Exploring Solar Wind Turbulence Evolution in the Heliosphere

1. Nature, Distribution and Evolution of Solar Wind Turbulence throughout the Heliosphere W. H. MatthaeusBartol Research Institute, University of Delaware Collaborators: P. Dmitruk, S. Oughton, L. Milano, D. Mullan, G. Zank, R. Leamon, C Smith, D. Montgomery, J. Bieber, A. Burger, S. Parhi Seminar presented at Southwest Research Institute, December 5, 2003

2. The solar wind orginates in the dynamically active (turbulent) chromosphere and coronaSOHO spacecraft UV spectrograph: EIT 340 A White light coronagraph: LASCO C3

3. Large scale features of the solar wind • Plasma outflow, spiral magnetic field • High and low speed streams • North south distorted magnetic dipole • Wavy, equatorial current sheet

4. Large scale features of the Solar Wind: Ulysses • High latitude • Fast • Hot • steady • Comes from coronal holes • Low latitude • slow • “cooler” (40,000 K @ 1 AU) • nonsteady • Comes from streamer belt McComas et al, GRL, 1995

5. Heliospheric turbulence: Applications • Coronal heating • Solar wind heating • Solar modulation of cosmic rays • Spatial diffusion of solar energetic particles • turbulence and “space weather” • Possible influence on large scale heliospheric structure.

6. Interplanetary Alfven waves Belcher and Davis, 1971

7. Broadband self-similar spectra are a signature of cascade “Powerlaws everywhere” Interstellar medium: Armstrong et al • Solar wind • Corona • Diffuse ISM • Geophysical flows SW at 2.8 AU: Matthaeus and Goldstein Tidal channel: Grant, Stewart and Moilliet Coronal scintillation results (Harmon and Coles)

8. Standard powerlaw cascade picture

10. Two-dimensional turbulence and random-convection-driven reconnection

11. Heating the solar wind in the outer heliosphere (> 1 AU)

12. Something is heating the solar wind in the outer heliosphere (> 1 AU) Voyager proton temperatures Richardson et al, GRL, 1995

13. Phenomenological model for radial evolution of SW turbulence • Transport equations for turbulence energy Z2, energy-containing scale l, and temperature T • effect of large scale wind shear DV ~100 km/sec • wave generation by pickup ions associated with interstellar neutral gas • Anisotropic decay and heating phenomenology Matthaeus et al, 1996; Zank et al, 1996; Matthaeus et al, PRL, 1999; Smith et al, JGR, 2001; Isenberg et al, 2003

14. Solar Wind Heating • Perpendicular MHD cascade/transport theory accounts for radial evolution from 1 AU to >50 AU • Proton temperature ADIABATIC Matthaeus et al, PRL, 1999 Smith et al, JGR 2001 Isenberg et al, 2002

15. Results of turbulence transport theory in outer heliosphere Turbulence energy Proton temp. correlation scale

16. Evolution of Alfvenicity with radial distance

17. Cross helicity/ Alfvenicity Normalized measure of energy in fluctuations that propagate counter to or along the large scale magnetic field

18. Decrease of Alfvenicity with heliocentric distance Helios and Voyager data Roberts et al, 1987b

19. Helios data Z+ and Z- spectra Marsch and Tu

20. sc tends to increase in time (homogeneous turbulence) Theory based on Kraichnan 65 ideas: Dobrowolny et al, 1980 3D: Pouquet et al 1986 2D: Matthaeus et al, 1983

21. sc does not always increase! Stribling and Matthaeus, 1992

22. Velocity shear reduction of cross helicity observations simulations Roberts et al, JGR 1992

23. Expansion  reduction of cross helicity Linear transport effect Zhou and Matthaeus, 1988

24. Cross helicity (Alfvenicity) in solar wind Competition between effects that -- increase σc: dynamic alignment -- decrease σc: expansion, shear, pickup ions

25. Transport equations modified for nonzero cross helicity I. Decay constants attenuated in energy and correlation scale equations. II. New equation for normalized cross helicity:

26. Cross helicity transport: theory and observations IMPROVED MODEL: Transport equation solved in radius Boundary conditions and parameters (density. wind speed vary with latitude Include cross helicity

27. Transport and evolution of turbulence including cross helicity and latititude effects Energy Correlation scale Temperature Cross helicity Latitude effects

28. Ab Initio theory of the solar modulation of galactic cosmic rays

29. Solar modulation couples cosmic rays and turbulence locally and globally • Modulation code solves Parker transport equation for cosmic ray spectrum throughout heliosphere. • Solutions depend sensitively on diffusion coefficients (parallel and perpendicular)  These depend on local turbulence properties such as magnetic variance and correlation scale.

30. Bartol –Potch collaboration Parhi et al, 2003 Sample modulation result • CR energy spectrum at 1AU • Radial gradient in ecliptic plane • Latitudinal gradient at 2.1 AU Simultaneous solution for CRs and turbulence with good agreement with many observations!

31. SW natural laboratory for study of turbulence as a fundamental physical process A prototype for astrophysical turbulence Mediates cross scale couplings Enhances transport and heating Couples energetic particles to the plasma Couplings to Geospace environment Coronal heating Solar wind evolution Modulation Solar energetic particles Influences on large scale structure and dynamics Conclusions: We are moving towards understanding the spatial distribution and dynamical evolution of MHD turbulence throughout the heliosphere • Consequences for upcoming NASA mission • - Magnetospheric Multiscale (MMS) • - L1 Cluster/Constellation/Diamond • - Solar Probe • - Interstellar Probe Turbulence and energetic particle observations are now providing Simultaneous constraints on theory!

32. Waves – Turbulence—Transport • Interplanetary medium shows characteristics of both waves and turbulence • These mediate many dynamical processes in the heliosphere • Need to know: • Source • Dynamics, couplings: local effects • Transport properties– interaction with large scale structure  distribution of turbulence throughout heliosphere

33. Fine scale activity in the corona FE IX/X lines, TRACE Drawings from Coronagraphs (Loucif and Koutchmy, 1989)

34. Low frequency Nearly Incompressible Quasi-2D cascade • Dominant nonlinear activity involves k’s such that Tnonlinear(k) < TAlfven (k) • Transfer in perp direction, mainly • k perp >> k par

35. Turbulence in the heliosphere