The MANA Magnetometer Array, and Magnetic Observations Across New Zealand From 2024

Disturbances of Earth’s magnetic field lead to the generation of geomagnetically induced currents (GICs) in infrastructure like power grids, which can cause damage and even power grid blackouts in some extreme cases. Thus, observations of the magnetic field are of practical importance. The Magnetometer Array for New Zealand Aotearoa (MANA) magnetometer array, set up to monitor these disturbances in New Zealand, is described. The network is made up of five magnetometers, devices that measure the Earth’s magnetic field. An explanation of how the network operates is given. It collects magnetic field data every second, and even faster if needed. These data are also live plotted on the MANA website (https://solartsunamis.otago.ac.nz/mana/data/). The paper shares examples of two very significant geomagnetic storms recorded in 2024. The first, in May, was the biggest storm in New Zealand since 1994, in terms of the rate of change of H, the magnetic field strength that points toward geomagnetic north. The second, in October, was the fifth largest storm since 1994. These storms peaked in New Zealand about 10 hr after the biggest global peaks, showing that local factors influenced what happened. These local factors were likely due to substorms, a magnetic field disturbance related to the night side of the Earth.