PROGRAM TITLE: High Latitude Dynamics, Arctic Ice Dynamics ACTIVITY STREAMS: Process Studies SCIENCE ELEMENT:
Climate and Hydrologic Systems DEPARTMENT OF DEFENSE OFFICE OF NAVAL RESEARCH (ONR)SCIENTIFIC MERIT: The ice cover of the Arctic Ocean significantly impacts climate. Vertical fluxes of mass, momentum and energy within the air-ice-ocean system are critical to prediction of the global heat budget. Air-sea fluxes are concentrated by fracture within the ice plate, a scale dependent process related to nonlinear stress and strain. Radiation is a major factor in the heat and mass balance of the ice pack, the thermohaline structure of the upper ocean, and biological activity. The full spectral radiation field in the snow-ice-water system depends on complex scattering and absorption mechanisms under investigation. Coupled air-ice-ocean models with adequate resolution to test the sensitivity of feedback mechanisms are being formulated. The water mass structure of the Arctic Ocean may be maintained by lateral advection/mixing from the broad continental shelves bordering the polar basin. Export of dense shelf water is being related to the thermodynamics of ice formation, the mechanics of ice divergence and cross shelf transport mechanisms. Arctic marginal seas (Greenland, Iceland, Norwegian, Barents, Kara, Laptev, Bering, Okhotsk) have effects far beyond their boundaries. In winter, deep convection, the pump that drives global deep ocean circulation, is possible at high latitudes due to the marginal stability of the water column and intense surface cooling. Circulation in the Fram Strait region is under study to determine transport between ocean basins that preconditions deep convection. In summer, the polar light cycle produces the global maximum open ocean primary productivity in the marginal ice zone. Principal questions include: how to incorporate leads and ridges (time- variable discontinuities) in continuum based ice dynamics models; how can temperature, albedo, and clouds be measured and incorporated in radiative transfer models to determine the surface heat balance; what observations are necessary to accurately predict polar ice cap melting; how do circulation and water masses in the Arctic Ocean pre-condition deep convection in the North Atlantic; how do atmospheric polar lows form and trigger deep convection; what are the relative roles of biological and physical mechanisms in regulating marginal ice zone biological productivity. The research community is ready to address these issues further now with focused initiatives to reduce current uncertainties. Error estimates (e.g., trends in ice cap melting, regional warming, deep convective activity) will be reduced significantly with five to ten years of sustained effort. Performance and quality is measured by peer-reviewed publications in quality journals. STAKEHOLDERS: This program links to the international WCRP Sea Ice and Climate Program, the Canadian RADARSAT Program, the NSF ARCSS Initiative, the developing GOOS Program, DOE's AMAP Program and NASA's Alaska SAR Facility Program. The research directly addresses the need to know the concentration and thickness distribution of ice in the Arctic basin and the movement of the ice edge in Arctic marginal seas, impacting from 20% of the world's commercial fisheries. Through a better understanding of the surface heat budget, improved prediction of high latitude weather and global climate change will be achieved. Results will also impact design of the optimal observational network to maintain forecasting skill. Benefits also include improved algorithms for satellite remote sensing, assessment of contaminant dispersal, design of offshore platforms and pipelines and transportation safety and efficiency. POLICY RELEVANCE: This activity contributes directly to the high priority issues of Climate Change and Global Warming and Seasonal and Interannual Prediction. Models predict global warming will first be detected in the Arctic. This research provides early warning signs and initial estimates of the rate of warming,indicating how fast control measures must be implemented. It is also an essential element of the national research plan mandated by the Interagency Arctic Research and Policy Act (1984). PROGRAM CONTACT: Dr. Thomas B. Curtin, ONR/Code 324AR, 800 N Quincy Street, Arlington, VA 22217, 703-696-4118.