2008 Alaska Park Science Symposium
October 14, 2008
Modeled Continual Surface Water Storage Change of the Yukon River Basin
Rena Bryan1, Larry Hinzman2, Robert Busey3
1International Arctic Research Center, University of Alaska Fairbanks, PO Box 757340, Fairbanks, AK, 99775-7340, USA, Phone 907-474-1556, rbryan@iarc.uaf.edu
2International Arctic Research Center, University of Alaska Fairbanks, PO Box 757340, Fairbanks, AK, 99775-7340, USA, Phone 907-474-7331, lhinzman@iarc.uaf.edu
3International Arctic Research Center, University of Alaska Fairbanks, PO Box 757340, Fairbanks, AK, 99775-7340, USA, Phone 907-474-2792, fnrcb1@uaf.edu
Large-scale modeling at high latitudes is a basis for analyzing the role of the Arctic in the global system. The area of the Yukon watershed, spanning Alaska, the Yukon Territory, and the tip of British Columbia, is 847,642 km2, representing a large part of the North American drainage basin. How will the size and distribution of northern lakes and wetlands change spatially and temporally under a warming climate scenario? We examine this research question within the Yukon River Basin by analyzing meteorology, topography, soils, vegetation, permafrost thermal composition, and hydraulic head.
A high-resolution temperature model, TopoClimate, references USGS determined topographic features and the National Weather Service weather forecast model, Global Forecast System, to represent synoptically and topographically driven processes at present. For future simulations, TopoClimate references GCM model ECHAM5/MPI-OM under balanced energy sources in an integrated world emissions scenario, A1B, and topography. ECHAM5/MPI-OM best reproduces the present key features of both Alaska and the Arctic observed synoptic climates.
A numerical model for estimating the permafrost thermal composition, TTOP, is used to improve the resolution of permafrost extent in the Yukon River Basin. TTOP references the TopoClimate temperature map, as well as maps of soil moisture and thermal properties, surface n-factors derived from landcover type, and snow cover. The propagation of surface temperature through soil is numerically modeled by TTOP, using soil properties and microclimatic effects. TTOP has been applied to the Seward Peninsula in estimating past, present, and future permafrost distributions.
A physically based, potentiometric surface algorithm extracts steepness and relative elevation from topography. Precipitation inputs are downscaled ERA-40 reanalysis and from ECHAM5/MPI-OM under the A1B scenario for future. Derived hydraulic head is used to determine local groundwater upwelling or surface water downwelling. Hydraulic gradient, analyzed in concert with permafrost distribution provides insight into surface water presence. The continual change of surface water presence is evaluated through time.
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