Customer announcement about upcoming changes to geomagnetic products and services

UPDATE: To ensure a smooth transition for all of our customers, the change in geomagnetic products originally scheduled for November 16th has been postponed until December 12th.
On December 12, 2011 the Space Weather Prediction Center (SWPC) will be making numerous changes to its geomagnetic product suite. SWPC’s nowcast and forecast products, alerts, watches, and warnings will transition to be based on an estimate or prediction of the Planetary indices Kp and Ap. Currently all of these products are based off of the K-index computed from the Boulder magnetometer and the A-index from Fredericksburg, Virginia.

A new, near-real time estimated Kp index is now possible thanks to the cooperative efforts between SWPC and data providers from around the world. Current contributors include the U.S. Geological Survey, the British Geological Survey, the Institut de Physique du Globe de Paris, and the Korea Communications commission. Near real-time magnetometer data is processed and used to estimate the Kp index on a minute-by-minute basis using the technique published by Takahashi et al., 2001 (JGR 106, A10, pp 21017). The new, near-real time, NOAA estimated Kp index will be the basis of geomagnetic alerts and warnings issued by SWPC, beginning on December 12. This change will bring the alerts and warnings into conformity with the NOAA space weather scales.

In addition, SWPC will begin to produce Ap and Kp forecasts as our primary quantity used to predict geomagnetic activity for the current day through three-day ahead forecasts. These predictions will become the basis for SWPC’s geomagnetic watch products, beginning on December 12. As with the alerts and warnings, this also brings SWPC geomagnetic watch products into conformity with the NOAA scales.

Users should note the NOAA’s Kp and Ap forecasts will appear on a new web page and will be a new, separate product from the Solar Geophysical Activity Report and Forecast (SGARF). This is because the SGARF is a joint product with the USAF and therefore will continue to have the USAF’s Ap forecast, but not NOAA’s Ap forecast. New activity probabilities for the planetary level of activity will also be produced which will have activity level descriptors that are consistent with the NOAA scales. The new NOAA Kp and Ap forecasts and associated probability forecasts will appear at the following link: New Web Page

The nowcast and forecast Kp/Ap parameters will be incorporated throughout SWPC products, web pages, and product subscription services. A detailed list of product changes can be found here: Product Changes

Detailed web page changes may be found here: Web Page Changes

Detailed PSS changes may be found here: PSS changes

Please note that forecasts for A-Fredericksburg, for mid-latitude K-indices, and for high latitude K-indices will continue to be supported but will be derived from the Ap and Kp forecasts using climatology tables.

Also note that joint NOAA-USAF products will remain unchanged and any references to the Kp or Ap in those products should be understood to be the USAF Kp/Ap predicted, estimated, or observed index. In addition, SWPC is considering the removal of the geomagnetic probabilities from the SGARF because the activity level descriptors are inconsistent with the NOAA scales. The change would only affect the SGARF; SWPC would continue to provide the mid and high latitude probability forecasts on the web page and in the 3 Day Space Weather Predictions text product (daypre.txt) so that users will have continuity. We are soliciting customer input concerning this change and are planning to make a final decision by December 2011. Please forward your comments to SWPC customer support at :

New Web Page (Content) for NOAA Ap/Kp forecasts

NOAA 3-day Geomagnetic Forecasts

NOAA Ap Index forecast
Observed Ap 04 Oct 006
Estimated Ap 05 Oct 018
Predicted Ap 06 Oct-08 Oct 015-008-008

NOAA Geomagnetic Activity Probabilities 06 Oct-08 Oct
Active                45/20/20
Minor storm           25/05/05
Moderate storm        05/01/01
Strong-Extreme storm  01/01/01

NOAA Kp Index forecast 06-08 Oct
                       Oct 06        Oct 07        Oct 08
00-03UT                   3             2             2
03-06UT                   3             1             1
06-09UT                   3             3             1
09-12UT                   3             2             1
12-15UT                   3             2             2
15-18UT                   3             2             2
18-21UT                   3             2             3
21-00UT                   3             2             3

Table of product changes

Product Description of change
K-index alerts & warnings Based on NOAA est Kp instead of Boulder
WWA GEOALERT Change observed AB to NOAA estimated Ap
WWV - nowcast portion
  1. Use NOAA estimated Kp instead of Boulder K
  2. Use NOAA Kp to specify NOAA scale level
Weekly (Daily Geomagnetic Data) change using USAF Kp/Ap to NOAA Kp/Ap
Weekly - Satellite Environment Plot Replace USAF Kp plot with NOAA Kp plot
A-index watches Based on predicted NOAA Ap instead of Afr
SGARF Generate Afr using climatology. (Add new web page with NOAA Ap/Kp forecasts)
Mid & High latitude K forecast Generate mid & high latitude K's using climatology
RWC GEOADVICE Base forecast conditions on Ap and update the category definitions
WWV - forecast portion Switch to predicted NOAA Kp/Ap to specify NOAA level scale
Weekly - 27 day forecast Use NOAA Ap forecast for first seven days

