South Magnetic Pole

Locations of South Magnetic Pole from direct observation and model prediction.^[1]

The South Magnetic Pole is the wandering point on the Earth's Southern Hemisphere where the geomagnetic field lines are directed vertically upwards. It should not be confused with the lesser known South Geomagnetic Pole described later.

For historical reasons, the "end" of a magnet that points (roughly) north is itself called the "north pole" of the magnet, and the other end, pointing south, is called magnet's "south pole". Because opposite poles attract, the Earth's South Magnetic Pole is physically actually a magnetic north pole (see also North Magnetic Pole – Polarity).

The South Magnetic Pole is constantly shifting due to changes in the Earth's magnetic field. As of 2005 it was calculated to lie at 64°31′48″S 137°51′36″E / 64.53000°S 137.86000°E / -64.53000; 137.86000,^[2] placing it off the coast of Antarctica, between Adelie Land and Wilkes Land. That point lies outside the Antarctic Circle. Due to polar drift, the pole is moving northwest by about 10 to 15 kilometers per year. Its current distance from the actual Geographic South Pole is approximately 2860 km.^[1] The nearest permanent science station is Dumont d'Urville Station. Wilkes Land contains a large gravitational mass concentration.

Expeditions

Early unsuccessful attempts to reach the South Magnetic Pole included those of French explorer Dumont d'Urville (1837–40), American Charles Wilkes (expedition of 1838–42) and Briton James Clark Ross (expedition of 1839–43).^[5]

The first calculation of the magnetic inclination to locate the magnetic South Pole was made January 23, 1838 by the hydrographer Clément Adrien Vincendon-Dumoulin (fr), member of the Dumont d'Urville expedition in Antarctica and Oceania on the Corvettes "L'Astrolabe "and" Zélée "in 1837-1840, expedition who discovered the Adelie Land.

On 16 January 1909 three men (Douglas Mawson, Edgeworth David, and Alistair Mackay) from Sir Ernest Shackleton's Nimrod Expedition claimed to have found the South Magnetic Pole,^[6] which was at that time located on land. However, there is now some doubt as to whether their location was correct.^[7]

The approximate position of the pole on 16 January 1909 was 72°15′S 155°09′E / 72.25°S 155.15°E / -72.25; 155.15.^[8]

Fits to global data sets

The South Magnetic Pole has also been estimated by fits to global sets of data such as the World Magnetic Model (WMM) and the International Geomagnetic Reference Model (IGRF).^[1] For earlier years back to about 1600, the model GUFM1 is used, based on a compilation of data from ship logs.^[9]

South Geomagnetic Pole

The Earth's geomagnetic field can be approximated by a tilted dipole (like a bar magnet) placed at the center of the Earth. The South Geomagnetic Pole is the point where the axis of this best-fitting tilted dipole intersects the Earth's surface in the southern hemisphere. As of 2005 it was calculated to be located at 79°44′S 108°13′E / 79.74°S 108.22°E / -79.74; 108.22,^[10] near the Vostok Station. Because the field is not an exact dipole, the South Geomagnetic Pole does not coincide with the South Magnetic Pole. Furthermore, the South Geomagnetic Pole is wandering for the same reason its northern magnetic counterpart wanders.

See also

Book: Geomagnetism

• North Magnetic Pole
• Polar alignment

References

External links

• Australian Antarctic Division