Evaluation of Arctic and Antarctic Sea Ice
This project is funded by NOAA
Given the short duration of the RAPID Proposals for Analysis of Climate Model Simulations for the IPCC AR5 (one year) we will limit our tasks to three achievable objective.
- Assess seasonal and interannual variability and trends in CMIP5 Arctic and Antarctic sea ice extent and mass budgets and how these compare with the observational record
- For models with ice age tracers (e.g. NCAR CCSM4), assess interannual variability and trends in ice age and how these compare with the observational record
- Assess mechanisms responsible for projected Arctic sea ice change and its inter-model scatter through analysis of 21st century mass balances and its relationship with changes in thermodynamic and dynamic processes
Stroeve et al.  previously investigated sea ice model output from models participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). The study noted that while all models realistically capture the climatological mean and seasonal cycle of Arctic sea ice as shown in a previous study [Zhang and Walsh, 2006], none of the models or individual model simulations show trends as large as observed over the period of reliable observations (1953-present). Even accounting for annual-to-decadal variability in both observed and modeled trends, the AR4 models as a group were found to be too conservative regarding the loss rate, and the date at which a seasonally ice free Arctic Ocean may be realized. This has become even more apparent after the last four years of continued record low ice extents.
We plan to repeat the study of Stroeve et al.  using the latest model data for the IPCC Fifth Assessment Report (AR5). Besides investigating trends in the modeled sea ice extent and how these compare with those in the observational record, we will also evaluate sea ice mass budgets for the 20th century and projected changes through the 21st century. Comparisons with limited amount of observational ice thickness data will be made, and models that incorporate ice age tracers will be compared with the Maslanik et al.  ice age product. Differences in modeled values of the ice extent and mass budgets will be then evaluated in terms of their thermodynamic and dynamic contributions.
Stroeve, J. C., V. Kattsov, A. Barrett, M. Serreze, T. Pavlova, M. Holland, and W. N. Meier. 2012. Trends in Arctic sea ice extent from CMIP5, CMIP3 and observations. Geophysical Research Letters 39(16), doi:10.1029/2012GL052676.
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