The MODerate MODerate resolution Imaging resolution Imaging Spectroradiometer Spectroradiometer (MODIS) on (MODIS) on- - The board the Earth Observing System/NASA Terra and Aqua satellites offers new offers new board the Earth Observing System/NASA Terra and Aqua satellites capabilities for the study of land surfaces with a spatial resolution up to 250 m. ution up to 250 m. capabilities for the study of land surfaces with a spatial resol Prior to the derivation of various land parameters from radiometrically radiometrically Prior to the derivation of various land parameters from calibrated MODIS data, the signals measured by the instrument at the top of the the top of the calibrated MODIS data, the signals measured by the instrument at atmosphere need to be converted to surface reflectance, that is, to the to the atmosphere need to be converted to surface reflectance, that is, reflectance that would be measured by MODIS at the ground level without the without the reflectance that would be measured by MODIS at the ground level atmosphere. atmosphere. The process necessary for that conversion is called atmospheric The process necessary for that conversion is called atmospheric correction. It uses the calibrated data as input and performs corrections for the rrections for the correction. It uses the calibrated data as input and performs co effect of gaseous absorption, molecules and aerosol scattering, coupling coupling effect of gaseous absorption, molecules and aerosol scattering, between atmospheric and surface bidirectional reflectance function. on. between atmospheric and surface bidirectional reflectance functi Goals: Goals: Present the Present the approaches and codes used approaches and codes used at at Altai State University for the Altai State University for the atmospheric correction of visible to middle- atmospheric correction of visible to middle -infrared MODIS data and for infrared MODIS data and for retrieval of land parameters such as the vegetation indices, bidirectional retrieval of land parameters such as the vegetation indices, bid irectional reflectance distribution function, albedo reflectance distribution function, albedo, snow mask. , snow mask.
The components affecting the remote sensing signal in The components affecting the remote sensing signal in the 0.4 0.4- -2.5 2.5 µ µm m range range the
Altai region, October 13 , 2003 Altai region, October 13 , 2003
and АОТ АОТ _ Atmospheric correction and _ 0,66 0,66 for fires for fires Atmospheric correction Scene of the Scene of the October 1 3 October 1 3 , , 2 0 0 3 2 0 0 3 1 .0 0 .5 0 .0 After atm ospheric After atm ospheric corrections ( PGE1 1 ) corrections ( PGE1 1 )
Fire. May 15 , 2006 Fire. May 15 , 2006
Altai region. May 12 , 2006 Altai region. May 12 , 2006
NDVI distribution function for the South NDVI distribution function for the South- - W estern Siberia W estern Siberia according to MODI S/ Terra data, October 1 3 , 2 0 0 3 according to MODI S/ Terra data, October 1 3 , 2 0 0 3 1 - without atmospheric corrections 2 - with atmospheric corrections. 3 - difference NDVI (2) – NDVI(1)
NDVI distribution function for the South- NDVI distribution function for the South - W estern Siberia, W estern Siberia, May May 1 2 , 2 0 0 6 1 2 , 2 0 0 6
NDVI distribution function for the South- NDVI distribution function for the South - W estern Siberia, W estern Siberia, May May 1 5 , 2 0 0 6 1 5 , 2 0 0 6
Key causes for land surface reflectance anisotropy Key causes for land surface reflectance anisotropy
MODIS BRDF/Albedo Albedo Processing Scheme Processing Scheme MODIS BRDF/
Nadir Sun- Nadir Sun - View reflectance ( bands 1 View reflectance ( bands 1 - - 4 4 - - 3 ) 3 ) ( From 1 1 th to 2 5 th Juny ( From 1 1 th to 2 5 th Juny, 2 0 0 6 ) , 2 0 0 6 )
Atm ospherically corrected Atm ospherically corrected reflectances reflectances, bands 1 , bands 1 - - 4 4 - - 3 3 ( June 2 2 , 2 0 0 6 ) ( June 2 2 , 2 0 0 6 )
Black - Black - sky sky albedo albedo for 4 5 degrees solar zenith, band 1 for 4 5 degrees solar zenith, band 1 ( From 1 1 th to 2 5 th ( From 1 1 th to 2 5 th Juny Juny, 2 0 0 6 ) , 2 0 0 6 )
W hite- W hite - sky sky albedo albedo, band 1 , band 1 ( From 1 1 th to 2 5 th ( From 1 1 th to 2 5 th Juny Juny, 2 0 0 6 ) , 2 0 0 6 )
Snow m apping Snow m apping Reflectance of snow Reflectance of snow, , water water, , soil and soil and vegetation ( vegetation (according to according to Klein A. G. Klein A. G. et al., 1998) , 1998) and location of the and location of the et al. MODIS channels (1 (1 – – 7) 7) MODIS channels Criteria applied in snow mapping using applied in snow mapping using MODIS data MODIS data Criteria Number Number Criterion Criterion ≥ 0,4 R6) / (R4 + R6) ≥ 1 1 NDSI = (R4 – NDSI = (R4 – R6) / (R4 + R6) 0,4 2 R2 > 0,11 2 R2 > 0,11 ≤ NDSI <0,4 and Є D 0,05 ≤ R1) / (R2+R1) Є 3 3 0,05 NDSI <0,4 and NDVI = (R2 NDVI = (R2 – – R1) / (R2+R1) D R4 ≥ ≥ 0,1 4 4 R4 0,1 • Hall D. K. et al. // Remote Hall D. K. et al. // Remote Sens Sens. Environ., 1995, v. 54, pp. 127 . Environ., 1995, v. 54, pp. 127- -140. 140. • • Hall D. K. et al. // Remote Hall D. K. et al. // Remote Sens Sens. Environ., 1998, v. 66, pp. 129 . Environ., 1998, v. 66, pp. 129- -137. 137. • • • Klein A. G. et al. // Klein A. G. et al. //Hydrol Hydrol. Process., 1998, v. 12, pp. 1723 . Process., 1998, v. 12, pp. 1723- -1744. 1744. • • Hall D. K. et al. Algorithm theoretical basis document (ATBD) f Hall D. K. et al. Algorithm theoretical basis document (ATBD) for the MODIS snow and sea ice or the MODIS snow and sea ice- -mapping mapping algorithms. NASA EOS- algorithms. NASA EOS -MODIS Doc., 2001, 55 p. MODIS Doc., 2001, 55 p.
NDSI versus versus NDVI NDVI plot for snow plot for snow- -covered covered siberian siberian forests. forests. NDSI - our data our data, , - - Klein A. G. et al. Klein A. G. et al., , 1998 - 1998
Snow m apping. MODI S data. March 2 1 2 1 , , 2 0 0 6 2 0 0 6 Snow m apping. MODI S data. March
Snow m apping. MODI S data. April 2 0 , 2 0 0 6 2 0 0 6 Snow m apping. MODI S data. April 2 0 ,
Snow m apping. MODI S data. May 1 5 1 5 , , 2 0 0 6 2 0 0 6 Snow m apping. MODI S data. May
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