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

The solar wind orginates in the dynamically active (turbulent) chromosphere and corona SOHO spacecraft UV spectrograph: EIT 340 AWhite light coronagraph: LASCO C3

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

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

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.

Interplanetary Alfven waves Belcher and Davis, 1971

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

Standard powerlaw cascade picture

Two-dimensional turbulence and random-convection-driven reconnection

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

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

Phenomenological model for radial evolution of SW turbulence Transport equations for turbulence energy Z 2, energy-containing scale  and temperature T effect of large scale wind shear  V ~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

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

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

Evolution of Alfvenicity with radial distance

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

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

Helios data Marsch and Tu Z+ and Z- spectra

 c tends to increase in time (homogeneous turbulence) 3D: Pouquet et al 1986 Theory based on Kraichnan 65 ideas: Dobrowolny et al, D: Matthaeus et al, 1983

 c does not always increase! Stribling and Matthaeus, 1992

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

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

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

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

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

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

Ab Initio theory of the solar modulation of galactic cosmic rays

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.

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! Bartol –Potch collaboration Parhi et al, 2003

Conclusions: We are moving towards understanding the spatial distribution and dynamical evolution of MHD turbulence throughout the heliosphere 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 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!

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

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

Low frequency Nearly Incompressible Quasi-2D cascade Dominant nonlinear activity involves k’s such that T nonlinear (k) < T Alfven (k) Transfer in perp direction, mainly k perp >> k par

Turbulence in the heliosphere