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Toshihiko Takemura Last modified date:2024.04.07

Graduate School

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Academic Degree
Doctor of Science
Country of degree conferring institution (Overseas)
Field of Specialization
Meteorology, Atmospheric Environment
Total Priod of education and research career in the foreign country
Outline Activities
Development of three-dimensional global aerosol transport model SPRINTARS, and anaysis of climate response to the aerosol-radiation interaction and aerosol-cloud interaction. Estimation of the radiative forcing for anthropogenic aerosols, and projection of cliamte change cooperating with the University of Tokyo, National Institute for Environmental Studies, and JAMSTEC. Operation of a weekly aerosol forecasting system every day. Highly Cited Researcher.
Research Interests
  • Estimation of aerosol effects on climate
    keyword : aerosol, atmospheric radiation, radiative forcing, general circulation model, cloud-aerosol interaction, climate change projection
    1997.04Development of three-dimensional global aerosol transport model, and anaysis of climate response to the aerosol direct and indirect effects. Estimation of the radiative forcing for anthropogenic aerosols, and prediction of cliamte change cooperating with the University of Tokyo and the National Institute for Environmental Studies..
Academic Activities
1. Yuki Kusakabe, Toshihiko Takemura, Formation of the North Atlantic Warming Hole by reducing anthropogenic sulphate aerosols, Scientific Reports, 10.1038/s41598-022-27315-3, 13, 1, 2023.01.
2. Toshihiko Takemura, Return to different climate states by reducing sulphate aerosols under future CO2 concentrations, Scientific Reports, 10.1038/s41598-020-78805-1, 10, 1, 2020.12, AbstractIt is generally believed that anthropogenic aerosols cool the atmosphere; therefore, they offset the global warming resulting from greenhouse gases to some extent. Reduction in sulphate, a primary anthropogenic aerosol, is necessary for mitigating air pollution, which causes atmospheric warming. Here, the changes in the surface air temperature under various anthropogenic emission amounts of sulphur dioxide (SO2), which is a precursor of sulphate aerosol, are simulated under both present and doubled carbon dioxide (CO2) concentrations with a climate model. No previous studies have conducted explicit experiments to estimate the temperature changes due to individual short-lived climate forcers (SLCFs) in different climate states with atmosphere–ocean coupled models. The simulation results clearly show that reducing SO2 emissions at high CO2 concentrations will significantly enhance atmospheric warming in comparison with that under the present CO2 concentration. In the high latitudes of the Northern Hemisphere, the temperature change that will occur when fuel SO2 emissions reach zero under a doubled CO2 concentration will be approximately 1.0 °C, while this value will be approximately 0.5 °C under the present state. This considerable difference can affect the discussion of the 1.5 °C/2 °C target in the Paris Agreement..
3. Toshihiko Takemura, Kentaroh Suzuki, Weak global warming mitigation by reducing black carbon emissions, Scientific Reports, 10.1038/s41598-019-41181-6, 9, 1, 4419, 2019.12, [URL], © 2019, The Author(s). Reducing black carbon (BC), i.e. soot, in the atmosphere is a potential mitigation measure for climate change before revealing the effect of reducing anthropogenic carbon dioxide (CO 2 ) because BC with shorter lifetime than CO 2 absorbs solar and infrared radiation. BC has a strong positive radiative forcing in the atmosphere, as indicated in many previous studies. Here, we show that the decline in surface air temperatures with reduced BC emissions is weaker than would be expected from the magnitude of its instantaneous radiative forcing at the top of the atmosphere (TOA). Climate simulations show that the global mean change in surface air temperature per unit of instantaneous radiative forcing of BC at the TOA is about one-eighth that of sulphate aerosols, which cool the climate through scattering solar radiation, without absorption. This is attributed to the positive radiation budget of BC being largely compensated for by rapid atmospheric adjustment, whereas the radiative imbalance due to sulphate aerosols drives a slow response of climate over a long timescale. Regional climate responses to short-lived species are shown to exhibit even more complex characteristics due to their heterogeneous spatial distributions, requiring further analysis in future studies..
