著者

Akihiko Shimpo Kazuto Takemura Shunya Wakamatsu Hiroki Togawa Yasushi Mochizuki Motoaki Takekawa Shotaro Tanaka Kazuya Yamashita Shuhei Maeda Ryuta Kurora Hirokazu Murai Naoko Kitabatake Hiroshige Tsuguti Hitoshi Mukougawa Toshiki Iwasaki Ryuichi Kawamura Masahide Kimoto Izuru Takayabu Yukari N. Takayabu Youichi Tanimoto Toshihiko Hirooka Yukio Masumoto Masahiro Watanabe Kazuhisa Tsuboki Hisashi Nakamura

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15A, pp.13-18, 2019 (Released:2019-06-15)

参考文献数

22

被引用文献数

80

---

An extreme rainfall event occurred over western Japan and the adjacent Tokai region mainly in early July, named “the Heavy Rain Event of July 2018”, which caused widespread havoc. It was followed by heat wave that persisted in many regions over Japan in setting the highest temperature on record since 1946 over eastern Japan as the July and summertime means. The rain event was attributable to two extremely moist airflows of tropical origins confluent persistently into western Japan and large-scale ascent along the stationary Baiu front. The heat wave was attributable to the enhanced surface North Pacific Subtropical High and upper-tropospheric Tibetan High, with a prominent barotropic anticyclonic anomaly around the Korean Peninsula. The consecutive occurrence of these extreme events was related to persistent meandering of the upper-level subtropical jet, indicating remote influence from the upstream. The heat wave can also be influenced by enhanced summertime convective activity around the Philippines and possibly by extremely anomalous warmth over the Northern Hemisphere midlatitude in July 2018. The global warming can also influence not only the heat wave but also the rain event, consistent with a long-term increasing trend in intensity of extreme precipitation observed over Japan.

著者

Hideo Shiogama Noriko N. Ishizaki Naota Hanasaki Kiyoshi Takahashi Seita Emori Rui Ito Toshiyuki Nakaegawa Izuru Takayabu Yasuaki Hijioka Yukari N. Takayabu Ryosuke Shibuya

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.57-62, 2021 (Released:2021-04-03)

参考文献数

20

被引用文献数

1 18

---

Climate change impact assessment studies often use future projections of only a few global climate models (GCMs) due to limited research resources. Here we develop a novel method to select a small subset of GCMs that widely capture the uncertainty range of large ensemble. By applying this method, we select a subset of five GCM projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) ensemble for impact and adaptation studies in Japan. At first, we omit GCMs whose global warming projections have been evaluated to be overestimated in the recent literature. Then, we select a subset of five GCMs that widely captures the uncertainty ranges for 8 climate variables and have good performances in present-climate simulations. These selected GCM simulations will be used to provide better climate scenarios for impact and adaptation studies than those in the previous impact assessment project.

著者

Takeshi Horinouchi Yu Kosaka Hiroshi Nakamigawa Hisashi Nakamura Norihisa Fujikawa Yukari N. Takayabu

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17B, no.Special_Edition, pp.1-8, 2021 (Released:2021-06-01)

参考文献数

30

被引用文献数

14

---

A prolonged heavy rainfall event occurred in Kyushu in early July 2020. Its large-scale environmental factors are investigated with observational and reanalysis data. Seven-day precipitation and moisture flux convergence around Kyushu were the greatest among the last 30 years. This pronounced convergence was maintained by nearly steady moisture influx, and the persistent upper-level trough to the northwest enhanced the ratio of moisture convergence to the influx. The magnitude of instantaneous moisture flux, however, was not particularly large among those along the subtropical jet axis or the Meiyu-Baiu rainband. What made this event unique is the persistence of the moisture flux peak anchored around Kyushu under the influence of the Silk-Road teleconnection. In June 2020, three upper-level troughs, whose easternmost one corresponding to the aforementioned trough, tend to form along the subtropical Asian jet. This wave train was persistent in the month and lasted until mid-July, 2020. Our analysis suggests that, prior to the rainfall event, the Silk-Road teleconnection was intensified through an interaction with a wave train at subpolar latitudes, which involves nonlinear processes including trough cut-off.

