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RADIO SOUNDING IN THE MAGNETOSPERE AND TOPSIDE IONOSPHERE

Explore the use of radio sounders to study the magnetosphere and topside ionosphere, focusing on space weather measurements, imaging techniques, RPI specifications, and TOPADS for topside Doppler sounding. Learn about signal processing and ionogram analysis.

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RADIO SOUNDING IN THE MAGNETOSPERE AND TOPSIDE IONOSPHERE

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  1. RADIO SOUNDING IN THE MAGNETOSPERE AND TOPSIDE IONOSPHERE BW Reinisch1, DM Haines1, RF Benson2, K Bibl1, G Cheney1, SF Fung2, J Grebowsky2, JL Green2, X Huang1, R Manning3, and WWL Taylor4 1- University of Massachusetts Lowell, 2- NASA Goddard Space Flight Center, 3- Observatoire Paris-Meudon, 4- Raytheon STX Deutsche URSI Tagung Kleinheubach 28. September 1998

  2. Space WeatherConnection • Solar Wind Effects • Changing Magnetopause • Changing Plasmasphere • High Latitude Ionosphere

  3. OUTLINE • The IMAGE Mission and RPI • http://image.gsfc.nasa.gov • http://ulcar.uml.edu/rpi • The WARNING Mission and TOPADS • http ://www.rada.kiev.ua

  4. IMAGE Instruments • Neutral Atom Imagers • High Energy Neutral Atom (HENA) imagers • Medium Energy Neutral Atom (MENA) imagers • Low Energy Neutral Atom (LENA) imagers • FUV Imagers • Spectrographic Imager (SI) • Geocorona (GEO) imager • Wideband Imaging Camera (WIC) • EUV Imager • Extreme Ultra-Violet (EUV) imager • Radio Sounder • Radio Plasma Imager (RPI)

  5. Orbital Characteristics

  6. Spectrographic Imager (SI) • SI Observations • Far ultraviolet imaging of the aurora • Image full Earth from apogee • Measurement Requirement • FOV: 15°x 15° for aurora (image full Earth from apogee), • Spatial Resolution: 90 km • Spectral Resolution (top): Reject 130.4 nm and select 135.6 nm electron aurora emissions. • Spectral Resolution (bottom): 121.6 nm • Storm/substorm Observations • Image Time: 2 minutes generating 720 images/day • Derived Quantities • Structure and intensity of the electron aurora (top) • Structure

  7. Simulated RPI Plasmagram • RPI browse product data will produce plasmagrams • Echoes shown in solid line, density features in dashed line. • Derived Quantities from Plasmagrams include: • Distance to Magnetopause, Plasmapause, Polar Cusp (when observed) • Magnetospheric shape (with model), structure, gross irregularities • Storm conditions from a plasma/radio wave perspective

  8. Simulated RPI Plasmagram

  9. Space Weather Measurements

  10. RPI Specifications

  11. RPI Waveforms • short pulse (3.2 ms) • long pulse (125ms) • half-sec pulse • 2-sec pulse • n-chip complimentary phase codes,n=4,8,16 • chirp pulse (125 ms) • staggered pulse sequence (768 chips)

  12. RPI Operational Modes • Echo Sounding w. Antenna Tuning • Relaxation w/o Antenna Tuning • Whistler Excitation (transmit f, receive diff. f’s) • Thermal Noise Passive Reception

  13. +Z +X +Y Radio Imaging E’ E Electric Field Ellipse E’ is phase quadrature sample of E E x E’ E-Plane Normal = EE’ E2 + E'2 Echo Amplitude = Polarization = Direction of E-Plane Normal

  14. Mapping of Reflection Points

  15. TOPSIDE AUTOMATED DOPPLER SOUNDER TOPADS

  16. TOPADS Specifications

  17. Topside Sounding - 1971 ISIS Topside Ionogram showing Plasma Resonance Modes Plasma resonance frequencies provide In-situ Ne and Magnetic Field Intensity Remote echoes provide vertical Ne profiles fN = O-mode Plasma Resonance fH = Gyro Resonance fT = Upper Hybrid Resonance fX = X-mode Plasma Resonance fZ = Z-mode Plasma Resonance

  18. TOPADS Signal Processing • High receiver sensitivity - 125 nV • pulse compression - compl. phase code • spectral coh. integration - ±1 kHz, 0.1 Hz res. • chirping

  19. Topside Irregularity Measurement

  20. Signal/Noise for 20m Antennas

  21. Antenna Performance (20m Tuned Dipole)

  22. BACKUP

  23. Transmitted Pulses and Raw Echoes (PRR = 100 Hz) Received Echoes after Compression (Effective PRR = 50 Hz) Complementary CodePulse Compression

  24. Sum CODE 1 + CODE 2 Code 1 Code 2 Result Signal Processing Gain = 15 db.

  25. Doppler Integration(8 Complementary Pulse Pairs, 1 Frequency, 2 Polarizations, 200 Hz PRR) Echoes from 8 pulses Spectrum at 300 km Signal Processing Gain = 9 db.

  26. Actual Doppler SpectraMillstone Hill - CORIS DPS1 30-Jun-1997(Courtesy of Alain Thomas)

  27. Sample Ionogram

  28. Quadrature Sampling

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