Mass-produced heavenly bodies/environment

Takeshi Horinouchi

Exploring the mysteries of weather and climate

Takeshi Horinouchi , Associate Professor

Graduate School of Environmental Earth Science, Graduate School of Environmental Science (School of Science, Earth and Planetary Sciences)

High school : Nirayama High School (Shizuoka Prefecture)

Academic background : Kyoto University, Graduate School, Faculty of Science

Research areas
Meteorology and climatology
Research keywords
Weather, climate, geophysical fluid dynamics

What kind of research are you carrying out?

I am researching the mechanisms of weather and climate. One example that can be considered is rainfall. Most people would be able to recollect times when rain fell continuously for several days, or did not fall for one or two weeks in a row, or a cycle of rainy weather and clear days alternating over a few days. Some of these people may have had the simple question as to why such things happen. However, observing only the symptoms of a disease, for example, does not mean that the causes are understood. Weather and climate are no different. The mechanisms behind them need to be understood. Our laboratory explores these subjects. The atmosphere changes over both small and large time scales, so we cover everything from daily weather to climate.


Please tell me about the specific topics of your research.

To give you a related example, we are now focusing on studying the mechanisms causing the formation and variability of the large scale rainfall zones seen in recent years in the summer in the middle latitudes in Asia and elsewhere. Investigations applying newly-developed diagnostic methods have shown clearly and concretely that waves in the upper troposphere called Rossby waves are closely interconnected with the flow of moisture and with causes of rainfall in the lower layers. I am excited to be continuing research in this area. We are also performing research to learn how one- to two-month fluctuations in the tropics cause weather changes in the middle latitudes. At a more fundamental level, we are doing research to revise theories about the formation of the large-scale circulation called Hadley cells that carry air and energy from the tropics to the middle latitudes. We are also working with researchers outside the University on the stratosphere and links between the troposphere and stratosphere. My research career started with investigating the mechanisms of influences from the troposphere in order to study the stratosphere. We are also hoping to move forward with joint studies with people outside the University on the Antarctic atmosphere. Recently, one of the students in my laboratory has even “left” Earth to study the atmosphere of Venus. Research on atmospheres far from Earth can also help us learn about the properties of our terrestrial atmosphere.


You are all over the place? So how do you perform your research?

Image of a global mesh used for a simulation
(A 3D mesh would be more detailed.)

Our research is mainly the investigation of large-scale phenomena in the atmosphere (on a global scale, starting with a horizontal scale of about 1,000 km). So we often use satellite data that covers the entire globe or worldwide meteorological data created through a consistent incorporation of various kinds of observational data, a process called objective analysis. But this alone is not enough, so we are aided by computer simulations. We can cover a broad range from the perspective of geophysical fluid dynamics.
When people think of science, they imagine that it is founded on experiments. History includes many epoch-making researches to mention that are based on well-thought out, brilliant experiments. But when it comes to Earth, experimentation is limited. For example, it is said that the existence of the Tibetan Plateau has a large impact on the process of our rainy season, but it is impossible to lower the elevation of the Tibetan Plateau to verify this. It can, however, be undertaken by simulations. Humans never stop asking "Why?" or "What?". In the field of atmospheric research, the deeper the understanding we seek, the more indispensable simulations become as a way to complement our theories. In performing simulations, we can vary conditions to study their impact, or simplify our settings step by step so that we can in the end closely examine the essential factors that remain (it is necessary to also study the suitability of the simulations, of course…). A thorough understanding, backed up by research like this, is indispensable in tackling issues such as the increasingly urgent one of global warming. Predicting the near future climate is very complex and dependent on large-scale simulations. This is some times criticized, but remember that scientists apply a wide variety of methods to perform simulations and conduct a large number of “numerical experiments” Predictions summarized in reports by the IPCC are built on massive accumulations of such efforts.
Observation data and simulation data are both analyzed using computers, so we are also working to develop a programing infrastructure.


Professor, how would you sum up your goal simply?

To provide the world with a deeper and clearer understanding of weather and climate. In this way, we aim to help society deal with environmental problems by, for example, making weather/climate predictions more reliable (or making it clearer what aspects of predictions are unreliable).


What should I do in order to study with you, Professor?

I regret that our organization is not easy to understand. The graduate school department I belong to is the Graduate School of Environmental Science, but we provide departmental education in the Earth and Planetary Sciences Department of the Faculty of Science. So please take this course. It is too early to discuss this with high school students, but the Graduate School of Environmental Science at Hokkaido University offers courses called Atmosphere-Ocean Physics and Climate Dynamics, with about twenty professors providing integrated research guidance and teaching. This is the largest faculty in this field of any university in Japan. Many of them also take part in teaching Earth and Planetary Sciences. Each professor conducts internationally top-class research on the atmosphere and the ocean from a wide variety of perspectives and methods. We respect the diversity of students, and the department regularly accepts people who have studied other fields (such students actually play major roles), so if you remember this interview once you have been at university for a while (or if you are a current student reading it), then please drop in to see me if you are interested.