KT17 1.1.1

KT17/KT14 magnetic field model for Mercury written in C++ with a Python wrapper. See Korth et al., 2015 (JGR) and Korth et al., 2017 (GRL) for more details.

KT17

KT17/KT14 magnetic field model for Mercury written in C++ with a Python wrapper. See Korth et al., 2015 (JGR) and Korth et al., 2017 (GRL) for more details on the models themselves.

Installation

Best to install using pip3:

pip3 install KT17 --user

The installation will require the following packages:

• numpy
• scipy
• matplotlib

Alternatively clone this repo and build a wheel:

git clone https://github.com/mattkjames7/KT17.git
cd KT17
python3 setup.py bdist_wheel
pip3 install dist/KT17-1.0.0-py3-none-any.whl

NOTE: This module includes C++ code which does all of the model calculating and tracing. The package includes libkt.so for Linux and libkt.dll for Windows 10 - if either of these files can't be loaded, the code will attempt to recompile. If the compilation fails, then make sure that you have g++(version >= 5) and make installed on your system. For Windows users, install TDM-GCC.

Usage

Model parameters

Both KT17.ModelField() and KT17.TraceField() functions accept five different keyword arguments (**kwargs) which affect the model:

Parameter	Model	Description
Rsm	KT14	Magnetopause standoff distance (RM).
t1	KT14	Disk current field magnitude.
t2	KT14	Quasi-Harris sheet field magnitude.
Rsun	KT17	Distance of Mercury from the Sun (AU)
DistIndex	KT17	Anderson et al., 2013 disturbance index, in the range 0-97

If the KT17 parameters are provided, they are used to calculate the appropriate KT14 set of parameters as defined in Korth et al., 2017.

Obtaining model field vectors

To get model field vectors for some position(s) in the magnetosphere:

import KT17

#default model
Bx,By,Bz = KT17.ModelField(x,y,z)

#Custom KT14 model
Bx,By,Bz = KT17.ModelField(x,y,z,Rsm=1.3,t1=7.0,t2=2.5)

#Custom KT17 model
Bx,By,Bz = KT17.ModelField(x,y,z,Rsun=0.4,DistIndex=25.0)

where x, y and z are either scalars or arrays of position(s) in the MSM coordinate system. The returned Bx, By and Bz contain the magnetic field vector(s) at each position in nT. For positions which are outside of the magnetopause, the magnetic field components are returned as NAN.

Tracing the magnetic field

To trace the magnetic field, use the TraceField object:

T = KT17.TraceField(x0,y0,z0,**kwargs)

where x0, y0 and z0 are the starting position(s) of the traces in MSM coordinates. The parameters of the trace can be provided using **kwargs - see the KT17.Tracefield dosctring for more information using help(KT17.TraceField) or KT17.TraceField? in ipython.

TraceField can be saved to a file and reloaded, e.g.:

#save the Trace object
T.Save('Trace.bin')

#load the file
T = KT17.TraceField('Trace.bin')

Other routines

For a quick plot of the magnetic field in the X-Z plane run:

KT17.TestTrace()

To find out if a position in MSM coordinates is actually within the magnetopause or not, run the following:

KT17.WithinMP(x,y,z,Rsm=1.42)

To get the latitude and local times of the northern and southern open-closed field line boundaries, run:

ocb = KT17.ReadOCB()

where ocb is a numpy.recarray object which contains the following fields:

Mlt	Magnetic local time of the boundary.
LctN	Local time in the northern hemisphere.
LctS	Local time in the southern hemisphere.
Mlat	Invariant latitude of the boundary.
LatN	Latitude of the northern boundary.
LatS	Latitude of the southern boundary.

References

Anderson, B. J., Johnson, C. L., and Korth, H. (2013), A magnetic disturbance index for Mercury's magnetic field derived from MESSENGER Magnetometer data, Geochem. Geophys. Geosyst., 14, 3875– 3886, doi:10.1002/ggge.20242

Korth, H., Tsyganenko, N. A., Johnson, C. L., Philpott, L. C., Anderson, B. J., Al Asad, M. M., Solomon, S. C., and McNutt, R. L. (2015), Modular model for Mercury's magnetospheric magnetic field confined within the average observed magnetopause. J. Geophys. Res. Space Physics, 120, 4503– 4518. doi: 10.1002/2015JA021022.Korth, H., Tsyganenko, N. A., Johnson, C. L., Philpott, L. C., Anderson, B. J., Al Asad, M. M., Solomon, S. C., and McNutt, R. L. (2015), Modular model for Mercury's magnetospheric magnetic field confined within the average observed magnetopause. J. Geophys. Res. Space Physics, 120, 4503– 4518. doi: 10.1002/2015JA021022.

Korth, H., Johnson, C. L., Philpott, L., Tsyganenko, N. A., & Anderson, B. J. (2017). A dynamic model of Mercury's magnetospheric magnetic field. Geophysical Research Letters, 44, 10,147– 10,154. https://doi.org/10.1002/2017GL074699