4. Toshihiko Takemura, Distributions and climate effects of atmospheric aerosols from the preindustrial era to 2100 along Representative Concentration Pathways (RCPs) simulated using the global aerosol model SPRINTARS, Atmospheric Chemistry and Physics, 10.5194/acp-12-11555-2012, 12, 23, 11555-11572, 2012.12, [URL], Global distributions and associated climate effects of atmospheric aerosols were simulated using a global aerosol climate model, SPRINTARS, from 1850 to the present day and projected forward to 2100. Aerosol emission inventories used by the Coupled Model Intercomparison Project Phase 5 (CMIP5) were applied to this study. Scenarios based on the Representative Concentration Pathways (RCPs) were used for the future projection. Aerosol loading in the atmosphere has already peaked and is now reducing in Europe and North America. However, in Asia where rapid economic growth is ongoing, aerosol loading is estimated to reach a maximum in the first half of this century. Atmospheric aerosols originating from the burning of biomass have maintained high loadings throughout the 21st century in Africa, according to the RCPs. Evolution of the adjusted forcing by direct and indirect aerosol effects over time generally correspond to the aerosol loading. The probable future pathways of global mean forcing differ based on the aerosol direct effect for different RCPs. Because aerosol forcing will be close to the preindustrial level by the end of the 21st century for all RCPs despite the continuous increases in greenhouse gases, global warming will be accelerated with reduced aerosol negative forcing..
5. Toshihiko Takemura, Hisashi Nakamura, Teruyuki Nakajima, Tracing airborne particles after Japan's nuclear plant explosion, Eos, 10.1029/2011EO450002, 92, 45, 397-398, 2011.11, [URL], The powerful Tohoku earthquake and consequent tsunami that occurred off the east coast of Japan on 11 March 2011 devastated dozens of coastal cities and towns, causing the loss of more than 15,000 lives and leaving close to 4000 people still missing. Although nuclear reactors at the Fukushima Daiichi Nuclear Power Plant, located on the Pacific coast, stopped their operation automatically upon the occurrence of the Mw 9.0 quake [Showstack, 2011], the cooling system for nuclear fuel broke down. From 12 to 16 March, vapor and hydrogen blasts destroyed the buildings that had contained the reactors, resulting in the release into the atmosphere of radioactive materials such as sulfur-35, iodine-131, cesium-134, and cesium-137, which collectively can cause harmful health effects such as tissue damage and increased risk of cancer (particularly in children), depending on dose. Most of those materials emitted from the power plant rained out onto the grounds within its vicinity and forced tens of thousands within a 20-kilometer radius to evacuate (residents to the northwest of the site within about 40 kilometers also were moved from their homes). Some of the radioactive materials were transported and then detected at such distant locations as North America and Europe, although the level of radiation dose was sufficiently low not to affect human health in any significant manner..
6. Toshihiko Takemura, Tomoe Uchida, Global Climate Modeling of Regional Changes in Cloud, Precipitation, and Radiation Budget Due to the Aerosol Semi-Direct Effect of Black Carbon, SOLA, 10.2151/sola.2011-046, 7, 181-184, 2011.11, [URL], The aerosol semi-direct effect is generally explained as follows: aerosols, such as black carbon (BC) and mineral dust, absorb solar radiation, which warms and stabilizes the atmosphere, resulting in reduced cloudiness and cloud formation. However, the present study suggests that BC can intensify atmospheric instability and thus increase cloud water and precipitation if the BC is concentrated near the surface. Simulations using a global aerosol climate model, based on a general circulation model, show decreased cloud water over biomass-burning regions where BC is emitted to the free troposphere through the boundary layer. In contrast, increased cloud water is indicated over East and South Asia where BC from urban and industrial activities is concentrated near the surface. While the global mean change in the radiation budget at the top of the atmosphere due to the semi-direct effect of BC is estimated to be as small as +0.06 W m(-2), regional changes in cloud water, precipitation, and shortwave radiation are suggested to be large enough to modify meteorological conditions in urban and biomass-burning regions..
