Model Development for Passive Microwave Remote Sensing ...
31' 11' 1
2BI'I
261'1
241'1
220
21' 11' 1
lBe
16111
14,.
121'1
10111
Bill
7111 -5
WHheit's model
horizon tal polarisation
Wind Speed = 0 m/s
-
..............
....
......
-
90 GHz
-
- -6.80 GHz
III
5
Ie
15
2111
25
38
35
SST (Sea Surface Tellperature : [OC])
583
Figure 21.7: Brightness temperature as function of sea surface temperature (SST) using Wilheit's model for partial foam covered sea (W = Om/s, e = 0°).
of SSM!I are used to perform this classification. An example using the set of formulae for
identification of natural high density forests, as found in the Amazon, Congo jungles or in the
Appalachian forest Dense Vegetation is presented below.
T 22V - T 19V :::: 4K
(21.6)
0,5 (T19V + T 37V - T 19H - T 37H ) :::: 1.9 K
(21.7)
T S5V - T 37V < 0.5 K
(21.8)
TS5H - T37H < 6.0 K
(21.9)
T 19V > 262 K
(21.10)
Each of these equations is related to the influence of a different physical parameter. Eq. 21.7
represents the polarization behaviour of the vegetation covered soil. In case of a lossy dense
canopy layer emission is isotropic showing very small polarimetric differences. As the density
decreases (jungle -+ desert) polarization differences caused by the soil become significant, thus
classifying the density of vegetation (Fig. 21.8).
Condition 21.8 is a precipitation flag showing precipitation clouds over vegetation. Rule 21.10
ensures that no ice or snow are present and that what the instrument is seeing is vegetation for
this class of land type. The two remaining conditions 21.6 and 21.9 check the presence of large
quantities of water on the surface or, on the other hand, differentiate between dry and moist
soil, depending on the vegetation coverage. This check is based on the influence of water in an
essentially bare soil as it decreases the brightness temperature and increases the polarization
difference.
All this rules can be explained by the physical behaviour of the soil types. However classification
is useful only for relatively large areas, with sizes greater than at least a couple of footprints
(pixels).
31' 11' 1
2BI'I
261'1
241'1
220
21' 11' 1
lBe
16111
14,.
121'1
10111
Bill
7111 -5
WHheit's model
horizon tal polarisation
Wind Speed = 0 m/s
-
..............
....
......
-
90 GHz
-
- -6.80 GHz
III
5
Ie
15
2111
25
38
35
SST (Sea Surface Tellperature : [OC])
583
Figure 21.7: Brightness temperature as function of sea surface temperature (SST) using Wilheit's model for partial foam covered sea (W = Om/s, e = 0°).
of SSM!I are used to perform this classification. An example using the set of formulae for
identification of natural high density forests, as found in the Amazon, Congo jungles or in the
Appalachian forest Dense Vegetation is presented below.
T 22V - T 19V :::: 4K
(21.6)
0,5 (T19V + T 37V - T 19H - T 37H ) :::: 1.9 K
(21.7)
T S5V - T 37V < 0.5 K
(21.8)
TS5H - T37H < 6.0 K
(21.9)
T 19V > 262 K
(21.10)
Each of these equations is related to the influence of a different physical parameter. Eq. 21.7
represents the polarization behaviour of the vegetation covered soil. In case of a lossy dense
canopy layer emission is isotropic showing very small polarimetric differences. As the density
decreases (jungle -+ desert) polarization differences caused by the soil become significant, thus
classifying the density of vegetation (Fig. 21.8).
Condition 21.8 is a precipitation flag showing precipitation clouds over vegetation. Rule 21.10
ensures that no ice or snow are present and that what the instrument is seeing is vegetation for
this class of land type. The two remaining conditions 21.6 and 21.9 check the presence of large
quantities of water on the surface or, on the other hand, differentiate between dry and moist
soil, depending on the vegetation coverage. This check is based on the influence of water in an
essentially bare soil as it decreases the brightness temperature and increases the polarization
difference.
All this rules can be explained by the physical behaviour of the soil types. However classification
is useful only for relatively large areas, with sizes greater than at least a couple of footprints
(pixels).