Thursday, January 16, 2020

Electricity Underfoot!

Graph of sudden changes in both the local magnetic field
and ground current at the Polarlightcenter geophysical
observatory in Lofoten, Norway, on January 6, when the Earth
apparently passed through a fold in the interplanetary
magnetic field. (Graph courtesy Rob Stammes /
Polarlightcenter, Norway < >)
CQ Propagation Editor Tomas Hood, NW7US, will be discussing in his February column the interplanetary magnetic field (IMF) on which the solar wind travels, and the fact that it resembles a wavy sheet, with a positive polarity on one side and a negative polarity on the other. When the Earth passes through one of these waves, it results in a quick flip-flop of the field's polarity as measured here, and that can have significant effects here on the ground. An apparent example occurred early this year. reported that, on January 6, electrical currents began flowing through the ground in Norway. Researcher Rob Stammes of the Polarlightcenter geophysical observatory (<>) reported measuring "a sudden strong variation in both ground currents and our local magnetic field" (see graph). Just 15 minutes earlier, according to the spaceweather report, NASA's ACE spacecraft detected a five-fold increase in the density of the solar wind and a 180-degree shift in the IMF's polarity. It was speculated that Earth had just passed through a fold in the heliospheric current sheet. 

These ground currents can cause significant problems here on Earth. Professor Louis Lanzerotti of the New Jersey Institute of Technology, an expert in the field, wrote on the HamSCI e-mail reflector that such currents have caused major power blackouts, such as the one that hit Quebec in 1989, as well as failures in undersea phone cables. 

The January 6 event also touched off auroras over Scandinavia. They were visible in Finland, but Stammes reported that the skies over his observatory in Lofoten, Norway, were cloudy so "we had to be satisfied with the electricity underfoot."