1. Dynasonde measurements advance understanding of the thermosphere- ionosphere dynamics Nikolay Zabotin 1 with contributions from Oleg Godin 2, Catalin Negrea 1,4, Terence Bullett 3,5, Liudmila Zabotina 1 1 Department of Electrical, Energy and Computer Engineering, University of Colorado, Boulder 2 Department of Physics, Naval Postgraduate School, Monterey, CA 3 Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder 4 NOAA/SWPC, Boulder, Colorado 5 NOAA/NCEI, Boulder, Colorado, United States CEDAR Meeting 20 June 2016 Santa Fe, NM

2. Distinguishing properties of Dynasonde data analysis  Comprehensive use of phase information in radio echoes. This is unique to Dynasonde approach to ionospheric radio sounding; in particular this enables processing the list of physical parameters of the echoes instead of traditional amplitude-based image analysis.  3-D structure of ionospheric plasma is accounted for. No unrealistic assumption of horizontally stratified ionosphere. NeXtYZ (“Next Wise”), plasma density inversion procedure, uses angles of arrival of all echoes and provides parameters of the Wedge Stratified Ionospheric Model instead. [Zabotin et al., Radio Sci., 2006]  All echoes are useful. Up to several thousand echoes per ionogram are detected and used. No echo rejection based on range or polarization. 2/9

3. Visualization tool for AGW activity is a standard Dynasonde product Plasma Frequency, MHz Doppler Speed, m/s Zonal Tilt Meridional Tilt 3/9 Time series of NeXtYZ results: Wallops Isl., VA, 7-8 August 2014

4. Capitalizing on ability to perform long-term measurements: Oceans are a major source ofStudying seasonal variations thermospheric wave activity of thermospheric wave activity  New kind of geophysical experiments  9 month long data series  Every 1 km altitude range is processed individually  12-hour sliding time interval  Lomb-Scargle spectral technique  IGW-AGW correlation reaches 0.43  Zabotin et al., JGR Space Phys., 121, 2016; Godin et al., Earth Planets Space, 2015 4/9 3-year series of the PSD integral over 4 frequency bands for two components of the ionospheric tilt over Wallops Island. [C. Negrea, PHD Thesis, 2016]

5. Capitalizing on precision and broad altitude coverage of Dynasonde measurements: Spectral characteristics of Comprehensive set thermospheric wave activity of TID propagation parameters Average PSDs of the zonal (a, c) and meridional (b, d) tilt, for Wallops Island (a, b) and Tromso (c, d) vs real altitude and period for April 2014. Successful comparison to model predicted ones [Negrea and Zabotin, Radio Sci., 51, 2016; Negrea et al., JGR Space Phys., 121, 2016] 5/9

6. Prospective application: Using AGWs to measure parameters of neutral atmosphere with Dynasonde arrays Input ₋ Altitude range ~100 km ₋ Altitude resolution 1 km ₋ Time resolution 2 min ₋ Spectral amplitudes and phases for 4 physical parameters ₋ Several identifiable spectral harmonics ₋ ω, k x, k y, k z Output ₋ Vertical profile of u x, u y ₋ Vertical profile of ρ ­Several Dynasonde locations at the distance of few 10s to few 100s km ­Transportable and/or receive-only systems (cost effectiveness) ­Ability of a long-term monitoring 6/9

7. Dynasonde measurements of tidal harmonics Wallops Isl., May 2013 San Juan, May 2013 Magnitude and phase of diurnal, semidiurnal and terdiurnal harmonics in the electron density variations (a,b), in the West-East gradient (c,d), and in the West-East tilt (e,f) for Wallops Isl., May 2013. 7/9 [Negrea et al., JGR Space Phys., 2016]

8. Training high-resolution solar flare models with Dynasondes Precision of ionization increase measurements is 0.1% in the F region and tens % in D-E regions; time mark accuracy 0.16 s NASA SDO images; X2.7 solar flare; May 5, 2015 8/9

9. Summary Dynasonde techniques fill the widely acknowledged thermospheric gap in tidal and gravity wave data. State-of-the-art algorithms and hardware are available now, not requiring much time for additional development. Some important results have been obtained using these techniques, including the exciting conclusion about a major role played in the thermosphere by AGWs of oceanic origin. With the ability to measure both vertical and horizontal parameters of the TIDs Dynasonde systems approach similar capabilities of ISRs with steerable or phased array antennas. Dynasonde products not mentioned in this presentation include vector velocities of plasma structures and parameters of the spectrum of km-scale irregularities, as well as standard ionospheric parameters. All products are available in a common mode and are obtained by autonomous analysis procedure. Dynasonde compatible radar hardware is relatively low cost already, with a clear perspective to drop to few $K range. Antenna construction is a more expensive component. Dynasonde can be a universal workhorse for Geospace community. 9/9