The first Russian Antarctic expedition of 1819—1821 led by Russian naval officers Thaddeus Bellingshausen and Mikhail Lazarev proved that the assumption about the existence of the sixth continent—was right. The Russian Antarctic expedition was a complete success and became (after James Cook) the second expedition to travel round the entire Antarctica and the first to prove that this continent existed (Bellingshausen, 2008). Observations by means of the ship compass during this expedition helped make the first instrumental measurement of the SMP position (Fig. 2, Table 1).
In 1841, during a sea expedition aimed at determining the position of the magnetic pole in the Southern Hemisphere, James Clark Ross managed to reach a point 250 km away from the magnetic pole and determine its position by a series of magnetic dip measurements (Dyachenko, 2003). A year before that, the expeditions led by D’Urville and Wilkes had also provided measurements of the SMP position. All the four determinations indicated that the SMP should have been within Victoria Land in the 133°—155° E sector and 71°—76° S sector, east of the Ross Sea (Table 1, Fig. 2). It is important to note that, although the SMP position was obtained in the 19th century without a direct visit, the scatter in coordinates turned out to be small relative to the Antarctic area (a sector of 500 km in longitude and 600 km in latitude) and shifted about 1800 km away from the South Geographical Pole. These determinations are important not only from a historical perspective (Table 1, Fig. 2). The pole position determined by the IGRF-13 model (Alken et al., 2021) is not more than 200 km away from the point indicated by J. Ross almost 200 years ago (Fig. 2).
It is generally believed that the SMP was reached by Shackleton’s expedition team in 1909. Despite the Herculean efforts of the team, given the circumstances of the time, the vertical inclination was determined once and without proper verification of the measurement results (Dyachenko, 2003). The SMP was more than 200 km away from the next determination in 1912, which corresponds to a linear movement velocity of 69.6 km/year during three years, which is unlikely according to the studied dynamics of the SMP shift. It is an interesting fact that the point of Shackleton’s expedition is in the epicenter of a positive magnetic field anomaly (Fig. 2b), which could have caused an additional error in determining the magnetic pole coordinates. The 1912 coordinates have to be considered unreliable, because they give an estimated velocity of 72 and 3.9 km/year from 1909 to 1912 and from 1912 to 1931, respectively.
According to subsequent instrumental determinations (in 1931, 1952, 1962), the SMP movement occurred at a strictly aligned azimuth (308 degrees, northwest) and at an average velocity of 15.4 km/year. The pole shift curve according to the IGRF-13 model runs along a more complex trajectory and at a variable velocity, but near the points of instrumental measurements. Just like Shackleton’s point, the 1952 and 1962 determinations gravitate toward local positive magnetic field anomalies.
In the first half of the 1960s, the SMP moved from land to the D’Urville Sea. The magnetic pole coordinates were first determined under marine conditions by the USSR Navy ships during the USSR Black Sea Fleet Hydrographic Service expedition on board the ORV Admiral Vladimirsky and Thaddeus Bellingshausen (1983–1984) according to a special program (Minligareev et al., 2020) (Fig. 3).
The fact of determining the pole coordinates is shown in a historical photograph of a buoy with the inscription: “South Magnetic Pole. February 3, 1983” taken by the Thaddeus Bellingshausen hydrographers (Zolotaykin, 2007) (Fig. 4).
At that time, the SMP was about 70 km away from the mainland and about 20 km away from the glacier edge. From 1962 to 1983, the average movement velocity was 10.7 km/year at an azimuth of 355 degrees (Fig. 2, Table 2).
Two subsequent instrumental determinations of the SMP were made in 1986 and 2000 by Australian scientists on board the Sir Hubert Wilkins (Barton, 2002). In the latter case, the problem was solved with a specially designed magnetometer which could measure the horizontal components of the magnetic field. The equipment was towed behind the ship on a nonmagnetic structure and was enclosed in Helmholtz coils to compensate for the ship’s interference with the magnetometer readings (Fig. 5). Charles Barton and his colleagues in their paper by (Barton, 2002) note that the only drawback of their methodology was that there was no accounting for variation, which caused the pole to “run” over the measurement area from day to day. And this is a very important fact, because during the expedition on board the ORV Admiral Vladimirsky (2019–2020), the EMF variations were taken into account based on magnetic observatories in Antarctica and on differential magnetometric measurements.
From 1983 to 2000, the SMP shifted 245 km at an average velocity of 6.6 km/year. At each successive time segment at sea, there is a consistent decrease in the movement velocity, in fact, from 18 to 6.5 km/year. This means that over the past 60 years, the SMP movement velocity has significantly decreased.
The deviation of the pole shift trajectory according to the IGRF-13 model in the 1983, 1986, and 2000 offshore SMP surveys is significantly less than that of the onshore determinations. This fact is certainly attributed to the use of a larger amount of updated and highly accurate information (satellite, magnetic variation) in constructing the normal-field model. At the same time, the offshore determinations themselves are more accurate, since, unlike onshore observations, they are made by continuous area measurements and in a much shorter time period, which minimizes the pole “wandering” effect in the presence of magnetic variations.
Beginning in 2016, the unusually high SMP movement velocity led to serious errors in the 2015 model calculations. To correct these types of errors, an early update of the EMF models began in early 2019. In February 2019, the US National Geophysical Data Center (NGDC) updated the international WMM model. In December 2019, the International Association of Geomagnetism and Aeronomy (IAGA) released another version of the IGRF-13 model (Minligareev et al., 2020).