The analysis of MODIS NDVI and EVI with LAI was
based on 2001 data only. The relationships between NDVI–
LAI and EVI–LAI throughout the year are also given in
Table 1. Since there was only one year of data available to
investigate the relationship of MODIS NDVI and EVI with
LAI, the focus must be on intraannual variations in the
relationships. Near-perfect linear relationships were
obtained for both LAI–MODIS NDVI (R2
=0.99) and
LAI–MODIS EVI (R2
=0.92) during the leaf production
period. On the contrary, no linear relationship was found for
either pair during the period of constant leaf area. The major
discrepancy was found during the leaf senescence period.
Whereas MODIS NDVI still showed a very strong linear
relationship with LAI (R2
=0.80), the relationship between
MODIS EVI and LAI was poor with R2 of 0.38. This was
the only case where R2 lower than 0.80 was found as related
to LAI during the leaf senescence period in an individual
year. Therefore, MODIS EVI has not demonstrated any
advantage over other indices (MODIS NDVI, VEGETATION
NDVI, and AVHRR NDVI) in relation to LAI.
However, given the limited data, this generalization may be
inappropriate.
The analysis of MODIS NDVI and EVI with LAI wasbased on 2001 data only. The relationships between NDVI–LAI and EVI–LAI throughout the year are also given inTable 1. Since there was only one year of data available toinvestigate the relationship of MODIS NDVI and EVI withLAI, the focus must be on intraannual variations in therelationships. Near-perfect linear relationships wereobtained for both LAI–MODIS NDVI (R2=0.99) andLAI–MODIS EVI (R2=0.92) during the leaf productionperiod. On the contrary, no linear relationship was found foreither pair during the period of constant leaf area. The majordiscrepancy was found during the leaf senescence period.Whereas MODIS NDVI still showed a very strong linearrelationship with LAI (R2=0.80), the relationship betweenMODIS EVI and LAI was poor with R2 of 0.38. This wasthe only case where R2 lower than 0.80 was found as relatedto LAI during the leaf senescence period in an individualyear. Therefore, MODIS EVI has not demonstrated anyadvantage over other indices (MODIS NDVI, VEGETATIONNDVI, and AVHRR NDVI) in relation to LAI.However, given the limited data, this generalization may beinappropriate.
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