11:05 AM - 11:25 AM
[O05-05] The appearance of line-shaped rainbands in synoptic and convective scale and the action response to disaster
★Invited Papers
Keywords:Disaster prevention actions, line-shaped rainbands, climate change, torrential rainfall
This study addresses the critical need for a paradigm shift in disaster response strategies, particularly in the context of windstorm and flood preparedness. Traditional measures undertaken by individuals and companies are often predicated on historical experiences of hydrological disasters, which may not adequately reflect the evolving nature of such events under the influence of climate change. Recent patterns of extreme rainfalls indicate an escalation in the intensity and frequency, and this trend is predicted to continue. Consequently, it is imperative that future-oriented strategies are developed, taking into consideration the likelihood of more severe windstorms and floods.
We project future changes in the appearance of line-shaped rainbands (hereafter, LRBs), which are one of the major causes of heavy rainfall disasters in Japan. We defined LRBs in two ways. The first is based on the definition of Hirockawa et al. (2020a, b), which target for the LRBs occurring once per year in Japan except for northern Japan during warm seasons. The threshold for the second is the amount of rainfall when disasters occurred in northern Japan from the viewpoint of disaster prevention, following Ohya and Yamada (2023). We clarify the interannual and seasonal changes in the frequency of LRBs over Japan, applying those definitions to rainfall observed by rain gauges and weather radars over the past 30 years.
First, to discuss the appearance characteristics of LRBs based on the synoptic scale of weather field, we conduct an analysis using information on the appearance of fronts detected from surface weather maps of Japan Meteorological Agency by Miyamoto and Yamada (2023). Besides, based on the classification of the output of regional climate model (RCM) using machine learning by Ohya and Yamada (2024), we discuss the appearance characteristics of LRBs by synoptic scale of weather field pattern. In addition to this, to examine future changes due to the effects of climate change, we conduct dynamical downscaling to a horizontal resolution of 5 km using RCM in the ensemble experiments for global warming (d4PDF). The change of the appearance of LRBs are clarified by applying the definition of LRBs to the high-resolution output.
Secondly, we demonstrate the characteristics of the appearance of LRBs in the convective scale based on the observation. The characteristics of the three-dimensional structure in the formation process of LRBs are discussed by tracking precipitation cells that compose LRBs using the method of Ohya and Yamada (2023) based on rainfall observed by weather radars with X-band (XRAIN) and by estimating wind speed fields optimized by the variational principle using Doppler radar observations.
Therefore, using the information on the occurrence of LRBs in synoptic and convective scales based on observations and projections by climate model, we discuss disaster prevention actions to heavy rainfall disasters associated with LRBs. This research promotes the Strategic Innovation Promotion Program (SIP) project, which aims at the "Development of a Resilient Smart Network System against Natural Disasters," under the Council for Science, Technology, and Innovation, Cabinet Office, Government of Japan. This research is supported by the SIP project, which launched in September of 2023, with the author as the principal investigator. At the conference, its latest findings for shaping future disaster response paradigms are presented.
1) Hirockawa et al. 2020a. DOI: https://doi.org/10.2151/sola.2020-044
2) Hirockawa et al. 2020b. DOI: https://doi.org/10.2151/jmsj.2020-043.
3) Y. Ohya and T. J. Yamada, 2023. DOI: 10.1088/1755-1315/1136/1/012025.
4) M. Miyamoto and T. J. Yamada, 2023. DOI: 10.1088/1755-1315/1136/1/012023.
5) Y. Ohya, T. J. Yamada, 2024. DOI: 10.2166/hydro.2024.121.
We project future changes in the appearance of line-shaped rainbands (hereafter, LRBs), which are one of the major causes of heavy rainfall disasters in Japan. We defined LRBs in two ways. The first is based on the definition of Hirockawa et al. (2020a, b), which target for the LRBs occurring once per year in Japan except for northern Japan during warm seasons. The threshold for the second is the amount of rainfall when disasters occurred in northern Japan from the viewpoint of disaster prevention, following Ohya and Yamada (2023). We clarify the interannual and seasonal changes in the frequency of LRBs over Japan, applying those definitions to rainfall observed by rain gauges and weather radars over the past 30 years.
First, to discuss the appearance characteristics of LRBs based on the synoptic scale of weather field, we conduct an analysis using information on the appearance of fronts detected from surface weather maps of Japan Meteorological Agency by Miyamoto and Yamada (2023). Besides, based on the classification of the output of regional climate model (RCM) using machine learning by Ohya and Yamada (2024), we discuss the appearance characteristics of LRBs by synoptic scale of weather field pattern. In addition to this, to examine future changes due to the effects of climate change, we conduct dynamical downscaling to a horizontal resolution of 5 km using RCM in the ensemble experiments for global warming (d4PDF). The change of the appearance of LRBs are clarified by applying the definition of LRBs to the high-resolution output.
Secondly, we demonstrate the characteristics of the appearance of LRBs in the convective scale based on the observation. The characteristics of the three-dimensional structure in the formation process of LRBs are discussed by tracking precipitation cells that compose LRBs using the method of Ohya and Yamada (2023) based on rainfall observed by weather radars with X-band (XRAIN) and by estimating wind speed fields optimized by the variational principle using Doppler radar observations.
Therefore, using the information on the occurrence of LRBs in synoptic and convective scales based on observations and projections by climate model, we discuss disaster prevention actions to heavy rainfall disasters associated with LRBs. This research promotes the Strategic Innovation Promotion Program (SIP) project, which aims at the "Development of a Resilient Smart Network System against Natural Disasters," under the Council for Science, Technology, and Innovation, Cabinet Office, Government of Japan. This research is supported by the SIP project, which launched in September of 2023, with the author as the principal investigator. At the conference, its latest findings for shaping future disaster response paradigms are presented.
1) Hirockawa et al. 2020a. DOI: https://doi.org/10.2151/sola.2020-044
2) Hirockawa et al. 2020b. DOI: https://doi.org/10.2151/jmsj.2020-043.
3) Y. Ohya and T. J. Yamada, 2023. DOI: 10.1088/1755-1315/1136/1/012025.
4) M. Miyamoto and T. J. Yamada, 2023. DOI: 10.1088/1755-1315/1136/1/012023.
5) Y. Ohya, T. J. Yamada, 2024. DOI: 10.2166/hydro.2024.121.