This award will support a quantitative assessment of the causes and effects of variations in the seasonal timing of sea ice melt onset and freeze initiation, through use of the observational record and earth system model projections of future climate. The study will synthesize existing datasets including results from ARCSS Synthesis of Arctic System Science (SASS) and Arctic Observing Network (AON) projects. This will be complemented by an analysis of control and sensitivity integrations from the Community Climate System Model, version 4 (CCSM4), which has improved polar processes and capabilities, including a more general and consistent sea ice albedo representation and an ecosystem/biogeochemistry component. Specifically, the study will (1) investigate interactions and feedbacks between seasonal changes in the sea ice and snow conditions, the amount of solar insolation, and the partitioning of this radiation, (2) assess the implications of these interactions for changes in ice-ocean-atmosphere heat, freshwater, and bio-available iron exchange and investigate their influence on ecosystem dynamics, biogeochemical cycling, and climate in the CCSM, and (3) evaluate and ultimately improve the capabilities of earth system models in light of these processes, specifically by improving the physics associated with surface albedo and light transmission parameterizations for ice covered seas.
This study has many 'Broader Impacts' for a variety of audiences. The results will be used to assess the representation of the seasonal cycle of Arctic climate and the Arctic ecosystem in earth system models, and will aid in understanding the intricate balance of key trigger events in the Arctic atmosphere-sea ice-ocean-biogeochemical system. The model simulation output will be freely available and useful to studies using ecosystem models that include higher trophic levels, as well as to researchers designing and analyzing observational field programs. The pan-Arctic focus of the study will provide context for measurements and studies undertaken at specific geographic locations. Through mentoring programs at NCAR and CRREL, two undergraduate students will work on the project. Results from this work will be introduced to the classroom through visits to local elementary schools, and inclusion in curricula at Dartmouth College, University of California Irvine and University of Washington. Museum presentations at the Pacific Science Center (Seattle), the Burke Museum (Seattle) and the Montshire Museum (Vermont) will reach wider audiences outside of the traditional classroom.
