著者

Hiroaki Kawase Akihiko Murata Ken Yamada Tosiyuki Nakaegawa Rui Ito Ryo Mizuta Masaya Nosaka Shunichi Watanabe Hidetaka Sasaki

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-001, (Released:2020-12-18)

被引用文献数

12

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We investigate regional characteristics of future changes in snowfall in Japan under two emission scenarios—RCP2.6 and RCP8.5—using a high-resolution regional climate model with 5 km grid spacing and discuss the influence of changes in atmospheric circulation. The high-resolution model can simulate details of changes in distributions of total snowfall in Japan. Under RCP2.6, the annual total snowfall decreases in most parts of Japan except for Japan's northern island, Hokkaido. In Hokkaido, the winter snowfall increases even under RCP8.5, especially in January and February. The snowfall peak is delayed from early December to late January in Hokkaido. Along the Sea of Japan in eastern Japan, the winter-total snowfall decreases even if the winter mean temperature is below 0°C in the future climate. The different snowfall changes in Hokkaido and on the Sea of Japan side of eastern Japan are caused by precipitation changes in each region. Future changes in atmospheric circulation related to the Aleutian low cause the enhancement and the inhibition of winter precipitation in Hokkaido and the Sea of Japan side of eastern Japan, respectively, contributing to changes in the regional characteristics of snowfall and snow cover in addition to moistening due to atmospheric and ocean warming.

著者

Sheau Tieh Ngai Hidetaka Sasaki Akihiko Murata Masaya Nosaka Jing Xiang Chung Liew Juneng Supari Ester Salimun Fredolin Tangang

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.132-139, 2020 (Released:2020-08-08)

参考文献数

60

被引用文献数

9

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The Non-Hydrostatic Regional Climate Model (NHRCM) was used in simulating the present and future rainfall climate over Malaysia under the RCP8.5 scenario in this study. Simulation and projection from 1979 to 2002 for present day and 2070 to 2100 for the end of century were conducted over the Malaysia. The 20 km resolution MRI-AGCM3.2 model simulation from Meteorological Research Institute (MRI) was used as boundary conditions. The objective of this study was to estimate the extreme rainfall projections in Malaysia at 5 km of resolution during the November to February period, representing the northeast monsoon season. Overall, the model was capable to simulate the historical rainfall climatology and distribution, but model tended to underestimate high rainfall frequency and mean rainfall intensity in Malaysia. However, compared with simulations at 25 km, added values have been shown at 5 km resolution. Based on the NHRCM05 simulations, a number of hotspots have been identified with significant projected increases up to 80% for the extreme rainfall indices (R20mm, RX1day, R95pTOT and R99pTOT), 30% increases in mean rainfall intensity (SDII) and 20% for consecutive dry days indices (CDD).

著者

Masaya Nosaka Hiroaki Kawase Hidetaka Sasaki Akihiko Murata

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.107-112, 2019 (Released:2019-05-22)

参考文献数

20

被引用文献数

3

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High-frequency variations are excluded in the merged satellite and in-situ data global daily sea surface temperature (MGDSST) used in weather forecasting in Japan Meteorological Agency. We investigated the importance of temporal resolution on sea surface temperature (SST) when predicting winter precipitation using the Non-Hydrostatic Regional Climate Model. We used seven-day temporal smoothing to investigate the influence of temporal resolution on prediction. The Gaussian filter was used as spatial smoothing for comparison with the influence of spatial resolution. The influence of the temporal resolution of SST on monthly precipitation is smaller than that of spatial resolution. However, the influence of the temporal resolution on daily precipitation is comparable to that of spatial resolution. The temporal resolution of SST greatly affects precipitation, particularly in December, as the variations in SST are largest compared to the rest of the year. Furthermore, the winter monsoon promotes the effect of SST on winter precipitation. Our experiments using seven-day moving average smoothing indicates that the temporal resolution of the SST on precipitation become about 15 %/K under the winter monsoon.

