Estimation of geomagnetic activity using measure of anomalousness

Abstract

Herein, we present a newly developed indicator for estimating geomagnetic activity. It is based on the magnitude of measure of anomalousness (MA) of magnetometer recordings at a given time or interval. It is intended for automated estimation of geomagnetic activity level in the area of a specific magnetic station or in a given region using data of a set of stations. It reflects geomagnetic activity level at different observatories in a single scale [-1, 1], regardless of their latitudinal location and consequently typical disturbance amplitudes. To a certain extent MA indicator is an analog of traditional K index. However, a well-known shortcoming of the latter is its long, 3-hour update rate. Moreover, K index calculation requires subtraction of Sq variation that also causes delays. At the same time there is a demand for operational geomagnetic indices that have maximal time resolution and are available in near real-time. The proposed MA indicator aims to address the shortcomings of the traditional K index. The MA calculation may be implemented automatically with the same time resolution as the initial data are recorded.