NWS Logo


Space Weather Prediction Center

National Oceanic and Atmospheric Administration

Sunday, August 07, 2022 18:59:32

Main menu

NOAA Scales mini

minimize icon
Space Weather Conditions
24-Hour Observed Maximums
no data
no data
no data
Latest Observed
no data
no data
no data
R1-R2 --
R3-R5 --
S1 or greater --
no data
R1-R2 --
R3-R5 --
S1 or greater --
no data
R1-R2 --
R3-R5 --
S1 or greater --
no data
maximize icon
no data
no data
no data
Current Space Weather Conditions
R1 (Minor) Radio Blackout Impacts
HF Radio: Weak or minor degradation of HF radio communication on sunlit side, occasional loss of radio contact.
Navigation: Low-frequency navigation signals degraded for brief intervals.
More about the NOAA Space Weather Scales

2001 Workshop Wrap Up

Issues by Industry

Part of the benefit of Space Weather Week was to hear what negative space weather impacts are experienced by various customers, and what information they find useful.

Effects on Navigation

  • Although there has been extensive science put to the problem, the knowledge of what users' really want is still sparse.
  • The FAA is becoming increasingly aware of ionospheric impacts on WAAS. (The Wide Area Augmentation System allows aircraft to land and fly using GPS as their principal position-finding tool).
  • The WAAS program does not use modelling but interpolates between measurements of the ionosphere.

Effects on HF propagation

Several airlines are flying commercial flights routinely over the polar cap. They are concerned about navigation, radiation, and communications (especially for contact with Air Traffic Control (ATC) centers on the Russian side of the Pole, which have HF capability only, for safety when changing routes or altitudes is desirable.

  • Space weather plays into routing decisions, e.g., the airline will delay or reroute a flight if a category S4 (severe) or S5 (extreme) solar radiation storm is in progress or expected.
  • Flight crew members expressed a desire for plain language, i.e., easy to interpret alerts, and warnings for S4 or S5 storms. (SWO has created plain language alerts and warnings, expressed in NOAA Space Weather Scale terms. Hopefully, these will be on-line within the next few months.)

Effects on Electric Power Industry

  • Eastward convective electrojet which occurs as a nearly immediate response to enhanced v x Bs conditions may well have been related to many problems that occurred in electrical power systems in the local evening hours. It is important for forecasters and power companies to consider not only the nighttime westward electrojets associated with substorms, but also the convective electrojet current systems.
  • GIC (geomagnetically induced currents) can affect a wide area, therefore affecting multiple system components at the same time; such widespread simultaneous difficulties are not envisioned by and prepared for by most system operators. Two capacitor banks tripped in July and one tripped in March, causing minor problems, compared with 6 that tripped at Hydro-Quebec during the 1989 storm.
  • NYISO goes into a special "alert state" and they reduce transfers and become "conservative" when K of 7 is predicted or observed and they start to measure some effects.
  • There is still a major risk to the system integrity if they should lose capacitor banks due to GIC during a high load condition (this hasn't happened yet).
  • They could lose voltage support where they had high load and had a sudden increase in GIC
  • There are also significant effects on power systems at mid and lower latitudes during sudden impulses and during extended enhanced ring current conditions.
  • Vendors fill an important need by doing both region-specific ionospheric current predictions, on doing the ground conductivity modeling, and on doing the modeling of the effect on specific grid configurations.
  • One researcher, A. Ridley, believes his model can predict Dst (a measure of geomagnetic activity) reliably from current Dst and solar wind conditions using his model.
  • George Siscoe suggested that for the 2-3 day prediction the research effort should focus on predicting dynamic pressure and the interplanetary magnetic field vector, and that the magnetospheric physicists can make magnetospheric predictions from those inputs.
  • SEC should also characterize the uncertainty of GIC levels in an electrical power grid, given a Kp value or a NOAA G-scale value. We haven't done the quantitative work, so we don't know how bad it is.

