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Published byCornelius Sharp Modified over 9 years ago
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A Project Linking In-situ and Satellite Measurements to Validate MODIS Terrestrial Ecology Products Warren B. Cohen, US Forest Service; Stith T. Gower, University of Wisconsin; David P. Turner, Oregon State University; Peter B. Reich, University of Minnesota; Steven W. Running, University of Montana
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Objectives Develop better understanding of the climatic and ecological controls on total net primary production and carbon allocation within and among biomes Learn how flux tower-measured NEE and field-measured NPP co-vary in time & how to translate between them using ecological models Explore errors and information losses that accrue when extrapolating field data to coarse- grained (1 km) surfaces Provide high quality site-specific data layers at four sites that can be compared to MODIS and other sensor products Technical Scientific
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Sites BOREAS Northern Old Black Spruce (NOBS) Muskeg (open black spruce), “Closed” black spruce, Aspen, Wetlands, Jack pine Harvard Forest (HARV) LTER Mixed hardwoods, Eastern hemlock, Red pine, Old-field meadow Konza Prairie Biological Station (KONZ) LTER Tallgrass, Shortgrass, Shrub, Gallery forest; grazing and burning regimes Bondville Agricultural Farmland (AGRO) Corn, Soybeans, Fallow
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Field-Based Sampling Design 100 25m 2 plots 80 in a nested spatial series 20 plots broadly distributed Plot measurements Vegetation cover LAI, fPAR Aboveground biomass Aboveground productivity Belowground productivity
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AGRO (29 July 99) 27 July 99 P vs. O r^2 = 0.72 LAI 98 % accurate (cross validation)
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ETM+ band 3 ETM+ band 4 ETM+ band 5 NOBS 57 % accurate (cross validation) ETM+ band 4 r = 0.42 2 7 0
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Vegetation Cover Component Characterization System (3CS): Quantitative measurements of cover proportions Basic building blocks for variety of classification systems Improved LAI mapping?
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sphagnum feathermoss n=48
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Correlations n=48 n=192
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Meeting Our Land Cover Mapping Needs AGRO corn (class--label fields in-situ) soybean (class--label fields in-situ) other (classes--label clusters in-situ & HD imagery) HARV hardwood/conifer (relative proportions--from HD imagery) other (classes--label clusters in-situ & HD imagery) KONZ grass (short/tall combined class--labels from plots & HD imagery) forest (one class--labels from plots & HD imagery) shrub (percent--from HD imagery calibrated with camera observations, plots) other (classes--label clusters in-situ & HD imagery) HD (high definition) imagery: ADAR, IKONOS, AVIRIS mission photos, MQUALS NOBS conifer/hardwood/standing dead (relative proportions--from camera observations, HD imagery) “ground” cover (relative proportions--from camera observations, moss classes from ocular estimate) other (classes--label clusters in-situ, camera observations, & HD imagery) “ground” cover classes: moss, lichen, herbaceous, shrub, fine litter, tree regeneration, coarse wood debris, water
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Leaf-off HARV Capturing seasonality With ETM+ is important to both land cover and LAI mapping Leaf-on JulyAprilSeptember HARV KONZ
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27-Jul-99 Preliminary calculations
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Regression Kriged residuals Kriging
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IGPB: Cropland UMD: Cropland Biome: Broadleaf Crops Percent Tree Cover: 0
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MODLand/BigFoot Comparisons Land cover (e.g.,…) aspatial: compare frequency distribution of translated site-specific classes with same from MODLand spatially explicit: summaries of site-specific cover proportions within MODLand- labeled cells LAI/fPAR (e.g.,…) mean 1 km cell values vs. MODLand values distributions of fine-grained values within MODLand cells NPP (e.g.,…) integrated 1 km cell values vs. MODLand values distributions of fine-grained values within MODLand cells spatially degrade land cover and LAI, repeat modeling, redo above NPP comparisons informationally degrade land cover, repeat modeling at fine grain, redo comparisons
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