Solar wind parameters

Using WIND data, check the statistical view of solar wind paramters.

WIND data at is taken from so-called P-FILES in MIT. It has ~96s resolution, which is about the double faster than IMAs of ASPERA-3/-4. So far only plasma data is considered.

The data coverage is from 2004 to mid-2013.

Data file

The data file is a text format. File name is rdP2009002.01, for example, namely rdpYYYYDOI.VE with YYYY the year DOI the day of year, and VE the version number.

The data is taken by WIND, aroudn L-1 point, and the abberation is “removed”. This means that the solar wind velocity at t0 is described in the datafile in the frame being defined at t0. The motion of the frame is NOT considered.

Distribution of the solar wind paramters

Simple analysis was done by making the histogram of parameters. See appl_130717_swparam_statistics.histall script.

Result

The plot shows the histograms of parameters. The blue curve is the histogram, red is the average +/- std, and green is median with 15/85 % percentile (about 1 sigma).

Here phi is the angle in the ecliptic plane. 0 is Sun-Earth line, + sign is +y component (note that the Solar wind has -x component) and - is -y component.

I am interested in angles more in detail. The phi is almost -0.3 degrees with standard deviation of ~3.0. This is consistent with the statement of “corrected abbrevaioation”, otherwise the phi should be biased to center at about +4 degrees. It is also noted that the Sun rotates at the speed of ~1.6 km/s and thus the solar wind may have that component in (mainly) -y component. This indicate that about -0.23 degrees of phi component may exist suppose the solar wind velocity to be 400 km/s.

The theta is peaks at around 0, while the average and emdian shift slightly in - direction. The s.td = 2.60.

The thermal spread is 3.0 – 6.0 degrees.

Conclusion

The solar wind is a beam with angular spread of ~4.5 (3-6) degrees aligned to -x direction, with deviation about 3 degrees. All the standard errors here is 1 sigma.