Supercomputers have long been used in weather forecasting but not for abrupt, highly localized events. Now for the first time, a group of researchers using the K computer used the powerful K computer and advanced radar observational data to accurately predict the occurrence of torrential rains in localized areas. These latter events can arise in just a few minutes when cumulonimbus clouds suddenly develop.
The key to the success is rapid “big data assimilation” using computational power to synchronize data between large-scale computer simulations and observational data. Researchers also used a much finer grid than the typical 1-2 km spacing of most models. The work done by an international team will be published later this month in the August issue of the Bulletin of the American Meteorological Society.
In this instance, researchers used the nonhydrostatic mesoscale model used by the Japan Meteorological Agency, but with 100-meter grid. Led by Takemasa Miyoshi of the RIKEN Advanced Center for Computational Science (AICS), researchers first carried out 100 parallel simulations of a convective weather system using the much finer grid spacing. They produced a high-resolution three-dimensional distribution map of rain every 30 seconds, 120 times more rapidly than the typical hourly updated systems operated at the world’s weather prediction centers today.
To test the accuracy of the system, the researchers attempted to model a real case—a sudden storm that took place on July 13, 2013 in Kyoto, close enough to Osaka that it was caught by the radars at Osaka University. Pure simulations without rapid incorporation of finer-grained observational data were unable to replicate the rain; incorporation of observational data allowed the computer to accurately represent the actual storm.
“Supercomputers are becoming more and more powerful, and are allowing us to incorporate ever more advanced data into simulations. Our study shows that in the future, it will be possible to use weather forecasting to predict severe local weather phenomena such as torrential rains,” said Miyoshi.
Link to release: http://www.riken.jp/en/pr/press/2016/20160809_1/