pyrfu.pyrf.pvi_4sc module#

pyrfu.pyrf.pvi_4sc.pvi_4sc(b_mms)[source]#

Compute the Partial Variance of Increments (PVI) using the definition in [1] as

\[PVI_{ij}(t) = \sqrt{\frac{|\Delta B_{ij}(t)|^2} {\langle|\Delta B_{ij}|^2\rangle}}\]

where \(\Delta B_{ij}(t) = B_i(t) - B_i(t)\) is the magnetic field increments, the average \(\langle . \rangle\) is taken over the whole interval, and \(i\), \(j\) = 1,2,3,4 is the MMS spacecraft number.

In addition, computes, the rotation of the magnetic field between two spacecraft, i.e., magnetic field shear angle, as :

\[\alpha_{ij}(t) = cos^{-1} \frac{B_i(t) . B_j(t)}{|B_i(t)| |B_j(t)|}\]
Parameters:

b_mms (list of xarray.DataArray) – List of the time series of the background magnetic field for the 4 spacecraft.

Returns:

  • pvi_ij (xarray.DataArray) – Time series of the Partial Variance of Increments for the 6 pairs of spacecraft.

  • alpha_ij (xarray.DataArray) – Time series of the magnetic field shear angle for the 6 pairs of spacecraft.

References

[1]

Chasapis, A., Retinó, A., Sahraoui, F., Vaivads, A., Khotyaintsev, Yu. V., Sundkvist, D., et al. (2015) Thin current sheets and associated electron heating in turbulent space plasma. Astrophys. J. Lett. 804:L1. doi: https://doi.org/10.1088/2041-8205/804/1/L1