PISM 2.2.1 is out

Published: Mar 17, 2025 by The PISM Authors

We are pleased to announce the release of PISM v2.2.1.

Changes since v2.2.0

• Fixed a minor bug: EISMINT II simplified geometry experiments should use the "cold" (temperature-based) energy conservation model. In PISM 2.2.0 the EISMINT II default of energy.model was mistakenly set to "none", i.e. isothermal mode without energy conservation.

  To get correct behavior with PISM 2.2.0 run pism -energy cold -eisII \... instead of pism -eisII \....

Notable changes compared to v2.1

• All executables and scripts installed in the bin sub-directory of PISM's installation location start with "pism" to make it easier to recognize ones that belong to PISM, especially when using a .deb package to install it.
• Rename the pismr executable to pism.
• Remove the pismv executable. Use pism -test X to run a verification test X.
• Add some automatic testing on macOS.
• Use pkg-config to look for all the dependencies that support it.
• Add the CMake flag Pism_PKG_CONFIG_STATIC to tell CMake to use the \--static flag when using pkg-config. See issue 529(https://github.com/pism/pism/issues/529).
• Add VERSION to ensure that tarballs with PISM's sources (e.g. archived by Zenodo) contain appropriate version info.
• Update some examples in examples/marine.
• Fix an bug reported by Ken Mankoff: scripts in examples/antarctica/ required PISM built with PROJ.
• Add a section about citing PISM to the manual; remove redundant and possibly inconsistent recommendations elsewhere in PISM's docs.
• Add a section about publishing PISM results to the manual. This section covers archiving the code, model inputs and outputs, etc.
• Add the configuration parameter energy.model (choices: none, cold, enthalpy); remove energy.enabled and energy.temperature_based.
• All bed deformation models use the load averaged over the duration of the (usually long) bed deformation time step (see issue 525(https://github.com/pism/pism/issues/525)). This requires saving the time integral of the load since the last bed deformation update (variable bed_def_load_accumulator and the time of the last update time_bed_deformation) as a part of the model state and reading them when re-starting the model. Rename bed_deformation.lc.update_interval to bed_deformation.update_interval since now all bed deformation models use this parameter. Add a new diagnostic variable: bed_def_load, the load used during the last bed deformation update.
• Replace the serial connected component labeling algorithm with a parallel version (see pull request 547(https://github.com/pism/pism/pull/547) for details). This should improve strong scaling of the ocean model PICO and (less noticeably) of some other PISM components.
• Require CMake 3.16 or newer.
• Support the current PETSc version (3.22).
• Update the oldest supported PETSc version from 3.7 to 3.11. (PISM's code still works with PETSc 3.7 and newer, but testing with PETSc older than 3.11 requires Python 2.7.x, which is no longer supported.)
• Refactor the SSAFD solver, adding the ability to use PETSc's infrastructure to manage Picard iterations (and even use Newton iterations with a finite difference approximation of the Jacobian computed using coloring). Unfortunately this approach appears to be more fragile than the old one, so the default solver implementation remains the same. On the plus side, we get the ability to compute and save the SSAFD residual, which may help one analyze the quality of a velocity approximation produced by the SSAFD solver.
• Create a Debian (Ubuntu) PISM package. This work required a number of changes to follow best practices when installing software in a standard location. For example: Python scripts in util/ are installed in /usr/share/pism/bin.
• Add a configuration flag stress_balance.ssa.fd.upstream_surface_slope_approximation. If "yes" (the default), use the first order "upstream" (more accurately: "uphill") biased FD approximation. This reduces oscillations of velocity approximations produced by SSAFD in areas where the surface slope is large (e.g. near the grounding line).
• Add a new diagnostic quantity: ice_mass_transport_across_grounding_line (in Gt/year). This quantity is similar to the 2D grounding_line_flux, but designed to be easily comparable to tendency_of_ice_mass_due_to_discharge and similar.
• Use "kelvin" (lowercase "k") in all temperature units and implement other similar changes to make PISM output files compatible with conventions used by xarray.
• Add flexible re-projection and interpolation (including conservative interpolation) using YAC(https://dkrz-sw.gitlab-pages.dkrz.de/yac/index.html). This work makes it possible to set up a PISM simulation using a grid in one projection and read inputs from NetCDF files that use different grids and projections (with some limitations). This should reduce the amount of pre-processing needed to use bed topography data sets (such as BedMachine), regional climate model outputs, etc.
• Improve support for coordinate reference system specification following Climate and Forecasting conventions.
• Add the configuration parameter grid.file and remove options -x_range, -y_range and -refinement_factor. The parameter grid.file specifies the grid definition file used to set the coordinate reference system plus default domain and grid sizes. See the manual for details.
• Add configuration parameters grid.dx and grid.dy (command line options -dx and -dy). These parameters allow users to set the domain size and location (using the input file, grid.file or grid.Lx and grid.Ly) and then select the grid resolution to use on this domain. Note that grid.dx and grid.dy are in meters, but PISM will automatically convert to meters from units specified using command line options, e.g. -dx 5km. Domain half widths Lx and Ly are re-computed to ensure that PISM uses exactly the requested grid resolution (this may slightly reduce the domain size compared to Lx and Ly provided by the user).
• Remove support for NCAR's ParallelIO library since (as far as we know) no one uses it.