Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 2D solar wind speeds from 6 to 26 solar radii in solar cycle 24 by using
  Fourier filtering   Measurement of the solar wind speed near the Sun is important for
understanding the acceleration mechanism of the solar wind. In this study, we
determine 2D solar wind speeds from 6 to 26 solar radii by applying Fourier
motion filters to \textit{SOHO}/LASCO C3 movies observed from 1999 to 2010. Our
method successfully reproduces the original flow speeds in the artificially
generated data as well as streamer blobs. We measure 2D solar wind speeds from
1-day to 1-year timescales and their variation in solar cycle 24. We find that
the solar wind speeds at timescales longer than a month in the solar maximum
period are relatively uniform in the azimuthal direction, while they are
clearly bimodal in the minimum period, as expected from the \textit{Ulysses}
observations and IPS reconstruction. The bimodal structure appears at around
2006, becomes most distinctive in 2009, and abruptly disappears in 2010. The
radial evolution of the solar wind speeds resembles the Parker's solar wind
solution.

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The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th