According to The Asahi Shimbun, a sophisticated system to warn people of localized heavy rain up to 30 minutes in advance is being tested in a demonstration experiment that began July 23 in areas around Tokyo.
The system, developed by National Institute of Information and Communications Technology and Nagoya University and others, is planned to be put into practical use in time for the Tokyo 2020 Olympics.
Cumulonimbus clouds that unleash torrential rain develop within as little as 10 minutes and can lead to flash floods and landslides. Downpours triggered by the clouds last up to several tens of minutes, lashing concentrated areas with sometimes lethal effects that have been felt increasingly in recent years, such as in this month’s rain and related disasters in western Japan.
Until now, weather radars have been only able to observe underneath cumulonimbus clouds, and so are unable to quickly detect when they are growing and likely to produce heavy rain.
The system being trialed uses a “multi-parameter phased array” weather radar that takes just 30 seconds to assess the 3-D forms of cumulonimbus clouds, compared to five minutes using conventional weather radars.
In addition, the new radar’s sophistication means it can produce weather maps of areas as small as 250 meters square, enabling it to forecast specific locations where heavy rain is set to fall 30 minutes beforehand.
The radar has been installed at Saitama University in Saitama Prefecture and covers a radius of up to 80 kilometers.
People taking part in the experiment, which runs until Oct. 31, receive e-mail alerts warning them of impending heavy rain in their areas.
Participants can register two locations, such as their home and workplace, to receive the notifications on.
Organizers gathered 2,000 volunteers to take part in the experiment to test the system’s effectiveness. Participants will be asked questions on their experience of the system after using it.
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