5:15 PM - 6:45 PM
[MTT37-P03] Analysis of quasi-stationary rainband occurred in west Kochi prefecture on June 2, 2023
Keywords:quasi-stationary rainband, heavy rainfall, water vapor, weather radar
Quasi-stationary rainband is one of representative precipitating systems which bring torrential rain in Japan. Heavy rain continues for more than several hours in a narrow line shape area. The accumulation of case studies are necessary to improve understanding and forecasting of the events. This study investigates the characteristics of the quasi-stationary rainband occurred in west Kochi prefecture in the morning of 2nd June 2023.
The event occurred when Typhoon Mawar was located southwest of Shikoku Island, and Baiu front was located just north of Shikoku Island. The convection developed in the convergence area of warm moist southerly air and relatively cooler northerly airflow over the Setouchi Sea. Gradualy the rainband developed along the area horizonal temperature gradient was large. The X-band dual polarimetric radar of Kochi University observed rear inflow, which was relatively dry air at around 3 km altitude toward convective area, and evaporation of raindrops in the flow and intensification of cold pool near the convective area was estimated. The structure of the precipitation system was similar to a squall line. Though the structure was observed at around 9 JST by the Kochi Univ. radar, the Doppler velocity of the JMA Muroto C-band radar implies the structure was established already since the formation of the precipitation system at around 7 JST. Squall lines are a characteristic precipitating system observed in various areas in the world. Several studies show a distinct variation in water vapor distribution. In the presentation, we will show how high temporal and spatial variation of the GNSS precipitable water distribution derived from Softbank's GNSS observation data relate to the formation and maintenance of the precipitation system.
The event occurred when Typhoon Mawar was located southwest of Shikoku Island, and Baiu front was located just north of Shikoku Island. The convection developed in the convergence area of warm moist southerly air and relatively cooler northerly airflow over the Setouchi Sea. Gradualy the rainband developed along the area horizonal temperature gradient was large. The X-band dual polarimetric radar of Kochi University observed rear inflow, which was relatively dry air at around 3 km altitude toward convective area, and evaporation of raindrops in the flow and intensification of cold pool near the convective area was estimated. The structure of the precipitation system was similar to a squall line. Though the structure was observed at around 9 JST by the Kochi Univ. radar, the Doppler velocity of the JMA Muroto C-band radar implies the structure was established already since the formation of the precipitation system at around 7 JST. Squall lines are a characteristic precipitating system observed in various areas in the world. Several studies show a distinct variation in water vapor distribution. In the presentation, we will show how high temporal and spatial variation of the GNSS precipitable water distribution derived from Softbank's GNSS observation data relate to the formation and maintenance of the precipitation system.