GPS Scintillation effects as observed from a location beyond the - PowerPoint PPT Presentation

GPS Scintillation effects as observed from a location beyond the anomaly crest in the Indian longitude sector Sarbani Ray Institute of Radio Physics and Electronics University of Calcutta Calcutta, India Ankita Pal Babita Chandel Applied Science and Physics Department Sri Sai University Palampur, India

Introduction • It is well-established that intense low-latitude scintillations, particularly that observed from locations near the crests of the Equatorial Ionization Anomaly (EIA) have largely impaired the performance of GNSS. • In this paper we present cases of intense scintillations observed from stations located poleward of the northern crest of the anomaly in the Indian longitude sector and examine the propagation conditions responsible.

Location of GPS Receivers in India 35 PALAMPUR SHIMLA 30 Geographic Latitude( deg. N) DELHI LUCKNOW BAGDOGRA JODHPUR GUWAHATI Northern crest of EIA BHOPAL 25 AIZWAL AHMEDABAD RAIPUR CALCUTTA 20 MUMBAI HYDERABAD VISHAKHAPATNAM 15 BANGALORE PORT BLAIR AGATTI 10 TRIVANDRUM Magnetic Equator 5 65 70 75 80 85 90 95 100 105 Geographic Longitude( deg. E)

Station Geographic and Magnetic coordinates Station Geographic Latitude(deg. N) Geographic Longitude(deg. E) Magnetic Latitude(deg. N) Trivandrum 8.47 76.91 3.66 Bangalore 12.95 77.68 8.22 Hyderabad 17.44 78.47 12.84 Bhopal 23.28 77.34 19.20 Delhi 28.58 77.21 24.93 Shimla 31.09 77.07 27.65 Agatti 10.83 72.18 7.08 Mumbai 19.09 72.85 15.49 Ahmedabad 23.06 72.61 19.68 Jodhpur 26.26 73.05 23.00 Aizwal 23.83 92.62 18.32 Guwahati 26.12 91.59 20.94 Port Blair 11.67 92.72 4.94 Calcutta 22.58 88.38 17.23 Bagdogra 26.68 88.32 21.76 Visakhapatnam 17.72 83.22 12.44 Raipur 21.18 81.74 16.40 Lucknow 26.76 80.88 22.56

N 1330-1430UT N 1430-1530UT Sv10 Sv17 Sv17 Sv15 Sv39 Sv6 Sv10 Sv24 Sv39 Sv40 Sv6 Sv26 Sv40 E E W W 0 30 60 0 30 60 Sv30 60 Sv23 60 Sv26 Sv24 Sv30 30 30 Sv42 Sv23 Sv5 Sv9 Receiver: GG24 Sv5 0 0 Station: Calcutta S S Date: February 12, 2001 LT=UT+6hr Scintillation Index N 0-5dB 1530-1630UT 1630-1730UT N 6-10dB 11-15dB Sv39 Sv15 16-20dB Sv56Sv40 Sv33 Sv26 Sv17 >20dB Sv40 Sv10 FSC Sv39 Sv26 INMARSAT Sv3 Sv17 Sv21 Sv23 Sv23 Sv15 E W 0 30 60 Sv21 Sv6 W E 0 30 60 Sv9 60 Sv14 60 Sv42 Sv42 Sv9 Sv14 30 Sv29 30 Sv29 Sv30 0 Sv6 S 0 S Elevation-Azimuth plots of GPS satellite tracks observed from Calcutta by GG24 during 1330-1730UT(1930-2330LT) on February 12, 2001.

