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Revision of the �Space Weather Scales

Bill Murtagh

NOAA Space Weather Prediction Center

ISWAT, 12 Feb 2025

Safeguarding Society with Actionable Space Weather Information

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Space Weather Scales—Background

NOAA introduced the �Space Weather Scales in 1999

Communicate to the general public current and future space weather conditions and possible effects
Unchanged since 1999, Scales are �used worldwide to initiate hazard preparedness and mitigation operations

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Space weather capabilities, user base, and user needs have grown and changed dramatically over the last two decades

Department of Commerce // National Oceanic and Atmospheric Administration // National Weather Service // Space Weather Prediction Center

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SWPC Product Subscription Service�Most Products Based on Scales

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Jan 2025: 94,000

Over 94,000 subscribers

All major airlines
Most major satellite companies
Power grid operators
Oil drilling
Precision Agriculture
National Security
many more

20% international

Department of Commerce // National Oceanic and Atmospheric Administration // National Weather Service // Space Weather Prediction Center

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Examples of Scales Use in the U.S.

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Energy Sector

G3 triggers notification to over 3,000 electric utility companies in the U.S. and 150 companies in Canada
Thresholds also regional, e.g., New York - G5 ‘Activate Thunderstorm Warning process’ �(a predetermined set of constraints)

Aviation

S3 is trigger for Polar operators �United Airlines, American Airlines, Delta, UPS, and FedEx
Reroute

Department of Commerce // National Oceanic and Atmospheric Administration // National Weather Service // Space Weather Prediction Center

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Examples of Scales Use in the U.S.

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Surveyors, Drilling, Precision Agriculture

G2 is used by high-precision GPS operators
High-precision GPS users, such as surveyors and drilling companies, rely on G2 as a proxy to measure ionospheric disturbances impacting GPS accuracy

Aurora viewing

Broad interests around the world
Scales used for improved understanding of southern/northern extent of aurora

Department of Commerce // National Oceanic and Atmospheric Administration // National Weather Service // Space Weather Prediction Center

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Examples of Scales Limitations

G5 Geomagnetic Storm on 10-11 May, 2024

G5 Geomagnetic Storm on 1-2 Sep, 1859 (Carrington)

Both storms categorized as G5, but differ greatly in intensity
May 2024 G5 not a superstorm, Carrington very much was!

_____________________________

Solar Flare Radio Blackout on 14 Dec 2023 - R3

Focuses on HF degradation but misses VHF

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Department of Commerce // National Oceanic and Atmospheric Administration // National Weather Service // Space Weather Prediction Center

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Revision of Space Weather Scales—policy drivers

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�Updates to the Space Weather Scales – Assess and update, as appropriate, the NOAA space weather scales, in coordination with public and private sector, including infrastructure owners and operators. (2021)

Space Weather Advisory Group – Findings and Recommendations (Apr 2023)

R.15.2. Update and expand NOAA space weather scales. NOAA scales should be updated…include spatial and temporal specificity relevant to user operational activities.

https://www.weather.gov/swag

White House Office of Science and Technology Policy (OSTP) — Space Weather Priorities (2021)

Department of Commerce // National Oceanic and Atmospheric Administration // National Weather Service // Space Weather Prediction Center

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The Response

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OSTP tasks Science and Technology Policy Institute (STPI) to conduct an initial assessment of the feasibility, requirements, and challenges to update the Space Weather Scales.

July 2023 – NWS commits to fund initiative - STPI to provide logistic support and objective analysis

Start and end dates are: Jan 2024 – Jan 2026

Department of Commerce // National Oceanic and Atmospheric Administration // National Weather Service // Space Weather Prediction Center

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Transforming How We Communicate

Scales revision a first step towards a broader transformation of �space weather communications

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Scales

Actionable

Space Weather Information

Department of Commerce // National Oceanic and Atmospheric Administration // National Weather Service // Space Weather Prediction Center

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Bill Murtagh

William.Murtagh@noaa.gov

Thank You

Safeguarding Society with Actionable Space Weather Information

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Study Findings on NOAA Space Weather Scales (SWS) Revisions

Asha Balakrishnan

Dan Pechkis

Kate Ross

Erin Saybolt

Casey Roepke

February 12, 2025

Science and Technology Policy Institute

1701 Pennsylvania Ave, NW ● Suite 500 ● Washington, DC 20006-5825

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The Science and Technology Policy Institute (STPI) is assisting the Space Weather Prediction Center (SWPC) in the revision and potential deployment of the revised space weather scales (SWS).

