Atmospheric and Environmental Science [AM Lab]
Yutaka MATSUMI, Akira MIZUNO (Professor)
Tomoo NAGAHAMA (Associate Professor)
Tomoki NAKAYAMA (Lecturer)
We are studying the global atmospheric environment, which is closely related to our life. Our goal is to understand the mechanism of global and local environmental changes, including ozone depletion and global warming, in order to help to solve environmental problems. To this end, we are conducting research on the following topics. Based on the latest technologies for radio waves (millimeter/submillimeter waves) and lasers, we are developing new, highly sensitive instruments to measure trace constituents and aerosol particles in the atmosphere. Using these instruments, we are examining changes and reaction processes of substances related to ozone depletion and global warming. In addition, we are using laser light to reproduce atmospheric reactions in the laboratory to study photochemical reaction processes as well as employing ground-based instruments to observe atmospheres on planets other than Earth.
Space Science - Experiment [SSE Lab]
Masafumi HIRAHARA (Professor)
Satonori NOZAWA, Yuichi OTSUKA (Associate Professor)
Shin-ichiro OYAMA (Lecturer)
The plasma and energy carried to the Earth and the other planets by the solar wind exert physical effects on the magnetosphere and ionosphere, which are called "Geospace" including the upper atmosphere (above 70 km altitude) in the case of the Earth. We are investigating these effects and associated phenomena, primarily through observational approaches. In addition, we strive to understand elementary processes of physical phenomena occurring in the Geospace and various planetary space environment. Topics of interest currently include the interaction and the energy transfer mechanisms among the solar wind and the terrestrial/planetary atmospheres and intrinsic magnetic fields especially in their boundaries in the near-planetary space, the polar regions, and the mid-low latitudes. Through international cooperation, we are using equipment, including EISCAT radars, MF radars, meteor radars, high-sensitivity cameras, and magnetometers, installed in the north polar region to observe the Geospace. The in-situ measurements based on the instruments onboard satellites/spacecraft, which are innovated/developed in our laboratory, are also powerful methods to elucidate the space dynamics. The remotely sensed data could also be combined with the data in space directly obtained by rockets and satellites/spacecraft to study dynamical phenomena in the Gospace such as auroras, magnetic (space) storms, ionospheric currents, and atmospheric waves (planetary, tidal and gravity waves). With respect to the mid-low latitude, we are using HF radars, high-sensitivity cameras, GPS multipoint observation networks, VHF radars, and magnetometers to remotely sense the ionosphere and upper atmosphere in the mid-low latitude and equatorial region. These data are then used to study the interactions between the space plasma and the Earth's atmosphere at the space-atmosphere interface as well as couplings between the high-latitude and mid-latitude regions, including auroras observed even in Japan and atmospheric waves from the polar regions.
Solar and Space Physics - Theory [SST Lab]
Kanya KUSANO (Professor)
Satoshi MASUDA (Associate Professor)
Akimasa IEDA (Assistant Professor)
Through integrated data analysis, we are studying the transport of energy and particles from the Sun to the Earth. Our research is primarily based on analysis of data obtained from satellites and ground-based observations, and computer-based numerical simulation/modeling. Specifically, we are focusing on the dynamics in solar and space plasmas (such as solar cycle, solar flares, coronal mass ejections, magnetic storms, and auroras), which result from nonlinear processes in multiple-layer and multiple-scale interactions in space. Recently, disturbances in space may cause failures in our infrastructures, including power-grids, communication systems, and satellites. This has been recognized as a serious problem in our economy and community, and the importance of "space weather" research to elucidate and predict events in the Sun and the "geo-space", that is space near the Earth, has increased. In our group, we are investigating space weather as well as "space climate", which is long-term influence of the solar activity upon the environment of the Earth.
Cosmic Ray Physics [CR Lab]
Yoshitaka ITOW, Hiroyasu TAJIMA (Professor)
Yutaka MATSUBARA, Fumio ABE, Kimiaki MASUDA, Fusa MIYAKE (Associate Professor)
Takashi SAKO (Lecturer)
Akira OKUMURA (Assistant Professor)
Cosmic Rays -- high-energy particles from space -- bring us new knowledge of nature; new species of elementary particles including dark matters, high-energy phenomena of the universe and signatures of past solar activities are notable examples. Through cosmic-ray observations we pursue a variety of interdisciplinary research topics between particle physics and astrophysics as follows:
a) The LHCf and RHICf experiment: a study of hadron interactions of ultra high-energy cosmic rays by using zero degree electro-magnetic calorimeters at the CERN Large Hadron Collider (LHC) and BNL Relativistic Heavy Ion Collider (RHIC).
b) Underground experiments in the Kamioka mine: neutrino observations at Super-Kamiokande and dark matter searches at the XMASS experiment.
c) The fully-active solar-neutron telescope SciCRT: A massive scintillator hodoscope at the top of a mountain in Mexico for measurement of solar flare neutron bursts and cosmic-ray modulation.
d) Measurement of radiocarbon (14C) contained in tree rings to probe solar activities in past and burst events. Also a tabletop experiment for cloud formation by cosmic rays.
e) The MOA experiment: Gravitational microlensing to search for exoplanets and MACHOs by using a dedicated 1.8 m optical telescope at New Zealand.
f) Gamma-ray observations: Investigation of origin and propagation of cosmic rays and search for dark matters with the Fermi gamma-ray satellite. Development of new gamma-ray instruments such as Cherenkov Telescope Array.
Heliospheric Plasma Physics [SW Lab]
Munetoshi TOKUMARU (Professor)
Kazumasa IWAI (Associate Professor)
Ken’ichi FUJIKI (Assistant Professor)
The Sun continuously emits a supersonic plasma flow called the solar wind, and all planets of the solar system are engulfed by this stream. A huge space called the heliosphere is created by the solar wind in the interstellar gas. The solar wind ceaselessly changes on a various time scales, and imposes some significant influences on the space environment and the upper atmosphere condition around the Earth. Strong interaction between the solar wind and the interstellar gas takes place in the boundary region of the heliosphere. Many fundamental properties of the solar wind such as the generation mechanism, 3D structure of the heliosphere, and the cause of variability have never been yet fully understood. Our SW group aims at elucidating these unsettled questions of the solar wind from ground-based observations of interplanetary scintillation (IPS) using large radio-telescopes, which have been developed at our lab. The IPS method we use here is unique in the world, and enables to investigate hidden aspects of the solar wind.