著者

Hidetaka Sasaki Noriko N. Ishizaki Akihiko Murata Hiroaki Kawase Masaya Nosaka

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.19, pp.9-15, 2023 (Released:2023-01-12)

参考文献数

16

被引用文献数

1

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The surface temperature was projected to increase from 4 to 5°C in most regions around Japan in winter at the end of the 21st century, according to the Non-Hydrostatic Regional Climate Model (NHRCM) under the Representative Concentration Pathway 8.5 scenario. The melting of sea ice in the Sea of Okhotsk significantly affected the temperature around Hokkaido Prefecture, raising it by more than 8°C in some places. The temperature also rose by more than 8°C in some areas in Honshu where the atmosphere was not susceptible to sea ice. The reduction in snow-covered areas due to global warming raised the temperature further and induced changes in local wind, such as airflows over mountains and wind blowing from the sea. These changes raised the seasonal average temperature and caused the temperature to rise by over 8°C. The dynamical downscaling method played a significant role in projecting such small-scale features in the future climate.

著者

Sheau Tieh Ngai Hidetaka Sasaki Akihiko Murata Masaya Nosaka Jing Xiang Chung Liew Juneng Supari Ester Salimun Fredolin Tangang

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2020-023, (Released:2020-06-25)

被引用文献数

9

---

The Non-hydrostatic Regional Climate model (NHRCM) was used in simulating the present and future rainfall climate over Malaysia under the RCP8.5 scenario in this study. Simulation and projection from 1979 to 2002 for present day and 2070 to 2100 for the end of century were conducted over the Malaysia. The 20 km resolution MRI-AGCM3.2 model simulation from Meteorological Research Institute, MRI was used as boundary conditions. The objective of this study was to estimate the extreme rainfall projections in Malaysia at 5 km of resolution during the November to February period, representing the northeast monsoon season. Overall, the model was capable to simulate the historical rainfall climatology and distribution, but model tended to underestimate high rainfall frequency and mean rainfall intensity in Malaysia. However, compared with simulations at 25 km, added values have been shown at 5 km resolution. Based on the NHRCM05 simulations, a number of hotspots have been identified with significant projected increases up to 80% for the extreme rainfall indices (R20mm, RX1day, R95pTOT and R99pTOT), 30% increases in mean rainfall intensity (SDII) and 20% for consecutive dry days indices (CDD).

著者

Hiroaki Kawase Akira Yamazaki Hajime Iida Kazuma Aoki Wataru Shimada Hidetaka Sasaki Akihiko Murata Masaya Nosaka

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.14, pp.39-45, 2018 (Released:2018-03-29)

参考文献数

22

被引用文献数

8

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Extremely small snow cover in the winter of 2015/16 and interannual variations of snow cover over the Japanese Northern Alps are simulated by a regional climate model with 2 km grid spacing based on the Japanese 55-year Reanalysis (JRA-55). Our simulation well reproduces the daily variation of snow depth along the Tateyama-Kurobe Alpine Route, located at the Japanese Northern Alps, as compared to snow depths observed by time-lapse cameras in 2014/15. Our simulations indicate that the maximum snow depth in 2015/16 was the lowest of 16 years at high elevations, especially in the spring. In March 2016, weak cold air outbreaks and inactive storm-tracks cause little precipitation around central Japan, resulting in greatly reduced annual accumulated snowfall than usual at high elevations. Warmer April conditions also contribute to accelerated snow melting, resulting in the disappearance of snow at high elevations one-month earlier than usual. Analysis of large-scale circulations related to past large El Niño years shows a warmer April is a typical response in El Niño events, while weak cold air outbreaks and inactive storm-tracks are contributed by the extratropical internal variation rather than lingering El Niño effects in tropics.

