Solar Radar and Distributed Multi-static meteor radars/receivers

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1 Solar Radar and Distributed Multi-static meteor radars/receivers J. L. Chau 1, W. Coles 2 et al. 1 Leibniz Institute of Atmospheric Physics University of Rostock, Kühlungsborn, Germany 2 University of San Diego, CA, USA. Thanks to: Gunter Stober Namir Kassim Joseph Helmboldt Chris Hall Masaka Tsutsumi Christoph Jacobi Quo Vadis Workshop, May 26, 2016, Boulder, CO, USA

2 Outline Solar Radar: Lessons learned from Jicamarca experiments MMARIA approach, a complement to a future GEO- Facility for MLT studies Stand-alone As part of a powerful VHF radar Personal opinions on what to consider

3 Solar Radar Bill Coles (UCSD) and Jorge Chau (IAP) What we learned from the Jicamarca Experiment: 1. The echo was much weaker (>10dB) than expected so we will need more power delivered to the Sun. 2. The solar noise was much stronger than expected. It comes from compact noise bursts, so we will need spatial resolution to observe between noise bursts.

4 Solar noise Feb 10-15, 2004, at 50 MHz integrated over entire disc solar activity was low to very low during entire period the quiet Sun is the lower envelope BW=1MHz; T=1s σp=0.013db expected echo is 10σP of quiet Sun (after decoding)

5 Four examples of delay-doppler maps during quiet periods RCP 2004/2/10 LCP 2004/2/10 CAL LCP 2004/2/11 LCP 2004/2/12

6 Implications for a new solar radar system 1. Since the echo is > 10 db weaker, we will need to deliver 10 db more power to the Sun - roughly 1 MW CW and the transmitter beam width must be roughly 1 degree. This implies a filled aperture > 60 wavelengths in diameter, comparable to JRO in fact. 2. We want to be able to observe the Sun more than 1000 s per day, so we will have to track the Sun. This implies that the elements in the transmitter array will need independent phase control. 3. The solar noise increased 30dB during a strong earthward CME - exactly what we want to detect. So the receiver must be able to resolve out solar noise bursts with a dynamic range of about 30dB. This will also require spatial resolution < 0.05 degree, which implies a thin array >1200 wavelengths in diameter.

7 Transmitter Design It is almost certainly cost-effective to use an array and very likely cost-effective to put a power amplifier on each linear element of the array. The size of the array must be 60 λ in diameter so the number of elements Ne depends on the element spacing. The element spacing (in λ) depends on the scan angle, so the spacing may have to be λ/ 2 E-W, but might be relaxed somewhat N-S. So Ne Regular spacing is probably most efficient as we would then transmit equal power from each element. A hexagonal arrangement is likely preferred. More elements increases the cost, but decreases the power requirement for each power amplifier, so the cost is < linear with the number of elements. Small power amplifiers can be made broad band (28 to 53 MHz?), and flexibility in transmitting frequency would be very useful for known applications. It would also, perhaps, permit unforeseen applications. It is probably efficient to put an intelligent transmitter controller on each element, which would require only a clock signal and a digital link, perhaps ethernet or even WiFi, to be distributed to each element. With independent control of each element we could transmit multiple beams in different directions with different power levels, different codes, and even different frequencies, provided only that the total transmitted power/element is respected. It would be valuable to be able to receive with the same antenna. With distributed power amplification the T/R switch should be relatively simple to design. In addition to receiving and analyzing an echo for scientific purposes, the echo can also be used for calibration of the array.

8 Other considerations Transmitter (cont) CW Broadband, able to work on pulsed mode. Linear, circular, elliptical polarizations. Broadband antenna element for transmission. Modified LOFAR LB or LWA? Array calibration Radio sources (e.g., Cygnus A, Cassiopeia, Hydra) Use of drones (reflectors or radio beacons).

9 Improved MLT wind measurements: MMARIA approach (Multi-static, Multi-Frequency Meteor Radar) J. Chau, G. Stober, J. Vierinen, et al. [see Stober and Chau, RS, 2015, Vierinen et al., 2016]

10 Wind field: First-order Taylor expansion

11 MMARIA: Multi-static, Multi-frequency, Multi-transmitter Northern Norway Northern Germany Andenes,Trømso,Kiruna, Sodankyla,Trondheim, Alta, Svalbard Juliusruh, Collm, Kborn

MMARIA Approach: Advantages Improvement (1) Increased number of detections (2) Observation of larger effective Bragg wavelengths (3) Multiple observing angles of common volume Relevance Better time

12 MMARIA Approach: Advantages Improvement (1) Increased number of detections (2) Observation of larger effective Bragg wavelengths (3) Multiple observing angles of common volume Relevance Better time and altitude resolution Higher altitude coverage Extraction of parameters like relative vorticity, horizontal divergence, shear, stretching, (1) and (3) Improve determination of GW parameters in both time and space (3D)

Example from simultaneous Pulsed and Spread-spectrum Campaign Rx 2 CW1 Pulsed + Rx1 CW2 200 100 0-100 -200 200 100 0-100 1.00UT 4.00UT 7.00UT 10.00UT 13.00UT 16.00UT 19.

