GPS to be used to predict heavy rain

TOKYO, July 4 Kyodo -
The Japan Meteorological Agency will use a global positioning system to improve
the accuracy of predicting localized torrential rain, analyzing water vapor
content via GPS, according to its officials.
While GPS observes seismic changes by receiving radio waves from satellites at
antennas on the ground, large amounts of water vapor slow the arrival of radio
waves, causing errors in observation.
The agency, together with the Meteorological Research Institute, developed the
method to estimate the water vapor quantity through the delay of the radio wave
arrival so they can predict the outbreak of heavy rain more accurately, the
officials said.
The new method will be introduced by the end of next March, they said.
Simulations using GPS enabled the agency to predict areas to be hit by heavy
rain one to five hours before in cases of flood disasters in the city of
Shizuoka, which saw many submerged houses on June 30, 2004, and in the city of
Kobe, where five people were killed due to a swollen river on July 28 last
year.
The agency was unable to made prediction in those days.
==Kyodo