著者

Hiroaki Kawase Akihiko Murata Ken Yamada Tosiyuki Nakaegawa Rui Ito Ryo Mizuta Masaya Nosaka Shunichi Watanabe Hidetaka Sasaki

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.1-7, 2021 (Released:2021-01-27)

参考文献数

29

被引用文献数

12

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We investigate regional characteristics of future changes in snowfall in Japan under two emission scenarios—RCP2.6 and RCP8.5—using a high-resolution regional climate model with 5km grid spacing and discuss the influence of changes in atmospheric circulation. The high-resolution model can simulate details of changes in distributions of total snowfall in Japan. Under RCP2.6, the annual total snowfall decreases in most parts of Japan except for Japan's northern island, Hokkaido. In Hokkaido, the winter snowfall increases even under RCP8.5, especially in January and February. The snowfall peak is delayed from early December to late January in Hokkaido. Along the Sea of Japan in eastern Japan, the winter-total snowfall decreases even if the winter mean temperature is below 0°C in the future climate. The different snowfall changes in Hokkaido and on the Sea of Japan side of eastern Japan are caused by precipitation changes in each region. Future changes in atmospheric circulation related to the Aleutian low cause the enhancement and the inhibition of winter precipitation in Hokkaido and the Sea of Japan side of eastern Japan, respectively, contributing to changes in the regional characteristics of snowfall and snow cover in addition to moistening due to atmospheric and ocean warming.

著者

Shiori Sugimoto Rui Ito Koji Dairaku Hiroaki Kawase Hidetaka Sasaki Shingo Watanabe Yasuko Okada Sho Kawazoe Takeshi Yamazaki Takahiro Sasai

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.14, pp.46-51, 2018 (Released:2018-04-01)

参考文献数

32

被引用文献数

7

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To evaluate the influence of spatial resolution in numerical simulations on the duration of consecutive dry days (CDDs) and near-surface temperature over the central mountains in Japan, a regional climate model was used to conduct two experiments with horizontal resolutions of 5 and 20 km. Compared with observations, the spatial and temporal features of the CDDs were simulated well in the 5 km experiment, whereas in the 20 km simulation they were overestimated over the mountains and underestimated in the surrounding regions. The accuracy in the simulated CDDs affected the near-surface temperature in the model. In years with a difference of more than five days in the CDDs between the 5 and 20 km experiments, near-surface temperatures over the mountains were 0.2-0.3 K lower in the 5 km simulation compared with the 20 km simulation. This was due to the lower number of CDDs in 5 km simulation causing active cloud convection and reduced net radiation at the ground, resulting from a large decrease in the solar radiation at the ground. In addition, a land surface wetness controls a spatial heterogeneity of temperature difference between two experiments.

著者

Hiroaki KAWASE Hidetaka SASAKI Akihiko MURATA Masaya NOSAKA Noriko N. ISHIZAKI

出版者

(公社)日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.93, no.5, pp.571-580, 2015 (Released:2015-11-17)

参考文献数

33

被引用文献数

3 19

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We investigate future changes in winter precipitation around Japan and their uncertainties using the downscalings of a non-hydrostatic regional climate model (NHRCM) with 20-km grid spacing according to global climate projections. The global climate projections were conducted by the atmospheric general circulation model with three patterns of sea surface temperature changes in the Coupled Model Intercomparison Project Phase 5 under the Representative Concentration Pathway 8.5. Moreover, three cumulus convective parameterizations were applied in the present and future climate experiments. The ensemble mean of nine future NHRCM experiments shows decreases in the winter precipitation on the coast of the Sea of Japan and over the Pacific Ocean in the south of the Japanese archipelago. The former decrease in precipitation results from a weakened winter monsoon. The latter corresponds to changes in extratropical cyclone number around Japan, which have a large uncertainty. On the other hand, winter precipitation increases over the northernmost part of Japan (Hokkaido) and the northeastern Asian continent. The strengthened northwesterly around Hokkaido, which results from the reduction of sea ice in the Sea of Okhotsk, causes increased precipitation in the inland area of Hokkaido. In addition, moistening due to global warming relates to increased precipitation in extremely cold regions. These signals are common to most experiments.

著者

Izuru Takayabu Noriko N. Ishizaki Tosiyuki Nakaegawa Hidetaka Sasaki Waranyu Wongseree

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.15, no.1, pp.1-8, 2021 (Released:2021-02-13)

参考文献数

39

被引用文献数

3

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The diurnal cycle of precipitation over northeast Thailand during the Southeast Asian summer monsoon season was examined using non-hydrostatic (5-km grid) and convection-permitting (2-km grid) regional climate models. The results indicate that these fine grid models exhibit a better performance in terms of representing the diurnal cycle of precipitation due to the realistic orographic representation. The models successfully simulated the local circulation corresponding to the intensification of precipitation and were consistent with the satellite-based observed diurnal cycle of precipitation. The model simulation indicated that the convergence area over the mountain on the south of the Khorat Plateau occurred in the afternoon in association with the occurrence of precipitation. The convergence area migrated northward and contributed to the precipitation peak over the plateau during the nighttime. A bias in terms of the amount of precipitation in the 5-km grid model was partially removed through the convection-permitting 2-km grid model.

著者

Faye T. Cruz Hidetaka Sasaki

出版者

(公社)日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.13, pp.13-18, 2017 (Released:2017-01-29)

参考文献数

37

被引用文献数

7

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This study evaluates the performance of the Non-hydrostatic Regional Climate Model (NHRCM) in simulating the present climate over Southeast Asia to determine its applicability in downscaling climate projections in the region. Simulations from 1989 to 2008 are conducted over the region at 25-km resolution using boundary conditions from the ECMWF ERA-Interim dataset. The topographic effect on rainfall is well represented in NHRCM but can result in wet (dry) biases in the windward (leeward) side of mountains. NHRCM is able to reduce the overestimated rainfall in ERA-Interim, particularly over eastern Philippines and in the Maritime Continent, with improvements in spatial patterns. Both seasonality and daily distribution of rainfall are represented in most regions. On the other hand, there is a tendency to underestimate the number of wet days, especially during the respective wet season of the subregion, and to overestimate daily rainfall intensity. NHRCM also has an overall cold model bias, which reduces the warm bias in ERA-Interim, except for some parts of Indochina during boreal winter and spring. These results indicate the improved representation of present climate in Southeast Asia using NHRCM, and its potential applicability in downscaling climate projections to increase projected climate scenarios for the region.

著者

Kazuo Kurihara Koji Ishihara Hidetaka Sasaki Yukio Fukuyama Hitomi Saitou Izuru Takayabu Kazuyo Murazaki Yasuo Sato Seiji Yukimoto Akira Noda

出版者

(公社)日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.1, pp.97-100, 2005 (Released:2005-09-14)

参考文献数

14

被引用文献数

36 48

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The Meteorological Research Institute (MRI) and the Japan Meteorological Agency (JMA) projected climate change over Japan due to global warming using a high-resolution Regional Climate Model of 20 km mesh size (RCM20) developed in MRI. Projection was made for 2081 to 2100 following a SRES-A2 scenario. Precipitation projected by RCM20 indicated that increased daily precipitation will be seen during the warm season from June to September. Except for this period, the precipitation amount will not change much or will slightly decrease around Japan. The increase during the warm season will be seen only in the western part of Japan. A possible cause of the increase is an El Niño-like SST pattern in the future. Due to the future increased summer SST in the eastern equatorial Pacific, anti-cyclonic circulation to the south of Japan will intensify and will induce a strong water vapor flux along the rim of the anti-cyclonic anomaly. The intensified flux will converge over the western part of Japan and may increase precipitation. Surface air temperature is projected to increase more than 2°C around Japan in January. In summer, the temperature increase will be lower by about 1°C than in winter.