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Federal dataMaps & Geospatial
AP Index
Published by National Centers for Environmental Information · Updated 09/18/2015 · Monthly
- Last updated
- 09/18/2015
- Update frequency
- Monthly
- Formats
- Web only
- Coverage
- Nationwide
- Federal data
About this dataset
Planetary Amplitude index - Bartels 1951. The a-index ranges from 0 to 400 and represents a K-value converted to a linear scale in gammas (nanoTeslas)--a scale that measures equivalent disturbance am- plitude of a station at which K=9 has a lower limit of 400 gammas.
Files and access
Links open the official government source
- Global Change Master Directory (GCMD) Keywordsearthdata.nasa.govWeb page
Links open outside websites we do not control.
Frequently asked questions
- Who publishes AP Index?
- National Centers for Environmental Information, part of National Oceanic and Atmospheric Administration, Department of Commerce, publishes this dataset on Data.gov.
- How often is it updated?
- The publisher lists the update frequency as monthly. The last update was on 09/18/2015.
- How do I download it?
- Use the official source link above to view or request the data.
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- Index MapState of Virginia · Prince William County1" = 5280' map shows the County 5K and 10K grid overlay. Recommended print size: 31" X 37". --- ### 🔗 Related Datasets - [Index Map](https://odgavaprod.ogopendata.com//dataset/e74d2a92-340c-44b9-93aa-de80dc2e19a9) - *Prince William County* - [Base Map](https:ArcGIS RESTUpdated 03/23/2026
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Where this catalog comes from
- Data.gov CatalogU.S. General Services Administration
- State and local open data portalsSocrata Discovery API
- State and city CKAN portalsCalifornia, Virginia, Boston, Houston and more
- Government ArcGIS Hub sitesCity and county GIS data
Catalog checked 10/24/2026
We list dataset descriptions only. Downloads and APIs link straight to the official government source, which holds the current version and its terms of use.
Source: Data.gov · Last updated 10/24/2026 · Listing only; the data stays with the publisher
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