HR: 1340h
AN: C33B-1132    [Abstracts]
TI: A New Look at the Northern Hemisphere Sea Ice Concentration
AU: * Stern, H
EM: harry@apl.washington.edu
AF: Polar Science Center, University of Washington, 1013 NE 40th Street, Seattle, WA 98105 United States
AU: Fetterer, F
EM: fetterer@kryos.colorado.edu
AF: CIRES, University of Colorado, 1540 30th Street, Boulder, CO 80309 United States
AU: Fowler, C
EM: cfowler@colorado.edu
AF: CCAR, University of Colorado, 431 UCB ECNT 323, Boulder, CO 80309 United States
AB: Arctic sea ice extent has decreased over the past 25 years by 7% in winter and 17% in summer, with record or near-record summer lows since 2002. These estimates come from satellite passive microwave (PM) data collected since 1979. In this study we use a new data set of Northern Hemisphere sea ice concentration, derived from weekly operational ice charts (1972-2004) produced by the U.S. National Ice Center (NIC), to re-examine regional variability and trends in Arctic sea ice area and extent. The ice charts through 1994 were quality-checked and converted to EASE-Grid format by the Arctic Climatology Project (2000). Charts for 1995-2004 were converted to EASE-Grid by us. Source data used by NIC to create the charts included visible and infrared satellite imagery, active radar imagery, PM data, aerial reconnaissance, ship and shore observations, buoys, model output, information from foreign ice services, and climatology. The PM data were incorporated into the charts only when all other forms of data were not available. We divide the Arctic and sub-Arctic seas into regions and compare chart-derived monthly sea ice concentration in each region to that derived from PM data. We find that the ice charts give a more realistic depiction of the ice edge, the marginal ice zone, and coastal areas. The PM data have the advantage of being available as a daily product rather than weekly or biweekly. The ice charts for 1995-2004 also include concentrations of multiyear ice, first-year ice, and new ice. We present results of our analysis of these data, as well as calculations of the duration of the ice season in each region, and the variability of the ice edge.
DE: 0750 Sea ice (4540)
SC: Cryosphere [C]
MN: Fall Meeting 2005