AOMIP status Experiments 1. Season Cycle 2. Coordinated - Spinup Coordinated - Analysis Coordinated 100-Year Run

AOMIP’s working plan for the next 2 years (June, 2005 to February 28, 2007) includes: A. Completion of analyses of coordinated 50-year experiments: · further intercomparison of model output · identification of key differences · determination of causes of differences among models · testing of proposed model improvements · formulation of major recommendations for model improvements B. Formulation of coordinated 100-year model runs: · analysis and intercomparison of model output · investigation of Arctic Ocean and sea ice variability based on model results and observations

Key topics Propagation and transformation of Atlantic waters in the Arctic Ocean Variability of the Arctic Ocean freshwater content Advection schemes Data assimilation techniques and philosophy Role of tides in the Arctic Ocean and in sea-ice dynamics and thermodynamics Arctic climate variability in global and regional models General model intercomparison issues AOMIP organization, goals and objectives.

JGR special section AOMIP 1. On the simulation of Atlantic Water circulation in the Arctic Ocean - lessons from the AOMIP experiments 2. Simulation of Atlantic Water Circulation in the Arctic Ocean and Barents Sea 3. Investigation of the Kara Sea circulation employing a variational data assimilation technique 4. The role of tides in Arctic ice/ocean climate 5. Simulating Arctic Ocean climatology and variability in the 20th century 6. Multi-decadal variability of the Arctic Atlantic Water during the 20 th century: Modeling vs. observation 7. Vertical mixing and its role in Atlantic Water propagation in the Arctic Ocean 8. Influence of sea ice on atmosphere: A study with an Arctic regional climate model 9. Modeling of snow and ice cover in the Arctic Ocean at different space and time scales 10. Greenland Sea Deep Water formation and its variability as simulated by AOMIP models 11. Diagnostics for atlantic water circulation and properties 12. The INM RAS coupled ice-ocean model and its assessment for Arctic Ocean simulation under AOMIP specifications 13. Comparison of sea ice variability in IPCC control experiments and in ocean-sea ice hindcasts 14. Sea level as an indicator of ocean dynamics in AOMIP models vs observations

Several scientific and modeling themes identified by AOMIP need serious attention in order to understand and to model Arctic Ocean behavior successfully. These themes are: A.Circulation and properties of the Arctic Ocean Atlantic Water Layer (cyclonic vs. anticyclonic) B.Variability of the freshwater content, and mechanisms of fresh water accumulation and release; uncertainties in the choices of boundary conditions for rivers, straits, and open boundaries; restoring or not restoring alternatives; and forcing data (rates of precipitation/evaporation and river runoff). All models (without restoring) have significant salinity drifts. C.Model improvements (i)Improvements in model numerics (advection) (ii)Improvements in model physics (tides, landfast ice) (iii)Improvements in model forcing and model validation and calibration technology

Model vs Observations IO145 Run- off Bering Strait Canad. Archipel Fram Strait BSOP-ENet- melt water Flux adjus tment Sum Observational estimates, Aargard &Carmack 2000 Prinsenberg and Hamilton LanS Model, Flux correction No restoring dFwC /dt difference 896 technic al resoluti on? Standard deviation

Standard model validation data sets: -Water temperature, salinity, and circulation (with a focus on AWL circulation and transformation). AOMIP requests this information from NABOS (Nansen and Amundsen Basin Observing System) - Radioactive tracer data (iodine, cesium) exist from 1980's. - Sea-ice drift and sea-ice deformation. - Sea-ice extent and concentration based on passive microwave data. - Monthly sea level at the most representative tide gauge stations. - Sea-ice thickness from submarines and ULS. - Long-term T and S time series from hydrographic sections (Kola Section, Faroe-Shetland Section, Fram Strait, SCICEX, etc. -Current meter data from all possible moorings. -Long-term data sets from ASOF. The AOMIP workshop participants recognize the importance of model forcing and recommend organizing a virtual workshop to formulate conditions for a new coordinated model run with a major focus on discussion of new and improved model forcing parameters.

Smean – Sclim, HRA Restoring flux HighResolutionModel LowResolutionModel

Salinity and how it “should be“ HRM S mean over 50 years S climatology(Levitus mix)

Salinity and how it “should be“ LRM S mean over last 54 years S climatology (PHC)

Surface salinity SSS mean Climatology(PHC) Modell, mean of last 54 years

Salinity deviation and resulting correction Smean - Sclim Resulting mean restoring flux

Salinity deviation in high resolution model