132
Channel
Retrieved Albedo
Rural
Maritime
Urban
Desert
Cl
20.00
20.42
18.26
20.29
C2
20.00
20.28
18.51
20.20
C3
20.00
20.74
18.74
20.24
C4
20.00
21.29
19.25
20.25
Channel
Retrieved Visibility
Rural
Maritime
Urban
Desert
Cl
20.01
18.33
43.88
16.87
C2
20.01
14.91
40.86
17.19
C3
20.02
12.03
39.17
17.08
C4
20.01
2.93
49.50
18.07
Table 1. Retrieval of albedo and visibility over a range of aerosol types at albedo=20%, visibility=20km
34. Natural surfi
The operational i
directional reflecl
surface is modelk
spot effect of fini
(Stoner et al. 1981
1990).
Table 3 shows n
sensitivity of the s
albedos for veget
atmospheres. Thi;
NDVI index vali
independence fro:
from top-of-atmc
currently being ui
Channel
Retrieved Albedo
Rural
Maritime
Urban
Desert
Cl
20.00
20.69
16.26
20.16
C2
20.00
21.09
17.01
20.55
C3
20.00
21.02
17.50
20.60
C4
20.00
*****
18.50
20.54
Channel
Retrieved Visibility
Rural
Maritime
Urban
Desert
Cl
9.98
8.11
32.%
6.12
C2
9.99
6.94
30.93
6.98
C3
9.99
4.03
27.99
6.92
C4
10.00
*****
34.05
7.86
Table 2. Retrieval of albedo and visibility for a range of aerosol types at albedo=20%, visibility=10km
corresponds to an x-axis value 0.39% while 12 bit quantisation corresponds to 0.024%. The results show the 8
bit quantisation results in an absolute error of approximately 1 % for these conditions.
Surface
a
Bare soil
Homogenous
canopy
LAI=2.0
Homogenous
canopy
LAI=4.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6
0.0 0.1 0.2 0.3 0.4 03 0.6
Table
4 - DISCUSSIOl
A method has be
The method uses
and surface refl&
use of accurate f
analysis has bee
accurate retrieva
variation. The n
and that this sens
Initial results usii
are robust to vari
Quantisation error (%) Quantisation error (%)
(a) Albedo error (b) Visibility error
Figure 5. Sensitivity of parameter retrieval to quantisation error at 20%albedo, 10km visibility
Further work is 1
inversion of mon
spectral variatio
reflectance and e:
