field distributing in the whole space have considerable com 
plexity. This paper cannot deal with the theory of the micro - 
wave radiometric field due to limited space, A brief explan 
ation of the general distributing regularity of the radiome 
tric field will be given. 
Water Bodies and Marshland 
For remote sensing of water, snow, ice and water related 
nhenomena, there exist no counterparts to the microwave reg 
ion in other parts of the EM spectrum. The microwave signa 
tures of them are much more detectable on the MICRAD imagery. 
This ease in interpretation has been attributed to a greater 
contrast range between these signatures and surrounding ter 
rain signatures. A digital image taken from the area of Xiao 
yinzi reservoir, Changchun, is shown in Fig. 2(a), where, 
digit"1" and "2" show the water bodies. It is to be noted 
that this image was taken penetrating through a cloud layer, 
and a co-mounted camera recorded the top of the cloud deck 
(see Fig.2(d) ). Fig. 2(b) is a microwave radiation isother 
mal map drawn from Fig. 2(a). The sketch map of topographic 
al features of this areas is shown as Fig. 2(c). 
c.8 3j îi.î.aîsMi'ti 3 
osîj a e i.e l $ l e s a a 
5. 33 I Ji 3« 3 3 8 1 N ÎH 
3551 I31l*lt ¡ill 5 
9 3 a » i » i » i / i i i e 3 
5 1 : i i I I : i i I i I i I 3 
C. 5. 5 5. 0.5. C. 0. 9 3 S 0 0.0. ft C. 
0.5. 3.5. 5. 0.5.1.2 3 0.3.8 3.1.6 
C. 0.1.0. a I ■ 3. 8 1.9 1.1.1.5. 3. 1 
5. 9 S /. a 1.3. 9 3. e. 9 3.0.1.5. a. 
C. c 5 . 5. ¡.5.1.0.3.1.3. 9 1.1.1.9 e. 
(a) 
mm it 
c, peat bod, 
d, cropland, 
e, paddy field, 
f, forst land, 
(b) g, mud, 
h, escape cannal. 
Fig. 2, A digital image of Xiaoyin- 
zi reservoir area, Changchun, at an 
altitude of 2000 m acquired on 
August 20, 1979. 
(d) 
Comparing Fig. 2(b) with Fig. 2(c), we found different sig 
natures from different typical targets.lt has been shown 
that water bodies is a colder radiometric region with low 
emissivity in comparison with land. The boundaries between 
land and water give a brightness temperature difference of 
about 100 K or even greater. There is evidently an excellent 
opportunity to map land/water limits from the MICRAD image. 
The microwave radiometer gives the average brightness tempe 
540