Evolution of Solar Wind Fluctuations Across Fast Interplanetary Shocks in Different Heliocentric Distances
Abstrakt
We investigate changes of spectral properties of interplanetary magnetic field fluctuations across different types of interplanetary (IP) shocks at 1 AU. We already found that these properties are conserved for all types of shocks if the re-scaling of the characteristic ion lengths is considered.
Nevertheless, the results obtained for fast reverse (FR) shocks are not so conclusive because our set of these shocks is limited and the spectral slope in the transition range of frequencies exhibit strong flattening across the shock. Nevertheless, FR shocks are naturally related mostly to high-speed streams and thus their upstream properties are, in a statistical sense, different than those of other shock types.
For this reason, we enlarged our data sets using observations of all available spacecraft providing data with a sufficient time resolution (PSP, Solar Orbiter, Wind, ACE, Stereo, DISCOVR, Maven) and compare fast forward (FF) and FR shocks. We analyze variations of turbulence properties as magnetic field intermittency, cross-helicity and others across both FF and FR shock types and study their relation to upstream conditions.
The new enlarged set of IP shocks allowed us to select a sufficient number of FF shocks with the upstream parameters similar to those upstream of FR shocks and a comparison of these two sets suggests that upstream environment govern the dissipating mechanisms and the spectral properties of turbulence transmitted downstream. This conclusion is valid for the whole range of investigated heliospheric distances.