The role of spatial and temporal variability of Pan-arctic river discharge and surface hydrologic processes on climate Dennis P. Lettenmaier Department.
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Presentation on theme: "The role of spatial and temporal variability of Pan-arctic river discharge and surface hydrologic processes on climate Dennis P. Lettenmaier Department."— Presentation transcript:
The role of spatial and temporal variability of Pan-arctic river discharge and surface hydrologic processes on climate Dennis P. Lettenmaier Department of Civil and Environmental Engineering University of Washington Eric F. Wood Department of Civil Engineering Princeton University Andrew Weaver School of Earth and Ocean Sciences University of Victoria ARCSS Freshwater Initiative All-investigators Meeting Boulder, CO February 18, 2003
Science questions: Overarching: How will the coupled arctic climate system respond to changes in riverine discharge of freshwater, and how do the temporal and spatial variability of freshwater discharge, and changes therein, interact with the dynamics of high latitude climate? Specific: What is the uncertainty in the discharge of ungaged areas draining to the Arctic, especially the Canadian Archipelago, and how can this uncertainty best be reduced? What are the relative effects of seasonal albedo changes over ocean and land associated with transitions from sea ice to open water, and snow cover to bare vegetation, respectively, and how are the relative sensitivities likely to change over the next century? How well do current coupled land-atmosphere-sea ice- ocean models represent the processes controlling the dominant modes of climate variability in the Arctic system, and where are the greatest weaknesses?
Experimental Design The project experimental design is based on a series of uncoupled, partially coupled, and fully coupled simulations with a combination of sea ice, atmosphere, land, and ocean models Sea ice, atmosphere, and ocean models are components of the University of Victoria’s Earth System Climate Model Land model is University of Washington/ Princeton University Variable Infiltration Capacity (VIC) land surface model. The science questions will be posed through a combination of model runs in which sea ice, ocean, and land surface models are run in off-line mode, and various aspects of the off-line climatologies will be prescribed in partially coupled ensemble runs of the fully coupled model system. Partially coupled model results will be compared with results of fully coupled ensemble climate simulations to isolate the effects of interactions among the land, sea ice/ocean, and atmosphere.
Land surface model updates – high latitude processes
Lakes and wetlands Source: San Diego State University Global Change Research Group
Saturated extent 1999 and 2000 20002000 = wet = dry a. b. c. d.e.
Predicting the effects of lakes and wetlands Lake energy balance based on: –Hostetler and Bartlein (1990) –Hostetler (1991) Assumptions: –One “effective” lake for each grid cell; –Laterally-averaged temperatures; and
Spatially-distributed frozen soils Soil node temperatures solved via heat diffusion equation Ice content, infiltration rate and heat capacity calculated at nodes Assumed uniform temperature distribution across the grid cell allows spatial variation of infiltration capacity