chaosmagpy.coordinate_utils.coupling_Newell

chaosmagpy.coordinate_utils.coupling_Newell(By, Bz, Vx)

Compute Newell’s coupling function from solar wind parameters.

Parameters:

Byndarray, shape (…)

Y-component of the IMF in GSM coordinates (nT).

Bzndarray, shape (…)

Z-component of the IMF in GSM coordinates (nT).

Vxndarray, shape (…)

X-component of the solar wind in GSM/GSE coordinates (km/s).

Returns:

Epsndarray, shape (…)

Newell’s coupling function.

Taundarray, shape (…)

Measure that maximizes for northward IMF.

Notes

Newell’s coupling function is proportional to the rate at which magnetic flux is openend on the dayside of the magnetopause through reconnection.

The original definition of the coupling function only differs in the factor \(10^{-3}\), which is included in the definition used here:

\[\begin{split}\epsilon &= 10^{-3} \mathit{V_x}^{4/3} B_T^{2/3} \sin\left(\frac{|\theta_c|}{2}\right)^{8/3} \\ \tau &= 10^{-3} \mathit{V_x}^{4/3} B_T^{2/3} \cos\left(\frac{|\theta_c|}{2}\right)^{8/3}\end{split}\]

where \(V_x\) is the solar wind speed in km/s, \(\theta_c\) is the clock angle and \(B_T\) the IMF strength in the y-z-plane of the GSM coordinate system in nT.