RADIO SOUNDING IN THE MAGNETOSPERE AND TOPSIDE IONOSPHERE

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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
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Space Weather Connection

• Solar Wind Effects
• Changing Magnetopause
• Changing Plasmasphere
• High Latitude Ionosphere

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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

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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)

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Orbital Characteristics
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Spectrographic Imager (SI)

• SI Observations
• Far ultraviolet imaging of the aurora
• Image full Earth from apogee
• Measurement Requirement
• FOV 15x 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

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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

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Simulated RPI Plasmagram
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Space Weather Measurements
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RPI Specifications
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RPI Waveforms

• short pulse (3.2 ms)
• long pulse (125ms)
• half-sec pulse
• 2-sec pulse
• n-chip complimentary phase codes,n4,8,16
• chirp pulse (125 ms)
• staggered pulse sequence (768 chips)

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RPI Operational Modes

• Echo Sounding w. Antenna Tuning
• Relaxation w/o Antenna Tuning
• Whistler Excitation (transmit f, receive diff.
  fs)
• Thermal Noise Passive Reception

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Radio Imaging
E
E
Electric Field Ellipse
E is phase quadrature sample of E
E x E
E-Plane Normal
EE
Echo Amplitude
E2 E'2
Polarization
Direction of E-Plane Normal
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Mapping of Reflection Points
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TOPSIDE AUTOMATED DOPPLER SOUNDER

• TOPADS

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TOPADS Specifications
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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
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TOPADS Signal Processing

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

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Topside Irregularity Measurement
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Signal/Noise for 20m Antennas
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Antenna Performance (20m Tuned Dipole)
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BACKUP
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Complementary CodePulse Compression
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Sum CODE 1 CODE 2
Code 1
Code 2
Result
Signal Processing Gain 15 db.
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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.
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Actual Doppler SpectraMillstone Hill - CORIS
DPS1 30-Jun-1997(Courtesy of Alain Thomas)
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Sample Ionogram
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Quadrature Sampling