Documentation for PISM, the Parallel Ice Sheet Model

NEWS: PISM version 1.0 is out!

PISM v1.0

olympics-crop.jpg

Modeled ice flow speed on the Olympic Peninsula, Washington state, USA, for conditions near the LGM.

The Parallel Ice Sheet Model PISM v1.0 is open source and capable of high resolution. It has been widely adopted as a tool for doing science since 2011.

Features include:

Application of the Month

September 2017

Whether a “tipping point” will be reached in the next few centuries, in the dynamics of various parts of the Antarctic ice sheet (AIS) as it responds to a warming world, is the most difficult prediction question. It is an extreme challenge to models. How complete a model must be, so as to resolve the relevant behavior of the (real) dynamical system, is unknown. A negative result from modeling (i.e. no tipping points seen in model runs) has minimal value because a more-complete, or merely different, model may show a tipping point. Insisting that a model include all possibly-relevant mechanisms is unfeasible to the point of silliness.

Tipping-point questions can be asked about the past states of the AIS, though using existing observations to resolve these questions is extraordinarily difficult. This paper uses GCM/RCM and ice-sheet modeling to recreate conditions of the early to mid-Pliocene when atmospheric CO2 concentrations were similar to present day. The focus of PISM application is on modeling grounding-line motion, ice shelf basal melt near the grounding line, and basal sliding. A novel method here, relative to other AIS modeling literature, is an autocorrelation analysis of time series for (modeled) ice mass to find early-warning signs of impending tipping points. A precursor to tipping-point-type destabilization, proximately by classic marine-based ice-sheet retreat, appears to be prolonged surface lowering in response to warm air temperatures.

2017/09/17 12:40 · Ed Bueler

Latest News

PISM v1.0 is out

This release has substantial changes to the code base, but users will not see many large differences. The goal of most code changes was to improve modularity and usability, making PISM easier to use, maintain and extend.

User-visible changes include the following.

  • New mass transport code makes it easier to “balance the books”.
  • PISM's grids are no longer transposed (y,x versus x,y).
  • Adds an optimized implementation of the GPBLD flow law for the Glen n=3 case.
  • Adds von Mises calving.
  • Adds more diagnostic quantities (127 spatially-variable fields and 38 scalar variables in total).
  • Better code, better documentation, more regression and verification tests.

For a more complete list of changes since v0.7, please see CHANGES.rst in the source release.

If you already have a Git repository for PISM then upgrade by doing

git fetch origin
git checkout master

in the PISM source tree. (Or get a new tagged .tar.gz or .zip at github.com/pism/pism/releases.) Then run

make install

in the build directory.

Please see the Installation Manual for detailed instructions.

Help with installation and usage is available through uaf-pism@alaska.edu.

2017/10/19 18:16 · Constantine Khroulev

The blog for HPC provider Mellanox Technologies, which supplies fast interconnects for many supercomputers, features Andy Aschwanden's work using PISM for studying the Greenland Ice Sheet.

2017/08/29 09:50 · Ed Bueler

EGU Early Career Award for PISM-author Ricarda Winkelmann

Congratulations to Ricarda Winkelmann of the University of Potsdam for receiving the EGU's Outstanding Early Career Scientists Award in Cryospheric Sciences. Her involvement with ice sheet modeling started with a very cold trip to Fairbanks Alaska in November 2008, leading to a 2011 paper on the design of PISM-PIK which is one of the most-cited PISM papers. (PISM-PIK introduced new features for marine ice sheets which were merged into PISM itself a few years later.) The EGU citation on her work, which has mostly been on the impact of large ice masses on global sea level change, says her papers are a “testament to her exceptional clarity of thought and physical insight.” Search “Winkelmann” in the publications page for many examples.

2017/04/27 13:25 · Ed Bueler

New PISM user help email: uaf-pism@alaska.edu

The core team at UAF continues to support PISM users. The new email for help is uaf-pism@alaska.edu; it replaces help@pism-docs.org. As before, email to this address will be distributed to all the UAF developers, and so it will get the most prompt response year-round.

2017/02/21 20:47 · Ed Bueler

Team

PISM is jointly developed at the University of Alaska, Fairbanks (UAF) and the Potsdam Institute for Climate Impact Research (PIK). For more about the team see the UAF Developers and PIK Developers pages.

UAF developers, who are in the Glaciers Group at the GI, are supported by NASA's Modeling, Analysis, and Prediction and Cryospheric Sciences Programs (grants NAG5-11371, NNX09AJ38C, NNX13AM16G, NNX16AQ40G, NNX17AG65G) and by NSF grants PLR-1603799 and PLR-1644277.

home.txt · Last modified: 2017/11/26 19:47 by Ed Bueler
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