Explanation of the criteria for classification and numbering of components     C33.3.02
 (JUL 00)
Explanation of the dates on the component's description



1.   Purpose and objectives

     Rainfall measurement system by radar. The system is used for measurement of areal rainfall amount and rainfall prediction in short time.

2.   Description

     The system consists of four major subsystems, which are the radar subsystem, the data processing subsystem, the controlling system and the data servicing subsystem.

     Rainfall rate is estimated by the ZDR method and the B method. That is, when a rainfall rate is strong, the ZDR method is applied, and the B method is applied when a rainfall rate is weak. It is called combined method.

     Rainfall rate is measured in mm/hr out to a range of 198 km (or 300 km) using a polar mesh of 256 sectors (1.4 degrees) by 1.5 km.

     After the data processing, the polar mesh is converted to the rectangular mesh (1km x 1km) and the rainfall is displayed on CRT display in 9 colour grades.

3.   Input

     Actual rainfall.

4.   Output

     Digitized rainfall amounts every 5 minutes on each mesh. Areal rainfall amounts every 5 minutes are also displayed. The outputs can be displayed on remote colour CRT displays in several formats.

5.   Operational requirements and restrictions

     Operating personnel with experience of large electronic systems are required. To extend the observing range the radar subsystem should be sited on a mountain-top, with data being transmitted to the data processing subsystem situated at the base of the mountain. Only a simple building is 
required at the mountain-top to house the radar subsystem.

     No telemetering raingauges are required for calibration.

6.   Form of presentation

     A catalogue and instrument specifications describing the radar equipment, communication subsystem and data processing subsystem are available.

8.   Operational experience

     Used successfully since 1998.

     One system is now in operation. This system consists of 26 radar raingauge systems.

8.   Originator and technical support

     Originator: Ministry of Construction (River Bureau).

     Technical support: Toshiba Corp., Mitsubishi Electric Corp. and Japan Radio Co., Ltd.

9.   Availability

     From the HOMS National Reference Centre for Japan.

10.  Conditions on use

     The system is for sale.


(First entered: FEB 01

Last updated: APR 00)