HR: 0800h
AN: C21C-1110    [Abstracts]
TI: Passive microwave detected snowmelt and streamflow responses, Matanuska Glacier, Alaska: 1995-2004
AU: * Kopczynski, S E
EM: seka@lehigh.edu
AF: Lehigh University, Earth Sciences 31 Williams Drive, Bethlehem, PA 18015
AU: Ramage, J M
C21C-1110 AF: Lehigh University, Earth Sciences 31 Williams Drive, Bethlehem, PA 18015
AU: Evenson, E B
C21C-1110 AF: Lehigh University, Earth Sciences 31 Williams Drive, Bethlehem, PA 18015
AU: Lawson, D E
C21C-1110 AF: CRREL, 72 Lyme Rd, Hanover, NH 03755
AU: Larson, G J
C21C-1110 AF: USGS-VT, PO Box 628, Montpelier, VT 05601
AU: Denner, J C
C21C-1110 AF: Michigan State University, Room 209 Natural Science Building, East Lansing, MI 48824
AU: Peters, S C
C21C-1110 AF: Lehigh University, Earth Sciences 31 Williams Drive, Bethlehem, PA 18015
AB: We test the notion that timing of passive microwave satellite-detected snowmelt predicts the timing of discharge ramp-up at Matanuska Glacier, Alaska. We use an unusually long dataset (1995-2004) of hourly field measurements of glacial discharge and suspended sediment in conjunction with twice-daily passive microwave satellite observations. In spite of coarse (25x25 km2) resolution, data from the Special Sensor Microwave Imager (SSM/I) show a robust snowmelt signal due to the strong increase in snow emissivity. Most of the time, satellite-detected snowmelt starts mid-April and persists on average for 40 days with an 11-14 day lag between the end of snowmelt and major ramp-up of spring discharge. Historically, discharge ramp-up occurs over an 11 day window in mid-June. There is a strong correlation (R2 0.83) between the end of satellite-detected snowmelt and subsequent discharge ramp-up; in most years timing of the ramp-up can be predicted within 4-days. Suspended sediment and discharge data collected prior to this high discharge event show a subdued diurnal signal, contrasted with stronger amplitude signals following ramp-up. Rain events occurring prior to the ramp-up show a subtler response of suspended sediment and discharge than comparable events after ramp-up. This suggests that prior to ramp-up the glacial drainage system is less developed and considerable rainwater is retained in a transitioning snow-pack. The strong correlation between the end of the SSM/I detected snowmelt and discharge ramp-up suggests meltwater from snowfields drives the timing of ramp-up. The glacial drainage system appears to be slowly evolving prior to the ramping-up of discharge, yet better developed following the event. We hope to refine this predictive relationship with higher resolution (15x15 km2) AMSR-E data.
DE: 0720 Glaciers
DE: 0740 Snowmelt
DE: 0758 Remote sensing
DE: 1860 Streamflow
SC: Cryosphere [C]
MN: Fall Meeting 2005