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• A daily index of geomagnetic activity derived as the average of the eight 3-hourly a indices.

  NOAA National Weather Service - Cite This Source - This Definition
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  Cite Definition for A Index

  American Psychological Association (APA)

  A Index. (n.d.). National Weather Service Glossary. Retrieved March 28, 2023, from website: http://www.expertglossary.com/definition/a-index.

  Chicago Manual of Style (CMS)

  A Index. www.weather.gov. National Weather Service Glossary. NOAA National Weather Service. http://www.expertglossary.com/definition/a-index (accessed: March 28, 2023).

  Modern Language Association (MLA)

  "A Index." National Weather Service Glossary. NOAA National Weather Service. 28 March. 2023 http://www.expertglossary.com/definition/a-index.

• Browse Related Terms: A Index, AVG, Climate, Composite, Maximum Sustained Surface Wind, mean, Mean Annual Temperature, Meteorology, Rogue Wave, Significant wave height, Smoothed Sunspot Number, Sustained Wind