7. Toshihiko Takemura, Hisashi Nakamura, Masayuki Takigawa, Hiroaki Kondo, Takehiko Satomura, Takafumi Miyasaka, Teruyuki Nakajima, A Numerical Simulation of Global Transport of Atmospheric Particles Emitted from the Fukushima Daiichi Nuclear Power Plant, SOLA, 10.2151/sola.2011-026, 7, 101-104, 2011.07, [URL], The powerful tsunami generated by the massive earthquake that occurred east of Japan on March 11, 2011 caused serious damages of the Fukushima Daiichi Nuclear Power Plant on its cooling facilities for nuclear reactors. Hydrogen and vapor blasts that occurred until March 15 outside of the reactors led to the emission of radioactive materials into the air. Here we show a numerical simulation for the long-range transport from the plant to the U. S. and even Europe with a global aerosol transport model SPRINTARS. Large-scale updraft organized by a low-pressure system traveling across Japan from March 14 to 15 was found effective in lifting the particles from the surface layer to the level of a westerly jet stream that could carry the particles across the Pacific within 3 to 4 days. Their simulated concentration rapidly decreases to the order of 10(-8) of its initial level, consistent with the level detected in California on March 18. The simulation also reproduces the subsequent trans-Atlantic transport of those particles by a poleward-deflected jet stream, first toward Iceland and then southward to continental Europe as actually observed..
8. Toshihiko Takemura, Mio Egashira, Kanako Matsuzawa, H. Ichijo, Ryota O'ishi, Ayako Abe-Ouchi, A simulation of the global distribution and radiative forcing of soil dust aerosols at the Last Glacial Maximum, Atmospheric Chemistry and Physics, 10.5194/acp-9-3061-2009, 9, 9, 3061-3073, 2009.05, [URL], In this study an integrated simulation of the global distribution and the radiative forcing of soil dust aerosols at the Last Glacial Maximum (LGM) is performed with an aerosol climate model, SPRINTARS. It is compared with another simulation for the present climate condition. The global total emission flux of soil dust aerosols at the LGM is simulated to be about 2.4 times as large as that in the present climate, and the simulated deposition flux is in general agreement with estimations from ice core and marine sediment samplings though it appears to be underestimated over the Antarctic. The calculated direct radiative forcings of soil dust aerosols at the LGM is close to zero at the tropopause and -0.4 W m(-2) at the surface. These radiative forcings are about twice as large as those in the present climate. SPRINTARS also includes the microphysical parameterizations of the cloud-aerosol interaction both for liquid water and ice crystals, which affect the radiation budget. The positive radiative forcing from the indirect effect of soil dust aerosols is mainly caused by their properties to act as ice nuclei. This effect is simulated to be smaller (-0.9 W m(-2)) at the LGM than in the present. It is suggested that atmospheric dust might contribute to the cold climate during the glacial periods both through the direct and indirect effects, relative to the interglacial periods..
9. Toshihiko Takemura, Yoram J. Kaufman, Lorraine A. Remer, Teruyuki Nakajima, Two competing pathways of aerosol effects on cloud and precipitation formation, Geophysical Research Letters, 10.1029/2006GL028349, 34, 4, L04802-L04802, L04802, 2007.02, [URL], Aerosols may influence cloud formation through two pathways: One is the effect on cloud microphysics by forming smaller and more numerous cloud droplets reducing precipitation and consequently enhancing cloud lifetime. The second is referred to as the aerosol dynamic-hydrological effect in which the aerosol direct, semi-direct, and indirect effects can modulate atmospheric radiation, which perturbs atmospheric circulation, leading to redistributions of clouds and precipitation. Here this study examines climate sensitivities using a general circulation model coupled with an aerosol transport-radiation model. The model is run first with prescribed meteorology in order to isolate the cloud microphysical effect. It is run in a separate experiment with internally generated meteorology that includes dynamic-hydrological effect as the aerosols modify clouds and interact with the radiation. We find in some regions that the dynamic-hydrological effect in the free model runs counteracts the microphysical effects seen in the prescribed runs..
