- 著者
- Tomomichi Ogata Hidenori Aiki
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.15, pp.262-267, 2019 (Released:2019-12-27)
- 参考文献数
- 45
- 被引用文献数
- 4
This study makes a first attempt to apply the diagnostic scheme of Aiki et al. (2017) to the output of an ocean general circulation model (OGCM), in order to investigate the basin-wide pathway of equatorial and mid-latitude wave energy associated with intraseasonal variability in the Indian Ocean. The vertical mode decomposition shows that 90-day variability of the second baroclinic mode is dominant in a realistic OGCM experiment. For 90-day equatorial Kelvin wave (KW) and Rossby wave (RW), energy input by wind stress appears in the eastern equatorial Indian Ocean that is then transferred eastward by KWs along the eastern equatorial waveguide (while westward as RW off equator). For 30-day Mixed-Rossby Gravity waves (MRG), wave energy is transferred eastward while wave phase propagates westward that is consistent with the dispersion relationship of low-frequency MRG. The new diagnostic scheme is able to show, particularly for 30-day MRG, eastward energy fluxes along the equatorial waveguide, while the other schemes in previous studies (e.g. pressure flux, quasi-geostrophic flux) cannot show the direction of the group velocity of equatorial waves.
- 著者
- Sachie Kanada Hidenori Aiki Kazuhisa Tsuboki
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.17A, no.Special_Edition, pp.38-44, 2021 (Released:2021-07-27)
- 参考文献数
- 32
- 被引用文献数
- 3
Torrential rain associated with Typhoon Hagibis (2019) caused extensive destruction across Japan. To project future changes of the record-breaking rainfall, numerical experiments using a regional 1-km-mesh three-dimensional atmosphere–ocean coupled model were conducted in current (CNTL) and pseudo-global warming (PGW) climates. The water vapor mixing ratio in the lower troposphere increased by 23% in response to a 3.34 K increase in sea surface temperature (SST) in the PGW climate. The abundant moisture supply by the westward winds of the typhoon caused strong precipitation from its rainbands for a long period, resulting in 90% increase in total precipitation in eastern Japan before landfall. However, the strong PGW typhoon caused high SST-cooling. Mean precipitation in eastern Japan during the typhoon passage increased by 22% when the SST-cooling east of Kanto was strengthened from 0.11 K to 0.72 K from the CNTL to PGW simulations; the increase was above 29% when the SST-cooling was lowered. Since Typhoon Hagibis accelerated as it traveled northward, the magnitude of the SST-cooling and weakening of the typhoon were suppressed. Consequently, strong precipitation in the inner-core of the strong PGW typhoon caused 30% increase in precipitation in the areas on the Pacific side of northern Japan.
- 著者
- Sachie Kanada Hidenori Aiki Kazuhisa Tsuboki
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.17A-007, (Released:2021-06-22)
- 被引用文献数
- 3
Torrential rain associated with Typhoon Hagibis (2019) caused extensive destruction across Japan. To project future changes of the record-breaking rainfall, numerical experiments using a regional 1-km-mesh three-dimensional atmosphere–ocean coupled model were conducted in current (CNTL) and pseudo-global warming (PGW) climates. The water vapor mixing ratio in the lower troposphere increased by 23% in response to a 3.34 K increase in sea surface temperature (SST) in the PGW climate. The abundant moisture supply by the westward winds of the typhoon caused strong precipitation from its rainbands for a long period, resulting in 90% increase in total precipitation in eastern Japan before landfall. However, the strong PGW typhoon caused high SST-cooling. Mean precipitation in eastern Japan during the typhoon passage increased by 22% when the SST-cooling east of Kanto was strengthened from 0.11 K to 0.72 K from the CNTL to PGW simulations; the increase was above 29% when the SST-cooling was lowered. Since Typhoon Hagibis accelerated as it traveled northward, the magnitude of the SST-cooling and weakening of the typhoon were suppressed. Consequently, strong precipitation in the inner-core of the strong PGW typhoon caused 30% increase in precipitation in the areas on the Pacific side of northern Japan.
- 著者
- Sachie Kanada Hidenori Aiki Kazuhisa Tsuboki Izuru Takayabu
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.17A-003, (Released:2020-12-16)
- 被引用文献数
- 8
Numerical experiments on Typhoon Trami (2018) using a regional 1-km-mesh three-dimensional atmosphere–ocean coupled model in current and pseudo-global warming (PGW) climates were conducted to investigate future changes of a slow-moving intense typhoon under the warming climate. Over the warmer sea in the PGW climate, the maximum near-surface wind speed rapidly increased around the large eye of the simulated Trami. The stronger winds in the PGW simulation versus the current simulation caused a 1.5-fold larger decrease of sea surface temperature (SST) in the storm core-region. In the PGW climate, near-surface air temperature increased by 3.1°C. A large SST decrease due to ocean upwelling caused downward heat fluxes from the atmosphere to the ocean. The magnitude of the SST decrease depended strongly on initial ocean conditions. Consideration of the SST decrease induced by an intense typhoon, and a slow-moving storm in particular, indicated that such a typhoon would not always become more intense under the warmer climate conditions. An atmosphere–ocean coupled model should facilitate making more reliable projections of typhoon intensities in a warming climate.
