DANTAS, F. R. C.; http://lattes.cnpq.br/2810602424397426; DANTAS, Fabiane Regina da Cunha.
Abstract:
In this study we try to find functional relationships between vegetation parameters
estimated by the sensors AVHRR/NOAA and TM/LANDSAT-5 over different targets at
Frutacor Farm and in the vicinity of Quixere, both located in the state of Ceara, in the years of
2005 and 2006. The TM/LANDSAT images were turned to a 1-km spatial resolution in order
to yield a comparable spatial grid as AVHRR/NOAA images. The image reprojections were
carried out by the Model Maker of the software ERDAS Image 8.7, using the SEBAL
(Surface Energy Balance Algorithm for Land) parameterisation. The Least-square linear
regression model was used to find functional relationships between various parameters
estimated by the satellite, namely, NDVI, SAVI, L A I and albedo. The results showed striking
differences in the spatial variability of the parameters over the two years studied. This is
partly because 2005 was predominantly dry whilst 2006 was characterized as a rainy year.
The functional relationship between AVHRR and TM data presented satisfactory correlation
coefficients (r): rO.87 for NDVI, r=0.81 for SAVI, r=0.84 for L A I . The correlation
coefficient for the albedo was, however, somewhat lower with a value o f r=0.62. Values of
albedo estimated by the AVHRR and TM, and compared against values measured by the net
radiometers CNR1, presented average errors of 1.25% and 3.57%, respectively. The
vegetation fraction increased over almost the entire region during 2006, except in the irrigated
area of Frutacor Farm which did not present any significant difference.