The Japan Meteorological Agency will introduce the so-called four-dimensional variation method in March to increase the accuracy of its six-hour rain forecasts, agency officials said Saturday.
It is expected to improve accuracy in predicting heavy rain caused by typhoons, they added.
A supercomputer will process ever-changing observational data collected by the weather satellite Himawari along four axes -- east-west, north-south, elevation and time.
The supercomputer currently does such calculations four times daily after the latest data is input. The new method will continuously process data collected by Himawari and wind profilers, they said.
The profilers were set up at 25 sites nationwide in the spring last year to observe wind changes at a maximum of once every 10 minutes.
The agency introduced a new supercomputer in spring last year that enables it to use data from Himawari and the profilers.
When it conducted a test forecast for heavy rain on Matsuyama, Ehime Prefecture, in June last year under the new method, the prediction was close to the actual weather events, the officials said. One person was killed by a mudslide in the downpour.
According to the agency, France has already introduced the method for weekly weather forecasts, but Japan will be the first country to use it for short-term forecasts.