HR: 17:12h
AN: A24A-07    [Abstracts]
TI: Storm impacts on the Arctic sea-ice export and melting observed by ice drifting buoys
AU: * Inoue, J
EM: jun.inoue@jamstec.go.jp
AF: Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AU: Kikuchi, T
EM: takashik@jamstec.go.jp
AF: Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AB: Drifting buoys deployed near the North Pole in the 2000s revealed that sea-ice export from the Arctic Ocean through the Fram Strait was large in 2005. The relationship between ice drift and sea-level pressure (SLP) showed that the mean SLP from June to September is conducive to continuous sea-ice drift offshore from Siberia. A record minimum of the ice extent in 2005 is partly explained by the strongest SLP gradient across the Transpolar Drift Stream for the recent 27 years from 1979. The SLP pattern regressed on the linear trends of ice extent is characterized by cyclonic circulation anomalies along the Eurasian coast, which tend to enhance the SLP gradient across the Transpolar Drift Stream. The large export of freshwater and sea ice in 2005 could increase the salinity of the upper ocean and lead to development of the mixed layer and suppression of sea-ice growth during the subsequent winter. The role of wind conditions on sea-ice melting was also investigated in detail, one in 2002 under stormy conditions, one in 2003 under calm conditions. Although the ice concentration near the North Pole was the same in 2002 and 2003 during early summer, the heat used in bottom melting in 2003 was almost half of that in 2002. To obtain the total heat input into the upper ocean, heat used in lateral melting was additionally derived from a time series of ice concentration in 2002. Assuming the same heat input into the upper ocean, the heat used in lateral and bottom melting was estimated and compared between the years. It is thought that the warm fresh water embedded within the ice cover was mixed downward during the frequently stormy mid-summer of 2002, enhancing bottom melting. By contrast, the warm water in 2003 tended to be used for lateral melting due to the relatively calm conditions, suggesting that a continuously weak wind is favorable to decrease the ice cover during summer.
DE: 0750 Sea ice (4540)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3349 Polar meteorology
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting