HR: 0800h
AN: PP21A-1367    [Abstracts]
TI: Seasonal Variations In Density Profiles And Densification Process At Mts. Logan And Wrangell
AU: * Kanamori, S
EM: kanasyo@pop.lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita19, Nishi 8, Kita-ku, Sapporo, 060-0041 Japan
AU: Shiraiwa, T
EM: shiraiwa@pop.lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita19, Nishi 8, Kita-ku, Sapporo, 060-0041 Japan
AU: Goto-Azuma, K
EM: kumiko@pmg.nipr.ac.jp
AF: National Institute of Polar Research, 1-9-10 Kaga, Itavashi-ku, Tokyo, 173-8515 Japan
AU: Benson, C S
EM: benson@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AU: Naruse, R
EM: ren@pop.lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, Kita19, Nishi 8, Kita-ku, Sapporo, 060-0041 Japan
AB: Detailed density measurements were carried out for ice cores which were drilled at Mt. Logan (60$\deg$35'20"N, 140$\deg$36'15"W; 4135m a.s.l.; Shiraiwa et al., 2003) and Mt. Wrangell (62$\deg$00'N, 140$\deg$03'W; 4100m a.s.l.; Shiraiwa et al., 2004). The detailed density profiles show periodic fluctuations which seem to indicate seasonal cycles. In Mt. Logan, the number of annual layers which are estimated from the density profile agrees well with that estimated from the oxygen isotope data (Goto-Azuma et al., 2003) and the age of the ice core estimated from tritium peaks. On the other hand, in Mt. Wrangell, the number of annual layers from the density profile is quite different from that of the hydrogen isotope profile. The accumulation time series reconstructed from the density profile in Mt. Wrangell shows significant correlations with precipitation data of weather stations that locate near Mt. Wrangell. Accumulation rate and mean annual temperature at both sites are estimated to be almost the same (Benson & Motyka, 1978; Shiraiwa et al., 2003; Goto-Azuma et al., 2003; Shiraiwa et al., 2004). However, their firn/ice transition depths (Mt. Logan: 50m, Mt. Wrangell: 90m) are considerably different. This difference cannot be explained only from the difference in initial densities. Densification rate in Mt. Logan is higher than in Mt. Wrangell, i.e. compactive viscosity coefficient calculated from depth-density profile in Mt. Wrangell is more than double of the value in Mt. Logan.
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting