pyrfu.pyrf.calc_sqrtq module#
- pyrfu.pyrf.calc_sqrtq.calc_sqrtq(p_xyz)[source]#
Computes agyrotropy coefficient as in [1]
\[Q = \frac{P_{12}^2 + P_{13}^2 + P_{23}^2} {P_\perp^2 + 2 P_\perp P_\parallel}\]- Parameters:
p_xyz (xarray.DataArray) – Time series of the pressure tensor
- Returns:
sqrt_q – Time series of the agyrotropy coefficient of the specie
- Return type:
References
[1]Swisdak, M. (2016), Quantifying gyrotropy in magnetic reconnection, Geophys. Res.Lett., 43, 43–49, doi: https://doi.org/10.1002/2015GL066980.
Examples
>>> from pyrfu import mms, pyrf
Time interval
>>> tint = ["2019-09-14T07:54:00.000","2019-09-14T08:11:00.000"]
Spacecraft index
>>> ic = 1
Load magnetic field and electron pressure tensor
>>> b_xyz = mms.get_data("b_gse_fgm_srvy_l2", tint, 1) >>> p_xyz_e = mms.get_data("pe_gse_fpi_fast_l2", tint, 1)
Rotate electron pressure tensor to field aligned coordinates
>>> p_fac_e_pp = mms.rotate_tensor(p_xyz_e, "fac", b_xyz, "pp")
Compute agyrotropy coefficient
>>> sqrt_q_e = pyrf.calc_sqrtq(p_fac_e_pp)