Making a main field model

Contents

Making a main field model#

Here we demonstrate how to make a simple time-independent main field model by fitting spherical harmonics to ground observatory measurements.

The principles of spherical harmonic analysis have been shown in the previous pages, so here we will take a shortcut and use utilties from ChaosMagPy.

ChaosMagPy, Clemens Kloss, https://doi.org/10.5281/zenodo.3352398
We will use:
- design_gauss to generate the design matrix for the inversion
- synth_values to run the forward model to get predictions for the magnetic field from our model

hvPlot is used to create some fancy visualisations but this library is more complex to use! so if you are newer to the Python ecosystem, you are better off using Matplotlib for your own work.

# Install pooch (not currently in VRE)
import sys
!{sys.executable} -m pip install pooch

import pooch
from chaosmagpy.model_utils import design_gauss, synth_values, power_spectrum
from chaosmagpy.plot_utils import plot_power_spectrum
import numpy as np
import pandas as pd
import xarray as xr
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature
import hvplot.xarray