!<-- Ieda -->

Yukiko Imada, Dr., Associate Professor

The University of Tokyo

  • Division of Climate System Research, Atmosphere and Ocean Research Institute
  • Atmospheric and Oceanic Science Group, Department of Earth and Planetary Science

Research Fields

images/various_predictions.jpg Nature fluctuates on various time scales, but so-called extreme weather events, such as heat waves, torrential rains, and droughts, which greatly affect the lives of citizens, appear irregularly over a period of a few days to two weeks. Behind such extreme weather events, there are large-scale flow fluctuations caused by the chaotic nature of the atmosphere itself, such as the meandering jet stream, but the effects of longer-term climate change cannot be ignored on the frequency and intensity of extreme weather events. In particular, the El Nino-Southern Oscillation (ENSO), an interannual climate variability that prevails in the equatorial Pacific Ocean, affects the occurrence of extreme weather events worldwide through changes in large-scale atmospheric circulation. Around Japan, ENSO is known to be a background factor for extreme weather events by modulating the Pacific subtropical high-pressure system and sea surface temperatures in the South China Sea. Therefore, to understand and predict extreme events, it is important to accurately predict the occurrence of ENSO in addition to the variability of the atmosphere itself. Understanding the dynamical processes of ENSO and exploring its predictability remain important issues in climate science. In recent years, heat waves, torrential rains, droughts, and associated wildfires have increasingly been occurring simultaneously in many parts of the world, and it has been suspected that natural variability on annual to decadal time scale and global warming on the scale of a century are behind this phenomenon.

We uses atmospheric models and coupled atmosphere-ocean models to study the mechanisms of climate change on scales ranging from annual to several decades. We also focus on climate change predictability research using climate model-based climate prediction systems. There are various types of forecasts, ranging from daily weather forecasts, seasonal forecasts, decadal-scale forecasts, and even global warming forecasts, and the way initial and boundary conditions are created differ according to the characteristics of each. By using these different types of models, we aim to identify the mechanisms of the phenomena that are the key to forecasting. It is hoped that these findings will lead to improved forecasting systems in the future.

We are also engaged in research focused on extreme phenomena. Utilizing large ensemble experiments (repeatedly running a large number of model simulations on a target to capture extreme events), we are challenging ourselves to study the relationship between the probability of extreme events and climate varaiblity, as well as their predictability on annual to decadal time scale.

Career

2023/04-Present   Associate Professor, Division of Climate System Research, Atmosphere and Ocean Research Institute, The University of Tokyo, Japan.
2020/04-2023/03   Visiting Associate Professor, Division of Climate System Research, Atmosphere and Ocean Research Institute, The University of Tokyo, Japan.
2019/04-2023/03   Senior Researcher, department of Climate and Geochemistry Research, Meteorological Research Institute, Japan Meteorological Agency, Japan.
2017/04-2019/03   Senior Researcher, Climate Research Division, Meteorological Research Institute, Japan Meteorological Agency, Japan.
2014/04-2017/03   Researcher, Climate Research Division, Meteorological Research Institute, Japan Meteorological Agency, Japan.
2013/01-2014/03   Project Research Associate, Division of Climate System Research, Atmosphere and Ocean Research Institute, The University of Tokyo, Japan.
2011/04-2012/12   Project Researcher, Department of Mechanical and Environmental Informatics, Tokyo Institute of Technology, Japan.
2010/04-2011/03   Project Researcher, Division of Climate System Research, Atmosphere and Ocean Research Institute, The University of Tokyo, Japan.



