ICAO APANPIRG, 3rd ISFT

Korean CAT-I GBAS Ionospheric Threat Model

Jiyun Lee

KAIST

Republic of Korea

3rd Ionospheric Studies Task Force Seoul, Republic of Korea

ICAO APANPIRG 16 October 2013

ICAO APANPIRG, 3rd ISFT

Ionospheric Threat Model Development for GBAS Category I Operation in the Korean

Region

• In order to mitigate ionosphere threats occurring in different geographical regions, ionospheric threat models have to be established for the relevant regions.

• To allow the certification of a GBAS ground facility in South Korea, a Korean ionospheric threat model has be determined

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ICAO APANPIRG, 3rd ISFT

Data Used to Construct Korean Ionospheric Threat Model

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YYYY MM/DD Kp (Final) Dst YYYY MM/DD Kp (Final) Dst

2000

04/06 8.3 -287 2002 09/07 7.3 -177

04/07 8.7 -288

2003

10/29 9.0 -350

07/15 9.0 -289 10/30 9.0 -383

07/16 7.7 -301 10/31 8.3 -307

08/12 7.7 -235 11/20 8.7 -422

09/17 8.3 -201 11/21 6.7 -309

2001

03/31 8.7 -387

2004

07/17 6.0 -76

04/01 5.7 -228 11/08 8.7 -374

04/11 8.3 -271 11/09 8.7 -214

04/12 7.3 -236 11/10 8.7 -263

11/06 8.7 -292

11/24 8.3 -221

Korean GNSS Reference Stations # of stations (as of 2004)

National Geographic Information Institute (NGII)

38

DGPS Central Office (DCO) 15

Korea Astronomy and Space Science Institute (KASI)

10

Total 63

125 126 127 128 129 130 131 132

33

34

35

36

37

38

Longitude

Lati

tud

e

KASI

NGII

DCO

10 dates previously chosen to construct the current CONUS threat model

12 additional dates were selected based on Kp and Dst

ICAO APANPIRG, 3rd ISFT

Korean CAT-I GBAS Ionospheric Threat Model

4

0 10 20 30 40 50 60 70 80 900

50

100

150

200

250

300

350

400

450

Elevation [deg]

Slo

pe

[m

m/k

m]

Flat 375

mm/km

Linear bound [mm/km]

y=375+50(el-15)/50

Flat 425 mm/km

UT DD/MM/YY

03/31/01

04/01/01

11/06/01

11/24/01

09/07/02

10/29/03

10/31/03

11/20/03

11/10/04160mm/km

• A total of 288 threat points were validated.

• By adding a margin of about 15% to the largest gradient, the upper bound on Korea ionospheric treat model is 160 mm/km (no elevation denpendency) and is well under the bound of the current LAAS CONUS threat model.

ICAO APANPIRG, 3rd ISFT

Case Study 1: The Most Extreme Ionospheric Gradient on Nov. 10, 2004

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Pair PRN Time

(HH:MM:SS) Slope

(mm/km) Elev. (deg.)

Dist. (km)

YOSU-HADG

31 14:18:00 138.5 22.6 44.95

12 12.5 13 13.5 14 14.50

5

10

Sla

nt

Dela

y (

m)

YOSU

HADG

12 12.5 13 13.5 14 14.5-100

0

100

Ion

o S

lop

e (

mm

/km

)

12 12.5 13 13.5 14 14.50

20

40

60

80

Ele

vati

on

(d

eg

)

b)

a)

c)

Dual-frequency, YOSU - HADG PRN31

Time (hour of 11/06/2004)

12 12.5 13 13.5 14 14.5-100

-50

0

50

100

150

Time (hour of 11/06/2004)

Ion

o G

rad

ien

t (m

m/k

m)

YOSU and HADG, Gradients Comparison; PRN31

DF (L1/L2) Gradient

L1-only Gradient

ICAO APANPIRG, 3rd ISFT

Station-Wide Validation and Localized Disturbances on Nov. 10, 2004

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13 13.5 14 14.50

5

10

15

Sla

nt

Dela

y (

m)

YOSU

HADG

JINJ

SORI

13 13.5 14 14.5-100

-50

0

50

100

150

Ion

o G

rad

ien

t (m

m/k

m)

YOSU-HADG

YOSU-JINJ

SORI-JINJ

SORI-YOSU

Time (hour of 11/10/2004)

• The ionospheric event observed in South Korea on November 10, 2004 was caused by localized disturbances, rather than the enhanced TEC around the geomagnetic equator.

<IPP tracks and regional vertical ionospheric delay map>

ICAO APANPIRG, 3rd ISFT

Case Study 2: The Second Largest Ionospheric Gradient on Nov. 6, 2001

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0 1 2 3 40

20

40

60

80

Sla

nt

Dela

y (

m)

Dual-frequency. NAMW/ SONC PRN 21

NAMW

SONC

0 1 2 3 4-50

0

50

100

Ion

o S

lop

e (

mm

/km

)

Time (hour of 11/06/2001)3 3.5 4 4.5

-50

0

50

100

Time (hour of 11/06/2001)

Ion

o G

rad

ien

t (m

m/k

m)

DF (L1/L2) Gradient

L1-only Gradient

NAWM and SONC, Gradients Comparison ; PRN21

Pair PRN Time

(HH:MM:SS) Slope

(mm/km) Elev. (deg.)

Dist. (km)

NAWM-SONC

21 04:15:00 91 mm/km 20.1 52.3

ICAO APANPIRG, 3rd ISFT

Station-Wide Validation and Enhanced TEC in Korea on Nov. 6, 2001

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3 3.5 4 4.5

20

30

40

50

60

70

80

90

Sla

nt

Dela

y (

m)

NAMW

SONC

GOCH

JINJ

YECH

KUNW

TEGN

3 3.5 4 4.5-50

0

50

100

Time (hour of 11/06/2001)

Ion

o G

rad

ien

t (m

m/k

m)

NAMW-SONC

GOCH-JINJ

YECH-KUNW

KUNW-TEGN

b)

a) Longitude

Lati

tud

e

-150 -100 -50 0 50 100 150

-80

-60

-40

-20

0

20

40

60

80

Vert

ical Io

no

sp

heri

c D

ela

y (

m)

0

5

10

15

Longitude

Lati

tud

e

-150 -100 -50 0 50 100 150

-80

-60

-40

-20

0

20

40

60

80

Vert

ical Io

no

sp

heri

c D

ela

y (

m)

0

5

10

15

20Global Ionosphere Map on Nov. 6, 2001 04:00 UT

ICAO APANPIRG, 3rd ISFT

Thank you for your attention

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