- 著者
- Kazuaki Yasunaga Atsushi Hamada Kazuaki Nishii
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.15, pp.238-243, 2019 (Released:2019-11-30)
- 参考文献数
- 21
- 被引用文献数
- 2
This study examines the factors responsible for the long-term changes of winter monsoonal flow around Japan in association with increasing precipitation trends in December along the coastal areas of Honshu (the main island of Japan) facing the Sea of Japan. The precipitation around the tropical eastern Indian Ocean and maritime continent has significantly increased in recent years. Thus, a packet of the stationary Rossby wave associated with the anomalous heating deflects the subtropical jet to the south over the eastern edge of the Eurasian continent. The deflection of the jet gives favorable conditions for the development of a low pressure trough in the lower level on the eastern side, leading to the formation of negative height anomalies near the surface around Japan.Although tropical precipitation also increases in November and January, the anomalous heating induces negative height anomalies and cyclonic circulations over the inland region of China and eastern offshore region of Japan (to the further west and east in comparison with those in December) in these months. As a result, monsoonal flow around Japan (and precipitation along the coastal areas of the Sea of Japan) shows no long-term trends in November or January.
- 著者
- Kazuaki Nishii Bunmei Taguchi Masato Mori Yu Kosaka Hisashi Nakamura
- 出版者
- 公益社団法人 日本気象学会
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.18, pp.199-204, 2022 (Released:2022-09-12)
- 参考文献数
- 23
Anomalous coldness was observed over midlatitude Eurasia in December 2020 and over subpolar Eurasia in January 2021. The former was accompanied by the Warm Arctic and Cold Eurasia (WACE) pattern, while the latter by the negative phase of the Arctic Oscillation (AO). A set of large ensemble experiments with an atmospheric general circulation model suggests a contribution of reduced Arctic Sea ice to the midlatitude cooling and WACE pattern in December 2020. The tropical and extratropical sea surface temperature (SST) anomalies, however, contribute to warming over midlatitude Eurasia. In January 2021, neither the sea ice nor SST anomalies can explain the subpolar Eurasian cooling and the negative AO in our experiments.
- 著者
- Kazuaki Yasunaga Atsushi Hamada Kazuaki Nishii
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.2019-043, (Released:2019-11-06)
- 被引用文献数
- 2
This study examines the factors responsible for the long-term changes of winter monsoonal flow around Japan in association with increasing precipitation trends in December along the coastal areas of Honhsu (the main island of Japan) facing the Sea of Japan. The precipitation around the tropical eastern Indian Ocean and maritime continent has significantly increased in recent years. Thus, a wave-packet of the stationary Rossby wave associated with the anomalous heating deflects the subtropical jet to the south over the eastern edge of the Eurasian continent. The deflection of the jet gives favorable conditions for the development of a low pressure trough in the lower level on the eastern side, leading to the formation of negative height anomalies near the surface around Japan.Although tropical precipitation also increases in November and January, the anomalous heating induces negative height anomalies and cyclonic circulations over the inland region of China and eastern offshore region of Japan (to the further west and east in comparison with those in December) in these months. As a result, monsoonal flow around Japan (and precipitation along the coastal areas of the Sea of Japan) shows no long-term trends in November or January.
- 著者
- Kazuaki NISHII Takafumi MIYASAKA Yu KOSAKA Hisashi NAKAMURA
- 出版者
- Meteorological Society of Japan
- 雑誌
- 気象集誌. 第2輯 (ISSN:00261165)
- 巻号頁・発行日
- vol.87, no.3, pp.581-588, 2009 (Released:2009-07-08)
- 参考文献数
- 17
- 被引用文献数
- 10 11
A reanalysis dataset is used to establish the relationship between the year-to-year fluctuations in the midwinter storm-track activity over the Far East measured by poleward heat flux associated with subweekly disturbances and the occurrence of the first spring storm with strong southerly winds over Japan (Haru-Ichiban). Our analysis reveals that its early (delayed) occurrence tends to follow the enhanced (suppressed) winter storm-track activity with less (more) apparent minimum in midwinter in the course of the seasonal march. A metric is defined on the basis of the eddy heat flux to measure the reproducibility of the particular seasonal march of the Far East storm-track activity simulated in each of the Coupled Model Intercomparison Project Phase 3 climate models under the present climate. Under a particular global warming scenario, ensemble projection based only on the several models that show the highest reproducibility of the storm-track activity measured with the particular metric indicates that the future enhancement is likely in the midwinter storm-track activity associated with the weakening of the East Asian winter monsoon, implying that Haru-Ichiban is likely to occur earlier in the late 21st century than in the 20th century.