1026 
12/im) scanner and flown at an altitude of about 1,500 meters (pixel size approximately one meter) over a 
cotton field at MAC in early July, 1993. Calibration and atmospheric correction refinements have not yet been 
applied to the data, but Figure 5 shows that an extrapolation of a subsample of the coarse airborne 
measurements nonetheless corresponds reasonably well to coincident ground-based measurements. 
210 220 230 240 250 260 270 280 
Day of Year 1989 
Figure 3. Values of Water Deficit Index (WDI) for sites A and B in the alfalfa field over a single harvest 
period. 
1 
0.9 
0.8 
x 0.7 
t> 
v 
£ 0.6 
0 0.5 
CO 
t 0.4 
u 
0) 
> 0.3 
0.2 
0 . 1 - 
ftoiviirciBtd, d»y toi 
W»wi...d • iW«ind.ina«liot 
McanepyXw W 
\ \ \ 
\ 
V _ _ - 
\ "V 
\ 
\ V 
liis.... \ 
\ \ 
. \ 
\ i 
* • V \ 
\ 
\ w 
\ 
\ ^ 
«•at ban aoS 
SybMHi 
-15 -10 -5 0 5 10 15 
Surface-Air temperature difference 
20 
25 
Figure 4. Hypothetical SAVI-(T,-TJ pairs in fields with variable stands in two scenarios: a non-stressed crop 
with a completely dry soil surface (x), and a crop experiencing moderate water stress with a damp soil surface 
(o).