Spatial correlation of plasma sheet and solar wind turbulence from two point measurements

WEYGAND J.M.; MATTHAEUS W.H.; DASSO S.; KIVELSON M.G.

San Francisco, USA

Conferencia; American Geophysical Union, Fall Meeting 2006; 2006

AGU

Interplanetary turbulence is the best studied case of low frequency plasma turbulence and the only directly quantified instance of astrophysical turbulence. Here, correlation analysis of interplanetary magnetic and plasma sheet turbulence is carried out, using for the first time only proper two point, single time measurements, providing a key step in unraveling the space-time structure of interplanetary turbulence. Simultaneous solar magnetic field data from the ACE, Cluster, Geotail, IMP 8, and Wind spacecraft are analyzed to determine the spatial correlation function, the correlation (outer) scale, and the inner (Taylor) microscale near Earth orbit. The two standard length scales are used to determine the effective magnetic Reynold number and the other standard turbulence length scale, the Kolmogorov scale. The correlation scale is determined to be 1.2 Mkm, the Taylor scale is 2500 km, and the effective magnetic Reynolds number is calculated to be 230,000 from the ratio of the Taylor scale and the outer scale. The Cluster magnetic field data are investigated to obtain the correlation scale and the Taylor scale in the Earth's plasma sheet. The correlation scale calculated is 22,000 km, the Taylor scale is 2200 km, and the effective magnetic Reynolds number is 100. This two point correlation method provides us with a means of determining the effective magnetic Reynolds number without having to make estimates of conductivity or assumption about wave particle interactions.