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WATER SURFACE CONDITION AND TWO CHANNEL MICROWAVE MEASUREMENTS
*
K. Tsuchiya , S. Yamamoto, C. Ishida and M. Shimada
National Space Development Agency of Japan (NASDA)
2-4-1, Hamamatu-cho, Minato-ku, Tokyo, 105 Japan
I. Isozaki
Meteorological Research Institute / Meteorological Agency
1-1, Nagamine, Yatabe-cho, Tsukuba-gun, Ibaragi, 305 Japan
Abstract
Passive microwave measurements of water surface: of the pool ( 12m X 25 m )
were made from a 20-m tower in October 1981.
Analysis of the data indicated that correlation between antenna temperature and
incident angle was positive for vertical polarization and negative for horizon-
tal polarization. It was found that effect of side lobe can not be neglected.
A method of eliminate side lobe effect is described.
LA Introduction
Marine Observation Satellite-1 (MOS-1) is the first Japanese earth obser-
vation satellite which will be launched in 1986. Two frequency ( 23.8 GHz and
31.4 GHz ) microwave scanning radiometer ( MSR ) are to be installed in MOS-1.
Makinq use of a bread board model of MSR, radiation emitted from the water sur-
face was observed at the test site of Meteorological Research Institute. In the
experiment, MSR was mounted on a 20-m tower and a 12 m X 25 m pool filled with
pure water was used. The objectives of the experiment are to get relationship
between antenna temperature and various parameters to make use of the data ob-
tained from the MSR onboard MOS-1 after it is launched.
2. Method of observation
The specification of MSR used the experiment is shown in Table 1. Output
signal is integrated for 10 msec and 47 msec simultaneously at the two frequen-
cies. It has a radiometric resolution of 1.0 K at 300 K. As is indicated
in the fuctional block diagram of Fig. 1, MSR is consisted of two .Dicke type
receivers, into which signals are fed by an antenna and calibration sources,
delivering analog output signals to an encoder. Observed. temperature
and calibration source temperature are recorded onto an instrumentation tape
together with auxiliary data such as annotation data which are manually input
and physical temperature of components of MSR which are necessary for computing
wave guide loss for radiometric calibration.
Antenna diameter is 50 cm and detailed antenna pattern measurements were
conducted before the experiment for each frequency. Fig. 2 shows MSR atenna
patterns at 23.8 GHz and 31.4 GHz.
MSR was installed in a frame with capability of adjustable elevation angle.
Polarization is also adjustable by rotating the radiometer about its electrical
* Current affiliation Chiba University
1-33, Yayoi-cho, Chiba-city, 260 Japan
253
