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II.

Activity Report of the National Committee for

Geomagnetism and Aeronomy

Yohsuke KAMIDE Chair of the National Committee for Geomagnetism and Aeronomy

W e report herewith on IAGA-related research activity in Japan over the period of 2004-2007 in terms of three areas: “Solar-Terrestrial Research,” “Earth and Planetary Interior,” and “Meetings, Reorganizations and Research Programs.” The following is a summary of what has been accomplished over the last four years in each of these three areas:

1. Solar-Terrestrial Research

1.1.

Sun and interplanetary space

The Japanese solar observation satellite “Hinode” was successfully launched in September 2006, and

a new solar observation system, “SMART,” was installed at the Hida Observatory.

They are expected to

be the new major data sources in the research of solar flares and coronal mass ejections.

Observations of the solar wind has continued using the interplanetary scintillation (IPS) technique, which is capable of observing the structure and dynamics of the solar wind in three dimensions (3D) with a relatively short time cadence. To make the solar wind observations with higher spatial and temporal resolution using the IPS tomographic method, construction of a large IPS antenna began in 2006. A test of solar wind predictions is being carried out under collaboration between CASS/UCSD and STEL. The 3D structure and propagation of coronal mass ejections (CMEs) have also been studied jointly by a cosmic ray group and a solar wind group.

Construction of a global network of muon detectors in four countries has been completed and high-quality observations of high-energy cosmic ray streaming, showing dramatic variations in response

to

every

CME

approaching

Earth,

has

started.

The

network

is

able

to

sense

cosmic

ray

precursors

for

the CME arrival at Earth.

In collaboration with the Tibet air shower experiment, the sidereal anisotropy

of

the

intensity

of

very

high

energy

cosmic

rays

was

examined,

indicating

that

the

observed

anisotropy

provides useful information on the local interstellar magnetic field surrounding the heliosphere.

The

Nozomi

spacecraft

has

proven

to

be

of

great

use

for

heliospheric

studies.

For

example,

longitudinal variations of interplanetary neutral hydrogen Lyman alpha emission, as well as their relation to the solar photon flux, have been reported. The first attempt to monitor long-term variations in the solar wind mass flux at all heliographic latitudes has been made by combining IPS observations and the

interplanetary

Lyman

alpha

emission

observations

with

the

Nozomi

spacecraft.

It

is

now

realized

that

the real heliospheric interaction is not simple and asymmetric, deflection in the global heliosphere structure are warranted.

suggesting

that

further

studies

of

the

1.2. Magnetosphere The major driver of observational space physics over the last four years has been the data from Cluster-II, which the Japanese community has joined to use. With unprecedented multi-point

measurements, the science community is setting the time series data obtained by each spacecraft.

up a scheme to separate spatial and temporal effects in Together with the results from full particle simulations

that have recently become available, the importance of multi-scale interactions plasmas in the solar-terrestrial system is increasingly recognized. The successful

as basic processes launch of THEMIS

in in

February in space.

2007

will

allow

the

community

to

study

data

obtained

simultaneously

from

more

than

10

points

Considerable advances in the studies of electron acceleration in the radiation belts during storms and substorms have been made by Japanese scientists through computer simulations of wave-particle

7

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