A brief history of PISM

Before 2001:

• First approach of a (nominally Antarctic) ice-sheet model by Craig Lingle
• Elena Suleimani (née Troshina) improves model based on Mahaffey’s equations and other numerical methods
• Accuracy test against the analytical solution for a circular ice cap on a flat bed with constant accumulation and for CLIMAP reconstruction of the Antarctic ice sheet (20 kyr BP)
• Model equations transformed to forms with a stretched vertical coordinate in Fortran 90 (3-D temperature equation not stable yet)
• First paper on “Relative magnitudes of shear and longitudinal strain rates in the inland Antarctic ice sheet, and response to increasing accumulation” by Lingle and Troshina (1998)

2001: A team forms

• Lingle attends talk by Ed Bueler on heat equations on manifolds with potential application to glacier models
• Short course by Lingle on glaciological basics, with Bueler, Latrice Bowman, Jed Brown, and Dave Covey in attendance at various points
• Application for NASA model-development funding with Bueler and Covey as Co-Is, to build an Antarctic model which added thermo-mechanical coupling and ice-shelf dynamics to the existing Fortran model, as a modeling component (sub-grant) of the U Kansas “Polar Radar for Ice Sheet Measurements” (PRISM) project
• Paper on understanding numerical models by checking them against exact predictions (solutions) of the differential equations: Bueler et al. (2005)
• Bowman first graduate student to work on ice flow with Bueler

2003: PETSc and C++ … and PISM

• Brown (as undergraduate) reports about PETSc library that allows to work in parallel at a higher conceptual level, requiring switch to C++
• Brown and Bueler define object classes and rebuild isothermal SIA model, with under-development thermomechanical coupling code
• Bueler adds thermocoupling to the SIA with Brown and Lingle assistance, and emphasizing exact solutions to check: Bueler et al. (2007)
• Brown adds and tests a SSA solver in PISM, leading to successful MS project defense in August 2006
• NetCDF is adopted as the input/output format (instead of PETSc binary files that lack included and standardized metadata)
• Bueler suggests model name “the C-plus-plus Object-oriented Multi-Modal, Verifiable Numerical Ice Sheet Model”, a.k.a. COMMVNISM
• Brown proposes new name “Parallel Ice Sheet Model”, short PISM

2006: PISM goes public

• In September 2006, PISM is for the first time hosted publicly on Gna! with a GNU General Public License (later moved to Git and GitHub)

2007: PISM gets ice streams

• Application of SSA solver also to ice streams in near-Coulomb basal drag regime in thermo-coupled context after Bueler reading Schoof’s (2006) isothermal paper
• Convex combination of two reasonable stress-balance solutions (i.e. SIA+SSA)
• Participation in ISMIP-HEINO proves that SIA is not sufficient to balance transitions in boundary shear stress with “membrane stresses” within the ice, supporting SSA-everywhere approach and having ice streams in the model for the right reasons as the core of PISM
• Most cited PISM-related paper by Bueler and Brown (2009)

2008: New team

• New proposal to a NASA Modeling, Analysis, and Prediction call, based on a team of Bueler, Constantine Khroulev, mathematician David Maxwell, and glaciologists Martin Truffer and Regine Hock, is funded
• Khroulev starts in spring 2008 after finishing his MS Math, producing startlingly-complete Antarctic results in Fall 2008 at the WAIS conference
• Nearly-untuned results for Greenland match observations reasonably well

2008: PIK collaboration

• Anders Levermann and students (Maria Martin and Ricarda Winkelmann) from PIK come to Fairbanks to propose a collaboration in which they would add what PISM needed for applications to the Antarctic Ice Sheet (ability to move the calving front and the grounding line)
• Model description paper by Winkelmann et al. (2011)
• Andy Aschwanden is hired as an ARSC PostDoc in Fall 2009, implementing an enthalpy formulation

2011: PISM goes viral

• Torsten Albrecht from PIK visits UAF and works on merging code versions including calving parameterization (Levermann et al., 2012) and fracture formation processes (Albrecht & Levermann, 2012)

2012: Community building

• European PISM ice sheet modeling workshop in Hamburg, Germany
• Nick Golledge et al. (2012) apply PISM to Last Glacial Antarctica
• PISM participates in MISMIP
• PISM participates in SeaRISE (Antarctica and Greenland)
• PISM participates in LARMIP
• PISM participates in ice2sea MISMIP3d

2014: More processes

• Albrecht and Levermann implement fracture density approach based on continuum damage mechanics
• Florian Ziemen et al. use PISM coupled to a climate model
• Matthias Mengel and Levermann (2014) investigate threshold melting and tipping behavior in East Antarctica
• Bueler and W. van Pelt implement a subglacial hydrology scheme
• Johannes Feldmann et al. implement subgrid grounding-line interpolation

2015: Paleo and WAIS

• PISM participates in PLISMIP-ANT
• WAIS destabilization study by Feldmann and Levermann (2015)

2016: High resolution

• Aschwanden et al. (2016) run high-resolution simulations for the Greenland Ice Sheet

2017: Inversion

• Marijke Habermann et al. implement inversion scheme for basal yield stress

2018: MIPs and PICO

• Ronja Reese et al. implement PICO melt module, which is applied during Antarctic deglaciation (Kingslake, Scherer, Albrecht et al., 2018)
• PISM participates in initMIP (Greenland and Antarctica)
• PISM participates in SHMIP

2019: Projections

• Feedback of ice-shelf melt on global climate by Golledge et al. (2019)
• Projections of sea-level contribution from Greenland by Aschwanden et al. (2019)

2020: MIPs and Antarctic thresholds

• PISM participates in ABUMIP
• PISM participates in ISMIP6 (Antarctica and Greenland)
• PISM participates in LARMIP-2
• PISM participates in MISMIP+
• Tipping points and hysteresis behavior in Antarctica in a warming climate by Julius Garbe et al. (2020)
• Description of PISM (parameter sensitivities and boundary conditions) for paleo applications in Antarctica by Albrecht et al. (2020)

2021: Coupling

• Moritz Kreuzer et al. use PICO to couple PISM with ocean model MOM5
• Maria Zeitz et al. implement the surface melt module dEBM-simple