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Multi-instrument observations of atmospheric gravity waves/traveling ionospheric disturbances associated with enhanced auroral activity

Zama Katamzi-Joseph*, Anasuya Aruliah, Kjellmar Oksavik, John Bosco Habarulema, Kirsti Kauristie, and Michael Kosch

4th International ANGWIN Workshop, Brazil, 24-26 April 2018

* South African National Space Agency, Hermanus, South Africa.

• Dept. Physics & Electronics, Rhodes University, Grahamstown, South Africa.

• Traveling ionospheric disturbances manifestation of atmospheric

gravity waves in the ionosphere

• appear as wave-like perturbations in measurements, e.g. TEC
• Classified into 2 main categories based on period, and horizontal

speed or wavelength:

– Medium scale: periods 15-60 minutes, horizontal speeds 100-250 m/s and wavelength <100 – 400 km. Mostly associated with meteorological events (Mayr et al., 1984; Hernàndez-Parajes et al., 2006). – Large scale: periods > 30 minutes, horizontal speeds > 400 m/s and wavelength > 1000 km. Typically associated with disturbed geomagnetic conditions (Ding et al, 2006).

• Aim: determine characteristics and source of AGWs/TIDs observed in

GNSS and FPI measurements during night of 6 January 2014

Atmospheric Gravity Waves/Traveling Ionospheric Disturbances (AGWs/TIDs)

• GNSS receivers (University of Bergen, Norway): GPS total electron content

(TEC), 60 s cadence,

• FPI (University College London): 630 nm intensity, emission height 240 km, 30°

elevation angle, 9 minutes cadence

• All sky camera (Finnish Meteorological Institute): 557.7 nm intensity, emission

height 110 km, 1 minute cadence

• Magnetometers (IMAGE): Horizontal X component, 1 minute cadence

Data

• Velocities obtained from Statistical Angle of Arrival and Doppler method for

GPS radio interferometry by Afraimovich et al. (1998).

– Also used by Valladares and Hei (2012) and Habarulema et al. (2013)

• Assume TID is plane sinusoidal traveling wave:

𝐽 𝑦, 𝑧, 𝑢 = 𝐵 sin(Ω𝑢 − 𝑙𝑦𝑦 − 𝑙𝑧𝑧 + 𝜒0)

𝐽𝑦

′ = 𝑧𝐿𝐼𝑃 𝐸𝑈𝐹𝐷𝐼𝑃𝑄 − 𝐸𝑈𝐹𝐷𝐶𝐾𝑂 − 𝑧𝐶𝐾𝑂(𝐸𝑈𝐹𝐷𝐼𝑃𝑄 − 𝐸𝑈𝐹𝐷𝐿𝐼𝑃)

𝑦𝐿𝐼𝑃𝑧𝐶𝐾𝑂 − 𝑦𝐶𝐾𝑂𝑧𝐿𝐼𝑃

𝐽𝑧

′ = 𝑦𝐶𝐾𝑂 𝐸𝑈𝐹𝐷𝐼𝑃𝑄−𝐸𝑈𝐹𝐷𝐿𝐼𝑃 − 𝑦𝐿𝐼𝑃(𝐸𝑈𝐹𝐷𝐼𝑃𝑄−𝐸𝑈𝐹𝐷𝐶𝐾𝑂) 𝑦𝐿𝐼𝑃𝑧𝐶𝐾𝑂 − 𝑦𝐶𝐾𝑂𝑧𝐿𝐼𝑃

• I’x and I’y are functions of t

Method: SADM-GPS

TID amplitude TEC Initial disturbance phase Angular disturbance frequency x and y components

• f wave number k

• Azimuthal propagation direction of phase wavefront:

𝛽 𝑢 = tan−1 𝑣𝑧(𝑢) 𝑣𝑦(𝑢) = tan−1 𝐽𝑧

′ (𝑢)

𝐽𝑦

′(𝑢)

• Horizontal phase velocity

𝑤ℎ 𝑢 = 𝑣 𝑢 + 𝑥𝑦 𝑢 sin 𝛽 𝑢 + 𝑥𝑧 𝑢 cos(𝛽(𝑢)) 𝑣 𝑢 = ห𝑣𝑦(𝑢) ห 𝑣𝑧(𝑢) 𝑣𝑦2 + 𝑣𝑧2 𝑣𝑦 𝑢 = 𝐽𝑢

′(𝑢)

𝐽𝑦

′

𝑏𝑜𝑒 𝑣𝑧 𝑢 = 𝐽𝑢

′(𝑢)

𝐽𝑧

′

𝐽𝑢

′ = 𝐸𝑈𝐹𝐷𝐼𝑃𝑄 𝑢 + 𝑒𝑢 − 𝐸𝑈𝐹𝐷𝐼𝑃𝑄

𝑒𝑢 𝑥𝑦 = 𝑦𝐽𝑄𝑄 𝑢 + 𝑒𝑢 − 𝑦𝐽𝑄𝑄(𝑢) 𝑒𝑢 and 𝑥𝑧 = 𝑧𝐽𝑄𝑄 𝑢 + 𝑒𝑢 − 𝑧𝐽𝑄𝑄(𝑢) 𝑒𝑢

Method: SADM-GPS

• TEC shows wave-like perturbations between 17 and 23 UT on 6 Jan 2014
• Approximate diurnal trend by 4th order polynomial and remove to get TEC

perturbations, and therefore determine characteristics of wavelike perturbations (e.g. periods, velocities)

