著者

Hiroaki Ueda Mikihiro Yokoi Masaya Kuramochi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17B, no.Special_Edition, pp.14-18, 2021 (Released:2021-09-09)

参考文献数

28

被引用文献数

7

---

During the early summer of 2020, a stagnation of the Meiyu-Baiu front brought torrential rainfall over East Asia. Meanwhile, the anticyclone was much enhanced over the subtropical western Pacific (SWP), which contributed abundant moisture to the Meiyu-Baiu rainband along the western rim of the anticyclone. Based on the sensitivity experiments of the linear baroclinic model by prescribing the observed diabatic heating anomalies, a combination of anomalous convection over the Indian Ocean and reduced rainfall over the western Pacific can account for the maintenance of zonally elongated SWP anticyclone. Interestingly, this period corresponded to the developing stage of La Niña, while the convective activities were notably suppressed over the warmed western Pacific. The sensitivity experiments to SST anomalies using the atmospheric general circulation model shows that the attenuated convection over the western Pacific can be ascribed to the warmed Indian Ocean associated with an atmospheric Kelvin wave wedge from the Indian Ocean. Overall, the suppressant SST effect of the Indian Ocean opposes and is greater than that of tropical Pacific. We issue a caveat regarding the additivity of the remote influence across the maritime continent. These results have important implications for the predictability of early summer rainfall over East Asia.

著者

Masaya Kuramochi Hiroaki Ueda Chiaki Kobayashi Youichi Kamae Koutarou Takaya

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17B, no.Special_Edition, pp.9-13, 2021 (Released:2021-08-26)

参考文献数

29

被引用文献数

7

---

The anomalous warm winter from December 2019 to February 2020 over East Asia, particularly the anticyclonic anomaly around Japan, was examined from the teleconnection perspective anchored by a warmed Indian Ocean and the El Niño Modoki. In the upper troposphere, high–low–high wave patterns progressing from the Arabian Sea toward Japan via the southern region of China, coupled with the wave-activity flux diagnosis, implicate the propagation of stationary Rossby waves caused by enhanced convection in the western Indian Ocean and suppressed convection around the Maritime Continent. These anomalous convective activities could be responsible for the northward displacement of the subtropical jet and the ensuing warm conditions over East Asia. The atmospheric response to the observed diabatic heating by means of the linear baroclinic model well reproduced the observations. Moreover, sensitivity experiments of the atmospheric general circulation model to sea surface temperature (SST) anomalies, especially in the warmed western Indian and central Pacific oceans, can help understand the anomalous subsidence over the Maritime Continent sector and subsequently weakened convection. The warmer SST observed around the Maritime Continent alone reproduces the enhancement of rainfall and subsequent cold anomalies around Japan, suggesting the importance of trans-basin interaction for teleconnection towards East Asia.

著者

Masaya Kuramochi Hiroaki Ueda Chiaki Kobayashi Youichi Kamae Koutarou Takaya

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.17B-001, (Released:2021-08-05)

被引用文献数

7

---

The anomalous warm winter from December 2019 to February 2020 over East Asia, particularly the anticyclonic anomaly around Japan, was examined from the teleconnection perspective anchored by a warmed Indian Ocean and the El Niño Modoki. In the upper troposphere, high–low–high wave patterns progressing from the Arabian Sea toward Japan via the southern region of China, coupled with the wave-activity flux diagnosis, implicate the propagation of stationary Rossby waves caused by enhanced convection in the western Indian Ocean and suppressed convection around the Maritime Continent. These anomalous convective activities could be responsible for the northward displacement of the subtropical jet and the ensuing warm conditions over East Asia. The atmospheric response to the observed diabatic heating by means of the linear baroclinic model well reproduced the observations. Moreover, sensitivity experiments of the atmospheric general circulation model to sea surface temperature (SST) anomalies, especially in the warmed western Indian and central Pacific oceans, can help understand the anomalous subsidence over the Maritime Continent sector and subsequently weakened convection. The warmer SST observed around the Maritime Continent alone reproduces the enhancement of rainfall and subsequent cold anomalies around Japan, suggesting the importance of trans-basin interaction for teleconnection towards East Asia.

著者

Hiroaki Ueda Mikihiro Yokoi Masaya Kuramochi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.17B-002, (Released:2021-08-04)

被引用文献数

7

---

During the early summer of 2020, a stagnation of the Meiyu-Baiu front brought torrential rainfall over East Asia. Meanwhile, the anticyclone was much enhanced over the subtropical western Pacific (SWP), which contributed abundant moisture to the Meiyu-Baiu rainband along the western rim of the anticyclone. Based on the sensitivity experiments of the linear baroclinic model by prescribing the observed diabatic heating anomalies, a combination of anomalous convection over the Indian Ocean and reduced rainfall over the western Pacific can account for the maintenance of zonally elongated SWP anticyclone. Interestingly, this period corresponded to the developing stage of La Niña, while the convective activities were notably suppressed over the warmed western Pacific. The sensitivity experiments to SST anomalies using the atmospheric general circulation model shows that the attenuated convection over the western Pacific can be ascribed to the warmed Indian Ocean associated with an atmospheric Kelvin wave wedge from the Indian Ocean. Overall, the suppressant SST effect of the Indian Ocean opposes and is greater than that of tropical Pacific. We issue a caveat regarding the additivity of the remote influence across the maritime continent. These results have important implications for the predictability of early summer rainfall over East Asia.