• lo--* 
4 ^ i Retrievals at: 
2 j i.4GHz -o- 
? -f- 5.05GHz 
£ . '-6.5GHz 1 
220 230 240 250 260 270 
DAY of YEAR 
Figure 3. Retrieved vegetation volume traction of a soybean crop, using the continuous 
approach, at 1.4GHz, 5.05GHz and 36.5GHz (from Wigneron et ai, 1993a). 
Figure 4. Composite discrete-continuous modeling of vegetation microwave emission 
(from Wigneron et ai, 1994).