1. The Polar Prediction Workshop, Oslo, Norway, 6-8 October 2010

2. Meteorologisk Institutt met.no 1. Background At its 15th session (November 2009), the WMO Commission of Atmospheric Sciences (CAS) recommended, as a legacy of the International Polar Year (IPY) to: Establish a THORPEX Polar Research project to improve understanding of the impact of polar processes on polar weather, the assimilation of data in Polar Regions, and the prediction of high impact weather over Polar Regions.

3. Meteorologisk Institutt met.no The Executive Council Panel of Experts on Polar Observations, Research, and Services (EC-PORS) recommended that efforts be made to further polar prediction for weather and climate and to extend efforts to snow, ice, carbon, and ecosystem modelling and analysis. This requires involvement from: –World Weather Research Programme (WWRP), including THORPEX, –the Global Atmospheric Watch (GAW), –and the World Climate Research Programme (WCRP) and support from WMO Members.

4. Meteorologisk Institutt met.no Improving Polar Predictions – General Recommendations Verification formal inter-comparison of polar predictions (pole-wards of 60 o N and 60 o S) using the existing WMO procedures and, if necessary, the adoption of new metrics for these comparisons need to be initiated strengthening of verification activity utilizing operational and research data bases such as the TIGGE data bases is needed Data Assimilation and Observation the establishment of the utility of existing surface based and satellite observations through data assimilation experiments (e.g. CONCORDIASI project) “data mining” to catalogue existing databases and reports – this may require the establishment (or nomination) of a few archive centres to manage IPY data and data from past campaigns there is a requirement for new observations for the Polar Regions

5. Meteorologisk Institutt met.no General Recommendations (ctd.) Predictability and Physical and Dynamical Processes There is an urgent need for concerted physical process studies which will need new field campaigns We need to establish well thought out numerical experiments with coupled models in the Polar Regions in collaboration with WCRP (CMIP5, SPARC) More efforts need to focus on research and development for coupled atmosphere–hydrological–cryosphere–surface modelling and observation

6. Meteorologisk Institutt met.no Scientific Challenges Assimilation must rely more on the use of satellites. most radiative channels used for satellite retrieval are for the free atmosphere, while near-surface and lower troposphere coverage is lacking the satellite data is more difficult to use over land and sea- ice than over the ocean due to snow covered (cold) surfaces when using data from microwave channels accurate values for sea-ice emissivity, penetration depth (into snow and ice) of microwave radiation, and a realistic first guess of surface temperature have all to be taken into account. There is a close link between the microphysical properties of the NWP model and successful satellite data retrieval.

7. Meteorologisk Institutt met.no Scientific Challenges (ctd.) The underlying surface and the need for surface– sea-ice coupled models : Need for an accurate and detailed description of the underlying surface in terms of ice, snow, leads, polynyas and tides and sea-ice characteristics and sea surface temperature There is a lack of observations and an understanding of the physical processes in Polar regions Other issues that were recognized as important for NWP are how to initialize (snow analysis) and how to treat blowing snow There is a need for detailed process studies and careful parameterizations supported by observations

8. Meteorologisk Institutt met.no Scientific Challenges (ctd.) Planetary Boundary Layer (PBL) parameterization including PBL clouds The Arctic offer significant challenges relative to the lower latitudes –semi-permanent Arctic inversion –very frequent occurrence of clouds peaking at more than 90% in summer –PBL schemes need to consider the presence of clouds, while in order to solve the polar cloud issue, one has to work on cross-cutting issues linked to the PBL, surface, microphysics, and radiation, as these processes are closely linked –to much stress (turbulence) in stable boundary layers in existing schemes –the lack of a spectral gap significantly complicates the parameterization problem as stability functions may have to depend on model resolution – our fundamental knowledge of cloud processes is highly limited, and we lack key observations to constrain even highly simplified cloud parameterizations –it is currently not known what determines the phase and mixture of clouds

9. Meteorologisk Institutt met.no Establishment of an IPY Legacy Project This legacy project should be based on a few NWP internationally coordinated polar initiatives (new or existing) A new IPY legacy project should tap into the scientific and human capacity of the National Meteorological and Hydrological Services (NMHSs) who have an interest in scientific, societal, and economic applications for Polar Regions and should include the participation of the WWRP (SERA, MFRWG, JVWG, NWG), THORPEX, and the WCRP (SPARC, CLIC, SOLAS) communities of scientists Additionally support for the observational component would be needed from: (GOS/WWW), (GAW), (GOOS), (WHYCOS), (GTOS – hydrological cycle parameters (GTN-H)), GCOS Terrestrial Network for Permafrost (GTN-P)), GCOS Terrestrial Network for Glaciers (GTN-G, – parameters of the cryosphere.

10. Meteorologisk Institutt met.no Establishment of a Joint International Polar Prediction Project Steering Group – A Proposal A Joint Polar Prediction Project, similar to the Year of Tropical Convection (YOTC) project, supported by WWRP, WCRP, and THORPEX should be established A Steering Group should be established First task: prepare an Implementation Plan consistent with the outcome of the Oslo workshop and which includes estimates of resources and a strategy for the coordination of polar prediction research A Project Office should be established at an institution with a major interest in polar prediction.

11. Meteorologisk Institutt met.no Improving Polar Predictions – Scientific Challenges Thank you