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Office of Climate, Water, and Weather Services

Integrated Service Change Plan
Termination of Solar Wind Data and Changes to Associated Products

Reason for service change: The NASA Advanced Composition Explorer (ACE) satellite was launched on August 25, 1997, with a design life of 5 years. The satellite continues to provide real-time solar wind data, but some of the instruments have already ceased to operate or are showing signs of degradation. At the current time there is no plan to replace ACE when the satellite or onboard instruments cease to function.

This integrated service change plan is designed to alert users of the ACE data and associated products of changes in space weather products or service given the loss of data from the ACE satellite. The following categories of data and/or products will be impacted by the loss of ACE.

List of those data/products which will be terminated entirely: There is no current plan to continue the provision of the following data and products in the event of ACE satellite failure:

  • Real-time solar wind plasma, particle, and magnetic field data
  • Geomagnetic sudden impulse warning
  • Radiation belt electron model output     
  • Geomagnetic activity prediction model (Forecasters use the Costello Model in formulating the Solar and Geophysical Activity Report and 3-Day Forecast Product)
  • Electron, Proton, and Alpha Monitor (EPAM) low-energy ion data (Forecasters use these data to predict the arrival of an interplanetary shock, and the intensity of the ensuing geomagnetic storm.

List of those data/products which will be substantially modified (impacted) and a description of the impact on each product

  • Geomagnetic storm magnitude warnings, i.e., K4, K5, K6, K7 (NOAA Scale level G1, G2, G3 - (K4 not on NOAA Scale))
    • Impact: 80% degradation in both the timing and accuracy of the warning
  •  Geomagnetic storm magnitude watches, i.e., A20, A30, A50, A100
    • Impact: 30%  degradation in both the timing and accuracy of the watch
  •  Middle and High Latitude three-day geomagnetic activity forecasts
    • Impact: 30% degradation of forecast skill
  •  Daily Space Weather briefing to Space Radiation Analysis Group (NASA)
    • Impact: 10% degradation of forecast skill
  •  Daily forecast of energetic electron flux/fluence at geosynchronous orbit
    • Impact: 80% degradation of forecast skill
  •  International Space Environment Service (ISES) daily World Warning Agency (WWA) summary forecast
    • Impact: 15% degradation of forecast skill
  •  Solar radiation storm warnings, i.e., NOAA Scale S1, S2, S3, S4, S5
    • Impact: 5% degradation in both the timing and accuracy of the warning
  • Three-hourly WWV/WWVH space weather summary and forecast
    • Impact: 15% degradation of forecast skill

List of those data/products whose service level remains unchanged

  • 26/37 of event-driven and 21/28 of routine products generated by SEC are unchanged. The following list identifies the event-driven products that are unaffected.
    • Solar flare alerts, i.e., NOAA Scale R2, R3, R4, R5
    • Geomagnetic storm magnitude alerts, i.e., K4, K5, K6, K7, K8, K9 (NOAA Scale level G1, G2, G3, G4, G5)
    • Solar radiation storm magnitude alerts, i.e., S1, S2, S3, S4, S5
    • Geomagnetic sudden impulse alert
    • Energetic electron flux alert

Alternative sources of data/products (as appropriate): None known.

When and how plan will take effect:
This integrated service change plan is not for a planned disruption of services, but rather in anticipation of the day the satellite or the onboard instruments will ultimately fail.  This plan will be implemented in two phases: first, as an avenue for seeking public comment on proposed changes to space weather products/services given ACE failure; and second, as a plan to notify the public of the demise of the ACE satellite or its instruments.  Some instruments have already experienced degradation and failure. NASA asserts there is sufficient fuel to control ACE until about 2022, and sufficient power output from the solar panels until 2025. The service change will be effective upon satellite failure.  Once failure of the ACE is confirmed a notice to that effect will be posted on the Space Environment Center web site, and a short notice Public Information Statement (PNS) would be issued.

Comment period:  NWS will invite public comment from users of solar wind data and products derived from such data.  Those comments will be incorporated into future plans to best meet the needs of the users.  The public comment period will be for 45 days, commencing no later than the 5th working day after this plan is approved for public release. Send comments and questions to the point of contact listed below.

Points of Contact (email preferred):

Beth McNulty, 301-713-1726 x116
Dorothy Haldeman, 301-713-1726 x130
Mail to:
National Weather Service
Office of Climate, Water and Weather Services
Aviation Services Branch
1325 East-West Highway, SSMC 2
Silver Spring MD 20910

NOAA, National Weather Service
Office of Climate, Water, and Weather Services
1325 East West Highway
Silver Spring, MD 20910
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Last Updated: April 3, 2006