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Reducing Canada's vulnerability to climate change - ESS Variation of land surface albedo and its simulation Shusen Wang Andrew Davidson Canada Centre for Remote Sensing Reducing Canada's vulnerability to climate change Earth Sciences Sector Acknowledgment: CCAF, PFRA, BOREAS Slide 2 Reducing Canada's vulnerability to climate change - ESS Albedo and climate control surface radiation and energy balances affects boundary-layer structure and dynamics e.g., albedo changes from forestation in temperate and boreal forest could offset C sequestration (A. Betts, 2000) Albedo and ecosystem control microclimate conditions affects biogeochemical cycles Slide 3 Reducing Canada's vulnerability to climate change - ESS Variations of albedo due to different vegetation types snow covering solar zenith angle and climate/weather impact plant development/phenology surface heterogeneity Slide 4 Reducing Canada's vulnerability to climate change - ESS Precipitation in 2001 and 2003 Slide 5 Reducing Canada's vulnerability to climate change - ESS Slide 6 Drought impact Chapin et al. (1999): net climate-forcing due to about 5% difference in albedo between forest tundra and shrub tundra of northern Alaska are in the order of 5.5 W m -2, which is comparable to the effect of a doubling of global atmospheric CO 2 concentration (4.4 W m -2, Wuebbles 1995). Slide 7 Reducing Canada's vulnerability to climate change - ESS Temporal variation Slide 8 Reducing Canada's vulnerability to climate change - ESS Spatial heterogeneity Slide 9 Reducing Canada's vulnerability to climate change - ESS Local vs. Regional Slide 10 Reducing Canada's vulnerability to climate change - ESS The albedo model 1. Based on ecosystem elements Leaf: ref., abs., trans. Stem/branch: ref., abs. Snow: snow age/condition Soil:texture, moisture 2. Ray tracing scheme for radiation transfer 3. Canopy gap probability Slide 11 Reducing Canada's vulnerability to climate change - ESS Shortwave albedo (SSA-OA) a: leafless canopy with snow- covered ground b: leafless canopy without snow cover c: leafed canopy during growing season Slide 12 Reducing Canada's vulnerability to climate change - ESS Reflected Radiation Slide 13 Reducing Canada's vulnerability to climate change - ESS Direct vs. diffuse, visible vs. NIR Slide 14 Reducing Canada's vulnerability to climate change - ESS Surface albedo and ecosystem conditions a: stand density b: leaf angular distribution c: leaf and wood area indices d: leaf reflectance e: tree bark reflectance f: soil reflectance Slide 15 Reducing Canada's vulnerability to climate change - ESS Clumping Index Slide 16 Reducing Canada's vulnerability to climate change - ESS Net Radiation, Jul. 1998 Slide 17 Reducing Canada's vulnerability to climate change - ESS E cological A ssimilation of L and and C limate O bservations - the EALCO model Slide 18 Reducing Canada's vulnerability to climate change - ESS Summary Drought, plant development, and spatial heterogeneity may induce significant changes of surface albedo; Radiation transfer model based on ecosystem structure and optical parameters can better represent dynamics; Albedo from site measurement has limitations in spatial representation. It can be improved by the model using RS inputs; Dew/frost & snow interception could significantly change . Coupling with EB model is necessary to capture this phenomena; Winter of high latitude ecosystems is very sensitive to LAI/WAI; Simulation at high spectral resolution can improve ecosystem C simulation.