Figure 2. Comparison between brightness temperature predicted from Cupid and 
measurements from the MMR instrument at the FIFE site 11 on Day 156 at 11:45 
Central Standard Time (leaf area index is 1.6). 
5.2. Directional Emissivity 
Palluconi and Kahle (1990) estimated directional emissivity of the soil-vegetation system at 
FIFE of 0.99 ± 0.01 based on their measurements. Using an erect leaf angle distribution, soil 
emissivity of 0.93, leaf emissivity of 0.96, leaf area index of 1.6, the Cupid model was used 
to estimate a soil-vegetation emissivity of 0.984 at nighttime with a very small dependence 
on view angle. 
Directional emissivity was measured for a recently-tilled, moist, bare silt loam soil and 
a mature com canopy using the new method described in this paper. The results are shown 
in Figure 3. 
Figure 3. Thermal emissivity of mature com canopy with leaf area index of 3.2, height 
of 2.5 m, and emissivity of moist silt loam soil with recent tillage.