TY - JOUR
T1 - Evaluating MODIS, MERIS, and VEGETATION vegetation indices using in situ measurements in a semiarid environment
AU - Fensholt, Rasmus
AU - Sandholt, Inge
AU - Stisen, Simon
N1 - Funding Information:
Manuscript received December 8, 2004; revised February 3, 2006. This work was supported in part by the Danish Research Councils, ESA-related research under Grant 990249, in part by the Danish Agricultural and Veterinary Research Council under Grant 23-01-0153, and in part by the Danish Scientific Research Council under Grant 21-03-0578.
PY - 2006/7
Y1 - 2006/7
N2 - New and improved satellite sensors specially designed for vegetation monitoring have been launched in recent years; including the Moderate Resolution Imaging Spectrometer (MODIS) onboard Terra and Aqua, the Medium Resolution Imaging Spectrometer (MERIS) on the ENVISAT satellite, and VEGETATION onboard the Systeme Pour l'Observation de la Terre (SPOT) satellite. The aim of this paper is to evaluate two different vegetation indices of these new sensors; the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI). This is done by radiometric in situ measurements covering natural grass savanna in Senegal. Variations in the dynamic range of in situ NDVI was found caused by the differences in spectral response functions, MERIS NDVI characterized by the largest dynamic range. Both daily MERIS and MODIS NDVI mirrored accurately in situ measured NDVI (MERIS r2 = 0.97 and MODIS r2 = 0.96). VEGETATION NDVI (only available as ten-day composites) was found to be significantly lower than MODIS NDVI due to lower VEGETATION near-infrared (NIR) reflectance values. A good agreement between the NDVI/EVI relation from satellite and from in situ measured MODIS NDVI/EVI was found. This indicates an accurate atmospheric correction of the MODIS red, NIR, and blue spectral bands, also confirmed by in situ measured reflectances. EVI is sensitive to variations in blue band reflectance, and the consistency between EVI from the different sensors is reduced when compared to NDVI due to the different atmospheric correction schemes of the blue band. Thus, it is recommended that vegetation index cross-sensor algorithms should be based on NDVI over EVI.
AB - New and improved satellite sensors specially designed for vegetation monitoring have been launched in recent years; including the Moderate Resolution Imaging Spectrometer (MODIS) onboard Terra and Aqua, the Medium Resolution Imaging Spectrometer (MERIS) on the ENVISAT satellite, and VEGETATION onboard the Systeme Pour l'Observation de la Terre (SPOT) satellite. The aim of this paper is to evaluate two different vegetation indices of these new sensors; the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI). This is done by radiometric in situ measurements covering natural grass savanna in Senegal. Variations in the dynamic range of in situ NDVI was found caused by the differences in spectral response functions, MERIS NDVI characterized by the largest dynamic range. Both daily MERIS and MODIS NDVI mirrored accurately in situ measured NDVI (MERIS r2 = 0.97 and MODIS r2 = 0.96). VEGETATION NDVI (only available as ten-day composites) was found to be significantly lower than MODIS NDVI due to lower VEGETATION near-infrared (NIR) reflectance values. A good agreement between the NDVI/EVI relation from satellite and from in situ measured MODIS NDVI/EVI was found. This indicates an accurate atmospheric correction of the MODIS red, NIR, and blue spectral bands, also confirmed by in situ measured reflectances. EVI is sensitive to variations in blue band reflectance, and the consistency between EVI from the different sensors is reduced when compared to NDVI due to the different atmospheric correction schemes of the blue band. Thus, it is recommended that vegetation index cross-sensor algorithms should be based on NDVI over EVI.
KW - Grassland
KW - In situ measurements Medium Resolution Imaging Spectrometer (MERIS)
KW - Moderate Resolution Imaging Spectrometer (MODIS)
KW - Senegal
KW - VEGETATION
KW - Vegetation index
UR - http://www.scopus.com/inward/record.url?scp=33746324527&partnerID=8YFLogxK
U2 - 10.1109/TGRS.2006.875940
DO - 10.1109/TGRS.2006.875940
M3 - Article
AN - SCOPUS:33746324527
SN - 0196-2892
VL - 44
SP - 1774
EP - 1786
JO - IEEE Transactions on Geoscience and Remote Sensing
JF - IEEE Transactions on Geoscience and Remote Sensing
IS - 7
M1 - 1645278
ER -