10. Toshihiko Takemura, Yoko Tsushima, Tokuta Yokohata, Toru Nozawa, Tatsuya Nagashima, Teruyuki Nakajima, Time evolutions of various radiative forcings for the past 150 years estimated by a general circulation model, Geophysical Research Letters, 10.1029/2006GL026666, 33, 19, L19705-L19705-5, L19705, 2006.10, [URL], Time series of the instantaneous radiative forcings for main anthropogenic and natural forcing agents from the year 1850 to 2000 are evaluated at the Earth's surface as well as at the tropopause with an atmospheric general circulation model. This evaluation corresponds to a simulation of 20th century climate with a synthetic coupled atmosphere-ocean general circulation model. The evaluation indicates that the positive radiative forcing at the tropopause rapidly increases from 1910 to 1950 and after 1970 principally due to long-lived greenhouse gases, while the negative radiative forcing at the surface sharply increases between 1955 and 1965 mainly due to the aerosol direct and indirect effects. This study suggests that a simultaneous analysis of changing rates of the radiative forcing both at the tropopause and surface can explain tendencies of changes in the surface air temperature..
11. Toshihiko Takemura, Toru Nozawa, Seita Emori, Takashi Y. Nakajima, Teruyuki Nakajima, Simulation of climate response to aerosol direct and indirect effects with aerosol transport-radiation model, Journal of Geophysical Research Atmospheres, 10.1029/2004JD005029, 110, D2, D02202, 2005.01, [URL], [ 1] With a global aerosol transport-radiation model coupled to a general circulation model, changes in the meteorological parameters of clouds, precipitation, and temperature caused by the direct and indirect effects of aerosols are simulated, and its radiative forcing are calculated. A microphysical parameterization diagnosing the cloud droplet number concentration based on the Kohler theory is introduced into the model, which depends not only on the aerosol particle number concentration but also on the updraft velocity, size distributions, and chemical properties of each aerosol species and saturation condition of the water vapor. The simulated cloud droplet effective radius, cloud radiative forcing, and precipitation rate, which relate to the aerosol indirect effect, are in reasonable agreement with satellite observations. The model results indicate that a decrease in the cloud droplet effective radius by anthropogenic aerosols occurs globally, while changes in the cloud water and precipitation are strongly affected by a variation of the dynamical hydrological cycle with a temperature change by the aerosol direct and first indirect effects rather than the second indirect effect itself. However, the cloud water can increase and the precipitation can simultaneously decrease in regions where a large amount of anthropogenic aerosols and cloud water exist, which is a strong signal of the second indirect effect. The global mean radiative forcings of the direct and indirect effects at the tropopause by anthropogenic aerosols are calculated to be -0.1 and -0.9 W m(-2), respectively. It is suggested that aerosol particles approximately reduce 40% of the increase in the surface air temperature by anthropogenic greenhouse gases on the global mean..
12. Toshihiko Takemura, Teruyuki Nakajima, Akiko Higurashi, Sachio Ohta, Nobuo Sugimoto, Aerosol distributions and radiative forcing over the Asian Pacific region simulated by Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS), Journal of Geophysical Research Atmospheres, 10.1029/2002JD003210, 108, D23, 8659, 8659, 2003.08, [URL], A three-dimensional aerosol transport-radiation model coupled with a general circulation model, Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS), simulates atmospheric aerosol distributions and optical properties. The simulated results are compared with aerosol sampling and optical observations from ground, aircraft, and satellite acquired by intensive observation campaigns over east Asia in spring 2001. Temporal variations of the aerosol concentrations, optical thickness, and Angstrom exponent are in good agreement between the simulation and observations. The midrange values of the Angstrom exponent, even at the Asian dust storm events over the outflow regions, suggest that the contribution of the anthropogenic aerosol, such as carbonaceous and sulfate, to the total optical thickness is of an order comparable to that of the Asian dust. The radiative forcing by the aerosol direct and indirect effects is also calculated. The negative direct radiative forcing is simulated to be over -10 W m(-2) at the tropopause in the air mass during the large-scale dust storm, to which both anthropogenic aerosols and Asian dust contribute almost equivalently. The direct radiative forcing, however, largely depends on the cloud water content and the vertical profiles of aerosol and cloud. The simulation shows that not only sulfate and sea salt aerosols but also black carbon and soil dust aerosols, which absorb solar and thermal radiation, make strong negative radiative forcing by the direct effect at the surface, which may exceed the positive forcing by anthropogenic greenhouse gases over the east Asian region..