著者

Takeshi Horinouchi Yu Kosaka Hiroshi Nakamigawa Hisashi Nakamura Norihisa Fujikawa Yukari N. Takayabu

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-019, (Released:2021-04-28)

被引用文献数

14

---

A prolonged heavy rainfall event occurred in Kyushu in early July 2020. Its large-scale environmental factors are investigated with observational and reanalysis data. Seven-day precipitation and moisture flux convergence around Kyushu were the greatest among the last 30 years. This pronounced convergence was maintained by nearly steady moisture influx, and the persistent upper-level trough to the northwest enhanced the ratio of moisture convergence to the influx. The magnitude of instantaneous moisture flux, however, was not particularly large among those along the subtropical jet axis or the Meiyu-Baiu rainband. What made this event unique is the persistence of the moisture flux peak anchored around Kyushu under the influence of the Silk-Road teleconnection. In June 2020, three upper-level troughs, whose easternmost one corresponding to the aforementioned trough, tend to form along the subtropical Asian jet. This wave train was persistent in the month and lasted until mid-July, 2020. Our analysis suggests that, prior to the rainfall event, the Silk-Road teleconnection was intensified through an interaction with a wave train at subpolar latitudes, which involves nonlinear processes including trough cut-off.

著者

Akihiko Shimpo Kazuto Takemura Shunya Wakamatsu Hiroki Togawa Yasushi Mochizuki Motoaki Takekawa Shotaro Tanaka Kazuya Yamashita Shuhei Maeda Ryuta Kurora Hirokazu Murai Naoko Kitabatake Hiroshige Tsuguti Hitoshi Mukougawa Toshiki Iwasaki Ryuichi Kawamura Masahide Kimoto Izuru Takayabu Yukari N. Takayabu Youichi Tanimoto Toshihiko Hirooka Yukio Masumoto Masahiro Watanabe Kazuhisa Tsuboki Hisashi Nakamura

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.15A-003, (Released:2019-05-17)

被引用文献数

80

---

An extreme rainfall event occurred over western Japan and the adjacent Tokai region mainly in early July, named “the Heavy Rain Event of July 2018”, which caused widespread havoc. It was followed by heat wave that persisted in many regions over Japan in setting the highest temperature on record since 1946 over eastern Japan as the July and summertime means. The rain event was attributable to two extremely moist airflows of tropical origins confluent persistently into western Japan and large-scale ascent along the stationary Baiu front. The heat wave was attributable to the enhanced surface North Pacific Subtropical High and upper-tropospheric Tibetan High, with a prominent barotropic anticyclonic anomaly around the Korean Peninsula. The consecutive occurrence of these extreme events was related to persistent meandering of the upper-level subtropical jet, indicating remote influence from the upstream. The heat wave can also be influenced by enhanced summertime convective activity around the Philippines and possibly by extremely anomalous warmth over the Northern Hemisphere midlatitude in July 2018. The global warming can also influence not only the heat wave but also the rain event, consistent with a long-term increasing trend in intensity of extreme precipitation observed over Japan.

著者

Hideo Shiogama Noriko N. Ishizaki Naota Hanasaki Kiyoshi Takahashi Seita Emori Rui Ito Toshiyuki Nakaegawa Izuru Takayabu Yasuaki Hijioka Yukari N. Takayabu Ryosuke Shibuya

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-009, (Released:2021-02-16)

被引用文献数

18

---

Climate change impact assessment studies often use future projections of only a few global climate models (GCMs) due to limited research resources. Here we develop a novel method to select a small subset of GCMs that widely capture the uncertainty range of large ensemble. By applying this method, we select a subset of five GCM projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) ensemble for impact and adaptation studies in Japan. At first, we omit GCMs whose global warming projections have been evaluated to be overestimated in the recent literature. Then, we select a subset of five GCMs that widely captures the uncertainty ranges for 8 climate variables and have good performances in present-climate simulations. These selected GCM simulations will be used to provide better climate scenarios for impact and adaptation studies than those in the previous impact assessment project.

著者

Ayako Seiki Yukari N. Takayabu Kunio Yoneyama Naoki Sato Masanori Yoshizaki

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.5, pp.93-96, 2009 (Released:2009-06-10)

参考文献数

26

被引用文献数

13 14

---

Oceanic responses to relatively strong Madden-Julian Oscillations (MJOs) and background winds controlled by El Niño-Southern Oscillation (ENSO) are examined. The MJO’s arrival excites dominant downwelling and upwelling Kelvin waves during El Niño developing (pre-El Niño: PEN) and other (non-PEN) phases, respectively. These opposite signals come from background wind directions under different ENSO phases and exert opposite impacts on SST. In addition, MJO convection itself develops accompanied by larger surface wind variations during PEN phases, which can be related to the interactive amplifications of synoptic- and planetary-scale disturbances when westerly wind bursts occur. Consequently, the strength of westerly forcing and its oceanic response during PEN phases are larger than that of the corresponding easterly forcing and its response during non-PEN phases. These results suggest that modulations of MJO amplitude and structure under the background westerly and easterly winds associated with ENSO phases exert opposite but asymmetric impacts on the ocean.