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Planetary turbulence

FP 7 STORM kick off meeting Brussels, 20 – 21 February, 2013 _________________________________________________________________________. Planetary turbulence. Z. Vörös Space Research Institute Austrian Academy of Sciences Graz, Austria Email: zoltan.voeroes@oeaw.ac.at. Outline. Methods

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Planetary turbulence

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  1. FP 7 STORM kick off meeting Brussels, 20 – 21 February, 2013 _________________________________________________________________________ Planetary turbulence Z. Vörös Space Research Institute Austrian Academy of Sciences Graz, Austria Email: zoltan.voeroes@oeaw.ac.at

  2. Outline • Methods • Observations • Future plans

  3. Methods • Single and multi-point measurements ESA/NASA spacecraft single and multi-point techniques Planned clusters of probes: Cluster (separations: 100s – 1000s km) Themis Artemis from 100s km to tens RE Non-planned configurations: Large separations mainly in the solar wind

  4. Methods • Approach • Fully developed turbulence • Description  fully statistical  second and higher order statistics • Wave turbulence • Description  statistical + wave modes .... and a mixture

  5. Methods - second order (Gaussian) - PSD ( matlab, eg. pwelch.m), wavelet, Hilbert transform, fractals (matlab libs) OUTPUT: spectral scaling, wave modes, dynamic spectra, anisotropy,etc. - correlation functions OUTPUT: de/correlation length, etc. • higher order (non-Gaussian) - Probability distribution function (PDF) of fluctuations - PDF moments, skewness, curtosis, etc. or L-moments better for short intervals - structure functions, LIM - multifractals • interdependence of statistical moments - nonlocality

  6. Methods can we observe intermittency? 1. NO 2. ???? non-stationarity mixing - second order (Gaussian) - PSD ( matlab, eg. pwelch.m), wavelet, Hilbert transform, fractals (matlab libs) OUTPUT: spectral scaling, wave modes, dynamic spectra, anisotropy, etc. - correlation functions OUTPUT: de/correlation length, etc. • higher order (non-Gaussian) - Probability distribution function (PDF) of fluctuations - PDF moments, skewness, curtosis, etc. or L-moments better for short intervals (matlab libs) - structure functions, LIM - multifractals • interdependence of statistical moments - nonlocality can we observe intermittency? 1. YES 2. ???? finite size effects in space??

  7. Observations • Intrinsic magnetospheres (Earth, Saturn) • Induced magnetospheres (Venus, Mars)

  8. Observations: Earth‘s magnetosphere Boundaries everywhere Walker et al., Space Sci.Rev., 1999 ~ 30-50 RE Bursty Flow 1-3RE e.g. Hughes, 1995; in K&R e.g. Kivelson & Russel, Intro to Space Physics,1995

  9. Observations: Earth‘s magnetosphere The first challange is that the magnetosphere is structured and the layers are thin  short in time The boundaries between different structures in terms of magnetic field, density, temperature, plasma beta, etc. are not always clear!! Warning: boundary crossing measurements lead to false intermittency spacecraft trajectory

  10. Turbulent spectra: geospace Downstream of the bow shock Alexandrova et al., 2004 slope:1.66 Cusp region Nykyri et al. 2006 slope:4.9 slope:2.4 Plasma sheet Volwerk et al., 2004 slope:3.5 slope:2.5-2.7 Magnetosheath Downstream of QP bow shock Yordanova et al., 2008

  11. Echim et al, 2007 ?? Magnetosheath LOBE CUSP Scale-dependent intermittency

  12. Observations: Earth‘s magnetosphere The first challange is that the magnetosphere is structured and the layers are thin  short in time The boundaries between different structures in terms of magnetic field, density, temperature, plasma beta, etc. are not always clear!! Warning boundary crossing measurements lead to false intermittency spacecraft trajectory The second challange is that the magnetosphere´s layers have finite thickness and are dynamically evolving in time and space; Warning false or different type of intermittency detection

  13. MAGNETOTAIL LOBE Vörös, 2013 Example of false intermittency due to the large-scale motions and flapping of the magnetotail

  14. Observations: Earth‘s magnetosphere The first challange is that the magnetosphere is structured and the layers are thin  short in time The boundaries between different structures in terms of magnetic field, density, temperature, plasma beta, etc. are not always clear!! Warning boundary crossing measurements lead to false intermittency spacecraft trajectory The second challange is that the magnetosphere´s layers have finite thickness and are dynamically evolving in time and space; Warning false or different type of intermittency detection The third challange is represented by scale-dependent instabilities and self-organisation: storm/substrom, reconnection. Warning false or different type of intermittency detection

  15. False intermittency due to multiple reconnection outflows Plasma sheet • Multiple flows: • (Intervals A, B) • V ~ (0-1000) km/s; •  ~ (0.5 – 3); • cf~ (0 – 150); • frequency ↛wavenumber. • Individual flows: • (e.g. interval C) • V ~ 750+- 150 km/s; •  ~ 2.5 +- 0.3; • cf >> 0 ; • frequency  wavenumber. Vörös et al. 2006

  16. Scaling within individual and multiple flows Independent driving sources Individual flows: stationary Multiple flows: mixed, non-stationary; signature of false intermittency

  17. Taylor hyp. is not working in slow/no tail flows TWO-POINT Spatial fluctuations between Cluster 1,4: Spatial temporal ONE-POINT Time-delayed fluctuations: (Vörös et al. 2006)

  18. Observations: VENUS (induced magnetosphere) Bow shock Vörös et al. 2008 Magnetopause

  19. Observations: VENUS (induced magnetosphere) Intermittency is present in turbulent boundaries over small scales. Vörös et al., 2008

  20. Observations: VENUS (induced magnetosphere) Hmmm...

  21. FUTURE PLANS = COLLECTING IDEAS

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