Uses of SEC data

  1. Anomaly investigation-satellites
  2. To direct queries from outside agencies
  3. Reschedule maneuvers-satellites, power industry
  4. Put Operations team on alert-satellites, power industry
  5. Examine archived data to design specification for short- and long-term effects-satellites
  6. Mitigation of impacts, counter measures-satellites, power industry
  7. SEC serves to define the radiation environment for manned space flight operations-astronauts
  8. Warning lessens the uncertainty and allows astronauts to "hide"-astronauts

Some suggestions or requests can be implemented relatively easily, others require extra resources, and other are technically infeasible or require policy decisions. This is the documentation of what was requested.

Suggestions and Requests


  • Need alerts in plain English
  • Need descriptive header at top level of alert advisories
  • Want descriptive effects with the alerts/advisories as now included in the NOAA Scales description
  • Differences of opinion in terms of using chest x-rays as compared to some other dose or equivalent dose.
  • Need to clarify time for doses in NOAA space Weather Scales description (typical of flight, hour, day?)
  • Need advisory/alerts with WMO headers for access through NWS/FAA channels
  • Want differential WMO headers depending on type of advisory/alert
  • U.S. Air Force (USAF) wants 50 MeV alert added to the current 10 and 100 MeV alerts
  • Airlines want warning for a K8 geomagnetic storm, not just an alert. There is already a 7+ warning
  • The airlines also want a different S scale for > 100 MeV
  • Power Companies want a warning for Earth-directed CMEs to give 24 - 48 hour lead-time

General Comments and Suggestions

  1. USAF prepares products for their users, but doesn't know how these products are used. Like the Air Force, SEC faces the dilemma of not knowing how to get users to tell what they do with a service
  2. Increase modeling capability
  3. Increase lead-time of warnings
  4. Provide alerts in plain language for some, keeping scientific language for others; use NOAA Scales; provide the level of degradation associated with each alert
  5. Post additional products on the NOAA Weather Wire
  6. A regional electric power pool requested an increased lead-time of 1 hour for geomagnetic storms. They mentioned that they could approach "other contractors" for information (as vendor ability increases, this will become a real opportunity)
  7. Provide length of anomaly and approximate time when things will return to "normal"
  8. Provide subsequent updates after the initial storm warning
  9. Clarify Kp index as a planetary, not local, index of geomagnetic activity
  10. Put descriptive header in subject line so it doesn't have to be opened to know its relevance (e.g., geomagnetic, radiation)
  11. Calculate radiation dose based on flux level
  12. Increase co-operation between NASA, USAF

Special Topic: Aviation


Individual airlines and the FAA have recently become concerned with both radiation effects and communication effects from space weather on new polar routes as well as on existing routes, especially those that go to high latitude. The issues seem to fall into the following categories

  • FAA oversight of the airlines' operations, including guidelines to consider space weather effects on operations
  • Operational plans and decision-making by the airlines
  • Education on the effects of space weather-where, when, and how significant
  • Resources available to the airlines to address space weather issues, other than SEC
  • Resources available or potentially available to the airlines from SEC

Players in the discussion

  • SEC (Various)
  • Other NOAA-Herb Sauer
  • National Weather Service support to the aviation industry (Mark Anderson, NWS)
  • FAA Met. requirements office (Paul Armbruster)
  • FAA working group on space weather (Avilas via Paul Armbruster)
  • FAA Civil Aeronautics Medical Unit (CAMI) (Wally Friedberg)
  • Airline representatives (including United, Northwest, American, Virgin, Delta, Continental)


  • Airlines and FAA use SEC data, especially from the Website, for various information. The primary need in this area is understanding of the data-see the education discussion below.
  • The CAMI Web page-an additional source of information, still being developed-would relieve SEC of some of the demand. The Webpage requires inclusion of solar particle events in addition to its current inclusion of galactic cosmic rays only. Anyone could go into the page, enter flight profiles and the software would use GOES data to give a current theoretical radiation dose being experienced on that flight.
  • Radiation Doses-In addition to the CAMI pages, Herb is tentatively proposing to the FAA to develop a simple algorithm that would compute a relative dose for an event based on GOES data. This could be in operational software that would reside at and be initiated by the FAA, the airlines, or third-party vendors after they receive SEC alerts. He also suggests SEC provide doses rather than fluxes in SEC alerts. Herb's proposal would take advantage of SEC data and distribute it independently of SEC alerts.


