Title: Analysis of Polar Motion Variations from 170-year Observation Series Authors: N. Miller, Z. Malkin
This work is devoted to investigation of low frequency variations in Polar motion (PM). It has been shown that the main PM features can be effectively investigated using not only time series of the Pole coordinates, but also using series of latitude variations obtained from observations at one observatory. Such an approach allows us to increase the length of observation series available for analysis. In our study, we extended the IERS PM series back to 1840. We investigate trends and (quasi) harmonic oscillations with periods from one year to decades. The main results were obtained making use of the Singular Spectrum Analysis. Other methods were also used for specific analysis and independent check. The most interesting results are detection of two new large phase jumps in the 1840s and 2000s, and revealing of 80-year period in the PM variations.
You may think of the North Pole only as the top of the worldits northernmost point and, if you're younger, Santa's home. But it turns out there are a host of "north (and south) poles" on our planet. First, and most simply, there is a town in Alaska called "North Pole" which isn't near any of the other north poles (but it does get snow and receives a lot of mail addressed to Santa Claus). Then there is the geographic north pole, also known as "true north." This is the spot in the Arctic Ocean where all the man-made lines of longitude converge on a map as well as the conceptual point on the ice-encrusted waters that countless explorers sought to stab with their national bannerbearing flagpoles, beginning in 1827 with British rear admiral, Sir William Edward Parry. Somewhat related to the geographic north pole is the considerably less famous instantaneous north pole, where Earth's rotational axis meets its surface, as well as the celestial north pole, where the axis spears the night sky (in an imaginary extension kind of way).