Monitoring the polar cap/ auroral ionosphere: Industrial applications. P. T. Jayachandran Physics Department University of New Brunswick Fredericton

Transcription

1 Monitoring the polar cap/ auroral ionosphere: Industrial applications P. T. Jayachandran Physics Department University of New Brunswick Fredericton

2 Outline Ionosphere and its effects on modern and old technological systems Global Navigation Satellite Systems (GNSS) High-Frequency (HF) communication systems Space Weather What is wrong? Industrial needs

3 The ionosphere Region of ionized plasma above 60 km from the Earth s surface Primarily produced by the solar EUV and particle precipitation Temporal variation from milliseconds to solar cycle Spatial variations from few cms to few thousand kms Affects the propagation of radiowaves of any frequency Significant impact on navigation and communication systems

4 Arctic ionosphere Direct interaction with solar wind and interplanetary magnetic field Additional source of ionization and variability due to this interaction Space Weather More on this later!

5 Temporal variability

6 Watson et al., JGR Space Phys., 121, 4784, 2016 Spatial variability

7 Spatial variability Pokhotelov et al., GPS Solu., DOI /s z, 2010

8 Sources of error in GNSS correctable/manageable ~5 m 1-2 m 5-40 m 1-2 m 50 cm 2 m 1-2 m Total : m

9 Sources of error in GNSS - Scintillation Rapid fluctuations of the amplitude and phase of a transionospheric radio signal Caused by the small scale irregularities in the ionosphere Earlier observation using signal from radio stars Early studies using geo-stationary satellite signals Many of the important characteristics are well known Two regions of intense scintillations High-latitude and equatorial regions

10 Scintillation A naïve picture Phase variations on wave front from satellite cause diffraction pattern on ground Interference pattern changes in time and space Observation of rapid fluctuations of signal amplitude and phase

11 A Example of GPS signal scintillation ΔN Mezaoui et al., GRL, 41, doi: /2014gl061331, 2014

12 Effect of scintillation ΔN Degrade the quality of the user measurements Degrade the quality of reference station measurements Disrupt the communication from SBAS GEO to the user receiver Effect on satellite data links

13 The problem High-Frequency Systems (HFS) High frequency (HF) propagation - Sky wave propagation - Ionospheric communication (one of the oldest forms of radio communication) Provide worldwide coverage Low power & cost equipment 5-40 m Accessibility to regions where commercial 50 cm 2 m cable and satellite services are limited 1-2 m The ionosphere -a facilitator and a disturber Over the Horizon Radar (OTH) systems 1-2 m Total : m Athieno et al., Rad. Sci., 50, doi: /2015rs005725, 2015

14 Users The problem Back up (ALE) communication for military and civilian Availability of broad band HF modems Amateur radio Non-commercial: wireless, experimentation & emergency, self- training 5-40 m 50 cm 2 m Citizens Band radio - General Radio Service 1-2 m Total : m International broadcast - VOA and BBC

15 Ionospheric effects - Absorption Absorption of HF signals due to high energy particle precipitation Solar Energetic Particles (SEP) and Flares Enhanced ionization Dimitriev et al., JGR Space Phys., 115, A12244, 2010

16 Maximum Usable Frequency (MUF) - Variability

17 One-Way Slant Range (km) One-Way Slant Range (km) Ionospheric effects Doppler spread and AOA 23 Sept 2013, 23:28 UT f c = MHz (a) (b) Frequency (MHz) 23 Sept 2013, 18:56 UT Doppler (Hz) f c = MHz (a) (b) Frequency (MHz) Courtesy: Dr. Paul Bernhart, NRL Doppler (Hz)

18 Space weather Space weather is a term which describes variations in the Sun, solar wind, magnetosphere, ionosphere, and thermosphere, which can influence the performance and reliability of a variety of space-borne and ground-based technological systems and can also endanger human health and safety (Koons et al., 1999). Figure source Royal academy of Engineering Report

19 What is wrong? In my opinion Too much focus on dramatic events Ming Le et al., Research in Astronomy and Astrophysics, 13, 6, 739, 2013 Prikryl et al., Ann. Geophys., 28, 1307, 2010

20 Other minor problems Historical emphasis on the Sun and GIC The Sun is going to do what the Sun is going to do. Its going to depend on how well we, as mankind, can prepare for this situation. John Foster, Perfect disasters- Solar storm, Discovery Channel Too much emphasis on prediction/forecast Too much emphasis on modeling without understanding Too little emphasis on practical solution - nowcasting

21 Industrial needs From my experience Practical solutions to issues Needs real time or near real time ionospheric information - nowcasting Improved design of devices to handle extreme events Better empirical ionospheric model for long term planning

22 CHAIN and Expanded CHAIN (ECHAIN) A network of radio instruments in the polar cap 45 high data rate dual frequency GPS receivers 9 Canadian Advanced Digital Ionosondes (a type of HF Current Stage 25 GPS and 6 ionosondes are installed and providing near real-time data (Phase 1 and II complete) Phase III will be completed by the end of 2020 Uniqueness of CHAIN 9 collocated GPS and Ionosondes Open access data through:

23 Where are they?

24 Real-time monitoring of the ionosphere

25 Why now? Existence of more and more sophisticated instruments and instrument arrays in the polar regions Collocation of different types of instruments Improved accuracy and resolution of measurements Increased capability of data storage and computing power for data analysis Near real-time data availability for applications Our understanding of the processes are changing due to all of the above Increased industrial demand