TEC Results

• Periods: normalised Lomb-Scargle least squares frequency analysis; 99.99%

confidence level

• PRN 3

– A: 29 minutes (KHO) – B: 32 minutes (BJN) – C: 37 minutes (HOP+KHO) – D: 58 minutes (BJN + HOP)

• PRN 11: 39 minutes (BJN+KHO)

D AB C

TEC Results

• PRN 3:

<Vh> = 760 ± 235 m/s <α > = 347˚ ± 19˚ (east of north)  poleward propagation

• PRN 11:

<Vh> = 749 ± 267 m/s α = 345˚ ± 20˚ (east of north)  poleward propagation

TEC Results

• Periodic enhancements in SE and SW between 15 and 02 UT
• Periodogram for data between 15 and 21 UT

– Period (ZEN and SW) = 128 minutes (2.1 hours) – Period (SE) = 174 minutes (2.9 hours)

• Not enough information at different directions to determine propagation

information

FPI Results

p = 128 min

• Kp max: 1 and min Dst: - 10 nT  quiet storm conditions
• Auroral geomagnetic disturbance observed, especially around 18UT

– AE max ~200 nT – PCN max ~1.5 mV/m Minor substorm conditions

Polar Magnetic Indices

• ASC keogram: intensity brightening at ~18 UT associated with aurora activity

 coincides with AGWs/TIDs observations

• Intensities extracted at specific latitudes corresponding to GPS receivers

shows shift in intensities peaks

– Poleward propagation, virtual horizontal velocity ~823 ± 143 m/s

All sky Camera Results

• Periodogram shows periods of 41 minute and 49 minutes

ASC Results

• X-components obtained from SuperMAG shows disturbance around 18 UT

– Baseline: yearly trend

• Periodogram obtained using data shows period of 53 minutes for BJN and

HOP stations

* Ignored since greater than half the data length

• Horizontal speed and azimuth (used altered SADM-GPS): 708 ± 261 m/s,

2˚±29˚ east of north

Magnetometer Results

*

• Correlation of AGWs/TIDs characteristics from instruments sampling

ionosphere/thermosphere at different heights

– TEC calculated assuming thin shell at 300km: period 29-58 minutes, velocity 749- 760 m/s poleward; – Intensities of 557.7 nm emission assumed height at 110 km: periods 41-49 minutes, velocity 823 m/s poleward; – X-magnetic field deflection infers about ionospheric currents at also ~ 110 km: period 53 minutes, velocity 708 m/s poleward.

• The AGWs/TIDs similar characteristics as those of large-scale TID class.
• Characteristics comparable to other high latitudes studies, e.g.

– Nicolls et al. (2012): 32.7±0.3 min, 560±270 m/s, 33.5±15.8° (Alaska) – Momani et al. (2010): 800-1200 m/s poleward propagation (Antarctica)

• Observations of similar velocities at various heights also observed by

Shiokawa et al. (2003):

– Obtained 640 m/s from all sky imager, 379-560 m/s from GPS and 580 m/s from ionosondes

Discussion

• Presented AGWs/TIDs observed with measurements from radio, optical and

magnetic field over Svalbard on a quiet geomagnetic night of 6 January 2014

– Properties match large scale TID characteristics

• At same time substorm and auroral disturbances of similar periods and

velocities observed from magnetometers and all-sky camera data.

• AGWs/TIDs generated through particle precipitation, Joule heating or Lorentz

forcing

Summary + Conclusion

Thank You

1South African National Space Agency, Hermanus, South Africa.

• 2Dept. Physics & Electronics, Rhodes University, Grahamstown, South Africa.
• 3Dept. Physics & Astronomy, University College London, UK.

4Dept Physics & Technology, University of Bergen, Norway. 5Arctic Geophysics, University Centre in Svalbard, Norway. 6Finnish Meteorological Institute, Finland. 7Dept Physics, Lancaster University, UK. 8Dept, Physics & Astronomy, University of the Western Cape, South Africa.

Zama Katamzi-Joseph1,2, Anasuya Aruliah3, Kjellmar Oksavik4,5, John Bosco Habarulema1,2, Kirsti Kauristie6, and Michael Kosch1,7,8

• Afraimovich, E., K. Palamartchouk, and N. Perevalova (1998), GPS radio

interferometry of traveling ionospheric disturbances, J. Atmos. Sol. Terr. Phys., 60, 1205-1223, dio: 10.1016/S1364-6826(98)00074-1.

• Habarulema, J., Z. Katamzi, and L.-A. McKinnell (2013), Estimating the

propagation characteristics of large-scale traveling ionospheric disturbances using ground-based and satellite data, J. Gophys. Res. Space Physics, 118, 7768-7782, doi: 10.1002/2013JA018997.

• Valladares, C., and M. Hei (2012), Measurements of the characteristics of

TIDs using small and regional networks of GPS receivers during the campaign

• f 17-30 July of 2008, Int. J. Geophys., doi: 10.1155/2012/548784.

References