Main content | Navigation bar | Inside menu | Footer
Search: 

NAVIGATION BAR

INSIDE MENU
Back to Top


MAIN CONTENT
Back to Top

aa planetary index


The aa index (in units of 1 nT) is the simplest three hourly global geomagnetic activity index, in fact it is estimated by the data of only two geomagnetic observatories. These are approximately antipodal and at present are Hartland observatory in the UK and Canberra observatory in Australia. 

Map of the geomagnetic observatories used for the evaluation of the aa index.

The main advantage in using aa index for research purposes is that its time series is the longest available among all the planetary indices, in fact the first values dates back to 1868. 

 

Values of aa index can be requested at this address:
http://www.geomag.bgs.ac.uk/gifs/aaindex.html


FOOTER
Back to Top