- 著者
- Sachie Kanada Hidenori Aiki Kazuhisa Tsuboki Izuru Takayabu
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.15, pp.244-249, 2019 (Released:2019-12-05)
- 参考文献数
- 36
- 被引用文献数
- 8
From 16 to 23 August 2016, typhoons T1607, T1609, and T1611 hit eastern Hokkaido in northern Japan and caused heavy rainfall that resulted in severe disasters. To understand future changes in typhoon-related precipitation (TRP) in midlatitude regions, climate change experiments on these three typhoons were conducted using a high-resolution three-dimensional atmosphere–ocean coupled regional model in current and pseudo-global warming (PGW) climates. All PGW simulations projected decreases in precipitation frequency with an increased frequency of strong TRP and decreased frequency of weak TRP in eastern Hokkaido. In the current climate, snow-dominant precipitation systems start to cause precipitation in eastern Hokkaido about 24 hours before landfall. In the PGW climate, increases in convective available potential energy (CAPE) developed tall and intense updrafts and the snow-dominant precipitation systems turned to have more convective property with less snow mixing ratio (QS). Decreased QS reduced precipitation area, although strong precipitation increased or remained almost the same. Only TRP of T1607 increased the amounts before landfall. In contrast, all typhoons projected to increase TRP amount associated with landfall, because in addition to increased CAPE, the PGW typhoon and thereby its circulations intensified, and a large amount of rain was produced in the core region.
- 著者
- Sachie Kanada Hidenori Aiki Kazuhisa Tsuboki Izuru Takayabu
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.17A, no.Special_Edition, pp.14-20, 2021 (Released:2021-01-28)
- 参考文献数
- 37
- 被引用文献数
- 8
Numerical experiments on Typhoon Trami (2018) using a regional 1-km-mesh three-dimensional atmosphere–ocean coupled model in current and pseudo-global warming (PGW) climates were conducted to investigate future changes of a slow-moving intense typhoon under the warming climate. Over the warmer sea in the PGW climate, the maximum near-surface wind speed rapidly increased around the large eye of the simulated Trami. The stronger winds in the PGW simulation versus the current simulation caused a 1.5-fold larger decrease of sea surface temperature (SST) in the storm core-region. In the PGW climate, near-surface air temperature increased by 3.1°C. A large SST decrease due to ocean upwelling caused downward heat fluxes from the atmosphere to the ocean. The magnitude of the SST decrease depended strongly on initial ocean conditions. Consideration of the SST decrease induced by an intense typhoon, and a slow-moving storm in particular, indicated that such a typhoon would not always become more intense under the warmer climate conditions. An atmosphere–ocean coupled model should facilitate making more reliable projections of typhoon intensities in a warming climate.
- 著者
- Sachie Kanada Hidenori Aiki Kazuhisa Tsuboki Izuru Takayabu
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.2019-044, (Released:2019-11-07)
- 被引用文献数
- 8
From 16 to 23 August 2016, typhoons T1607, T1609, and T1611 hit eastern Hokkaido in northern Japan and caused heavy rainfall that resulted in severe disasters. To understand future changes in typhoon-related precipitation (TRP) in midlatitude regions, climate change experiments on these three typhoons were conducted using a high-resolution three-dimensional atmosphere–ocean coupled regional model in current and pseudo-global warming (PGW) climates. All PGW simulations projected decreases in precipitation frequency with an increased frequency of strong TRP and decreased frequency of weak TRP in eastern Hokkaido. In the current climate, snow-dominant precipitation systems start to cause precipitation in eastern Hokkaido about 24 hours before landfall. In the PGW climate, increases in convective available potential energy (CAPE) developed tall and intense updrafts and the snow-dominant precipitation systems turned to have more convective property with less snow mixing ratio (QS). Decreased QS reduced precipitation area, although strong precipitation increased or remained almost the same. Only TRP of T1607 increased the amounts before landfall. In contrast, all typhoons projected to increase TRP amount associated with landfall, because in addition to increased CAPE, the PGW typhoon and thereby its circulations intensified, and a large amount of rain was produced in the core region.