著者

Bahareh KAMRANZAD Nobuhito MORI

出版者

公益社団法人 土木学会

雑誌

土木学会論文集B2(海岸工学) (ISSN:18842399)

巻号頁・発行日

vol.74, no.2, pp.I_1351-I_1355, 2018 (Released:2018-11-10)

参考文献数

11

被引用文献数

1

---

High quality wave data in data-scarce regions are required in order to provide a reliable source for wave climate assessment. In this study, numerical modeling was utilized in order to generate the wave characteristics in the Indian Ocean (IO) region using super-high-resolution wind field MRI-AGCM3.2S as forcing. The model was evaluated in comparison to the satellite data and the validated model was performed to simulate historical and future projections of the wave in the study area (25 years for each period). Comparison of mean annuals of the wave indicated a slight decrease of significant wave height (SWH) in the Northern Indian Ocean (NIO) and middle parts of the Southern Indian Ocean (SIO) while there is a considerable increase near the southern ocean adjacent to Antarctica. The change of mean wave period (Tm01) will be less in the future, however, there will be a considerable increase in the south of India. The results of this study indicate the different patterns of change for wind and wave parameters in different regions of the IO.

著者

Keita Fujiwara Tetsuya Takemi Nobuhito Mori

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

pp.2023-019, (Released:2023-06-03)

---

To investigate the effects of global warming on Typhoon Jebi (2018), we performed high-resolution pseudo-global 2-K and 4-K warming simulations with initial time ensembles using a regional atmospheric model. The pseudo-global warming experiments demonstrated the further facilitation of Jebi's development with a higher rise in the temperature. The intensity over the ocean to the south of Japan increased by 8% (20%) in the climate warmed 2-K (4-K) to the current climate. Typhoon Jebi, in the 4-K warming simulations, maintained a robust inner-core characterized by a compact and deep eyewall and well-developed primary and secondary circulations even immediately before landfall, in contrast to the result in the 2-K warming simulations. The sustained robust axisymmetric structure immediately before landfall in the 4-K warming runs was strongly associated with the enhanced ocean warming around Japan, notable moistening of the lower-to-middle troposphere in the vicinity of Typhoon Jebi, and a significant decrease in vertical wind shear under the extremely warmed future climate. The nonlinear responses of Typhoon Jebi to the tropospheric temperature rise are attributable to the drastic changes in the midlatitude's thermodynamic and dynamic environments under climate changes resulting from 2-K to 4-K global warming.

著者

Bahareh Kamranzad Nobuhito Mori

出版者

日本地球惑星科学連合

雑誌

日本地球惑星科学連合2019年大会

巻号頁・発行日

2019-03-14

---

Indian Ocean experiences intensive tropical cyclones in both northern and southern parts. The Northern Indian Ocean (NIO) includes 7% of the global tropical cyclones which results in generating severe wave climate during the extreme events. In this study, future change of tropical cyclone-induced waves due to climate change is assessed in terms of change in the spatial distribution patterns and magnitude. The cyclone seasons in NIO are divided by pre-monsoon (especially May) and northeast monsoon (October–December). Moreover, there are few cyclones form the southwest monsoon during June and September. Hence, the assessment of future change of intensity of tropical cyclones and the generated waves is necessary to be performed on a monthly scale. For this purpose, wind field obtained from super-high-resolution atmospheric global climate model MRI-AGCM3.2S of the Japan Meteorological Agency (JMA) -with horizontal spatial and temporal output resolutions of 20 km and 1 hr., respectively- was used to force a numerical wave model (SWAN) in historical (1979-2003) and future (2075-2099) periods (based on Representative Concentration Pathway (RCP) 8.5 scenario).Spatial distribution of annual extreme events in the domain shows that the concentration of tropical cyclones is in the NIO and around Madagascar (located in the Southern Indian Ocean (SIO)) generating high waves of the magnitudes of around 20 m during the events. Spatial distribution of monthly maximum values of the historical and future wind speed (WS) and significant wave height (SWH) indicates that according to historical projection, intense cyclones happen during May and June in NIO, while they can be observed mostly during December to April in the SIO. The future monthly distribution of cyclone induced waves in SIO shows a similar pattern to the historical events, except for winter tropical cyclones (November and December), which are decreased in the future, while increasing in the intensity can be observed during October and April in NIO.Monthly variation of maximum events in the domain was assessed in the NIO and SIO, separately. According to the past studies, due to the global warming, tropical cyclones of hurricane intensity -which currently occur only in the pre and post-monsoon seasons- will likely be formed even during the summer monsoon in NIO. Our results illustrate an increase in the intensity of cyclones in the future, not only during the summer monsoon (July) but also during the winter monsoon (September and October). Results show that the range of change in the highest SWH in NIO is between -27% (in February) and +26% (in October). In the northern part of SIO, the intensity of future tropical cyclones will increase during the southwestern inter-monsoon season (March and April), whereas it will decrease at the end of southwestern monsoon season (September). In the southern part of SIO, the intensity of tropical cyclones will increase around 20% during northeastern monsoon (February and March), which results in a future increase of 40% in maximum SWH in February. Generally, change in highest SWH in the future follows the pattern of WS except for the northern parts of SIO when the highest increase in maximum SWH (21%) occurs in March whereas the highest increase in maximum WS occurs in April (25%). There is a 20% increase in maximum WS during February in southern parts of SIO which can be a reason for the increase of SWH during March in northern parts. It can be concluded that the change in the intensity of future tropical cyclones in NIO is higher than SIO. The range of change in highest SWH in NIO is larger than SIO, except for February when the maximum wave height in southern parts of SIO will increase about 40% in the future. Furthermore, the change in maximum SWH in northern parts of SIO seems to be affected by the change of tropical cyclones in southern parts of SIO.

著者

Nobuhito Mori Tomohiro Yasuda Hajime Mase Tracey Tom Yuichiro Oku

出版者

Japan Society of Hydrology and Water Resources (JSHWR) / Japanese Association of Groundwater Hydrology (JAGH) / Japanese Association of Hydrological Sciences (JAHS) / Japanese Society of Physical Hydrology (JSPH)

雑誌

Hydrological Research Letters (ISSN:18823416)

巻号頁・発行日

vol.4, pp.15-19, 2010 (Released:2010-03-03)

参考文献数

11

被引用文献数

126 187

---

The influence of global climate change due to greenhouse effects on the earth’s environment will require impact assessment, mitigation and adaptation strategies for the future of our society. This study predicts future ocean wave climate in comparison with present wave climate based on the atmospheric general circulation model and global wave model. The annual averaged and extreme sea surface winds and waves are analyzed in detail. There are clear regional dependences of both annual average and also extreme wave height changes from present to future climates. The wave heights of future climate will increase at both middle latitudes and also in the Antarctic Ocean, with a decrease at the equator.