Publications

  • Imada, Y. and H. Kawase, 2021: Potential seasonal predictability of the risk of local rainfall extremes estimated using high-resolution large ensemble simulations. Geophys. Res. Lett., 48, e2021GL096236. [link]
  • Imada, Y., H. Kawase, M. Watanabe, M. Arai, and I. Takayabu, 2020:　Advanced event attribution for the regional heavy rainfall events. npj Climate and Atmospheric Science, 3, 35. [link]
  • Imada, Y., H. Kawase, M. Watanabe, H. Shiogama, and M. Arai, 2019: The July 2018 high temperature event in Japan could not have happened without human-induced global warming. SOLA, 15A, 8-12. [link]
  • Imada, Y., H. Shiogama, C. Takahashi, M. Watanabe, M. Mori, Y. Kamae, S. Maeda, 2018: Climate change increased the likelihood of the 2016 heat extremes in Asia. Bull. Amer. Meteor. Soc., 99, S97-S100. [link]
  • Imada, Y., S. Maeda, M. Watanabe, H. Shiogama, R. Mizuta, M. Ishii, M. Kimoto, 2017: Recent enhanced seasonal temperature contrast in Japan from large ensemble high-resolution climate simulations. Atmosphere, 8, 57. [link]
  • Imada, Y., H. Tatebe, M. Watanabe, M. Ishii, M. Kimoto, 2016: South Pacific influence on the termination of El Nino in 2014. Scientific Reports, 6, 30341. [link]
  • Imada, Y., H. Tatebe, M. Ishii, Y. Chikamoto, M. Mori, M. Arai, M. Watanabe, M. Kimoto, 2015: Predictability of Two Types of El Nino Assessed Using an Extended Seasonal Prediction System by MIROC. Monthly Weather Review, 143, 4597-4617. [link]
  • Imada, Y., S. Kanae, M. Kimoto, M. Watanabe, M. Ishii, 2015: Predictability of Persistent Thailand Rainfall during the Mature Monsoon Season in 2015 Using Statistical Downscaling of CGCM Seasonal Prediction. Monthly Weather Review, 143, 1166-1178. [link]
  • Imada, Y., H. Shiogama, M. Watanabe, M. Mori, M. Kimoto, M. Ishii, 2014: The Contribution of anthropogenic forcing to the Japanese heat waves of 2013. Bull. Amer. Meteor. Soc., 95, S52-S54.[link]
  • Imada, Y., H. Shiogama, M. Watanabe, M. Mori, M. Kimoto, M. Ishii, 2013: Contribution of atmospheric circulation change to the 2012 heavy rainfall in southern Japan. Bull. Amer. Meteor. Soc., 94, S52.[link]
  • Imada, Y., H. Tatebe, Y. Komuro, M. Kimoto, 2013: Multi-Decadal Modulation of Tropical Pacific Instability Wave Activity since the Middle of the Twentieth Century. SOLA, 9, 102-105.[link]
  • Imada, Y., S. Kanae, M. Watanabe, M. Ishii, and M. Kimoto, 2013: Seasonal predictability of Thailand heavy rainfall in 2011. Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 69, I_391-I_396.[link]
  • Imada, Y., M. Kimoto, 2012: Parameterization of tropical instability waves and examination of their impact on ENSO characteristics. Journal of Climate, 25, 4568-4581.[link]
  • Imada. Y., M. Kimoto, X. Chen, 2012: Impact of atmospheric mean state on tropical instability wave activity. Journal of Climate, 25, 2341-2355.[link]
  • Imada, Y., M. Kimoto, and S. Kanae, 2012: Seasonal prediction by statistical downscaling using singular value decomposition analysis - Predictability of autumn precipitation over Indochina -. Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 68, I_1369-I_1374.[link]
  • Imada, Y. and M. Watanabe, 2011: ENSO metric, Tenki, 58, 87-89 (Japanese only).[link]
  • Imada, Y., M. Kimoto, 2009: ENSO amplitude modulation related to Pacific decadal variability. Geophysical Research Letters, 36, L03706.[link]
  • Imada, Y., M. Kimoto, 2006: Improvement of thermocline structure that affect ENSO perfor-mance in a coupled GCM. SOLA, 2, pp164-167.[link]

