Ap index

Ap index

A space weather related index that denotes a formally determined value from the daily, mean 3-hourly equivalent amplitude of magnetic activity from a planetary network of 11 Northern and 2 Southern Hemisphere magnetic observatories. It is a measure of the global scale of disturbance of the Earth's magnetic field and correlates to the breadth of the auroral oval.

GFZ German Research Centre for Geosciences, 2018: Indices of global geomagnetic activity. Accessed 13 August 2018. Available at https://www.gfz-potsdam.de/en/kp-index/.

Space Weather Prediction Center, 2018: Station K and A indices. Accessed 13 August 2018. Available at https://www.swpc.noaa.gov/products/station-k-and-indices.

Term edited 13 August 2018.

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A space weather related index that denotes a formally determined value from the daily, mean 3-hourly equivalent amplitude of magnetic activity from a planetary network of 11 Northern and 2 Southern Hemisphere magnetic observatories. It is a measure of the global scale of disturbance of the Earth's magnetic field and correlates to the breadth of the auroral oval.

Measure of the effective concentration of a chemical in the gas or liquid phase.