著者

Shimizu Shingo

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.19A, no.Special_Edition, pp.i-iii, 2023 (Released:2023-10-24)

参考文献数

11

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Catastrophic disasters triggered by mesoscale convective systems occur annually in East Asia, with a notable increase in casualties and extensive damages between 2019 and 2021 due to record-breaking rainfall in Japan. There is an urgent need for a comprehensive understanding of the physical processes and dynamic mechanisms behind these extreme rainfall events. This requires the integration of various research approaches, including observational analysis, statistical data analysis, and weather forecasting with data assimilation. Additionally, we must consider the impact of large-scale atmospheric circulation on extreme weather in East Asia. In this special edition, jointly coordinated with Journal of the Meteorological Society of Japan, we have published nine articles covering extreme events in East Asia from 2017 to 2022. Here, we provide an overview of these papers. From a large-scale view perspective, Horinouchi et al. (2021) and Ueda et al. (2021) examined the influence of synoptic-scale moisture conditions and sea surface temperatures on severe rainfall events in Kyushu, Japan during the summer of 2020. Additionally, Takemura et al. (2022) investigated the large-scale atmospheric factors contributing to the record-breaking early onset of Baiu season in most parts of western Japan in 2021. Furthermore, Kuramochi et al. (2021) conducted a study on the causes of the anomalous warm conditions in winter 2019 and 2020 over East Asia, utilizing large-scale atmospheric analysis and global simulations. Three papers focused on the statistical features of environmental conditions suitable for the occurrence of “senjo-kousuitai” (Kato 2020). Goto and Satoh (2022) applied a similar definition of senjo-kousuitai as proposed by Kato 2020 to a satellite-based precipitation dataset covering 20 years from 2000 to 2019. They confirmed a high occurrence frequency in Kyushu, the Nansei Islands (South of Kyushu), and the East China sea. Based on analysis using reanalysis datasets, it was determined that low-level water vapor flux and vertical wind shear are essential for the development of senjo-kousuitai. Sato and Hosotani (2023) also confirmed the importance of these two factors based on reanalysis data spanning the past 20 years. Additionally, Naka and Takemi (2023) proposed the significance of moist absolutely unstable layers (MAULs) in enhancing heavy rainfall in the preceding hours. Numerical simulations were also employed in research efforts. Tochimoto et al. (2022) conducted sensitivity experiments to investigate the impact of the upper-level trough on the heavy rainfall. In another study, Terasaki and Miyoshi (2022) demonstrated the high predictability of heavy rainfall by utilizing data assimilation with 1024-ensemble members. Doyle et al. (2023) indicated the importance of a mesoscale convective system, orographic ascent, and equatorial wave components in contributing to the extreme flood that occurred in southwestern Sulawesi, Indonesia in January 2019 by conducting adjoint model simulations and the sensitivity analysis. To mitigate the damages caused by various extreme weather events, it is essential to consolidate our research achievements and further enhance the predictability of these events.

著者

MORODA Yukie TSUBOKI Kazuhisa SATOH Shinsuke NAKAGAWA Katsuhiro USHIO Tomoo SHIMIZU Shingo

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2021-038, (Released:2021-03-16)

被引用文献数

3

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A phased array weather radar (PAWR) can complete one volume scan in 30 seconds, thus enabling us to obtain high spatiotemporal resolution echo intensities and wind fields of storms. Using its rapid scanning capability, we investigated the evolution of a convective storm in detail. To describe evolution of convective storms, we used the following definitions. The precipitation cell is defined as a three-dimensionally contiguous region of 40 dBZ or greater. The precipitation core is defined by a threshold of positive deviation greater than 7 dBZ, which is a difference from the average reflectivity during the mature stage of the cell. An updraft core is defined as an updraft region of 1 m s−1 or stronger at a height of 2 km. An isolated convective storm was observed by two PAWRs on 7 August 2015 in the Kinki District, western Japan. The storm was judged as a single cell, according to the above definition. We identified nine precipitation cores and five updraft cores within 49 minutes in the mature stage of the cell. A long-lasting updraft core and its branches moved southwestward or southeastward. Around these updraft cores, the precipitation cores were generated successively. The updraft core with the longest duration lasted 73.5 minutes; in contrast, the lifetimes of precipitation cores were from 4.5 to 14.5 minutes. The precipitation cell was maintained by the successive generations of updraft cores which lifted humid air associated with a low-level southwesterly inflow. The total amounts of water vapor inflow supplied by all the identified updraft cores were proportional to the volumes of the precipitation cell, with a correlation coefficient of 0.75. Thus, the extremely high spatiotemporal resolution of the PAWR observations provides us with new evidence that an isolated convective storm can be formed by multiple precipitation cores and updraft cores.