Table of web page changes

Web Page Description of change
Top level home page (index.html) Geomagnetic storms scale based on NOAA est Kp Satellite Environment Plot to use NOAA est Kp Drop the Boulder K plot
Today's space weather (today.html) Change Satellite Environment Plot to have NOAA est Kp and drop Boulder-K plot.
Space Weather Now (SWN) NOAA G scale driven by NOAA est Kp
Estimated Planetary K index: real-time and historic plots
  • Change from using USAF est Kp to NOAA est Kp
  • Change caption
  • Remove Boulder K plot
NOAA Space Weather Scales (NOAAscales/index.html) The text on the G-scale will be updated
Alerts web pages: K alerts & warnings (alerts/index.html) K-index alerts and warnings based on NOAA est Kp instead of Boulder
Alerts web pages: A watch (alerts/index.html) A-index watch based on NOAA Ap forecast instead of Fredericksburg
Alerts Geomagnetic K-indices Plot (alerts/k-index.html) Replace USAF est planetary with NOAA est planetary
Alerts Geomagnetic A-indices Plot (alerts/a-index.html) Replace USAF est planetary with NOAA est planetary
Geomagnetic & Solar Indices (solar_indices.html) Replace USAF Planetary with NOAA Planetary
Current Space Weather Indices (curind.txt) Estimated Planetary A and K indices change from USAF values to NOAA values
Geophysical Alert Message (wwv.txt)
  1. References to mid-latitude K-index and A-index change to estimated planetary K-index and A-Index
  2. Geomagnetic Storms past 24 hours are based on NOAA estimated Kp index
Glossary of Solar-Terrestrial Terms (glossary.html)
  • Ap index definition will be updated
  • estimated Kp definition will be updated
  • Geomagnetic activity definition will be updated
The K-index (Kindex.html) Text discussing Kp will be updated
Users Guide to the PRF (Weekly) (weekly/Usr_guide.pdf) Text discussing geomagnetic activity levels, the Kp and the Ap index will be updated
Daily Space Weather Indices (dayind.txt) Geomagnetic Indices: estimated planetary K-indices are derived from NOAA est Kp instead of USAF est Kp
Satellite Environment Plot Change from using USAF estimated Kp to using NOAA estimated Kp
Space Wx for Aviation (aviation/index.html) NOAA Scales Activity Chart driven by NOAA est Kp Est Planetary Kp plot switch to NOAA est Kp and drop Boulder K plot
Daily Geomagnetic Data (DGD.txt, quar_DGD.txt, yyyy_DGD.txt) Daily geomagnetic data - replace USAF est Kp with NOAA est Kp
Geomagnetic Data (AK.txt, 7day _AK.txt) Change Planetary K and A to read from NOAA est Kp and Ap (other *_AK.txt variations follow the same change)
Recent Solar Indices (weekly/RecentIndices.txt) Change note on source Ap for final month is NOAA estimated Ap Pull data from NOAA estimated Ap for final month
New Ap/Kp forecast web page (new) New product displaying NOAA's Ap and Kp forecast for next three days along with planetary geomagnetic probabilities.
3-day Space Weather Predictions (daypre.txt)
  1. A_Planetary switches to NOAA Ap predictions
  2. Add Predicted 3-hour Planetary K-indices section
  3. Add Probability of Planetary Geomagnetic conditions
  4. The Afr forecast, mid-latitude K forecast, high latitude K forecast will continue to be provided using climatology
Geophysical Alert Message (wwv.txt) Geomagnetic Storms for next 24 hours are based on predicted NOAA Ap/Kp indices

Table of Product Subscription Service changes (PSS)

PSS Service Description of change
Geomagnetic Storm Products K-index alerts and warnings based on NOAA est Kp instead of Boulder
WWV nowcast/forecast changes from Kb to Kp
Geoalert small change Ab to Ap
Geomagnetic Storm Products A-index watches will be based on NOAA predicted Ap index
Forecasts and Summaries Add new product with NOAA Ap/Kp forecast and planetary probabilities for geomagnetic activity (See example )