10:45 AM - 12:15 PM
[ACG43-P05] The Impact of Warm SST and Cold SST over the Kuroshio Large-Meander to the Rainfall around the Kii Peninsula
Keywords:Typhoon Talas 2011, Kuroshio large meander, heavy rainfall, SST, coastal area
The Kii peninsula is one of the heaviest rainfall areas in Japan. In September 2011, typhoon Talas brought disastrous rainfall. This typhoon only developed to 970 hPa, and moved very slowly, its average speed was 11.1km/h. According to an analysis product by merging the rain radar and weather station, the total amount of rainfall from 30 August to 5 September exceeded 1,000 mm over the wide area of the Kii peninsula, with some areas receiving more than 2,000 mm of rainfall. The total number of dead and missing persons reached 98, and completely destroyed houses were 379, partially destroyed houses were 3,159, flooding above the floor was 5,500, and flooding below the floor was 16,594 (Damage caused by Typhoon No. 12 in 2011, Cabinet Office). If this had been an urban area, it could have caused many times more damage.
It is said that the warm Kuroshio Current flowing south of the peninsula is responsible for the high rainfall of the Kii Peninsula, but there are few research papers dealing with this issue. The Kuroshio Current supplies tropical warm water to the seas around Japan, and large amounts of water vapor and heat are transported from the Kuroshio Current to the overlying atmosphere (Kubota et al. 2008; Bond and Cronin 2008). Therefore, it can be inferred that the weather and climate in the Kii Peninsula are greatly influenced by the Kuroshio Current. Recently the Kuroshio large meander has begun in the summer of 2018, and it is currently the longest in recorded history since modern observations began. The ocean temperatures around the Kii Peninsula in the meander year are also significantly different from those of non-meandering years. Especially, a warm core offshore of Tokaido and a cold core offshore of the Kii peninsula were seen associated with the meander, compared to the period of none large meander.
Assuming that the Kuroshio large meander like in recent years had occurred in 2011, how the precipitation would have been changed? Answering this question will provide us with various perspectives on meteorology and oceanography along with disaster prevention. Furthermore, how large does such a horizontally small-scale SST anomaly as the Kuroshio large meander have influence the Typhoon precipitation? If it is large enough, predicting the Kuroshio meander and understanding whether the meandering is likely to occur with global warming is important from the perspective of disaster prevention.
Our numerical experiments showed that the warm water core offshore of the Tokaido coast increases the water vapor flux, latent heat flux, and sensible heat flux. As a result, it was found that this could lead to an increase in precipitation of about 300 mm in the eastern part of the Kii Peninsula and a decrease in precipitation of about 400 mm in the central part of the Kii Peninsula. In addition, we found not only this uneven distribution of local precipitation but also the total average rainfall over the region, including most of the Kii Peninsula, could increase by more than 80 mm.
In conclusion, in preparing for typhoons such as Typhoon Talas, it is necessary to carefully monitor the flow paths and meandering trends of the Kuroshio Current and the associated sea surface temperature distribution from a disaster prevention perspective.
It is said that the warm Kuroshio Current flowing south of the peninsula is responsible for the high rainfall of the Kii Peninsula, but there are few research papers dealing with this issue. The Kuroshio Current supplies tropical warm water to the seas around Japan, and large amounts of water vapor and heat are transported from the Kuroshio Current to the overlying atmosphere (Kubota et al. 2008; Bond and Cronin 2008). Therefore, it can be inferred that the weather and climate in the Kii Peninsula are greatly influenced by the Kuroshio Current. Recently the Kuroshio large meander has begun in the summer of 2018, and it is currently the longest in recorded history since modern observations began. The ocean temperatures around the Kii Peninsula in the meander year are also significantly different from those of non-meandering years. Especially, a warm core offshore of Tokaido and a cold core offshore of the Kii peninsula were seen associated with the meander, compared to the period of none large meander.
Assuming that the Kuroshio large meander like in recent years had occurred in 2011, how the precipitation would have been changed? Answering this question will provide us with various perspectives on meteorology and oceanography along with disaster prevention. Furthermore, how large does such a horizontally small-scale SST anomaly as the Kuroshio large meander have influence the Typhoon precipitation? If it is large enough, predicting the Kuroshio meander and understanding whether the meandering is likely to occur with global warming is important from the perspective of disaster prevention.
Our numerical experiments showed that the warm water core offshore of the Tokaido coast increases the water vapor flux, latent heat flux, and sensible heat flux. As a result, it was found that this could lead to an increase in precipitation of about 300 mm in the eastern part of the Kii Peninsula and a decrease in precipitation of about 400 mm in the central part of the Kii Peninsula. In addition, we found not only this uneven distribution of local precipitation but also the total average rainfall over the region, including most of the Kii Peninsula, could increase by more than 80 mm.
In conclusion, in preparing for typhoons such as Typhoon Talas, it is necessary to carefully monitor the flow paths and meandering trends of the Kuroshio Current and the associated sea surface temperature distribution from a disaster prevention perspective.