NOAA / Space Weather Prediction Center

Estimated Ap Forecast Verification

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Forecasts of Estimated Ap index are integer forecasts of the observed daily (24 hour) geomagnetic Ap index estimated by the USAF through 2011 and by NOAA from 2012 onward. Forecast lead times range from 1-day to 7-days. Verification results are provided on forecasts from July 1986 (the beginning of solar cycle 22) through December 2013. The USAF estimated Ap index is a real-time estimate of the official Göttingen Ap values using ground-based magnetometers at Meanook, Canada; Sitka, Alaska; Glenlea, Canada; Saint Johns, Canada; Ottawa, Canada; Newport, Washington; Fredericksburg, Virginia; Boulder, Colorado; and Fresno, California. A comparison of the USAF estimated Ap to the Göttingen Ap can be found in: Gehred, P.A., et al.: 1995, 'A Comparison of USAF Ap Indices to Göttingen Indices', NOAA Technical Memorandum, ERL SEL-88. The NOAA estimated Ap is a real-time estimated Ap currently derived from geomagnetic ground stations at Sitka, Alaska; Meanook, Canada; Ottawa, Canada; Fredericksburg, Virginia; Hartland, UK; Wingst, Germany; Niemegk, Germany; and Canberra, Australia.


Stats Table Thumbnail Statistics Summary Tables

Observations Thumbnail Estimated Ap Observed Plot

Joint Distribution Joint Distribution of Forecasts and Observations Plot

Quantile Thumbnail Conditional Quantile Plot

Stack Plot Thumbnail Forecast Mean Error, RMS Error, and Linear Association Plot

Skill Thumbnail Forecast Skill vs Lead Time