1830-1930 UT N N 1730 - 1830 UT Sv42 Sv33 Sv33 Sv26 Sv40 Sv9 Sv21 Sv21 Sv9 Sv23 Sv56 Sv15 Sv3 Sv29 Sv23 Sv14 Sv5 Sv14 Sv3 Sv39 Sv42 E W E W 30 60 0 0 30 60 Sv15 Sv40 Sv17 Sv56 60 Sv39 60 Sv29 Sv5 Sv17 Sv30 30 30 Sv30 Sv25 Sv6 Sv25 Receiver: GG24 0 0 Station: Calcutta S S Date: February 12, 2001 LT=UT+6hr Scintillation Index N 0-5dB 2030-2130 UT N 1930-2030 UT 6-10dB 11-15dB Sv9 Sv11 Sv5 16-20dB Sv11 >20dB Sv14 Sv29 Sv29 FSC Sv14 INMARSAT Sv21 Sv25 Sv30 Sv23 Sv30 Sv21 Sv33 E E W W 0 30 60 60 0 30 60 60 Sv40 Sv23 Sv3 Sv33 Sv25 Sv15 30 30 Sv40 Sv22 Sv15 0 0 S S Elevation-Azimuth plots of GPS satellite tracks observed from Calcutta by GG24 during 1730-2130UT(2330-2730LT) on February 12, 2001.

Propagation E Magnetic N Pole F Satellite Geometry A S Station D B Satellite Magnetic Equator Plasma Bubble a) C Magnetic S Pole Geomagnetic Field Line Magnetic N Pole A S2 S1 B2 D B1 Satellite Magnetic Equator Plasma Bubble b) C (Not to scale) Magnetic S Pole Geomagnetic Field Line

Calcutta Calcutta Calcutta during Calcutta

(a) Maximum propagation angle for the (b) Magnetic Latitude of the center of the station vs. station Magnetic Latitude maximum propagation angle region vs. Magnetic Latitude of the station 180 25 175 Maximum Propagation angle(deg.) 20 170 Magnetic latitude(deg.N) 15 165 10 160 5 155 150 0 0 5 10 15 20 25 30 145 -5 y = 1E-05x 5 - 0.001x 4 + 0.032x 3 - 0.427x 2 + 4.430x + 134.2 y = -3E-06x 6 + 0.000x 5 - 0.010x 4 + 0.192x 3 - 1.810x 2 + 9.299x - 21.30 140 -10 0 5 10 15 20 25 30 Station Magnetic Latitude(deg.N) Station Magnetic Latitude(deg.N) (c) Geographic Latitude of the center of the (d) Geographic Longitude of the center of the maximum propagation angle region vs. maximum propagation angle region vs. Geographic Latitude of the station Geographic Longitude of the station 30 100 y = -4E-06x 6 + 0.000x 5 - 0.021x 4 + 0.525x 3 - 6.812x 2 + 46.28x - 127.4 y = -2E-06x 6 + 0.000x 5 - 0.163x 4 + 17.95x 3 - 1109.x 2 + 365x - 49944 25 95 Geographic Longitude(deg.E) Geographic Latitude(deg.N) 20 90 15 85 10 80 5 75 0 70 0 5 10 15 20 25 30 35 70 75 80 85 90 95 100 Station Geographic Latitude(deg.N ) Station Geographic Longitude(deg.E)

FROM PROPAGATION GEOMETRY… • The zone of maximum propagation angle for any station in the northern magnetic hemisphere is located to the south of the station. • The value of maximum propagation angle for a particular station depends on the magnetic latitude of the station, progressively increasing as one moves north from the magnetic equator. This is due to the fact that the magnetic field lines have minimum curvature over the magnetic equator, but the field lines gradually converge at higher latitudes and ultimately coalesce at the poles.

Station: Trivandrum Period: August-October 2004 13UT-14UT 14UT-15UT 15UT-16UT 16UT-17UT Subionospheric Latitude(deg.N) ⃝ S4 < 0.3 □ 0.3 ≤ S4 < 0.6 ∆ S4 ≥ 0.6 LT = UT + 05.17h Subionospheric Longitude(deg.E)

Station: Trivandrum Period: August-October 2004 17UT-18UT 18UT-19UT 19UT-20UT 20UT-21UT Subionospheric Latitude(deg.N) ⃝ S4 < 0.3 □ 0.3 ≤ S4 < 0.6 ∆ S4 ≥ 0.6 LT = UT + 05.17h Subionospheric Longitude(deg.E)

