Intercomparison of MODIS Albedo Retrievals and in Situ Measurements across the Global FLUXNET Network

Intercomparison of MODIS Albedo Retrievals and in Situ Measurements across the Global FLUXNET Network. Cescatti, A., Marcolla, B., Santhana Vannan, S. K., Pan, J. Y., Román, M. O., Yang, X., Ciais, P., Cook, R. B., Law, B. E., Matteucci, G., Migliavacca, M., Moors, E., Richardson, A. D., Seufert, G., & Schaaf, C. B. 121:323–334.

Paper doi abstract bibtex

[Abstract] Surface 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 (r2 = 0.82). The mismatch is correlated with 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 are considered for different plant functional types, the match with surface observations is extremely good at all forest sites. On the contrary, satellite retrievals at non-forested sites (grasslands, savannas, croplands) underestimate in situ measurements across the seasonal cycle. The mismatch observed at grassland and cropland sites is likely due to the extreme fragmentation of these landscapes, as confirmed by geostatistical attributes derived from high resolution scenes. [Highlights] [::] In situ and satellite albedo are in good agreement at 53 FLUXNET sites (r2 0.83). [::] MODIS albedo is systematically lower than in situ measurements for non-forest PFTs. [::] The mismatch increases with the spatial heterogeneity of albedo in a 7 × 7 km area. [::] The seasonal pattern of MODIS albedo matches extremely well for forest PFTs.

@article{cescattiIntercomparisonMODISAlbedo2012,
  title = {Intercomparison of {{MODIS}} Albedo Retrievals and in Situ Measurements across the Global {{FLUXNET}} Network},
  author = {Cescatti, Alessandro and Marcolla, Barbara and Santhana Vannan, Suresh K. and Pan, Jerry Y. and Román, Miguel O. and Yang, Xiaoyuan and Ciais, Philippe and Cook, Robert B. and Law, Beverly E. and Matteucci, Giorgio and Migliavacca, Mirco and Moors, Eddy and Richardson, Andrew D. and Seufert, Günther and Schaaf, Crystal B.},
  date = {2012-06},
  journaltitle = {Remote Sensing of Environment},
  volume = {121},
  pages = {323--334},
  issn = {0034-4257},
  doi = {10.1016/j.rse.2012.02.019},
  url = {http://mfkp.org/INRMM/article/10492690},
  abstract = {[Abstract]

Surface 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 (r2 = 0.82). The mismatch is correlated with 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 are considered for different plant functional types, the match with surface observations is extremely good at all forest sites. On the contrary, satellite retrievals at non-forested sites (grasslands, savannas, croplands) underestimate in situ measurements across the seasonal cycle. The mismatch observed at grassland and cropland sites is likely due to the extreme fragmentation of these landscapes, as confirmed by geostatistical attributes derived from high resolution scenes.

[Highlights]

[::] In situ and satellite albedo are in good agreement at 53 FLUXNET sites (r2 0.83). [::] MODIS albedo is systematically lower than in situ measurements for non-forest PFTs. [::] The mismatch increases with the spatial heterogeneity of albedo in a 7 × 7 km area. [::] The seasonal pattern of MODIS albedo matches extremely well for forest PFTs.},
  keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-10492690,~to-add-doi-URL,agricultural-land,albedo,comparison,crops,data-uncertainty,field-measurements,fluxnet,forest-resources,grasslands,mcd43,mcd43a,modelling-uncertainty,modis,remote-sensing,savannas,uncertainty}
}

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