[1] Using Radarsat Synthetic Aperture Radar (SAR) imagery of northern Alaska and northwestern Canada, we calculated a mean climatology of the annual landfast ice cycle for the period 1996-2004. We also present the monthly minimum, mean, and maximum landfast ice extents throughout the study area. These data reveal where and when the landfast is most stable and which sections of the coast are susceptible to midseason breakout events. Stabilization of landfast ice is strongly related to the advance of the seaward landfast ice edge (SLIE) into waters around 18 m deep. Isobaths near this depth are a good approximation for midseason landfast ice extent. Comparison with work from the 1970s suggests a reduced presence of landfast ice in this region of the Arctic, due to later formation and earlier breakup. This will likely lead to an increase in coastal erosion and may also have profound effects upon subsistence activities, which are intimately linked to the timing of marine mammal migration patterns. Interannually, landfast ice formation correlates with the incursion of pack ice into coastal waters, suggesting that the later mean date of formation in recent years may be related to the increasingly northward location of the perennial sea ice edge. The timing of breakup correlates well with onset of thawing air temperatures. Analysis of regional data shows a multidecadal trend toward earlier thaw onset, which suggests that the observed change in breakup dates may be part of a longer-term trend.

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Data management is integral to sound polar science. Through analysis of documents reporting on meetings of the Arctic data management community, a set of priorities and strategies are identified. These include the need to improve data sharing, make use of existing resources, and better engage stakeholders. Network theory is applied to a preliminary inventory of polar and global data management actors to improve understanding of the emerging community of practice. Under the name the Arctic Data Coordination Network, we propose a model network that can support the community in achieving their goals through improving connectivity between existing actors.

ABSTRACT. By March each year, coast-influenced sea ice in Alaska's northern Chukchi Sea consists of the shorefast ice itself plus ice floes moving in a zone that extends from immediately beyond the shorefast ice to coherent pack ice, some 100 km farther offshore. Because westward-drifting polar pack ice encounters fewer landmasses (and less resistance from them) once it passes Point Barrow, a semipermanent polynya or flaw zone dominates coastal ice in this region. Iñupiat residents use open water in flaw leads to hunt migrating bowhead whales from mid-April to early June. Although Iñupiat hunters grasp the nature and importance of ice in motion beyond their horizon, the flaw zone has received less scientific attention than either shorefast ice or polar pack ice farther offshore. Synthetic aperture radar (SAR) satellite imagery is a form of remote sensing recently made available that allows us to address ice movement at a spatial scale familiar to traditional hunters. SAR-tracked ice movements differed between 2000 and 2001, illustrating contrasts between adverse and optimal conditions for spring whaling at Barrow. Case studies of icefloe accelerations in the two contrasting seasons suggest that many variables influence ice motion. These include weather, seafloor topography, currents, sea-level changes, and events that occurred earlier during an annual accretion of ice. Adequate prediction of threats to ice integrity in the northern Chukchi Sea will require adjustments of our current concepts, including 1) recognizing the pervasive influence of the flaw zone; 2) replacing a focus on vessel safety in ice-dominated waters with an emphasis on ice integrity in high-energy environments; and 3) chronicling ice motions through coordinated ground observation and remote sensing of March-June events in future field studies.Key words: Chukchi Sea, flaw zone, spring whaling, nearshore sea ice, ice motion RÉSUMÉ. Quand arrive mars chaque année, la banquise soumise à l'influence de la côte dans la partie nord de la mer des Tchouktches de l'Alaska est formée de la glace côtière elle-même plus des floes en mouvement dans une zone qui s'étend de la lisière de la glace côtière au pack cohérent, à quelque 100 km plus au large. Vu que, une fois passée la pointe Barrow, le pack polaire dérivant vers l'ouest se heurte à moins de masses continentales (et donc moins de résistance), une polynie ou zone de séparation semi-permanente domine la banquise côtière dans cette région. Les résidents Iñupiat utilisent l'eau libre des zones de séparation pour chasser la baleine boréale sur sa route de migration de la mi-avril au début juin. Même si les chasseurs Iñupiat saisissent bien la nature et l'importance de la glace en mouvement au-delà de leur horizon, la zone de séparation a fait l'objet de beaucoup moins de recherches que la banquise côtière ou le pack polaire plus au large. L'imagerie satellitaire obtenue par radar à antenne synthétique (SAR) est une forme de télédétection toute récente qui nous permet d'étudier le déplacement de la glac...