13. T Takemura, Uno, I, T Nakajima, A Higurashi, Sano, I, Modeling study of long-range transport of Asian dust and anthropogenic aerosols from East Asia, Geophysical Research Letters, 10.1029/2002GL016251, 29, 24, 2158, 2002.12, [URL], [1] A three-dimensional aerosol transport-radiation model, SPRINTARS, successfully simulates the long-range transport of the large-scale Asian dust storms from East Asia to North America which crossed the North Pacific Ocean during the springtime of 2001 and 2002. It is found from the calculated dust optical thickness that 10 to 20% of the Asian dust around Japan reached North America. The simulation also reveals the importance of the contribution of anthropogenic aerosols, which are carbonaceous and sulfate aerosols emitted from the industrialized areas in East Asia, to air turbidity during the dust storms. The contribution of the anthropogenic aerosol to the total optical thickness is simulated to be of a comparable order to that of the Asian dust, which is consistent with the observed values of the particle size index from the satellite and ground-based sun/sky photometry..
14. Toshihiko Takemura, Teruyuki Nakajima, Oleg Dubovik, Brent N. Holben, Stefan Kinne, Single-scattering albedo and radiative forcing of various aerosol species with a global three-dimensional model, Journal of Climate, 10.1175/1520-0442(2002)0152.0.CO;2, 15, 4, 333-352, 2002.02, [URL], Global distributions of the aerosol optical thickness, Angstromngstrom exponent, and single-scattering albedo are simulated using an aerosol transport model coupled with an atmospheric general circulation model. All the main tropospheric aerosols are treated, that is, carbonaceous (organic and black carbons), sulfate, soil dust, and sea salt aerosols. The simulated total aerosol optical thickness, Angstromngstrom exponent, and single-scattering albedo for mixtures of four aerosol species are compared with observed values from both optical ground-based measurements and satellite remote sensing retrievals at dozens of locations including seasonal variations. The mean difference between the simulation and observations is found to be less than 30% for the optical thickness and less than 0.05 for the single-scattering albedo in most regions. The simulated single-scattering albedo over the Saharan region is, however, substantially smaller than the observation, though the standard optical constant of soil dust is used in this study. The radiative forcing by the direct effect of the main tropospheric aerosols is then estimated. The global annual mean values of the total direct radiative forcing of anthropogenic carbonaceous plus sulfate aerosols are calculated to be -0.19 and -0.75 W m(-2) under whole-sky and clear-sky conditions at the tropopause, respectively..
15. Toshihiko Takemura, Teruyuki Nakajima, Toru Nozawa, Kazuma Aoki, Simulation of future aerosol distribution, radiative forcing, and long-range transport in East Asia, Journal of the Meteorological Society of Japan, 10.2151/jmsj.79.1139, 79, 6, 1139-1155, 2001.12, [URL], Distributions of aerosol concentrations, optical properties, and wet deposition fluxes are simulated for the next fifty years using an aerosol transport model coupled with an atmospheric general circulation model. Treated species are sulfur dioxide, and all the main tropospheric aerosols, i.e., carbonaceous (black and organic carbons), sulfate, soil dust, and sea salt. We especially pay attention to distributions of anthropogenic carbonaceous aerosols, sulfate aerosols, and sulfur dioxide. The simulation uses the Special Report on Emissions Scenarios (SRES) of the Intergovernmental Panel on Climate Change (IPCC) as the future emission scenarios of anthropogenic pollutants. Simulated results suggest that carbonaceous aerosols continue to increase over industrial and densely populated regions for the next five decades, whereas sulfate aerosols decrease around Europe and North America. The aerosol single scattering albedo in the future is, therefore, calculated to become small gradually in the mid- and high-latitudes of the Northern Hemisphere. Sulfate aerosols and sulfur wet deposition fluxes are, on the other hand, simulated to increase only over East Asia. Black carbon and sulfate aerosols around Japan in 2050 are simulated to be two or three times as large as those in 2000 with one of the SIZES scenarios. Hence this suggests that pollutants originating from the East Asian continent can seriously affect the atmospheric quality in Japan in the next several decades..
