116 
with relatively large and mainly in the horizontal direction ba 
orientated leaves. Previous investigations on sugar beet leaves 0 r 
showed an emissivity value of £ - 0.86 at X - 3 cm . Hence they th 
turned out to be clearly discernable from soil. The lower value of ¿ r 
the microwave signal on the second date can therefore be explained tl 
by an increase of plant cover degree because of the plant growth. 
Based on the emissivity values which were obtained in the 
preinvestigations on sugar beet leaves and soil as well as the 4^ 
field measurements of temperature and moisture for plants and soil 
during the airborne missions the plant cover degree takes the 
estimated values shown in fig. 4 which coincides well with the 0 f 
terrestrial estimations. tl 
ab 
CL Experiment TELEGEO in 
12 
The experiment TELEGEO took place on two test sites in Poland in ta 
1987. The radiometer complex including the microwave radiometer m0 
was used on the test site Narev in the east of Poland near Q n 
Bialystok from the 15.5. to the 30.5.1987. ou 
The scientific program of the complex experiment was aimed at <j e 
investigating the impact of drainage measures over the last 20 co 
years in a territory comparable to the Havel depression area near w i 
Potsdam. Of special interest in interpretating the microwave pr 
radiometer data was the profile section of the Narev flood plain me 
which is used as grass land. Because of the river nearness a 
remarkable changing water influence could be expected. In addition i n 
to the CIPE radiometer complex a soviet microwave radiometer with by 
a wavelength of A - 30 cm could be used in the experiment. This j n 
supported the conclusions about the wavelength dependency of the to 
vegetation influence, i.e. for corn fields and pasture this ¿r 
influence was significantly lower at the greater wavelength. The s 0 
same tendency is also valid for the profile sections shown as co 
example. While the vital grassland vegetation masks the soil c b 
almost entirely in case of the 3 cm radiometer the higher moisture 
content in the depression and with decreasing distance to the to 
river is clearly deductable for the 30 cm microwave signal (fig v j_ 
5). Trees while not being unambigously identified in the 30 cm