著者

Kosuke Ito Hiroyuki Yamada Munehiko Yamaguchi Tetsuo Nakazawa Norio Nagahama Kensaku Shimizu Tadayasu Ohigashi Taro Shinoda Kazuhisa Tsuboki

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.14, pp.105-110, 2018 (Released:2018-07-28)

参考文献数

30

被引用文献数

1 23

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The inner core of Tropical Cyclone Lan was observed on 21-22 October 2017 by GPS dropsondes during the first aircraft missions of the Tropical Cyclones-Pacific Asian Research Campaign for the Improvement of Intensity Estimations/Forecasts (T-PARCII). To evaluate the impact of dropsondes on forecast skill, 12 36-h forecasts were conducted using a Japan Meteorological Agency non-hydrostatic model (JMA-NHM) with a JMA-NHM-based mesoscale four-dimensional data assimilation (DA) system. Track forecast skill improved over all forecast times with the assimilation of the dropsonde data. The improvement rate was 8-16% for 27-36-h forecasts. Minimum sea level pressure (Pmin) forecasts were generally degenerated (improved) for relatively short-term (long-term) forecasts by adding the dropsonde data, and maximum wind speed (Vmax) forecasts were degenerated. Some of the changes in the track and Vmax forecasts were statistically significant at the 95% confidence level. It is notable that the dropsonde-derived estimate of Pmin was closer to the real-time analysis by the Regional Specialized Meteorological Center (RSMC) Tokyo than the RSMC Tokyo best track analysis. The degeneration in intensity forecast skill due to uncertainties in the best track data is discussed.

著者

Udai Shimada Munehiko Yamaguchi Shuuji Nishimura

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.1-5, 2020 (Released:2020-01-28)

参考文献数

42

被引用文献数

6 8

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Japan Meteorological Agency (JMA) best track data indicate that the number of rapid intensification (RI) tropical cyclone events in the western North Pacific increased from 1987 to 2018. To clarify whether this increase is due to climatological changes or qualitative changes in the data, the long-term trend of RI events in JMA operational Dvorak data, which have been used as the first guess for best track analysis, was investigated. Because the JMA Dvorak analysis procedure has remained almost unchanged since 1987, the temporal homogeneity of the Dvorak data is expected to be much better than that of the best track data. The results showed no discernable trend in Dvorak-based RI events over the 32 years. Although the frequency distribution of 24-h intensity changes changed slightly in the Dvorak analysis, that of the best track data changed significantly; as a result, the frequency of best track-based RI events increased after 2006. JMA started using microwave satellite imagery for best track analysis in 2006. This change likely affected the temporal homogeneity of the best track data. These results suggest that the increase in best track-based RI events was due mainly to qualitative changes related to advances in observational techniques.

著者

Munehiko Yamaguchi Hiromi Owada Udai Shimada Masahiro Sawada Takeshi Iriguchi Kate D. Musgrave Mark DeMaria

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.14, pp.138-143, 2018 (Released:2018-10-06)

参考文献数

22

被引用文献数

1 15

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This study investigates prediction of TC intensity in the western North Pacific basin using a statistical-dynamical model called the Statistical Hurricane Intensity Prediction Scheme (SHIPS), with data sources in operations at the Japan Meteorological Agency (JMA) such as the JMA/Global Spectral Model forecast fields. In addition to predicting the change in the maximum wind (Vmax) as in the original SHIPS technique, another version of SHIPS for predicting the change in the minimum sea-level pressure (Pmin) has been developed. With 13 years of training samples, a total of 26 predictors were selected from among 52 through stepwise regression. Based on three years of independent samples, the root mean square errors of both Vmax and Pmin by the 26-predictor SHIPS model were found to be much smaller than those of the JMA/GSM and a simple climatology and persistence intensity model, which JMA official intensity forecasts are currently mainly based on. The prediction accuracy was not sensitive to the number of predictors as long as the leading predictors were included. Benefits of operationalizing SHIPS include a reduction in the errors of the JMA official intensity forecasts and an extension of their forecast length beyond the current 3 days (e.g., 5 days).

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

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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

Junya Fukuda Munehiko Yamaguchi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.250-256, 2019 (Released:2019-12-26)

参考文献数

19

被引用文献数

2

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The effectiveness of multiple ensembles to determine 70% probability-circle radii of operational tropical cyclone (TC) track forecasts in the Japan Meteorological Agency (JMA) is investigated. The ensembles used in this study are global ensembles from JMA, the European Centre for Medium-Range Weather Forecasts (ECMWF), the National Centers for Environmental Prediction (NCEP) and the Met Office in the United Kingdom (UKMO). The verification for all TCs from 2016 to 2018 reveals that the multiple ensemble-based method has stronger correlation with operational TC track forecast errors and the clearer degree of separation among confidence levels derived from the ensemble spreads than the conventional statistical and single ensemble-based methods. It indicates that the multiple ensemble method provides situation-dependent forecast uncertainty most appropriately. As the effectiveness of the multiple ensemble method has been confirmed, JMA started to operate the multiple ensemble-based 70% probability-circle radii for its operational TC track forecasts for all forecast times up to 120 hours in June 2019. The radii are based solely on confidence levels derived from cumulative ensemble spreads of the multiple ensemble from the 4 centers. This is a good example of successful research to operation transfer of The International Grand Global Ensemble (TIGGE) project.

著者

Udai Shimada Munehiko Yamaguchi Shuuji Nishimura

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2020-001, (Released:2019-12-17)

被引用文献数

8

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Japan Meteorological Agency (JMA) best track data indicate that the number of rapid intensification (RI) tropical cyclone events in the western North Pacific increased from 1987 to 2018. To clarify whether this increase is due to climatological changes or qualitative changes in the data, the long-term trend of RI events in JMA operational Dvorak data, which have been used as the first guess for best track analysis, was investigated. Because the JMA Dvorak analysis procedure has remained almost unchanged since 1987, the temporal homogeneity of the Dvorak data is expected to be much better than that of the best track data. The results showed no discernable trend in Dvorak-based RI events over the 32 years. Although the frequency distribution of 24-h intensity changes changed slightly in the Dvorak analysis, that of the best track data changed significantly; as a result, the frequency of best track-based RI events increased after 2006. JMA started using microwave satellite imagery for best track analysis in 2006. This change likely affected the temporal homogeneity of the best track data. These results suggest that the increase in best track-based RI events was due mainly to qualitative changes related to advances in observational techniques.

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

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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.