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The TIDDBIT HF Doppler Radar G. Crowley and F. Rodrigues

The TIDDBIT HF Doppler Radar G. Crowley and F. Rodrigues. Atmospheric & Space Technology Research Associates (ASTRA).

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The TIDDBIT HF Doppler Radar G. Crowley and F. Rodrigues

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  1. The TIDDBIT HF Doppler Radar G. Crowley and F. Rodrigues Atmospheric & Space Technology Research Associates (ASTRA) Abstract: HF Doppler sounders represent a low-cost and low-maintenance solution for monitoring gravity wave activity in the F-region ionosphere. HF Doppler sounders together with modern data analysis techniques provide both horizontal and vertical velocities across the entire TID spectrum. ASTRA has extensive experience with HF systems, and is currently building Doppler sounders in Texas, Virginia, and Peru. (TIDDBIT = TID Detector Built In Texas)

  2. HF DOPPLER SOUNDER PRINCIPLE F-Region Ionosphere 200-400 km Radar Principle Df = -1/l (dP/dt) dP can be caused by: a) changes in reflection height b) changes in refractive index (electron density profile) 3-10 MHz Tx Rx

  3. HF DOPPLER SOUNDER ARRAY F-Region Ionosphere 200-400 km Tx 3-10 MHz Rx Tx Tx

  4. TYPICAL RADAR SPECIFICATIONS 3 Transmitters, Single Receiver Spacing: 50 – 300 km Dual Frequency (Altitude separation) CW system Advantages: Power: 20-100 W Continuous 30 sec cadence Tx X X Rx Tx X Scale: 50 – 300 km Tx

  5. Original TIDDBIT Array in Texas The TIDDBIT array has baseline dimensions of 140 x 210 km, ideal for TID studies.

  6. Typical Doppler Data TIDs on three propagation paths for 4.5 MHz sounding frequency on January 30th, 2002

  7. 1 3 Rx 2 TIDDBIT Radar at Wallops Island Rocket

  8. TIDDBIT Data Depends on Propagation Conditions Wallops Island IRI Sept 1, 2006

  9. Gravity Waves – An Introduction Waves Everywhere! Growth with Altitude rV2 Sources: Aurora Weather Fronts Thunderstorms Topography & winds Explosions Restoring Force Acoustic Waves - Pressure Gravity Waves - Gravity Measures Acoustic waves (τ ~ 1 min) to Large Scale TIDs (τ ~ 4 hrs)

  10. Classification of Gravity Waves/TIDs Medium ScaleLarge Scale Period 10-30 min 0.5-5 hr VH (m/s) 50-300 300-1000 lH (km) 100-300 300-5000 Measures Acoustic waves (τ ~ 1 min) to Large Scale TIDs (τ ~ 4 hrs)

  11. Measures Acoustic waves (τ ~ 1 min) to Large Scale TIDs (τ ~ 4 hrs)

  12. Raw Data • 1. Calculate mean and standard deviation for each peak range. • 2. Find values above threshold (set in number of standard deviations from the mean). • 3. Calculate equation parameters for Gaussian curve with IDL gaussfit routine. • 4. Calculate peak values with equation parameters. • 5. Get Chi-squared value. Peak Detection 1. Detrend the data 2. Calculate Variance 3. Perform FFT 4. Compute the Period FFT Calculation 1. Take input from two stations. 2. Perform cross-spectral analysis 3. Compute relative time delays Delays Calculation 1. Test to see if data is usable for horizontal velocity calculation (based on coherency). 2. Determine the two largest coherencies 3. Compute 95% confidence intervals based on coherencies 4. Call separate subroutine for each pair. 5. Take relative times and compute velocity and azimuth for station configuration. Horizontal Velocity

  13. Observed TID Spectra Measures Acoustic waves (τ ~ 1 min) to Large Scale TIDs (τ ~ 4 hrs)

  14. 1 hr 1 hr 30 min 30 min Horizontal Phase Trace Speed 500 Measures Acoustic waves (τ ~ 1 min) to Large Scale TIDs (τ ~ 4 hrs) 0 Horizontal Azimuth

  15. Quiet Day Wave Propagation(1/30/2002) Wave periods 30 min – 4 hr. Wave periods 10 – 45 min.

  16. Wave velocities for periods of 10 – 45 minutes. Active Day(2/6/2002) Quiet Day(1/30/2002)

  17. Wave velocities for periods of 30 minutes – 4 hours. Active Day(2/6/2002) Quiet Day(1/30/2002)

  18. QUIET DAY STORM DAY

  19. Azimuth versus Local Time (Oct 11-26, 2006) Period = 30 min 0 90 180 Horiz Azimuth ( ºE of N) TIMEGCM Wind Azimuth 270 360 Local Time

  20. Horiz. Phase Speed versus Local Time (Oct 11-26, 2006) Period = 30 min Horiz Phase Trace Speed ( m/s) TIMEGCM Wind Speed Local Time

  21. Deriving Horizontal Thermospheric Winds from Gravity Waves From Vadas and Fritts (2005): Given GW wave-vector and background neutral parameters, one can try to solve for UH ! First successful attempts made with multi-beam ISR observations (Vadas and Nicolls, 2008)

  22. TIDDBIT Radar Planned for Jicamarca Tx-1 Tx-3 Rx 50 km Tx-2 100 km

  23. C/NOFS-RELATED SCIENCE STUDIES • Possible Triggers for Instability generation • TID Studies • Spectral Morphology • Underlying Wave Characteristics • Effects of Waves • Separation of triggering mechanisms • E-field measurement capability • Continuous measurement of iso-ionic contour drifts

  24. TIDDBIT Radar in New Mexico 75 km 50 km 25 km

  25. Value of Deploying a 2nd system around Socorro 100 km

  26. Conclusions • Successfully built and operated TIDDBIT radar. • Continuous operation: 2002, January - April 2005, Jan - May • Successfully developed end-to-end data analysis. • Complete description of TID characteristics: Period, VH, VZ, λH, λZ, as a function of τ. • Acoustic waves (τ ~ 1 min) to Large Scale TIDs (τ ~ 4 hrs) • Day-to-day variability in TID characteristics. • Developed real time displays • Deployment near Wallops (July 2006) • Continuous operation: 2006, July-Sept • Continuous operation: 2007, Aug-Nov • Partial deployment in New Mexico: June 2008 • Deployment at Jicamarca, Peru – Oct 2008 • C/NOFS – TIDs, Triggers of ESF, E-fields • Gravity wave propagation/raytracing studies

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