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

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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

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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

Takenari Kinoshita Koutarou Takaya Toshiki Iwasaki

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.193-197, 2019 (Released:2019-09-13)

参考文献数

16

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The mass-weighted isentropic zonal mean (Z-MIM) equations derived by T. Iwasaki are powerful tools for diagnosing meridional circulation and wave-mean interaction, especially for the lower boundary and unstable waves. Recently, some studies have extended the equations to three dimensions by using the time mean instead of the zonal mean. However, the relation between wave activity flux and residual mean flow (not mass-weighed mean flow) is unclear. In the present study, we derive the three-dimensional (3D) wave activity flux and residual mean flow for Rossby waves on the mass-weighted isentropic time mean equations. Next, we discuss the relation between the obtained formulae and 3D transformed Eulerian-mean (TEM) equations.