16. Toshihiko Takemura, Hajime Okamoto, Yoshihiro Maruyama, Atusi Numaguti, Akiko Higurashi, Teruyuki Nakajima, Global three-dimensional simulation of aerosol optical thickness distribution of various origins, Journal of Geophysical Research Atmospheres, 10.1029/2000JD900265, 105, 14, 17853-17873, 2000.07, [URL], A global three-dimensional model that can treat transportation of various species of aerosols in the atmosphere is developed using a framework of an atmospheric general circulation model (AGCM). Main aerosols in the troposphere, i.e., soil dust, carbonaceous (organic and black carbon), sulfate, and sea-salt aerosols, are introduced into this model. Prior to the model calculations the meteorological parameters are calculated by the AGCM with the nudging technique using reanalysis data. To evaluate aerosol effects on the climate system and to compare simulated results with observations, the optical thickness and Angstrom exponent are also calculated taking into account the size distribution and composition. The model results are validated by both measured surface aerosol concentrations and retrieved aerosol optical parameters from National Oceanic and Atmospheric Administration/Advanced Very High Resolution Radiometer. A general agreement is found between the simulated result and the observation globally and seasonally. One of the significant results is that the simulated relative contribution of anthropogenic carbonaceous aerosols to the total optical thickness is comparable to that of sulfate aerosols at midlatitudes of the Northern Hemisphere, which agrees with recent observations. This result leads to a conclusion that the radiative effect evaluation of aerosols on the climate system is necessary to be modified because optical properties of carbonaceous aerosols are different from those of sulfate aerosols. The other finding is that the seasonal shift off the west coast of North Africa observed by satellites, i.e., the latitude of the maximum optical thickness moves seasonally, is also reproduced in consideration of a mixed state of soil dust and carbonaceous aerosols. Copyright 2000 by the American Geophysical Union..
Works, Software and Database
2. .
Membership in Academic Society
  • American Geophysical Union
  • European Geosciences Union
  • Meteorological Society of Japan
  • Japan Association of Aerosol Science and Technology
  • Japan Geoscience Union
  • World's most influential 1000 top climate scientists.
  • Awards for Science and Technology (Research Category) of the Commendation for Science and Technology
  • Highly Cited Researchers 2020
  • Highly Cited Researchers 2019
  • JSPS Prize
  • Japan Academy Medal
  • Highly Cited Researchers 2018
  • Highly Cited Researchers 2017
  • Highly Cited Researchers 2016
  • Highly Cited Researchers 2015
  • Nishida Prize for Promotion of Geoscience
  • Highly Cited Researchers 2014
  • Society Award, Meteorological Society of Japan
  • Asian Young Aerosol Scientist Award
  • Young Scientist Award, Japan Association of Aerosol Science and Technology
  • Young Scientists' Prize of the Commendation for Science and Technology
  • Young Scientist Award, International Radiation Commission
  • Yamamoto-Syono Award for Outstanding Papers, Meteorological Society of Japan
Educational Activities
Climate Change Science Section, Major of Earth System Science and Technology, Interdisciplinary Graduate School of Engineering Sciences.
Professional and Outreach Activities
See each item of "Social Contribution and International Cooperation"..