On this page you’ll find the Current Geomagnetic Overview as observed by NOAA and the US Space Weather Prediction Centre.
A general overview of current conditions can be found on the space weather page.
Daily A Indicies over the past 30 days
The A-index was invented because there was a need to derive some kind of daily average level for geomagnetic activity. Because of the non-linear relationship of the K-scale to magnetometer fluctuations, it is not meaningful to take averages of a set of K indices. What is done instead is to convert each K back into a linear scale called the “equivalent three hourly range” a-index (note the lower case). The daily A index is merely the average of eight “a” indices. The following table illustrates the conversion between K and “a”:
The OVATION aurora forecast maps above use the latest solar wind condition data and formulates a forecast for the next 30 minutes approximately. This time frame is based on a solar wind speed of 800 km/s which is sometimes common following a coronal mass ejection (CME) passage. Delay times vary from less than 30 minutes to an hour or so for average solar wind conditions.
The USGS Geomagnetism Program currently operates 14 magnetic observatories.
Magnetometer data are collected at these facilities, and the data are then transmitted to Program headquarters in Golden Colorado. The geographic distribution of the Program’s observatories, shown below, has been determined by the need to monitor and study the geomagnetic field on a global scale, primarily for purposes of space-weather diagnosis and main field modelling and mapping, as well as the practical issues of availability of land, communication and operational logistics, and the relative locations of observatories operated by other foreign-national programs. Source and read more at USGS.