HR: 1455h
AN: U33B-06 INVITED    [Abstracts]
TI: Interdependencies of Arctic land surface processes: A uniquely sensitive environment
AU: * Bowling, L C
EM: bowling@purdue.edu
AF: Purdue University, 915 W. State Street, W. Lafayette, IN 47907, United States
AB: The circumpolar arctic drainage basin is composed of several distinct ecoregions including steppe grassland and cropland, boreal forest and tundra. Land surface hydrology throughout this diverse region shares several unique features such as dramatic seasonal runoff differences controlled by snowmelt and ice break-up; the storage of significant portions of annual precipitation as snow and in lakes and wetlands; and the effects of ephemeral and permanently frozen soils. These arctic land processes are delicately balanced with the climate and are therefore important indicators of change. The litany of recently-detected changes in the Arctic includes changes in snow precipitation, trends and seasonal shifts in river discharge, increases and decreases in the extent of surface water, and warming soil temperatures. Although not unique to the arctic, increasing anthropogenic pressures represent an additional element of change in the form of resource extraction, fire threat and reservoir construction. The interdependence of the physical, biological and social systems mean that changes in primary indicators have large implications for land cover, animal populations and the regional carbon balance, all of which have the potential to feed back and induce further change. In fact, the complex relationships between the hydrological processes that make the Artic unique also render observed historical change difficult to interpret and predict, leading to conflicting explanations. For example, a decrease in snow accumulation may provide less insulation to the underlying soil resulting in greater frost development and increased spring runoff. Similarly, melting permafrost and ground ice may lead to ground subsidence and increased surface saturation and methane production, while more complete thaw may enhance drainage and result in drier soil conditions. The threshold nature of phase change around the freezing point makes the system especially sensitive to change. In addition, spatial and temporal variability in both water storage as soil moisture, surface water or snow, and the associated heat storage, leads to a phase shift between atmospheric forcings and land surface response. Continued efforts to link observed change with these interdependent processes rely on the interpretation of historic data, as well as maintaining or increasing current monitoring efforts.
DE: 0702 Permafrost (0475)
DE: 0736 Snow (1827, 1863)
DE: 1621 Cryospheric change (0776)
DE: 1807 Climate impacts
DE: 1890 Wetlands (0497)
SC: Union [U]
MN: 2007 Fall Meeting