HR: 0800h
AN: C41A-0173    [Abstracts]
TI: Exploring the Role of Land Surface Changes on the Variability of Pan-Arctic River Discharge
AU: * Adam, J C
EM: jadam@u.washington.edu
AF: Department of Civil and Environmental Engineering, University of Washington, BOX 352700, Seattle, WA 98195-2700 United States
AU: Su, F
EM: fgsu@hydro.washington.edu
AF: Department of Civil and Environmental Engineering, University of Washington, BOX 352700, Seattle, WA 98195-2700 United States
AU: Bowling, L C
EM: bowling@purdue.edu
AF: Department of Agronomy, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054 United States
AU: Lettenmaier, D P
EM: dennisl@u.washington.edu
AF: Department of Civil and Environmental Engineering, University of Washington, BOX 352700, Seattle, WA 98195-2700 United States
AB: The export of freshwater to the Arctic Ocean plays a key role in both regional and global climates (e.g. via effects on the strength of the North Atlantic Deep Water (NADW) formation that drives the thermohaline circulation). Observed changes in streamflow may be linked both to direct and indirect effects of climate change. For example, a general warming leads to earlier spring runoff, however changes in high arctic vegetation such as increased incidence of brush can lead to increased snow accumulation, and hence sustained runoff later in the summer. Also, vegetation changes can substantially change evapotranspiration. Changes in snow cover extent and the distribution of vegetation and wetlands over the pan-arctic domain affect land-atmosphere energy exchanges, and the seasonality of river flow. Furthermore, recent research has suggested that changes in permafrost extent and the active layer depth may also be affecting river flow. We report a 46-year (1950-95) run of the Variable Infiltration Capacity (VIC) macroscale hydrology model over the pan-arctic land domain, designed to offer insights into the nature and causes of observed long term trends in river discharge. VIC is a semi-distributed grid-based model that parameterizes the processes occurring at the land-atmosphere interface. The most recent version of the model includes several recent improvements specific to cold-land regions. We summarize a set of model runs from which we have estimated the inflow to the Arctic Ocean from all pan-arctic land areas (including the Canadian Archipelago) and an assessment of the capability of the land surface model to simulate the observed changes in gauged streamflow. These results utilize precipitation and temperature fields that incorporate a method of adjustment to reflect the best current understanding of long-term precipitation and temperature trends over the pan-Arctic domain. Finally, we describe an exploratory analysis in which we use the model to evaluate the effects of changes in snow cover extent, land cover classification, and active layer depth on streamflow variability and trends over the last half century.
DE: 3322 Land/atmosphere interactions
DE: 1833 Hydroclimatology
DE: 1860 Runoff and streamflow
DE: 1863 Snow and ice (1827)
DE: 1655 Water cycles (1836)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting