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AJahn - Observational Large Scale Sea Ice Modeling Needs


Observational Large Scale Sea Ice Modeling Needs
- Alexandra Jahn, Marika Holland and Jennifer Kay, NCAR, USA

Observations of sea ice are used in several ways for large-scale sea ice models: for model and parameterization development, for climate simulation skill evaluation and model testing, for model intercomparisons (CMIP3/5), and for model weighting. While in situ observations are needed for model development and parameterization development, large-scale gridded long-term (>10 years) observations are needed for all other purposes. Currently sea ice extent is the most widely used quantitative metric to evaluate model skill and to discriminate between models. Sea ice thickness from ICESat is a new quantitative variable that has started to be used more frequently, and which provides many added benefits to sea ice extent alone. In the future we hope to use many more sea ice variables for quantitative model development and evaluation purposes.

Several datasets are highly desired by modelers, including snow thickness on sea ice, derivates of sea ice variables (e.g. sea ice formation and melt rates in addition to thickness), ocean-ice and ice-atmosphere fluxes, and ice volume fluxes through gates. Other gridded sea ice datasets like sea ice age and velocity already exist but are underutilized because of difficulties with the definition of variables in observations and models, difficulties because of the grids the data is on, and/or the availability of the datasets. This highlights the important roles of data availability and data documentation, which are crucial for data to be used for model evaluation and development. The NCAR Climate Data guide ( is one place where observationalists can document data suitable for climate model comparisons and can highlight the key strengths and limitations of the dataset. While new sea ice datasets are always welcome, better documentation and the improved availability of existing data sets could already help a lot to improve large-scale sea ice models. In the future we hope to be able to use more quantitative metrics for model development and evaluation, rather than relying primarily on sea ice extent metrics and expert judgment for the other sea ice parameters.

Presentation given at the CliC Sea Ice Modeling and Observing Workshop held at the Fram Centre in Tromsø, Norway from 5 - 7 June 2013.

(Media / 2012-Boundary-Layer-Workshop-Report)
The atmosphere-ocean boundary layer in which sea ice resides includes many complex processes that require a more realistic treatment in GCMs, particularly as models move toward full earth system descriptions. The primary purpose of the workshop was to define and discuss such coupled processes...
2008-01 No. 10 Ice and Climate News
(Media / 2008-01 No. 10 Ice and Climate News)
- CliC Scientific Steering Group (comings and goings) - Atmosphere-Ocean General Circulation Models - Global Prediction: Permafrost - Operational Sea-Ice Analysis and Forecasting at - Arctic Council Climate and Cryosphere Project - Seasonal Forecast of Antarctic Sea Ice - The Global...
1995-December: ACSYS Arctic Forecast
(Media / 1995-December: ACSYS Arctic Forecast)
1. Introduction to ACSYS 2. Sea-Ice Modelling Workshop 3. SSG-IV Toronto, Canada 4. Arctic Run-off Database 5. Solid Precipitation Workshop

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