10:45 AM - 12:15 PM
[ACG43-P04] Influence of coastal warming off Tokai attributable to Kuroshio large meander on rainfall of Typhoon Talas (2022)
Keywords:Typhoon, Kuroshio Large Meander, Coastal Warming, Water Vapor Flux
Typhoon Talas (2022) occurred on September 21 (Japan Standard Time) and approached the Tokai and Kanto regions. It brought record-breaking rainfall around Shizuoka Prefecture from the night of September 23 to the morning of September 24, even though its central pressure was 1000 hPa and its maximum wind speed was 18 m/s at a mature phase. The rainfall was particularly heavy in the area around Shizuoka City, recording 404.5 mm in 12 hours, the highest in recorded history. At this time, coastal temperature off the Tokai district increased more than 2 degrees Celsius above normal attributable to the Kuroshio large meander. Therefore, it is expected that Kuroshio large meander influences rainfall of this typhoon.
We estimated the water vapor flux by using analysis data from the Japan Meteorological Agency Meso Scale Model (MSM), and found the inflow of water vapor from the southern ocean before the onset of precipitation in the Tokai region. Especially, the water vapor flux increased over the coastal warming area off Tokai. In order to evaluate the influence of coastal warming, we conducted sea surface temperature sensitivity experiment by using a non-hydrostatic Weather Research Forecasting (WRF) model : control run, driven by raw sea surface temperature, and cold run, removing positive temperature anomaly representing the coastal warming. The results showed that there was little difference in the central pressure of the typhoon at each time between the control and cold runs. Precipitation in control run increased in the Tokai region, especially around Shizuoka City, the value of which was about 75% higher than in the cold run. A comparison of water vapor fluxes in the lower troposphere identified an increase in the inflow from off the Tokai, suggesting the influence of sea surface temperature increase. We will discuss differences in structure in atmosphere between the two runs while also examining the influence of topography.
We estimated the water vapor flux by using analysis data from the Japan Meteorological Agency Meso Scale Model (MSM), and found the inflow of water vapor from the southern ocean before the onset of precipitation in the Tokai region. Especially, the water vapor flux increased over the coastal warming area off Tokai. In order to evaluate the influence of coastal warming, we conducted sea surface temperature sensitivity experiment by using a non-hydrostatic Weather Research Forecasting (WRF) model : control run, driven by raw sea surface temperature, and cold run, removing positive temperature anomaly representing the coastal warming. The results showed that there was little difference in the central pressure of the typhoon at each time between the control and cold runs. Precipitation in control run increased in the Tokai region, especially around Shizuoka City, the value of which was about 75% higher than in the cold run. A comparison of water vapor fluxes in the lower troposphere identified an increase in the inflow from off the Tokai, suggesting the influence of sea surface temperature increase. We will discuss differences in structure in atmosphere between the two runs while also examining the influence of topography.