Underhill, Vivian R听1听;听Wood, Kevin R听2听;听Mahoney, Andy听3
1听乐播传媒, Environmental Sciences Department
2听Joint Institute for the Study of the Atmosphere and Ocean
3听University of Alaska, Geophysical Institute
The amount of sea ice remaining in the Chukchi Sea by the September summer minimum has shrunk dramatically over the last ten years. This decrease is even more striking when compared to historical reports describing heavy sea ice along the Siberian coast and extending into the western Bering Strait through September. We reconstructed a simple index of sea ice presence along the Chukchi coast based on historical observations. This index shows that late-summer sea ice has appeared along the coast with some frequency since 1849 but has not been present since 1998. Its appearance is linked to northwesterly winds and varies on synoptic to decadal time scales. Its recent disappearance is probably due to decreases in the multi-year sea ice fraction in the vicinity of Wrangell Island. Since both the coastal ice belt and the intermittent Siberian Coastal Current (SCC) can be related to similar wind fields, it is possible that our index may be a proxy for the SCC. Documenting longer-term variations in sea ice distribution allows us to show how unusual current ecosystem changes may be.