An ice sheet model validation framework for the Greenland ice sheet
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Univ. of South Florida, Tampa, FL (United States)
- The Ohio State Univ., Columbus, OH (United States)
- NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
- NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Science, Systems, and Applications, Inc., Lanham, MD (United States)
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Sigma Space Corp., Lanham, MD (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Univ. of Utrecht (Netherlands)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Here, we propose a new ice sheet model validation framework – the Cryospheric Model Comparison Tool (CmCt) – that takes advantage of ice sheet altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice sheet. We use realistic simulations performed with the Community Ice Sheet Model (CISM) along with two idealized, non-dynamic models to demonstrate the framework and its use. Dynamic simulations with CISM are forced from 1991 to 2013, using combinations of reanalysis-based surface mass balance and observations of outlet glacier flux change. We propose and demonstrate qualitative and quantitative metrics for use in evaluating the different model simulations against the observations. We find that the altimetry observations used here are largely ambiguous in terms of their ability to distinguish one simulation from another. Based on basin-scale and whole-ice-sheet-scale metrics, we find that simulations using both idealized conceptual models and dynamic, numerical models provide an equally reasonable representation of the ice sheet surface (mean elevation differences of < 1 m). This is likely due to their short period of record, biases inherent to digital elevation models used for model initial conditions, and biases resulting from firn dynamics, which are not explicitly accounted for in the models or observations. On the other hand, we find that the gravimetry observations used here are able to unambiguously distinguish between simulations of varying complexity, and along with the CmCt, can provide a quantitative score for assessing a particular model and/or simulation. The new framework demonstrates that our proposed metrics can distinguish relatively better from relatively worse simulations and that dynamic ice sheet models, when appropriately initialized and forced with the right boundary conditions, demonstrate a predictive skill with respect to observed dynamic changes that have occurred on Greenland over the past few decades. Lastly, an extensible design will allow for continued use of the CmCt as future altimetry, gravimetry, and other remotely sensed data become available for use in ice sheet model validation.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR); USDOE Office of Science (SC), Biological and Environmental Research (BER); National Aeronautics and Space Administration (NASA)
- Grant/Contract Number:
- AC05-00OR22725; AC52-06NA25396; NNX11AR47G; ANT-0424589; AC02-05CH11231
- OSTI ID:
- 1340442
- Alternate ID(s):
- OSTI ID: 1345150
- Report Number(s):
- LA-UR-16-22797; KP1703020; ERKP814
- Journal Information:
- Geoscientific Model Development, Vol. 10; ISSN 1991-959X
- Publisher:
- European Geosciences UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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