Documentation for PISM, a parallel Ice Sheet Model

NEWS: EGU Early Career Award for PISM-author Ricarda Winkelmann

The Parallel Ice Sheet Model pism0.7 is open source and capable of high resolution. It is widely adopted as a tool for doing science. Features include:

PISM Application of the Month

August 2017

After the surface slope and the ice thickness, which determine the effect of the body force of gravity (the driving stress), the basal thermal state of an ice sheet is the most important boundary condition determining the stresses on a flowing ice sheet. The basal thermal regime is, however, the integrated effect of flow history. To model it one must track viscous dissipation of flow, sliding friction, and geothermal input, and compute the balance. Whether the balance is just above (thawed, wet, and weak) or just below (frozen and strong) the freezing point is then critical to dynamical boundary condition.

The thermal state can only be observed directly at boreholes, which are few and biased toward cold, near-divide locations. To determine the basal temperature and melt rates for the Greenland Ice Sheet (GrIS), this paper combines a survey of observations, including borehole and less-direct observations (surface velocity, surface texture, and radiostratigraphy), with analysis of 3D thermomechanically-coupled model results from eight different models, including PISM, which participated in the SeaRISE assessment process. Such a synthesis has not been attempted before. Its conclusions about the distribution of melting conditions, such as the map at left, are much more likely to withstand scientific scrutiny than any individual model results or point measurements. The paper also delimits a specific large portion of GrIS, about one third by area, where additional observations would most improve knowledge of the basal thermal state.

2017/08/15 21:52 · Ed Bueler

Latest News

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.” Find “Winkelmann” in the publications page for 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

Study of Juneau Ice Field in Cambridge Core news

A recent PISM application Ziemen et al (2016) is covered by a news item in Cambridge Core news.

The 4000 square km ice field in Southeast Alaska is well-known and accessible since its outlets are in the suburbs of the Alaska state capital, Juneau. But climate data for the area are sparse.

Those model runs that agreed well with observations for 1971 to 2010 generated volume and area losses of more than half by 2099. While co-author Regine Hock (UAF) is quoted as saying “The massive icefield that feeds Alaska’s Mendenhall Glacier may be gone by 2200 if warming trend predictions hold true,”, the authors emphasize that spatially-distributed mass balance measurements and improved climate projections that resolve the local temperature and precipitation patterns are essential to solidifying these predictions.

2016/10/06 14:26 · Ed Bueler

PISM 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.

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