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Figure 4. Atmospheric effects on four of the selected vegetation indices. Different lines represent 
vegetation index values at different visibilities ranging from 5 km to 500 km. 
Figure 5. Graphic presentation of the sensitivity analysis of vegetation indices when considering all 
possible external factors, (a) vegetation sensitivity, (b) soil sensitivity, (c) atmosphere sensitivity, and 
(d) all three factors considered, where SB is soil brightness scaled by a factor 600.