pyrfu.pyrf.calc_agyro module#

pyrfu.pyrf.calc_agyro.calc_agyro(p_xyz: DataArray) → DataArray[source]#

Compute agyrotropy coefficient as

\[A\Phi = \frac{|P_{\perp 1} - P_{\perp 2}|}{P_{\perp 1} + P_{\perp 2}}\]
Parameters:

p_xyz (DataArray) – Time series of the pressure tensor

Returns:

Time series of the agyrotropy coefficient of the specie.

Return type:

DataArray

Raises:

  • TypeError – If input is not a xarray.DataArray.

  • ValueError – If input is not a time series of a tensor (n_time, 3, 3).

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_qq = mms.rotate_tensor(p_xyz_e, "fac", b_xyz, "qq")

Compute agyrotropy coefficient

>>> agyro_e = pyrf.calc_agyro(p_fac_e_qq)