HR: 08:30h
AN: H11H-03    [Abstracts]
TI: Quantifying the Spatial Distribution of Evapotranspiration over Canada With a Process Model Using Remote Sensing, Meteorological, and Soil Data
AU: Liu, J
EM: jliu@atmosp.physics.utoronto.ca
AF: Atmospheric Science, Department of Physics, University of Toronto, 60 St. George Street , Toronto, ON M5S 1A7 Canada
AU: Liu, J
EM: jliu@atmosp.physics.utoronto.ca
AF: Canada Centre for Remote Sensing, 588 Booth Street, Ottawa, ON K1A 0Y7 Canada
AU: * Chen, J
EM: chenj@geog.utoronto.ca
AF: Department of Geography, University of Toronto, 100 St. George Street, Toronto, ON M5S 3G3 Canada
AU: * Chen, J
EM: chenj@geog.utoronto.ca
AF: Canada Centre for Remote Sensing, 588 Booth Street, Ottawa, ON K1A 0Y7 Canada
AU: Cihlar, J
EM: josef.cihlar@ccrs.nrcan.gc.ca
AF: Canada Centre for Remote Sensing, 588 Booth Street, Ottawa, ON K1A 0Y7 Canada
AB: The evapotranspiration (ET) from all Canadian landmass is estimated at daily steps and 1 km resolution using a process model named Boreal Ecosystem Productivity Simulator (BEPS). The model is driven by remotely sensed leaf area index and land cover maps, as well as soil water holding capacity and daily meteorological data. All the major ET components are considered: transpiration from vegetation, evaporation of canopy-intercepted rainfall, evaporation from soil, sublimation of snow in winter and in permafrost and glacier areas, and sublimation of canopy-intercepted snow. In forested areas, the transpiration from both the overstory and understory vegetation is modelled separately. The Penman-Monteith method was applied to sunlit and shaded leaf groups individually in modelling the canopy-level transpiration, a methodological improvement necessary for forest canopies with considerable foliage clumping. The modelled ET map displays pronounced east-west and north-south gradients as well as detailed variations with cover types and vegetation density. It is estimated that, for a relative wet year of 1996, the total ET from all Canada's landmass (excluding inland waters) was 2037 km3. If compared with the total precipitation of 5351 km3 based on the data from a medium range meteorological forecast model, the ratio of ET to precipitation was 38 %. The ET averaged over Canadian land surface was 228 mm/yr in 1996, partitioned into transpiration of 102 mm/yr and evaporation and sublimation of 126 mm/yr. Forested areas contributed the largest fraction of the total national ET at 59 %. Averaged for all cover types, transpiration accounted for 45 % of the total ET, while in forested areas, transpiration was contributed 51 % of ET. Modelled results of daily ET are compared with eddy covariance measurements at three forested sites with a r2 value of 0.61 and a root mean square error of 0.7 mm/day.
DE: 3322 Land/atmosphere interactions
DE: 1818 Evapotranspiration
DE: 1833 Hydroclimatology
DE: 1836 Hydrologic budget (1655)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting