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A graph of sunspot counts from 1700 to 1993.
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Image courtesy NOAA/NGDC.

Metrics & Indices that Describe Space Weather

As with weather on Earth, there are space weather reports and forecasts. In these reports and forecasts, scientists use metrics and indices.

Just what are these metrics and indices? They are numbers that have to do with the different players in the space weather scene during that time period. One example might be the number of sunspots on the Sun at that time. The higher the number of sunspots, the more active the Sun is likely to be. The more active the Sun, the more flares or coronal mass ejections we might see coming from the Sun. So, you can see that number of sunspots is a good metric for telling how active the Sun will be.

Other metrics and indices deal with the solar wind, the magnetic field out in space (IMF), the Earth's magnetic field and the Earth's atmosphere.

Last modified September 11, 2008 by Randy Russell.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA