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

---

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

Shin Fukui Akihiko Murata

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-036, (Released:2021-10-11)

---

This study statistically investigated sensitivities of simulated precipitation to horizontal resolution of a regional climate model, instead of focusing on particular cases. We performed long-term integrations of models with horizontal grid spacings of 20, 5, 2, 1 and 0.5 km over Kyushu in the Baiu seasons of 2009-2020. The 2-km grid model improves simulated precipitation to the 5-km grid models with and without cumulus parameterization. Further decreasing the gird spacing from 2 km to 1 and 0.5 km reduces the dependency of the frequency biases on intensities of hourly precipitation and mitigates the excessive concentration of heavy precipitation in small scale, approaching that of the radar/raingauge analysis. The features of individual deep moist convections, specifically the horizontal scale of updrafts, the representation of downdrafts and the number of convections, start to converge when the grid spacing is reduced from 1 to 0.5 km. The results suggest models with grid spacing of 1 km or less are needed to resolve deep moist convections and represent the resulting precipitations. The 2-km grid models can partly resolve the deep moist convections, but their effective resolution is still insufficient, requiring some parameterizations to simulate convective precipitations appropriately.

著者

Hiroaki Kawase Munehiko Yamaguchi Yukiko Imada Syugo Hayashi Akihiko Murata Tosiyuki Nakaegawa Takafumi Miyasaka 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.7-13, 2021 (Released:2021-01-28)

参考文献数

34

被引用文献数

20

---

Impacts of historical warming on extremely heavy rainfall induced by Typhoon Hagibis (2019) are investigated using a storyline event attribution approach with the Japan Meteorological Agency Nonhydrostatic Model (JMA-NHM). Control experiments based on JMA mesoscale analysis data well reproduce the typhoon's track, intensity, and heavy precipitation. First, two non-warming experiments are conducted: One excludes both 40-year atmospheric and oceanic temperature trends from 1980 to 2019, and the other excludes the oceanic trend only. A comparison between control and non-warming experiments indicates that historical warming strengthens typhoons and increases the amount of total precipitation by 10.9% over central Japan. The difference between CTL and non-warming experiments without both atmospheric and oceanic temperature trends is larger than that without just the oceanic trend (7.3%). Additional sensitivity experiments without Japan's topography indicate that topography enhances not only total precipitation but also the changes in total precipitation due to historical warming. Through the storyline event attribution approach, it is concluded that historical warming intensifies strength of Typhoon Hagibis (2019) and enhances the extremely heavy precipitation induced by the typhoon.

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

---

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

Shun-ichi I. Watanabe Hiroyuki Tsujino Akihiko Murata Masayoshi Ishii

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.183-188, 2019 (Released:2019-09-05)

参考文献数

31

被引用文献数

1

---

We evaluated the impact of sea surface temperature (SST) improvement realized by increasing horizontal resolution of an ocean model on dynamical downscaling (DDS) over Japan, focusing on the effects of the Kuroshio on summer precipitation in Japan. Two sets of SSTs were simulated using a high-resolution North Pacific (NP) model and a low-resolution global (GLB) ocean model. Using these SSTs as the lower boundary conditions for the atmosphere, two DDS experiments were conducted (NP-run and GLB-run). In NP-run, summer precipitation increases over the Kuroshio and reduces over Pacific coastal areas of Japan compared with GLB-run. Due to weaker southerly winds north of the Kuroshio in NP-run, the water vapor flux transported to Japan is smaller than in GLB-run. Both the pressure adjustment and the vertical mixing mechanisms weaken the southerly winds, with the latter being slightly more effective. Increasing the horizontal resolution of the ocean model, so that the Kuroshio is more realistically reproduced, improves the accuracy of simulated precipitation over Japan.

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

---

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

---

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

Shin Fukui Akihiko Murata

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.207-212, 2021 (Released:2021-11-25)

参考文献数

40

---

This study statistically investigated sensitivities of simulated precipitation to horizontal resolution of a regional climate model, instead of focusing on particular cases. We performed long-term integrations of models with horizontal grid spacings of 20, 5, 2, 1, and 0.5 km over Kyushu in the Baiu seasons of 2009-2020. The 2-km grid model improves simulated precipitation to the 5-km grid models with and without cumulus parameterization. Further decreasing the gird spacing from 2 km to 1 and 0.5 km reduces the dependency of the frequency biases on intensities of hourly precipitation and mitigates the excessive concentration of heavy precipitation in small scale, approaching that of the radar/raingauge analysis. The features of individual deep moist convections, specifically the horizontal scale of updrafts, the representation of downdrafts, and the number of convections, start to converge when the grid spacing is reduced from 1 to 0.5 km. The results suggest models with grid spacing of 1 km or less are needed to resolve deep moist convections and to represent the resulting precipitations. The 2-km grid models can partly resolve the deep moist convections, but their effective resolution is still insufficient, requiring some parameterizations to simulate convective precipitations appropriately.

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

---

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

---

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

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

---

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

Hiroaki Kawase Munehiko Yamaguchi Yukiko Imada Syugo Hayashi Akihiko Murata Tosiyuki Nakaegawa Takafumi Miyasaka Izuru Takayabu

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.17A-002, (Released:2020-12-24)

被引用文献数

20

---

Impacts of historical warming on extremely heavy rainfall induced by Typhoon Hagibis (2019) are investigated using a storyline event attribution approach with the Japan Meteorological Agency Nonhydrostatic Model (JMA-NHM). Control experiments based on JMA mesoscale analysis data well reproduce the typhoon's track, intensity, and heavy precipitation. First, two non-warming experiments are conducted: One excludes both 40-year atmospheric and oceanic temperature trends from 1980 to 2019, and the other excludes the oceanic trend only. A comparison between control and non-warming experiments indicates that historical warming strengthens typhoons and increases the amount of total precipitation by 10.9% over central Japan. The difference between CTL and non-warming experiments without both atmospheric and oceanic temperature trends is larger than that without just the oceanic trend (7.3%). Additional sensitivity experiments without Japan's topography indicate that topography enhances not only total precipitation but also the changes in total precipitation due to historical warming. Through the storyline event attribution approach, it is concluded that historical warming intensifies strength of Typhoon Hagibis (2019) and enhances the extremely heavy precipitation induced by the typhoon.