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Poster Session 3
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Radar Backscattering of Vegetation from ERS-1 SAR
Data and a Radiative Canopy Model
Backscatter from model
In order to understood radar backscatter from vegetation, the University of Texas at Arlington (UTA) Radiative Transfer Canopy model (Karam et al., 1992) was used to derive backscatter values expected from the three dominant vegetation in the study area, i.e. rubber, oil palm and paddy. The parameters used in the model were obtained from ground observations which included tree height, soil roughness, soil moisture, leaf radius, leaf orientation, branch radius, branch density, trunk radius, trunk density, etc. Table 1 shows an example of parameter values for matured rubber plantation and Figures 3(a),
3(b) and 3(c) shows the graph of backscatter values obtained for three leave densities i.e. 30, 50 and 120 and three soil moisture values i.e. 0.1, 0.2, 0.35 and 0.5.
Table 1: parameter values for matured rubber plantation
| Height of upper, middle and lower layer |
4.0 m, 2.4 m , 5.9 m |
| Soil roughness : rms height and autocor, length |
1.2 cm, 24 cm |
| Soil moisture |
Variable |
| Soil texture: sand and clay factions |
0.50, 0.25 |
| Leaf scatterer classes: total, upper, middle and lower |
1,1,0,0 |
| Leaf radius and half-thickness |
3.5 cm, 0.2 mm |
| Leaf moisture content |
0.55 |
| Leaf density |
Variable |
| Leaf orientation |
120, 0, 90, 30, 1 |
| Branch/trunk scatterer classes: total, upper , middle and lower |
4, 2, 1, 1 |
| Branch radius |
0.265 cm, 1.05 cm, 10 cm |
| Branch half-length |
4.5 cm, 23.5 cm, 120 cm |
| Branch moisture content |
0.50, 0.50, 0.50 |
| Branch density |
4.37, 0.467, 0.033 |
| Branch orientation |
Spherical, spherical, spherical |
| Trunk radius and half-length |
18 cm, 295 cm |
| Trunk moisture content |
0.48 |
| Trunk density |
0.0067 |
| Trunk orientation |
Vertical within 4 degrees |
Figure 3(a): Backscatter values for rubber derived from the UTA model
Figure 3(b): Backscatter values for oil palm derived from the UTA model
Figure 3(c): Backscatter values for paddy derived from the UTA model
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