Features of small-scale solar wind mass flux fluctuations

We analyze solar wind mass flux data measured with the PROGNOZ 8 satellite. The temporal resolution of the data reaches 0.02 sec, such that also the range is probed where finite Larmor radius effects become increasingly important. We find a general tendency for steepening of the power spectra towards higher frequencies, similar to what is observed in spectra of magnetic field fluctuations. A significant peak is found near f = 3.2 Hz in a high-resolution spectrum. Possible causes for this feature are discussed. Using the same data we also study the practical applicability of the wavelet transform as a tool for the analysis of non-stationary data with the emphasis on the search for transient spatial structures which are often not easily resolved using spectral analysis.