Title: Global Scale Comparison of MISR and MODIS Land Surface Albedos
Citation: JOURNAL OF CLIMATE vol. 24 no. 3 p. 732-749
Publication Year: 2011
JRC N°: JRC68748
ISSN: 0894-8755
URI: http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3709.1
DOI: 10.1175/2010JCLI3709.1
Type: Articles in periodicals and books
Abstract: MODIS white sky surface albedos are compared with similar products generated on the basis of the MISR surface BRF model parameters available for year 2005. The analysis is achieved using global scale statistics in order to characterize the broad patterns of these two independent albedo datasets. The results obtained in Taberner etal. (2010) have shown that robust statistics can be established and that both datasets are highly correlated. As a result, the slight but consistent biases and trends identified in this paper, derived from statistics obtained on a global basis, should be considered sufficiently reliable to merit further investigation. The present paper reports on the zonal and seasonal mean differences retrieved from the analysis of the MODIS and MISR surface albedo broadband products. The MISR-MODIS differences exhibit a systematic positive bias or offset in the range 0.01-0.03 depending on the spectral domain of interest. Results obtained in the visible domain exhibit a well-marked and very consistent meridional trend featuring a `smile effect' such that the MISR-MODIS differences reach maxima at the highest latitudes in both hemispheres. The analysis of seasonal variations observed in MISR and MODIS albedo products reveals that, in the visible domain, the MODIS albedos generate weaker seasonal changes than MISR and that the differences increase polewards from the equatorial regions. A detailed investigation of MODIS and MISR aerosol optical depth retrievals suggests that this large scale meridional trend is probably not caused by differences in the aerosol load estimated by each instrument. The scale and regularity of the meridional trend suggests that this may be due to the particular sampling regime of each instrument in the viewing azimuthal planes and/or approximations in the atmospheric correction processes. If this is the case, then either MODIS is underestimating, or MISR overestimating, the surface anisotropy, or both.
JRC Directorate:Sustainable Resources

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