    • Others (click to expand)
  • Kawase, H., S. Watanabe and Y. Imada, 2022: Impacts of historical atmospheric and oceanic warming on heavy snowfall in December 2020 in Japan. Journal of Geophysical Research - Atmospheres, 127, e2022JD036996, https://doi.org/10.1029/2022JD036996.
  • Ito, R., H. Kawase, and Y. Imada, 2022: Regional differences in summertime extremely high temperature in Japan due to global warming. Journal of Applied Meteorology and Climatology, 61, 1573–1587, https://doi.org/10.1175/JAMC-D-22-0062.1.
  • Kawase, H., S. Watanabe, Y. Hirockawa, and Y. Imada, 2022: Timely Event Attribution Strategy in Japan: An Example of Heavy Rainfall in July 2020. Bulletin of the American Meteorological Society, 103, S118–S123, https://doi.org/10.1175/BAMS-D-21-0192.1.
  • Hermanson, L., et al.: WMO Global Annual to Decadal Climate Update: A prediction for 2021-2025. Bulletin of the American Meteorological Society, 103, E1117–E1129, https://doi.org/10.1175/BAMS-D-20-0311.1.
  • Kamae, Y., Y. Imada, H. Kawase, and W. Mei, 2021: Atmospheric Rivers Bring More Frequent and Intense Extreme Rainfall over East Asia under Global Warming. Geophys. Res. Lett., e2021GL096030, https://doi.org/10.1029/2021GL096030.
  • Takahashi, C., Y. Imada, and M. Watanabe, 2021: Influence of the MJO on Wintertime Extreme Snowfall and Precipitation in Japan. J. Meteorol. Soc. Japan, https://doi.org/10.2151/jmsj.2022-014.
  • Hirabayashi, Y., H. Alifu, D. Yamazaki, Y. Imada, H. Shiogama, and Y. Kimura, 2021: Anthropogenic climate change has changed frequency of past flood during 2010-2013. Progress in Earth and Planetary Science 8 (1), 1-9.
  • Kawase, H., M. Yamaguchi, Y. Imada, S. Hayashi, A. Murata, T. Nakaegawa, T. Miyasaka, and I. Takayabu, 2021: Enhancement of extremely heavy precipitation induced by Typhoon Hagibis (2019) due to historical warming. SOLA, 17A-002.
  • Hasegawa, A., Y. Imada, H. Shiogama, M. Mori, H. Tatebe, and M. Watanabe, 2020: Impact of air–sea coupling on the probability of occurrence of heat waves in Japan. Progress in Earth and Planetary Science 7 (1), 1-12.
  • Kataoka, T., H. Tatebe, H. Koyama, T. Mochizuki, K. Ogochi, H. Naoe, Y. Imada, H. Shiogama, M. Kimoto, and M. Watanabe, 2020: Seasonal to decadal predictions with MIROC6: description and basic evaluation. Journal of Advances in Modeling Earth Systems 12 (12), e2019MS002035.
  • Miyasaka, T., H. Kawase, T. Nakaegawa, Y. Imada, I. Takayabu, 2020: Future projections of heavy precipitation in Kanto and associated weather patterns using large ensemble high-resolution simulations. SOLA, 16, 125-131, https://doi.org/10.2151/sola.2020-022.
  • Shiogama, H., R. Ito, Y. Imada, T. Nakaegawa, N. Hirota, N. N. Ishizaki, K. Takahashi, I. Takayabu, S. Emori, 2020: Selecting future climate projections of surface solar radiation in Japan. SOLA, 16, 75-79, https://doi.org/10.2151/sola.2020-013.
  • Shiogama, H., T. Hasegawa, S. Fujimori, D. Murakami, K. Takahashi, K. Tanaka, S. Emori, I. Kubota, M. Abe, Y. Imada, M. Watanabe, D. Mitchell, N. Schaller, J. Sillmann, E. Fischer, J. Scinocca, I. Bethke, L. Lierhammer, J. Takakura, T. Trautmann, P. Doell, S. Ostberg, H. Müller Schmied, F. Saeed, C.-F. Schleussner, 2019: Limiting global warming to 1.5C will lower increases in inequalities of four hazard indicators of climate change. Env. Res. Lett., 14, 124022.
  • Kawase, H., Y. Imada, H. Tsuguti, T. Nakaegawa, N. Seino, A. Murata, and I. Takayabu, 2020: The Heavy Rain Event of July 2018 in Japan enhanced by historical warming. Bull. Amer. Meteor. Soc., 101, 109-114, DOI:10.1175/BAMS-D-19-0173.1.
  • Kawase, H., Y. Imada, H. Sasaki, T. Nakaegawa, A. Murata, M. Nosaka, and I. Takayabu, 2019: Contribution of historical global warming to local‐scale heavy precipitation in western Japan estimated by large ensemble high‐resolution simulations. J. Geophys. Res., 124, 6093-6103.
  • Takahashi, C., M. Arai, M. Watanabe, H. Shiogama, Y. Imada, Y. Kosaka, M. Mori, and Y. Kamae, 2019: The effects of natural variability and climate change on the record low sunshine over Japan during August 2017. Bull. Amer. Meteor. Soc., 100, S67–S71.
  • Tsuguti, H., N. Seino H. Kawase Y. Imada, T. Nakaegawa, I. Takayabu, 2018: Meteorological overview and mesoscale characteristics of the Heavy Rain Event of July 2018 in Japan. Landslides, https://doi.org/10.1007/s10346-018-1098-6.
  • Scaife, A. A., L. Ferranti, O. Alves, P. Athanasiadis, J. Baehr, M. Dequé, T. Dippe, N. Dunstone, D. Fereday, R. G. Gudgel, R. J. Greatbatch, L. Hermanson, Y. Imada, S. Jain, A. Kumar, C. MacLachlan, W. Merryfield, W. A. Müller, H.-L. Ren, D. Smith, Y. Takaya, G. Vecchi, X. Yang, 2018: Tropical rainfall predictions from multiple seasonal forecast systems. Int. J. Climatology, 39, 974-988.
  • Iizumi, T., H. Shiogama, Y. Imada, N. Hanasaki, H. Takikawa, M. Nishimori, 2018: Crop production losses associated with anthropogenic climate change for 1981–2010 compared with preindustrial levels. International J. Climatology, 38, 5405-5417.
  • Saito, N., S. Maeda, T. Nakaegawa, Y. Takaya, Y. Imada and C. Matsukawa, 2017: Seasonal predictability of the North Atlantic Oscillation and zonal mean fields associated with stratospheric influence in JMA/MRI-CPS2. SOLA, 13, 209-213.
  • Adrian, M. T., M. Inés, O. Zárate, R. I. Saurral, C. Vera, C. Saulo, W. J. Merryfield, M. Sigmond, W.-S. Lee, J. Baehr, A. Braun, A. Butler, M. Déqué, F. J. Doblas-Reyes, M. Gordon, A. A. Scaife, Y. Imada, M. Ishii, T. Ose, B. Kirtman, A. Kumar, W. A. Müller, A. Pirani, T. Stockdale, M. Rixen, T. Yasuda, 2017: The climate-system historical forecast project: providing open access to seasonal forecast ensembles from centers around the globe. Bull. Amer. Meteor. Soc., 98, 2293–2301, DOI:10.1175/BAMS-D-16-0209.1.
  • Mizuta, R., A. Murata, M. Ishii, H. Shiogama, K. Hibino, N. Mori, O. Arakawa, Y. Imada, K. Yoshida, T. Aoyagi, H. Kawase, M. Mori, Y. Okada, T. Shimura, T. Nagatomo, M. Ikeda, H. Endo, M. Nosaka, M. Arai, C. Takahashi, K. Tanaka, T. Takemi, Y. Tachikawa, K. Temur, Y. Kamae, M. Watanabe, H. Sasaki, A. Kitoh, I. Takayabu, E. Nakakita, M. Kimoto, 2017: Over 5000 years of ensemble future climate simulations by 60 km global and 20 km regional atmospheric models. Bull. Amer. Meteor. Soc., 98, 1383-1398.
  • Sugi, M., Y. Imada, T. Nakaegawa, K. Kamiguchi, 2017: Estimating probability of extreme rainfall over Japan using Extended Regional Frequency Analysis. Hydrological Research Letters, 11, 19-23.
  • Takahashi, C., M. Watanabe, H. Shiogama, Y. Imada, M. Mori, 2016: A persistent Japanese heat wave in early August 2015: roles of natural variability and human-induced warming. Bull. Amer. Meteor. Soc., 97, S107-S112.
  • Kamae, Y., H. Shiogama, Y. Imada, M. Mori, O. Arakawa, R. Mizuta, K. Yoshida, C. Takahashi, M. Arai, M. Ishii, M. Watanabe, M. Kimoto, S.-P. Xie, H. Ueda, 2017: Forced response and internal variability of summer climate over western North America. Clim. Dyn., 49, 403-417.
  • Shiogama, H., Y. Imada, M. Mori, R. Mizuta, D. Stone, K. Yoshida, O. Arakawa, M. Ikeda, C. Takahashi, M. Arai, M. Ishii, M. Watanabe, M. Kimoto, 2016: Attributing Historical Changes in Probabilities of Record-Breaking Daily Temperature and Precipitation Extreme Events. SOLA, 12, 225-231.
  • Butler, A. H., O. Alves, A. Arribas, M. Athanassiadou, J. Baehr, N. Calvo, A. Charlton-Perez, M. Déqué, D. I. V. Domeisen, Y. Imada, M. Ishii, M. Iza, A. Karpechko, A. Kumar, C. MacLachlan, B. Merryfield, W. A. Müller, A. O’Neill, A. A. Scaife, J. Scinocca, M. Sigmond, T. N. Stockdale, T. Yasuda, 2016: The Climate-system Historical Forecast Project: do stratosphere-resolving models make better seasonal climate predictions in boreal winter? Q. J. R. Meteorol. Soc., 142, 1413-1427, doi:10.1002/qj.2743.
  • Kimura, Y., M. Tanoue, Y. Imada, and Y. Hirabayashi, 2016: An event attribution of the 2012 Amazon flood. Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research), 72, I_1-I_6.
  • Kimura, Y., M. Tanoue, Y. Imada, and Y. Hirabayashi, 2016: An event attribution of the 2012 Amazon flood. Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research), 72, I_1-I_6.
  • Jaranilla-Sanchez, P. A., T. Koike, L. Wang, T. Ohta, Y. Imada, M. Kimoto, 2014: Extreme events prediction from seasonal climate forecasting and crop production simulations in Pampanga river basin, Philippines. Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 70, I_139-I_144I13.
  • Shiogama, H., M. Watanabe, Y. Imada, M. Mori, Y. Kamae, M. Ishii, M. Kimoto, 2014: Attributioin of the June-July 2013 Heat Wave in the Southwestern United States.
  • Hamaguchi, K., Y. Imada, H. Shiogama, S. Kanae, 2014: Attribution analysis for heavy rainfall in Pakistan in 2010 using event attribution experiments, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 70.
  • Mori, M., M. Kimoto, M. Ishii, S. Yokoi, T. Mochizuki, Y. Chikamoto, M. Watanabe, T. Nozawa, H. Tatebe, T. Sakamoto, Y. Komuro, Y. Imada, H. Koyama, 2013: Hindcast Prediction and Near-Future Projection of Tropical Cyclone Activity over the Western North Pacific Using CMIP5 Near-Term Experiments with MIROC, J. Meteor. Soc. Ja-pan, 91, 431-352.
  • Shiogama, H., M. Watanabe, Y. Imada, M. Mori, M. Ishii, M. Kimoto, 2013: An event attribution of the 2010 drought in the sourthern Amazon region using the MIROC5 model. Atmos. Sci. Lett., 14, 170-175.
  • Watanabe, M., H. Shiogama, Y. Imada, M. Mori, M. Ishii, M. Kimoto, 2013: Event attribution of the August 2010 Russian heat wave, SOLA, 9, 64-67.
  • Tatebe, H., Y. Imada, M. Mori, M. Kimoto, H. Hasumi, 2013: Control of Decadal and Bidecadal Climate Variability in the Tropical Pacific by the Off-Equatorial South Pacific Ocean, J. Climate, 26, 6524–6534.
  • Chikamoto Y., M. Kimoto, M. Ishii, T. Mochizuki, T. T. Sakamoto, H. Tatebe, Y. Komuro, M. Watanabe, T. Nozawa, H. Shiogama, M. Mori, S. Yasunaka, Y. Imada, 2013: An overview of decadal climate predictability in a multi-model ensemble by climate model MIROC, Clim. Dyn., 40, 1201-1222.
  • Hamaguchi, K., Y. Imada, H. Shiogama, S. Kanae, 2013: Event attribution for the Pakistan heavy rainfall in 2010. Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 69, I_337-I_342.
  • Sato, T., K. Kusuhara, Y. Imada, N. Utsumi, S. Kanae, 2013: Projection of extreme precipitation induced by typhoons -Applicatioin to the flood-control plan in the Kagami river of Kochi- Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 69, I_379-I_384.
  • Chikamoto, Y., M. Kimoto, M. Ishii, M. Watanabe, T. Nozawa, T. Mochizuki, H. Tatebe, T. T. Sakamoto, Y. Komuro, H. Shiogama,M. Mori, S. Yasunaka, Y. Imada, H. Koyama, M. Nozu, F.-F. Jin, 2012: Predictability of a stepwise shift in Pacific climate during the late 1990s in hindcast experiments using MIROC. J. Meteor. Soc. Japan, 90A, 1-21.
  • Sakamoto T. T., Y. Komuro, T. Nishimura, M. Ishii, H. Tatebe, H. Shiogama, A. Hasegawa, T. Toyoda, M. Mori, T. Suzuki, Y. Imada, T. Nozawa, K. Takata, T. Mochizuki, K. Ogochi, S. Emori, H. Hasumi, M. Kimoto, 2012: MIROC4h - A New High-Resolution Atmosphere-Ocean Coupled General Circulation Model, J. Meteor. Soc. Japan, 90, 325-359.
  • Kusuhara, K., Y. Imada, Y. Iseri, M. Mori, S. Kanae, 2012: Risk Assessment of near-future typhoon using a stochastic typhoon model. Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 68, I_1393-I_1398.
  • Sato, T., Y. Imada, S. Kanae, 2012: The change in frequency of extreme daily precipitation events associated with tropical cyclones in Asia-Pacific. Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 68, I_1393-I_1398.
  • Watanabe, M., M. Chikira, Y. Imada, M. Kimoto, 2011: Convective control of ENSO simulated in MIROC. J. Climate, 24, 543-562.
  • Toyoda, T., T. Awaji, N. Sugiura, S. Masuda, H. Igarashi, Y. Sasaki, Y. Hiyoshi, Y. Ishikawa, T. Mochizuki, T. T. Sakamoto, H. Tatebe, Y. Komuro, T. Suzuki, T. Nishimura, M. Mori, Y. Chikamoto, S. Yasunaka, Y. Imada, M. Arai, M. Watanabe, H. Shiogama, T. Nozawa, A. Hasegawa, M. Ishii, M. Kimoto, 2011: Impact of the assimilation of sea ice concentration data on an atmos-phere-ocean-sea ice coupled simulation of the Arctic Ocean climate. SOLA, 7, 37-40.


Editor

  • (2022/07- ): Journal of the Meteorological Society of Japan (JMSJ), Editor


Commitee Member

  • (2023/01- ): WCRP Decadal Climate Prediction Panel (DCPP), Member
  • (2022/01- ): WCRP Light House Activity (LHA) - Explaining and Predicting Earth System Change (EPESC), Member
  • (2018/01-2022/12): WCRP/CLIVAR Pacific Regional Panel, Member




Contact

Yukiko Imada (Associate Professor)

Division of Climate System Research, Atmosphere and Ocean Research Institute (AORI), The University of Tokyo
5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8568, Japan

yimada(at)aori.u-tokyo.ac.jp

Go to the laboratory site