Also is provided to the WMO SG-RFC for information purposes.
This document is for information to the SG-RFC.
JAPAN METEOROLOGICAL AGENCY
WEATHER RADAR OBSERVATIONs IN JMA The purpose of radar observation in Japan Meteorological Agency (JMA) is to acquire information on meteorological conditions in the wide range of space by radiating radio wave and by receiving reflected signals by precipitation targets.
The observational results contribute effectively to the meteorological services such as weather forecasting and warning. They are also used for researches and studies.
Ordinary Weather Radar
JMA operates a nationwide network of 20 ordinary weather radars which covers almost whole country. Principal specifications of these radars are listed in Table 1.
These radars have three acquisition modes: three-hour interval, one-hour interval, and continuous mode. They are operated under selected one mode according to weather conditions.
Radiating radio wave, controlling the antenna elevation angle, signal receiving, data processing and dissemination to users are performed automatically. Intensity of precipitation echo at every 2 kilometres height is reported at every 10 minutes interval. At every one hour, amount of precipitation for an hour just before is also estimated and reported based on 10 minutes interval data.
JMA is now considering a plan for the future upgrading of weather radar using Doppler function to obtain not only echo intensity but also information of wind field. Data of Doppler weather radar will improve detectability of small-scale meteorological phenomena.
Airport Weather Radar
JMA operates airport weather radars at 9 main international airports and monitors precipitation in areas around the airport and along the flight routes in order to ensure the flight safety. Principal specifications of these radars are listed in Table 2.
As shown in Table 2, five of these radars (Kansai, New Tokyo, Tokyo, New Chitose and Osaka) are Doppler radars. These Doppler radars measure not only intensity of precipitation, but also Doppler velocity of wind, and detect micro down burst and low level wind shears by special software. Information of these dangerous phenomena for airplane detected by the Doppler radars are provided to the airport weather services and air traffic controls in real time.
JMA is planning to replace the remaining four non-Doppler airport weather radars with Doppler weather radars at next renewal.
JMA has two research weather radars. Principal specifications of these radars are listed in Table 3.
These radars are mainly used for intensive observational experiments to investigate the mechanisms of various meteorological phenomena such as typhoons, depressions, fronts, heavy rains and snows, thunderstorms, etc. They are also used for studies to develop various radar observational technologies and signal/data processing algorithms.