Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantifying the Anisotropy and Solar Cycle Dependence of "$1/f$" Solar
  Wind Fluctuations Observed by Ace   The power spectrum of the evolving solar wind shows evidence of a spectral
break between an inertial range of turbulent fluctuations at higher frequencies
and a "$1/f$" like region at lower frequencies. In the ecliptic plane at $\sim
1$ AU, this break occurs approximately at timescales of a few hours, and is
observed in the power spectra of components of velocity and magnetic field. The
"$1/f$" energy range is of more direct coronal origin than the inertial range,
and carries signatures of the complex magnetic field structure of the solar
corona, and of footpoint stirring in the solar photosphere. To quantify the
scaling properties we use generic statistical methods such as generalised
structure functions and PDFs, focusing on solar cycle dependence and on
anisotropy with respect to the background magnetic field. We present structure
function analysis of magnetic and velocity field fluctuations, using a novel
technique to decompose the fluctuations into directions parallel and
perpendicular to the mean local background magnetic field. Whilst the magnetic
field is close to "$1/f$", we show that the velocity field is "$1/f^{\alpha}$"
with $\alpha\neq1$. For the velocity, the value of $\alpha$ varies between
parallel and perpendicular fluctuations and with the solar cycle. There is also
variation in $\alpha$ with solar wind speed. We have examined the PDFs in the
fast, quiet solar wind and intriguingly, whilst parallel and perpendicular are
distinct, both the ${\boldmath$B$}$ field and velocity show the same PDF of
their perpendicular flucutations, which is close to gamma or inverse Gumbel.
These results point to distinct physical processes in the corona, and to their
mapping out into the solar wind. The scaling exponents obtained constrain the
models for these processes.

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The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
3
The categories of this paper are: physics
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The categories of this paper are: eess
0
The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg