Solar Wind Data

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Solar Wind Data

Solar Wind data has been propagated to the front of the magnetosphere (courtesy Dr. James Weygand) using the pseudo-minimum variance technique of Dan Weimer et al. [2003; 2004]. Data are included in both line plots and polar plots. ASCII data can be downloaded through the Data or Indices page.

Data gaps are indicated by 999999.

Clock angle:

where  is the interplanetary magnetic field y and z component (GSM coordinates).  Units are degrees.

The Epsilon Parameter:

where  is the clock angle,  is the solar wind speed, and .  Units are GW.

The Newell Coupling Function:

where  is the clock angle,  is the solar wind speed, and  is the interplanetary field magnitude. Units are Wb/s. The original function has been converted to Wb/s by multiplying by CMP = 100 to convert the units to Wb/s (based on the observational estimate made by Cai and Clauer [2013]).

Dynamic Pressure:

where  is the mass density.  We assume charge neutrality and that the ions and electrons have identical flow velocities.  Further assuming that the ions in the solar wind consist of 96% H+ and 4% He++ ions.  Hence for 1000 electrons there are 923 protons and 77 He ions.  Units are nPa.

References

Akasofu, S.-I. (1981) Energy coupling between the solar wind and the magneto- sphere, Space Sci. Rev., 28, 121.

Cai, X., and Clauer C. R. (2013), Magnetospheric sawtooth events during the solar cycle 23, J. Geophys. Res.: Space Physics, 118, 6378-6388, doi:10.1002/2013JA018819.

Newell, P. T., T. Sotirelis, K. Liou, C.-I. Meng, and F. J. Rich (2007), A nearly universal solar wind-magnetosphere coupling function inferred from 10 magnetospheric state variables, J. Geophys. Res., 112, A01206, doi:10.1029/2006JA012015.

Perreault, P., and S.-I. Akasofu (1978), A study of geomagnetic storms, Geophys. J. R. Astron. Soc., 54, 547–573.

Weimer, D.R., D.M. Ober, N.C. Maynard, M.R. Collier, D.J. McComas, N.F. Ness, C.W. Smith, and J. Watermann (2003), Predicting interplanetary magnetic field (IMF) propagation delay times using the minimum variance technique, J. Geophys. Res., 108, doi:10.1029/2002JA009405.

Weimer, D. R. (2004), Correction to ''Predicting interplanetary magnetic field (IMF) propagation delay times using the minimum variance technique’', J. Geophys. Res., 109, A12104, doi:10.1029/2004JA010691.