InterPlanetary ScintillationIPS

induced Pluripotent Stem celliPS

What is the InterPlanetary Scintillation (IPS)?

Why is the IPS a useful and powerful tool for space weather forecast?

Interplanetary Scintillation

V & Ne△

1964

Discovery of interplanetary scintillation

Antony Hewish

1min

81.5 MHz 36000 m2

• Large aperture (high gain) antenna• Short-time constant receiver

5 years later after IPS discovery

IPS observations were begun in Japan.

STEL Radiotelescope Array dedicated for IPS Observations

Kiso Sugadaira

Fuji

Toyokawa

Data• Solar Wind

Speed• Scintillation level

(g-value)

Frequency 327MHz Aperture Size = ~ 2000 　 or ~ 3400㎡

STEL IPS Antennas as Viewed in Google Earth

Fuji IPS Telescope (FIT) Kiso IPS Telescope (KIT)

Toyokawa Observatory

SWIFT

Solar Wind Imaging Facility at Toyokawa

327 MHz EW40m×NS106m

a

z

Fresnel filter

k

zqdzqF

2sin

22

E Radio source

wei

ght

/2 2az

Radio source size

2

exp222 zq

dzqF

Eza /w

eigh

tRadio source

z

a

Solar wind electron distribution

2)(zNdzqF

★

2 RN

E

E

Sun

wei

ght

Radio source

Line

of s

ight

less weighted by Fresnel filter and lower SW density

less weighted by radio source size effect and lower SW density

22222

2

2exp

2sin N

zq

k

zqdzqF

Highest SW density

Fresnel filter　ｚ o=2πa2/λ

Radio source　 a/zo>θ

zo=1 AU =1.5×108 kmλ=1 m

⇒ a=150 km θ<0.2 arcsec

after Coles (1978)

IPS vs. in situ

cross-correlation functions

2 2

2 2

( ) ,

( ) 2

( ) ( ) ( ) 2 ( )( )x y x y

x y f Q x y

Q x y ax by cxy

Q x y t a x V t b y V t c x V t y V t

Heliocentric Distance (Rs)

Scin

tilla

tion

inde

x

It can observe the near Sun region.

It has wide spatial coverage of 3D space.

Interplanetary Scintillation

It can observe high latitude regions.

It can observe vast space in a short time.

Complementary observations to spacecraft

Major issues on solar wind

Complementary to spacecraft measurements

Ulysses

First and only one Solar polar orbiter

bimodal

Velocitygradient

NS asymmetry

V

B

Plasma density distribution,

IPS diffraction pattern

cross-correlation functions

2 2

2 2

( ) ,

( ) 2

( ) ( ) ( ) 2 ( )( )x y x y

x y f Q x y

Q x y ax by cxy

Q x y t a x V t b y V t c x V t y V t

VLA