Station: Trivandrum [ Latitude:8.47 o N, Longitude: 76.91 o E (geographic) ;Magnetic Latitude:3.66 o N] IGRF-9 (2000) Propagation angle(deg.) 20 15 Subionospheric Latitude(deg.N) 180.0 175.0 170.0 15 10 Subionospheric Latitude(deg.N) 165.0 160.0 Magnetic Latitude(deg.N) 155.0 150.0 145.0 140.0 10 5 135.0 130.0 125.0 120.0 115.0 110.0 5 0 105.0 100.0 95.00 90.00 85.00 80.00 75.00 0 -5 70.00 65.00 60.00 55.00 50.00 45.00 -5 -10 65 70 75 80 85 90 65 70 75 80 85 90 Subionospheric Longitude(deg.E) Subionospheric Longitude(deg.E) Subionospheric Longitude(deg.E) (a) (b) (c) ⃝ S4 < 0.3 □ 0.3 ≤ S4 < 0.6 ∆ S4 ≥ 0.6 LT = UT + 05.17h Maximum Propagation Angle :146.69 o Zone: 0.06 o to 2.73 o N and 73.38 o to 76.56 o E (geographic) ;-5.35 o to -2.10 o N (magnetic ) a)Propagation angle map in terms of Subionospheric Latitude and Longitude for Trivandrum. b)Scintillation observed from Trivandrum during 15:00-16:00UT on September 15, 2004. c) Propagation angle map in terms of Magnetic Latitude and Subionospheric Longitude for Trivandrum.

Station: Bangalore Period: August-October 2004 13UT-14UT 14UT-15UT 15UT-16UT 16UT-17UT Subionospheric Latitude(deg.N) ⃝ S4 < 0.3 □ 0.3 ≤ S4 < 0.6 ∆ S4 ≥ 0.6 Subionospheric Longitude(deg.E) LT = UT + 05.17h

Station: Bangalore Period: August-October 2004 17UT-18UT 18UT-19UT 19UT-20UT 20UT-21UT Subionospheric Latitude(deg.N) ⃝ S4 < 0.3 □ 0.3 ≤ S4 < 0.6 ∆ S4 ≥ 0.6 Subionospheric Longitude(deg.E) LT = UT + 05.17h

Station: Bangalore [ Latitude:12.95 o N, Longitude: 77.68 o E (geographic) ;Magnetic Latitude:8.22 o N] 25 20 Propagation angle(deg.) IGRF-9 (2000) IGRF-9 (2000) 180.0 175.0 170.0 15 20 165.0 Subionospheric Latitude(deg.N) 160.0 155.0 Magnetic Latitude(deg.N) 150.0 145.0 140.0 135.0 15 10 130.0 125.0 120.0 115.0 110.0 105.0 10 5 100.0 95.00 90.00 85.00 80.00 75.00 0 5 70.00 65.00 60.00 55.00 50.00 45.00 0 -5 65 70 75 80 85 90 65 70 75 80 85 90 Subionospheric Longitude(deg.E) Subionospheric Longitude(deg.E) (a) (b) Maximum Propagation Angle :155.46 o Zone: 4.48 o to 6.25 o N and 75.73 o to 76.50 o E (geographic) ;-0.32 o to 1.48 o N (magnetic ) a)Propagation angle map in terms of Subionospheric Latitude and Longitude for Bangalore. b) Propagation angle map in terms of Magnetic Latitude and Subionospheric Longitude for Bangalore.

Station: Hyderabad Period: August-October 2004 13UT-14UT 14UT-15UT 15UT-16UT 16UT-17UT Subionospheric Latitude(deg.N) ⃝ S4 < 0.3 □ 0.3 ≤ S4 < 0.6 ∆ S4 ≥ 0.6 Subionospheric Longitude(deg.E) LT = UT + 05.17h

Station: Hyderabad Period: August-October 2004 17UT-18UT 18UT-19UT 19UT-20UT 20UT-21UT Subionospheric Latitude(deg.N) ⃝ S4 < 0.3 □ 0.3 ≤ S4 < 0.6 ∆ S4 ≥ 0.6 Subionospheric Longitude(deg.E) LT = UT + 05.17h