Aerial view of Accomplishment Creek and the Sagavanirktok River in the Brooks Range of Alaska.  Photo by D.L. Kane


Assessing the Long-term Contribution of Landfast Ice To the Arctic Freshwater Budget


Yanling Yu (yanling@apl.washington.edu), University of Washington
Harry Stern, PSC



Landfast ice contributes directly to the Arctic freshwater budget. Through its seasonal growth and melt, fast ice can store and release a large amount of freshwater from river discharge and ice melt on the shelves, comparable to the total runoff of the four largest Arctic rivers. Since landfast ice is primarily thermodynamically controlled, its growth and melt patterns show large interannual variability as evidenced by the Arctic environment changes over several decades. The long-term changes in ice freeze and thaw will affect the net storage and release of freshwater by landfast ice, which will have a significant impact on the Arctic freshwater cycle.

Despite its significance, the interannual variability of landfast ice is not well studied and thus poorly understood. This proposed research is to provide a new understanding of the large-scale interannual variability of landfast ice and its long-term contribution to the Arctic freshwater budget. Our goals are to (1) examine the interannual variability of landfast ice extent for the whole Arctic basin; (2) investigate the spatial and temporal changes in fast ice growth and melt as well as brine flux due to ice formation; (3) analyze the long-term changes in fast ice volume in terms of freshwater storage by landfast ice in response to the Arctic climate variations, such as changes in snowfall, surface air temperatures, wind, and major river discharge. The NSF's Arctic Freshwater program seeks to address the physical processes of the Arctic freshwater system and its connections with the Arctic environmental change. This proposed study is directly related to the objectives of NSF and the scientific goals of the CHAMP and SEARCH programs, i.e., to understand the Arctic climate change and its impact on the Arctic environment.

In our approach, we will divide the Arctic shelves into seven regions that correspond to the major Arctic drainage basins. Focusing on these areas, we will combine a 26-year record (1976-2001) of landfast ice observations with a thermodynamic model to examine the interannual variability of landfast ice volume and freeze/melt patterns. The fast ice observations will come from the ice charts recently released by the National Ice Center (NIC), which provide weekly view of landfast ice conditions over the whole Arctic Basin. To analyze the long-term freshwater contribution from landfast ice, we will construct time series to determine landfast ice: thickness and volume; freezing and melting dates; brine and freshwater fluxes; and the length of freezing and melting periods. With these time series, we will determine their interannual variabilities, particularly focusing on decadal changes associated with the Arctic Oscillation and the spatial variations among the seven regions. Our proposed work is both timely and unique. The NIC ice charts provide the first comprehensive observation on landfast ice over the whole Arctic Basin for decades, excellent for examining the landfast ice role in the Arctic freshwater system and its connections with the Arctic environmental change. The results on the large-scale interannual variability of landfast ice will contribute to understanding and predicting the changes in Arctic climate and coastal environment, which will broadly benefit the general public and scientific community.




Arctic CHAMP
Science Management Office

Contact Information
Role of the Arctic-CHAMP Science Management Office
Photo: Aerial view of Accomplishment Creek and the
     Sagavanirktok River in the Brooks Range of Alaska.  Photo by D.L. Kane