SEC alerts are already used by some of the airlines and FAA. The primary issues are

  • Completion of the alerts/advisories based on the NOAA scales
  • Contents and frequencies of these alerts/advisories.
  • Obtaining NWS/WMO codes so these can be routed through the NWS/FAA networks
  • Education about the content of the alerts (see below)

Communication issues

  • NWS, FAA, and airlines seem to be unaware that the SEC alerts are included in the NOAA family of Services (NOAA Weather Wire).
  • Airlines need to know the NWS/WMO designator to route these alerts to various operating (dispatch) positions. It is simple to add the designators to the tables they already have in place to route conventional weather information to the correct operator positions.
  • SEC needs to complete the SEC alerts to include NOAA scales, obtain NWS/WMO code approval, and add products to the existing flow into the NWS system.
  • At present, FAA regulations forbid reliance on the Internet for critical operating information. They expect to get this changed later this year.

Educational Issues

Airlines have asked for educational presentations from SEC or even a workshop. Herb Sauer is sending educational material to his contacts in the industry and giving seminars at their invitation. NWS suggest a combined presentation on space weather issues at the Business Owners Aircraft Association Annual Meeting in New Orleans in September. Paul Armbruster of the FAA suggests maybe FAA would host an educational meeting before then in Washington and include Wally Friedberg, SEC, and others.

Education from an SEC perspective should include the following information

  • General discussion about space weather, solar radiation storms, and the other phenomena of concern to airlines (e.g. Radio Blackouts)
  • Discussion about the sources of space weather information and what they provide.
  • Explanation of SEC products, especially the alerts but also of the data on the Web page

Immediate SEC actions

  • Complete the upgraded alerts including the alerts/advisories based on NOAA Scales with consideration of the requests for some additional information about the higher energy particle fluxes. This discussion will represent some give and take between SEC possibilities and user desires.
  • Develop a consistent policy on what we will provide for training and how we will provide it. New technologies using the Web are of interest to us.
  • Work with NWS, FAA, and others to develop and implement an aviation program that is able to make better use of SEC space weather products and services. This implies that SEC will provide information and discussion and will work with the other parties to maximize their use of SEC products while minimizing any new work to be taken on by SEC.

Radiation Alert Possibilities

Users need some indication of radiation dose with Solar Radiation Storm alerts.

  1. One straightforward possibility: Include the values of NOAA scale, Flux level of >10 MeV, Flux level of >50 MeV, Flux level of >100 MeV in each alert.

For example, an alert might be S2, 300, 295, 120

This alternative provides recipients with numbers that can be used to compute an actual dose using a model from some other source. The model can come from the FAA or a third-party supplier. But the alert in this form (with data) requires some supplementary handbook, table, or computer algorithm to know the dose.

  1. Another alternative that is straightforward:

SEC computes a soft, medium or hard spectral indicator for each event at the time of an alert and includes it in the alert. Hard, Moderate, and Soft to be based on the defined limits in flux ratios for top, middle, and lowest third of all events or samples in the GOES observation database.

Example: S2, HARD

This does not state a dose and only an approximate dose range could be defined from this information using a table from some other source (example below).

However, the alert/advisory is self-contained and does not require a dose calculation. The contingency plans are worked out by the airline in advance with the assistance of a radiation expert.

Example: Hop and Skip Airline procedures for Solar Radiation Storms

Example of possilbe procedures 
for Solar Radiation Storms

NOAA Scale
NOAA Modifier
Airline Action Plan




  1. Other alternatives are possible. The Alerts Working Group needs to lay out these possibilities and arrive at some closure so the alerts software can proceed.