5:15 PM - 7:15 PM
[MTT37-P05] An analysis of the quasi-stationary rainband developed in the Midwest Kochi on 4-5 July 2022
Keywords:Senji-kousuitai, radar, GNSS precipitable water
A quasi-stationary rainband developed in the Midwest Kochi prefecture from the midnight of July 4, 2022 to the early morning of the 5th, resulting in over 300 mm of rainfall within five hours, leading to flooding and other damages. The rainband had two rainfall peaks, one between 21:30 JST to 22:30 JST, and another between 00:00 JST and 01:00 JST. Using rapid RHI sector scan observations from Kochi University X-band polarimetric Doppler radar, the internal structure of the rainband during the second rainfall peak was observed. The precipitation peaks, which produced rainfall intensities greater than 120 mm/h, were particularly associated with the development of strong precipitation cells. These developed precipitation cells had larger horizontal scales and higher precipitation top heights reached 15 km altitude, but the upper part of the precipitation system was immediately advected eastward, causing the system to tilt to the east.
Upstream of the region where the rainband developed, a plain between mountains stretches east-west. Around 19:00 JST, the wind direction at the western edge of the plain in the Sukumo area changed from a northerly wind to a warm southerly wind from the eastern side of the Typhoon Aere, and the temperature rose by 2 degree C. Meanwhile, at around 21:00 JST, the wind direction at the eastern edge of the plain at the AMeDAS Saga station changed from westward to eastward, and the temperature also rose by 2 degree C.
Using SoftBank GNSS observation along with GEONET observation, the spatiotemporal changes in the precipitable water were investigated. The variation in precipitable water around the rainband during its formation was much smaller compared to the increase in precipitable water during the daytime. However, at certain locations, an increase in precipitable water was observed between around 21:00 JST and the time of heavy rainfall. The analysis results, including the precipitable water variations and their relationship with the meteorological field and the development of precipitation clouds, will be presented during the presentation.
Upstream of the region where the rainband developed, a plain between mountains stretches east-west. Around 19:00 JST, the wind direction at the western edge of the plain in the Sukumo area changed from a northerly wind to a warm southerly wind from the eastern side of the Typhoon Aere, and the temperature rose by 2 degree C. Meanwhile, at around 21:00 JST, the wind direction at the eastern edge of the plain at the AMeDAS Saga station changed from westward to eastward, and the temperature also rose by 2 degree C.
Using SoftBank GNSS observation along with GEONET observation, the spatiotemporal changes in the precipitable water were investigated. The variation in precipitable water around the rainband during its formation was much smaller compared to the increase in precipitable water during the daytime. However, at certain locations, an increase in precipitable water was observed between around 21:00 JST and the time of heavy rainfall. The analysis results, including the precipitable water variations and their relationship with the meteorological field and the development of precipitation clouds, will be presented during the presentation.