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Intercomparison of MODIS Albedo Retrievals and In Situ Measurements Across the Global FLUXNET NetworkSurface albedo is a key parameter in the Earth's energy balance since it affects the amount of solar radiation directly absorbed at the planet surface. Its variability in time and space can be globally retrieved through the use of remote sensing products. To evaluate and improve the quality of satellite retrievals, careful intercomparisons with in situ measurements of surface albedo are crucial. For this purpose we compared MODIS albedo retrievals with surface measurements taken at 53 FLUXNET sites that met strict conditions of land cover homogeneity. A good agreement between mean yearly values of satellite retrievals and in situ measurements was found (R(exp 2)= 0.82). The mismatch is correlated to the spatial heterogeneity of surface albedo, stressing the relevance of land cover homogeneity when comparing point to pixel data. When the seasonal patterns of MODIS albedo is considered for different plant functional types, the match with surface observation is extremely good at all forest sites. On the contrary, in non-forest sites satellite retrievals underestimate in situ measurements across the seasonal cycle. The mismatch observed at grasslands and croplands sites is likely due to the extreme fragmentation of these landscapes, as confirmed by geostatistical attributes derived from high resolution scenes.
Document ID
20120013275
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Cescatti, Alessandro (Joint Research Centre of the European Communities Ispra, Italy)
Marcolla, Barbara (Fondazione Edmunc Mach San Michele all'Adige, Italy)
Vannan, Suresh K. Santhana (Oak Ridge National Lab. TN, United States)
Pan, Jerry Yun (Oak Ridge National Lab. TN, United States)
Roman, Miguel O. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Yang, Xiaoyuan (Boston Univ. Boston, MA, United States)
Ciais, Philippe (Centre National de la Recherche Scientifique Gif-sur-Yvette, France)
Cook, Robert B. (Boston Univ. Boston, MA, United States)
Law, Beverly E. (Oregon State Univ. Corvallis, OR, United States)
Matteucci, Girogio (CNR-ISAFoM Rende, Italy)
Migliavacca, Mirco (Joint Research Centre of the European Communities Ispra, Italy)
Moors, Eddy (Wageningen Univ. Wageningen, Netherlands)
Richardson, Andrew D. (Harvard Univ. Cambridge, MA, United States)
Seufert, Guenther (Joint Research Centre of the European Communities Ispra, Italy)
Schaaf, Crystal B. (Boston Univ. Boston, MA, United States)
Date Acquired
August 26, 2013
Publication Date
January 1, 2012
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
GSFC.JA.6291.2012
Report Number: GSFC.JA.6291.2012
Funding Number(s)
CONTRACT_GRANT: NNX08AE94A
CONTRACT_GRANT: DE-FG02-04ER63911
CONTRACT_GRANT: DE-FG02-04ER63917
Distribution Limits
Public
Copyright
Public Use Permitted.

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