| Ken'ichi Okamoto |
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[Slide 16]
[Slide 17]
[Slide 18]
[Slide 19]
[Slide 20]
[Slide 21]
[Slide 22]
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[Slide 16, 17]
As time is short, I will skip the explanation of pulse compression. We thought about which one was better to adopt, either a planar array antenna or an offset cylindrical parabolic antenna. As there was 'spill-over,' the size of offset cylindrical parabolic antenna becomes large. The planar array antenna is small in size. If the good sidelobe characteristics can be attained by the slotted waveguide planar array antenna, it is better from the point of loading on the satellite. Finally we selected the slotted waveguide planar array type.
[Slide 18]
We had made up the Bread Board Model with the help of Toshiba and NEC Corporation. And also we had done the experiment to measure the precipitation from the ground. We had made the radar beam scan electrically. We had the confidence to develop spaceborne precipitation radar. Since we had the confidence to achieve this radar in the TRMM project, we requested NASDA to develop the flight model.
[Slide 19]
TRMM was launched in November 1997. This launch window was newly opened. We could successfully observe the later half of El Nino event. If we had launched TRMM six month later, we couldn't have got the data of the disappearing process of El Nino. Due to the excellent decision by Mr. Yoshimura, executive director of NASDA and Mr.Moriguchi, the director of space development division of Science and technology Agency at that time, TRMM could be launched in November. This year, El Nino might be observed. In order to extend the life of TRMM, we have increased the altitude of TRMM satellite to 402.5 km in August 2001. This time, we hope to observe the El Nino from the beginning to the end.
[Slide 20]
The block diagram of the flight model of the TRMM precipitation is shown in this slide. The active array radar with solid state power amplifiers was used in the TRMM PR and it has been operated in space.
[Slide 21]
This slide shows the overall diagram of TRMM PR algorithms. Even when the hardware has been completed, it does not mean the end point of the development. As I mentioned before, the algorithm is very important for the radar. I want to emphasize the importance of the algorithm, which is used for retrieving the rainfall rate from the observed data. It is NASA which pointed out this importance first. In 1991, NASA issued an announcement of opportunity to organize TRMM science team. At that time, the Japan side was worried if the project was approved or not. The aims of this science team included the development of the algorithm for the precipitation radar. As the PR had been developed in Japan, I thought that its algorithm also should be developed in Japan. At that time a team leader for developing the algorithm for PR was also being sought by NASA. The announcement of opportunity of a team leader for developing the TRMM PR algorithm was directed to all the excellent scientists in the world. I decided to put every effort into making a proposal from Japan. At that time I was young, so I sat up late for writing the proposal. Finally I received endorsement from Dr. Fugono, the director of the planning division of CRL at that time. The US side was very fair for the selection and I was successfully selected as the leader. The US and Japan joint research was successful in completing the PR algorithm before launching the TRMM satellite.
[Slide 22]
This is the data sample and the typhoon image is shown. The distribution of rain under cloud is clearly seen and an eye of the typhoon is obviously shown.
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