Analysis of Multi-Dimensional Correlation Functions in the Solar Wind

Single-spacecraft techniques for the determination of multi-dimensional correlation functions in the solar wind were pioneered by [4]. Their production of the so-called "Maltese Cross" result shows that magnetic f uctuations near the correlation scale at 1 AU are divided into two components: quasi-parallel and quasi-perpendicular wave vectors. A later ref nement by [2] revealed that the two components were largely separated according to wind speed with the slow wind possessing largely perpendicular wave vectors and the fast wind possessing largely parallel wave vectors. We extend those analyses using four different techniques and compare the results of those techniques. As a demonstration of the techniques, we analyze the geometry of magnetic f uctuations at scales comparable to the correlation length. We then examine the underlying geometry for magnetic, velocity, density and temperature f uctuations. We limit the analysis to fast wind observations and show that the underlying geometry for density and temperature f uctuations is a good match to that of magnetic and velocity f uctuations.