Space weather phenomena in the ionosphere and their effect on GNSS

(Presented by Japan)

IPXX 　 ICAO ISTF/4 New Delhi, India, 5th to 7th February 2014

SUMMARY

This paper presents a short review of major space weather phenomena observed in mid- and low-latitude ionosphere. Their effect on GNSS also mentioned.

Sudden Ionospheric Disturbance (SID)G

OE

SX

-ray

flu

x[W

/m2 ]

UT [hour]

SO

HO

/SE

ME

UV

[co

un

t/s]

GP

ST

EC

[TE

CU

]

TIM

ED

/GU

VI

O,

N2

[R]

[Tsurutani et al., 2005]

10 15

0

35

[Tsugawa et al., 2007]

Sudden Ionospheric Disturbance (SID)

Amplitude +Several　10　TECU

Depending　on　flare　class

Time　scale Increase　in　several　minutes

Enhancement　lasts　for　several　hours

Spatial　structure Global　scale　in　the　sunlit　hemisphere

Depending　on　solar　zenith　angle

Other　characteristics

HF　radio　absorption　(Dellinger　phenomena)

Possibility　of　loss-of-lock　on　GNSS　signals　due　to　solar　radio　burst

Effect　on　GNSS Augmented　GPS　(due　to　TEC　model　correction　error)

Loss-of-lock　on　GPS　signals

JST

Wakkanai

Okinawa

foF

2 [M

Hz]

JST (UT+9h)

Ionospheric Storm

One-month　Average

Negative Storm

Kp

PositiveStorm

Ionospehric Storm

Amplitude ±Several　 10　 TECU　 compared　 to　 quiet　conditions

Time　scale Several　hours　to　several　days

Spatial　structure Small　spatial　TEC　gradient

Other　characteristics

Basically　occurring　during　and/or　after　magnetic　storms

Effect　on　GNSS Augmented　GPS　(due　to　TEC　model　correction　error)

Equatorial Ionization Anomaly20:40 JST, 23 Jan 2002

20:40 JST, 24 Jan 2002

Equatorial Ionization Anomaly

Amplitude ±Several　10　TECU

Time　scale

Spatial　structure Large　latitudinal　TEC　gradient

Other　characteristics

Day-to-day　variation　is　not　negligible(increase,　disappearance,　hemispheric　asymmetry,　etc)

Affected　by　magnetic　storms

Effect　on　GNSS Augmented　GPS　(due　to　TEC　model　correction　error)

Storm enhanced density (SED)

[Foster et al., JGR, 2005]

Short summary of SED

Amplitude +Several　10　to　100TECU

Time　scale Several　hours　(?)

Spatial　structure Steep　horizontal　TEC　gradient

Narrow　in　zonal　direction

Extending　in　NW-SE　direction

Other　characteristics

Often　observed　from　noon　to　sunset　during　the　large　geomagnetic　storm

Sometimes　accompanied　with　ionospheric　irregularity

Effect　on　GNSS Differential　GPS

Augmented　GPS　(due　to　TEC　model　correction　error)

Loss-of-lock　on　GPS　signals

GPS-TEC Observations for Space WeatherAbsolute　TEC ROTI　(~10km　scale　

irregularity)Loss-of-Lock　(~100m　scale　irregularity)

12:20　UT

(21:20　JST)

12:40　UT

(21:40　JST)

13:00　UT

(22:00　JST)

3D　simulation　of　plasma　bubble　[Courtesy　of　Dr.　T.　Yokoyama　(NICT)　]

Short summary of EPB

Amplitude -Several　10　to　-100TECU

Time　scale Several　10　minutes　to　several　hours

Spatial　structure Steep　horizontal　TEC　gradient

Narrow　in　zonal　direction

Extending　along　the　magnetic　field　line

Other　characteristics

Often　observed　mid-　to　low　latitudes　after　the　sunset.　

Almost　always　accompanied　with　ionospheric　irregularity

Effect　on　GNSS Differential　GPS

Augmented　GPS　(due　to　TEC　model　correction　error)

Loss-of-lock　on　GPS　signals

Traveling Ionospheric Disturbances (TID)

[Tsugawa et al., GPS solut., 2007]

[Tsugawa et al., JGR., 2003]

Large

-scale

TID

(LSTID)

Medium

-scale

TID

(MSTID)

Amplitude A　few　TECU

Time　scale MS:　Several　10　minutes

LS:　Several　hours

Spatial　structure MS:　Wavelengths　of　several　100　km　

LS:　Wavelengths　of　1,000　–　3,000　km,　Zonally　extended　wavefront

Other　characteristics

MS:　Southwestward　and　Southeastward　propagations　in　nighttime　and　daytime,　respectively.　

LS:　Related　with　magnetic　storm

Effect　on　GNSS Differential　GPS

Augmented　GPS　(due　to　TEC　model　correction　error)

Traveling Ionospheric Disturbances (TID)

Summary of Ionospheric Space Weather Phenomena

Spatial Scale

Solar Act./Mag. Stormdependence

Lower Atm.dependence

10km 100km 1000km Global

Plasma Bubble

SED

Ion. Strom

SID

MSTID

LSTID

Large

Med.

Small

Sporadic E

Eq. Ion. Anomaly

Amplitude