Magnetic Poles¶
drift between 2010-01-01 and 2020-01-01¶
The calucation uses the Fortran libraty of Emmert et al.[2010[1] and wrapped by the apexpy Python package.
[1] Emmert, J. T., A. D. Richmond, and D. P. Drob (2010), A computationally compact representation of Magnetic-Apex and Quasi-Dipole coordinates with smooth base vectors, J. Geophys. Res., 115(A8), A08322, doi:10.1029/2010JA015326
In [1]:
from apexpy import Apex
def qd2geo(time, qdlat, qdlon, height=0, precision=1e-5):
""" Get geographic coordinates for the given QD coordinates. """
apex = Apex(time)
lat, lon, error = apex.qd2geo(qdlat, qdlon, height, precision)
if error > precision:
raise RuntimeError(
"The result precision %gdeg is not within the required limit %gdeg!"
"" % (error, precision)
)
return lat, lon
In [2]:
from datetime import datetime
from itertools import product
start_year = 2010
end_year = 2020
times = [datetime(year, 1, 1) for year in range(start_year, end_year + 1)]
In [3]:
magnetic_poles = [
(time, qd2geo(time, 90, 0), qd2geo(time, -90, 0))
for time in times
]
In [4]:
from pandas import DataFrame
DataFrame([
(t, nmp[0], nmp[1], smp[0], smp[1])
for t, nmp, smp in magnetic_poles
], columns = ("date", "northMagPoleLat", "northMagPoleLon", "southMagPoleLat", "southPoleLon"))
#DataFrame(magnetic_poles, columns=("date", "north_magnetic_pole", "south_magnetic_pole"))
Out[4]:
| date | northMagPoleLat | northMagPoleLon | southMagPoleLat | southPoleLon | |
|---|---|---|---|---|---|
| 0 | 2010-01-01 | 82.627205 | -83.919785 | -74.283615 | 126.011719 |
| 1 | 2011-01-01 | 82.716835 | -84.043762 | -74.303459 | 125.956863 |
| 2 | 2012-01-01 | 82.806381 | -84.168839 | -74.323334 | 125.902046 |
| 3 | 2013-01-01 | 82.895844 | -84.295052 | -74.343239 | 125.847267 |
| 4 | 2014-01-01 | 82.985222 | -84.422462 | -74.363159 | 125.792534 |
| 5 | 2015-01-01 | 83.074516 | -84.551102 | -74.383118 | 125.737839 |
| 6 | 2016-01-01 | 83.158089 | -84.696404 | -74.400307 | 125.661491 |
| 7 | 2017-01-01 | 83.241623 | -84.842804 | -74.417557 | 125.585182 |
| 8 | 2018-01-01 | 83.325127 | -84.990356 | -74.434868 | 125.508926 |
| 9 | 2019-01-01 | 83.408600 | -85.139091 | -74.452225 | 125.432732 |
| 10 | 2020-01-01 | 83.492035 | -85.289047 | -74.469643 | 125.356590 |
In [5]:
from matplotlib import pyplot as plt
#from cartopy import crs
from mpl_toolkits.basemap import Basemap
from numpy import arange, asarray
lats_nmp = asarray([v for _, (v, _), _ in magnetic_poles])
lons_nmp = asarray([v for _, (_, v), _ in magnetic_poles])
lats_smp = asarray([v for _, _, (v, _) in magnetic_poles])
lons_smp = asarray([v for _, _, (_, v) in magnetic_poles])
In [7]:
fig=plt.figure(figsize=(16, 16), dpi= 100, facecolor='w', edgecolor='k')
plt.subplot(121)
plt.title("north magnetic pole 2010 - 2020")
map = Basemap(projection='ortho', lon_0=0, lat_0=90)
map.drawcoastlines(color="silver")
map.fillcontinents(color=(1.0, 1.0, 0.9), lake_color=(0.9, 1.0, 1.0))
map.drawmapboundary(fill_color=(0.9, 1.0, 1.0))
map.drawmeridians([-135, -90, -45, 0, 45, 90, 135, 180], color="silver")
map.drawparallels([10, 20, 30, 40, 50, 60, 70], color="silver")
map.plot(lons_nmp, lats_nmp, 'r-', latlon=True)
h1, = map.plot(lons_nmp[0], lats_nmp[0], 'r+', latlon=True, markersize=8)
h2, = map.plot(lons_nmp[-1], lats_nmp[-1], 'rx', latlon=True, markersize=8)
plt.legend((h1, h2), (times[0].date(), times[-1].date()), loc=1)
plt.subplot(122)
plt.title("south magnetic pole 2010 - 2020")
map = Basemap(projection='ortho', lon_0=0, lat_0=-90)
map.drawcoastlines(color="silver")
map.fillcontinents(color=(1.0, 1.0, 0.9), lake_color=(0.9, 1.0, 1.0))
map.drawmapboundary(fill_color=(0.9, 1.0, 1.0))
map.drawmeridians([-135, -90, -45, 0, 45, 90, 135, 180], color="silver")
map.drawparallels([-70, -60, -50, -40, -30, -20, -10], color="silver")
map.plot(lons_smp, lats_smp, 'r-', latlon=True)
map.plot(lons_smp[0], lats_smp[0], 'r+', latlon=True, markersize=8)
map.plot(lons_smp[-1], lats_smp[-1], 'rx', latlon=True, markersize=8)
plt.legend((h1, h2), (times[0].date(), times[-1].date()), loc=1)
plt.show()
