Background magnetic spectra: ∼10−5 to ∼105 Hz

The Arrival Heights area of the Hut Point Peninsula on Ross Island has been designated the 2nd Site of Special Scientific Interest (SSSI) on the Antarctic continent. It is the only SSSI in Antarctica designated as a natural electromagnetically ‘quiet site’. As the electromagnetic noise levels of civilization increase world‐wide, such sites around the world, if preserved, will be of increasing scientific importance. We report here the determination of the amplitude and functional form of the geomagnetic fluctuations measured at Arrival Heights in June 1986. The frequency range covered is from ∼10−5 to ∼105 Hz, with a gap between ∼10−1 to ∼10¹ Hz due to instrumentation limitations. Over this frequency range, which is larger than any reported previously from any site on Earth, the magnetic field amplitude spectrum in units of / falls with increasing frequency f as ∼f−1 to ∼f−1.5, and has a value of ∼108/ at f∼10−3 Hz.