2 kw avg Pulsed). -200-200 -100 0 100 200-200 -100 0 100 200-200 -100 0 100 200-200 -100 0 100 200 From: 14-Mar-2016, to: 20-Mar-2016 1.00UT 4.00UT 7.00UT 10.

13 Example from simultaneous Pulsed and Spread-spectrum Campaign Rx 2 CW1 Pulsed + Rx1 CW UT 4.00UT 7.00UT 10.00UT 13.00UT 16.00UT 19.00UT 22.00UT Only Pulsed-Link Four links: Pulsed Rx1 Pulsed Rx2 CW1 Rx2 CW2 Rx2 Transmission in the same frequency! Only 400 W CW Power on each CW link (compared to 1.2 kw avg Pulsed) From: 14-Mar-2016, to: 20-Mar UT 4.00UT 7.00UT 10.00UT UT 16.00UT 19.00UT 22.00UT From: 14-Mar-2016, to: 20-Mar-2016 All bistatic links

Example from Composite over Andenes-Tromso (69.

Climatology 82 200 100 0-100 andenes,tromso, 12.

un-2015 1.00UT 4.00UT 7.00UT 10.00UT 13.00UT 16.00UT 19.00UT 22.

200-200 -100 0 100 200 From: 20-J un-2015, to: 29-J un-2015

2004-2005-2006-2007-2008-2009-2010-2011-2012-2013-2014-2015 m/s

14 Example from Composite over Andenes-Tromso (69.4N) Andenes-Tromso NS (km) Climatology andenes,tromso, 12.00UT From: 20-J un-2015, to: 29-J un UT 4.00UT 7.00UT 10.00UT 13.00UT 16.00UT 19.00UT 22.00UT From: 20-J un-2015, to: 29-J un-2015 (km) (km) (km) (km) (km) U (VVP) V (VVP) Hor. div Rel. Vort. w, wtop = D J F M A M J J A S O N D Day of the year m/s m/s m/s/km m/s/km m/s

15 MMARIA and Solar Radar/Radio A solar radar would be a superb all-in-one meteor radar: Head-echoes: Meteor mass, Meteor populations, etc. Non-specular: Higher altitude winds, plasma physics Specular echoes: MMARIA wind fields within km radius (for all practical purposes, a solar radar would be an all-sky illuminator). Technical Requirements: Multi-static capabilities Knowledge of transmitting sequence. Solar VHF receivers are excellent for MMARIA applications, either receiving solar radar signals or receiving other existing transmitters (FM, TV, existing meteor radars, etc.). Technical Requirement: Access to few (5-7) closely spaced antennas in parallel to any solar/astronomical application. We are currently evaluating such possibility with LOFAR.

16 Personal opinions on what to consider The US space science community needs a better coordination (or integration) between NSF Geospace and NSF Astronomy on solarrelated research. Similarly, a better coordination between NASA and NSF Geospace (e.g., would Geospace cubesats be a good idea for an NSF-MREFC?) The next Geospace NSF-MREFC? DASI-like small/large instruments or single Large facility (and clustered instrumentation)? DASI is not just about resources, national and international collaboration is crucial. Transformational science and/or Service? A facility with a significant better capability, or a network of standard instruments with 24/7 capabilities (analogy with Ocean, a ship or buoys?). Towards research or towards operations. One Giant facility or a Giant Umbrella of smaller systems?

18 Additional material

19 Tropospheric/Stratospheric forcing, e.g., planetary waves, tides, GWs Sun Ionosphere Forcing Magnetosphere Earth Ionosphere Lower atmosphere Solar/Magnetospheric forcing, e.g., geomagnetic storms [adapted from Marchavilas, 2007] Ionosphere

20 The wind field problem where for the monostatic case

21 Mesospheric winds and shears 100 Meteor winds from 3 days Altitude (km) Velocity (m/s) [from Larsen, 2002]

22 Example from Andenes-Trømso Selected Climatological Profiles Height (km) Temporal cuts over Andenes-Tromso (69.4N) U (VVP) V (VVP) Hor. div Rel. Vort. w, wtop = DOY: 160 Height (km) DOY: 185 Height (km) DOY: 210 Height (km) DOY: m/s m/s m/s/km m/s/km m/s

Solar Radiophysics with HF Radar

Solar Radiophysics with HF Radar Workshop on Solar Radiophysics With the Frequency Agile Solar Radiotelescope (FASR) 23-25 May 2002 Green Bank, WV Paul Rodriguez Information Technology Division Naval Research