Ionospheric observations in Japan andSoutheast Asia (June 2014 - March 2015)
Tatsuhiro Yokoyama, Michi Nishioka, and Hidekatsu Jin
Space Weather and Environment Informatics Laboratory
National Institute of Information and Communications Technology
Contact： iono@nict.go.jp

SunX Ray

EUV

Ionosphere and Radio Propagation
Global Navigation Satellite Systems(GPS/GNSS)

Visible light

Communication /Broadcasting Satellites

Ionosphere
Ionospheric storm
Radio absorption

Es layerF region
E region

Anomalous propagation

Propagation delay

Scintillation

FM/Community radios
HF communication/broadcast

Satellite operation

Positioning/Navigation

Ionospheric Observatories in Japan and Southeast Asia

Middle and Upper
Atmosphere (MU) Radar
Equatorial Atmosphere
Radar (EAR)

Currently available GPS receivers
for the measurement of total electron content (TEC)Long-term variation of foF2 over
Okinawa and Kokubunji at 12LT

2010

2011

2012

2013

2014

http://wdc.nict.go.jp/IONO/index_E.html

2015Long-term variation over Kokubunji at all local time

foF2

ΔfoF2
foEs

2010

2011

2012

2013

2014

2015

Long-term variation of GPS scintillation at Indonesia

2014

Courtesy of T. Ogawa

Recent activity of GPS ROTI in Southeast Asia

2014

2015
Courtesy of S. M Buhari; G2-5 on Friday session

Ionospheric Storm
Positive Storm• F2-region plasma density
enhancement• Caused by disturbed
electromagnetic force/thermospheric wind
• Frequently occurs at the initial
phase of magnetosphericstorms• Positioning/navigation error

Negative Storm• F2-region plasma density
decrease• Mainly caused by compositionchange in the thermosphere([O]/[N2])• Often continues for one toseveral days after positivestorm• HF communication outage

26-30 August 2014

Wakkanai (45.16°N, 141.75°E)
foF2

ΔfoF2foEs

Kokubunji (35.71°N, 139.49°E)
foF2

ΔfoF2
foEs

Yamagawa (31.20°N, 130.62°E)
foF2

ΔfoF2
foEs

Okinawa (26.68°N, 128.15°E)
foF2

ΔfoF2
foEs

TEC over Japan
8/26

8/27

8/28

Positive storm

Time (UT)

LatitudeAbsolute TEC

Differential TEC(5-day quiet period)

8/29

Absolute TEC

Differential TEC
Negative storm

8/30

6-9 January 2015

Wakkanai (45.16°N, 141.75°E)
foF2

ΔfoF2
foEs

Wakkanai (45.16°N, 141.75°E)

Kokubunji (35.71°N, 139.49°E)
foF2

ΔfoF2
foEs

Kokubunji (35.71°N, 139.49°E)

Yamagawa (31.20°N, 130.62°E)
foF2

ΔfoF2
foEs

Yamagawa (31.20°N, 130.62°E)

Okinawa (26.68°N, 128.15°E)
foF2

ΔfoF2
foEs

Okinawa (26.68°N, 128.15°E)

Ionosphere over Thailand on 7 January 2015
Chumphon (10.72°N, 99.37°E)

Frequency

Chiang Mai (18.76°N, 98.93°E)

Virtual Height

No Spread FTime (LT)TEC over Japan
1/6

1/7

LatitudeAbsolute TEC

Differential TEC(5-day quiet period)
Time (UT)
1/8

Absolute TECDifferential TEC

Positive storm at day and night
1/9

High-resolution TEC on 7 January 2015

Absolute TEC

60-min detrended TEC

High-resolution TEC on 7 January 2015

TEC over Japan on 7 January 2015

Absolute TEC

60-min detrended

5-min ROTITEC over Japan on 7 January 2015

Absolute TEC

60-min detrended

5-min ROTITEC over North America on 7 January 2015

Absolute TEC

5-min ROTI

60-min detrended

TEC over North America on 7 January 2015

Absolute TEC

5-min ROTI

60-min detrended

TEC over Europe on 7 January 2015

Absolute TEC

60-min detrended

5-min ROTITEC over Europe on 7 January 2015

Absolute TEC

60-min detrended

5-min ROTIGlobal TEC on 7 January 2015

Absolute TEC

5-min ROTI

60-min detrended

Summary Peculiar ionospheric storm was observed on 7 January2015.
 Strong spread F over northern Japan Unusually strong ROTI enhancement (like equatorialplasma bubbles) Did not reach lower and equatorial latitudes
 TEC enhancement in the nightside (Japan and US),and TEC decrease in the dayside (Europe)
simultaneously (around the same UT)→→→ Any suggestions for this event??
IONOGRAMhttp://wdc.nict.go.jp/IONO/index_E.html
GPS-TEC
http://seg-web.nict.go.jp/GPS/DRAWING-TEC/