 27 :cite:`PayneBaldwin`, :cite:`BBL` adequately explains the "spokes" in EISMINT II 28 experiment F as a genuine fluid instability, while :cite:`Fowler01` and Appendix B of 29 :cite:`BBssasliding` adequately cautions against the continuum model that generates the 30 "spokes" in EISMINT II experiment H. Thus we can move on from that era of controversy. In 31 any case, PISM has built-in support for all of the published and unpublished EISMINT II 32 experiments; these are described in the next subsection. 33 34 The ISMIP (Ice Sheet Model Intercomparison Project) [#]_ round of intercomparisons covers 35 2008--2013 (at least). There are four components of ISMIP substantially completed, namely 36 HOM = Higher Order Models :cite:`ISMIPHOM`, :cite:`HOMelmer`, HEINO = Heinrich Event 37 INtercOmparison :cite:`GreveTakahamaCalov`, :cite:`Calovetal2009HEINOfinal`, MISMIP 38 (below), and MISMIP3d (also below). 39 40 PISM participated in HEINO, but this ability is unmaintained. We believe the continuum 41 problem described by HEINO, also used in EISMINT II experiment H (above), is not 42 meaningfully approximate-able because of a required discontinuous jump in the basal 43 velocity field. The continuum problem predicts infinite vertical velocity because of this 44 jump (:cite:`BBssasliding`, Appendix B). Details of the numerical schemes and their results are 45 irrelevant if the continuum model makes such a prediction. PISM offers the physical 46 continuum model described in :cite:`BBssasliding`, an SIA+SSA hybrid, as an alternative to the 47 continuum model used in ISMIP-HEINO and EISMINT II experiment H. Indeed the SIA+SSA hybrid 48 is offered as a unified shallow model for real ice sheets (section :ref:`sec-dynamics`). 49 50 There is no current plan to support ISMIP-HOM :cite:`ISMIPHOM`, :cite:`HOMelmer`, but 51 comparison of shallow PISM results to exact Stokes solutions is a goal for PISM 52 evaluation. 53 54 A third and fourth ISMIP parts are the two parts of the Marine Ice Sheet Model 55 Intercomparison Project, MISMIP :cite:`MISMIP2012` and MISMIP3D :cite:`MISMIP3d2013`. These 56 experiments are supported in PISM, as described in subsections :ref:`sec-MISMIP` and 57 :ref:`sec-MISMIP3d` below. 58 59 .. toctree:: 60 :caption: Intercomparison projects 61 62 eismint-2.rst 63 64 mismip.rst 65 66 mismip3d.rst 67 68 .. rubric:: Footnotes 69 70 .. [#] See |eismint-url| 71 72 .. [#] See |ismip-url|