HR: 0800h
AN: C41B-0200    [Abstracts]
TI: Tracking the Arctic's Shrinking Ice Cover: Another Extreme Minimum in 2004.
AU: * Stroeve, J C
EM: stroeve@kryos.colorado.edu
AF: National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado (CU), Campus Box 449, Boulder, CO 80309-0449 United States
AU: Fetterer, F
EM: fetterer@kryos.colorado.edu
AF: National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado (CU), Campus Box 449, Boulder, CO 80309-0449 United States
AU: Knowles, K
EM: knowlesk@kryos.colorado.edu
AF: National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado (CU), Campus Box 449, Boulder, CO 80309-0449 United States
AU: Meier, W
EM: walt@nsidc.org
AF: National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado (CU), Campus Box 449, Boulder, CO 80309-0449 United States
AU: Serreze, M
EM: serreze@kryos.colorado.edu
AF: National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado (CU), Campus Box 449, Boulder, CO 80309-0449 United States
AU: Arbetter, T
EM: arbetter@nsidc.org
AF: National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado (CU), Campus Box 449, Boulder, CO 80309-0449 United States
AB: Of all the recent observed changes in the Arctic environment, the reduction of sea ice cover stands out most prominantly. Several independent analysis have established a trend in Arctic ice extent of -3% per decade from the late 1970s to the late 1990s, with a more pronounced trend in summer. The overall downward trend is characterized by strong interannual variability, with a low September ice extent in one year typically followed by recovery the next September. Having two extreme minimum years, such as what was observed in 2002 and 2003 is unusual. 2004 marks the third year in a row of substantially below normal sea ice cover in the Arctic. Early summer 2004 appeared unusual in terms of ice extent, with May a record low for the satellite period (1979-present) and June also exhibiting below normal ice extent. August 2004 extent is below that of 2003 and large reductions in ice cover are observed once again off the coasts of Siberia and Alaska and the Greenland Sea. Neither the 2002 or 2003 anomaly appeared to be strongly linked to the positive phase of the Arctic Oscillation (AO) during the preceding winter. Similarly, the AO was negative during winter 2003/2004. In the previous AO framework of Rigor et al (2002), a positive winter AO implied preconditioning of the ice cover to extensive summer decay. In this hypothesis, the AO does not explain all aspects of the recent decline in Arctic ice cover, such as the extreme minima of 2002, 2003 and 2004. New analysis by Rigor and Wallace (2004) suggest that the very positive AO state from 1989-1995 can explain the recent sea ice minima in terms of reductions in the overall age of ice driven by the previous high AO state. However, it is also reasonable to expect that a general decrease in ice thickness accompanying warming would manifest itself as greater sensitivity of the ice pack to wind forcings and albedo feedbacks. The decrease in multiyear ice and attendant changes in ice thickness distribution could in turn precondition the Arctic ice cover to further reductions in the subsequent summer(s) regardless if the summer temperatures were anomalously warm. The NSIDC Sea Ice Index (http://nsidc.org/data/seaice_index/) can be used to view trends and anomalies from 1979 on.
DE: 9315 Arctic region
DE: 4215 Climate and interannual variability (3309)
DE: 1827 Glaciology (1863)
DE: 1635 Oceans (4203)
DE: 1640 Remote sensing
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting