Kyushu University Academic Staff Educational and Research Activities Database
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Hiroki Tokinaga Last modified date:2020.07.02

Graduate School

 Reseacher Profiling Tool Kyushu University Pure
Academic Degree
Ph.D (Environmental Earth Science)
Country of degree conferring institution (Overseas)
Field of Specialization
Climate Dynamics
ORCID(Open Researcher and Contributor ID)
Total Priod of education and research career in the foreign country
Outline Activities
My research interests include climate variability and change, with a particular focus on basin-scale ocean-atmosphere interactions over the tropical oceans. We aim to clarify physical mechanisms for and improve future predictions of climate phenomena by synthesizing ocean and atmospheric observations and climate model experiments.
Research Interests
  • Tropical Basin Interaction
    keyword : climate variability, ocean-atmosphere interaction, atmospheric teleconnection, climate change
  • Reconstruction of global marine surface wind dataset from ship observations
    keyword : Marine surface wind, ship observations, climate change
  • Influence of persistent El Niño/Southern Oscillation events on the Atlantic Niño
    keyword : El Niño/Southern Oscillation, Atlantic Niño, atmospheric teleconnection
  • Arctic warming and interdecadal oscillation over the Pacific and Atlantic
    keyword : Arctic amplification, Interdecadal Pacific Oscillation, Atlantic Multidecadal Oscillation
  • Mechanisms for climate change pattern formation over tropical oceans
    keyword : Climate change, ocean-atmosphere interaction, climate models
  • Ocean-atmosphere interaction near the mid-latitude sea surface temperature fronts
    keyword : Satellite and ship observations, radiosonde, surface heat flux, atmospheric boundary layer, high-resolution ocean-atmosphere coupled models
Academic Activities
1. Hiroki Tokinaga, Shang-Ping Xie, Fumiaki Kobashi, Youichi Tanimoto, Local and remote influences of the Kuroshio Extension on the atmosphere, U. S. CLIVAR Variations, 2009.12.
1. Hiroki Tokinaga, Ingo Richter, Yu Kosaka, ENSO influence on the Atlantic Niño, revisited: Multi-year versus single-year ENSO events, Journal of Climate, 10.1175/JCLI-D-18-0683.1, 32, 14, 4585-4600, 2019.06, The influence of El Niño-Southern Oscillation (ENSO) on the Atlantic Niño over the past 113 years is investigated by comparing multi-year and single-year ENSO events. Multi-year ENSO events sustain an anomalous zonal gradient of sea surface temperature (SST) in the equatorial western to central Pacific even during boreal spring and summer. This SST gradient is coupled with an anomalous Walker circulation and atmospheric deep convection through the Bjerknes feedback. During multi-year La Niñas, for example, a strengthened Pacific Walker circulation extends into the tropical Atlantic in boreal spring, a season when both the Pacific and Atlantic intertropical convergence zones become more symmetric about the equator. As a result, surface westerly wind anomalies appear over the equatorial Atlantic, triggering an Atlantic Niño. By contrast, such a teleconnection is not found in the spring following the peak of single-year ENSO events. A Pacific pacemaker model experiment reproduces the observed atmospheric response and its impact on the Atlantic Niño, further supporting the importance of prolonged ENSO forcing. The contrasting influence of multi-year and single-year events explains the fragile relationship between ENSO and the Atlantic Niño. An empirical orthogonal function (EOF) analysis shows that the leading EOF mode (EOF-1) for the spring tropical western to central Pacific SST anomalies captures the characteristics of multi-year ENSO events. EOF-1 is highly correlated with the summer Atlantic Niño over the past 113 years while the Niño-3 SST is not. These correlations indicate that ocean-atmosphere coupling in the equatorial western to central Pacific plays a major role in shaping ENSO teleconnections in boreal spring..
Works, Software and Database
1. Hiroki Tokinaga, Shang-Ping Xie, Hitoshi Mukougawa, Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability, 9th International Workshop on Tropical-subtropical Weather, Climate and Oceans, 2017.11.
2. Hiroki Tokinaga, Patterns and influence of tropical ocean warming: Observations and simulations, 2nd JSPS Core-to-core International Workshop, 2016.08.
3. Hiroki Tokinaga, Shang-Ping Xie, Axel Timmermann, Shayne McGregor, Tomomichi Ogata, Hisayuki Kubota, Yuko M. Okumura, Regional patterns of tropical Indo-Pacific climate change: Evidence of the Walker Circulation weakening, AGU Fall Meeting, 2012.12.
4. Hiroki Tokinaga, Shang-Ping Xie, Clara Deser, Yu Kosaka, Axel Timmermann, Shayne McGregor, Tomomichi Ogata, Hisayuki Kubota, Yuko M. Okumura, Observed and simulated patterns of tropical Indo-Pacific climate change over the past six decades: Evidence of the Walker circulation slowdown, The 3rd International Conference on Earth System Modeling, 2012.09.
5. Hiroki Tokinaga, Shang-Ping Xie, A long, consistent surface wind dataset for climate change analysis: Application over the tropical Indo-Pacific, WCRP Open Science Conference, 2011.10.
6. Hiroki Tokinaga, Shang-Ping Xie, Shoshiro Minobe, Atmospheric effects of the Gulf Stream and Kuroshio Extension, AGU Fall Meeting, 2008.12.
Membership in Academic Society
  • The Oceanographic Society of Japan
  • Japan Geoscience Union
  • The Meteorological Society of Japan
  • American Meteorological Society
  • American Geophysical Union
Educational Activities
Descriptive Marine Physics/Environmental Metrology/Earth System Science and Technology/Interdisciplinary Graduate School of Engineering Sciences