Review and suggest revisions to the SWS for use by the domestic and international space weather community
Consider the 3 existing SWS, and potential new scales

G-Scale – measure of global geomagnetic activity
S-Scale – measure of energetic proton flux correlating to the levels of solar radiation
R-Scale – measure of x-ray flux correlating to levels of radio interference on the sunlit side of the Earth

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Credit: NASA/Goddard//SDO

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We facilitated input from nearly 500 people through over 170 engagements.

USG Experts

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International Community

USG Experts

Space Weather Prediction Center

(SWPC)

Space Weather Operations, Research and Mitigation Subcommittee

Broader Community

Space Weather Advisory Group

Academia

End Users

Satellites

Power Grid

Aviation

Emergency Management

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We engaged the space weather stakeholders domestically and internationally over a 10-month period in 2024.

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Event	Dates	Location
Project Kickoff	Jan 10	Washington, DC
American Meteorological Society Annual Meeting	Jan 28 – Feb 1	Baltimore, MD
Ongoing interviews and group discussions	Feb – Oct	Virtual
Space Weather Week	Apr 15 – 19	Boulder, CO
Request for Information (RFI)	May – Aug	Virtual
Asia-Pacific Region	May 20 – 24	Adelaide, Australia
European Region	June 24 – 25	Dublin, Ireland
Asia-Pacific Region at COSPAR Meeting	July 13 – 16	Busan, Korea
Survey	Aug 7 – Oct 23	Virtual
Americas Region at Brazilian Embassy in U.S.	Oct 10	Washington, DC
Space Weather Advisory Group Discussion	Oct 22	Virtual
Space Weather Fast Track Action Committee	Oct 24	Washington, DC

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What we heard: How should the scales improve?

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Examples of Other (these are quotes from the coding)

“There is currently no mention of radio frequency bursts which can impact a wide spectrum of frequency bands.”
“Even just a way to convert between the two scales would enhance the efficiency of communicating hazards and at risk-locations.”
“Even just a way to convert between the two scales would enhance the efficiency of communicating hazards and at risk-locations.”
“It will be extremely important for NOAA to be very careful and thorough about any changes they are making to the scales”
“Scales should show more differentiation between effects on levels.”

Additional Data:

Really, no changes are needed unless you want to add other sources of information.
If an almost “live” graphical presentation showing S scale WITH G scale adding or incorporating something like the data from the Chris Prankratz 3D viewer of the Enlil model
I wouldn't want to lose the current scale as we have so much historical data based on it but any additional information we can add that would provide greater detail would be welcomed. Bonus 6TH: Both polarity (with respect to Earth's magnetic field) AND (very important) angle of incidence (head on, parallel, in between?) should be included: Maximum interaction occurs when a CME hits perpendicular to Earth's field, but NO interaction if fields are parallel. That's why there's more slip by at the N & S poles where fields are parallel: Aurora are a result.
My Comment is that the scales and proposed changes is that nothing should be changed, other than adding the percentage of loss of the Earth's geomagnetic protect as "polar excursion" takes place, as it is now.
I overlooked the 2 most important scales not listed or included: Both the LOCATION (latitude and longitude) of earth's geomagnetic north and south poles as well as the overall strength (in nanoTesla) of the earth's dipole equivalent geomagnetic field strength, that is, how much nT of "protection" earth's "protective" geomagnetic field offers us against solar events, cosmic radiation, CME's, etc. We need both real-time and historical data on these 2 fronts, which would help me update the linear regression graph on my popular paper (see attached or, if it's published, my prior comment).
We would appreciate more granularity within the S-scales in the biological area. Perhaps a broad expectation for µSv per hour given latitude�and/or altitude would ensure all users have a common understanding of an event. More research is likely needed in this area.
Higher cadence measurements also improve utility of nowcasting, kp is only every three hours
AE for auroral electrojet, uses 40-80 stations, not available in real time, higher latitude 1 minute, westward and eastward and the maximum difference between these two, use this to catch these substorms affects catches moments you get larger db/dts. But only such high mag stations. Super mag version uses much wider range of altitude of stations.

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What we heard: Improve Communication

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Introduce SWS with plain-language descriptions
Replace jargon and acronyms with language understandable by general users
Rename S- and R- scale to better align with the phenomenology
Replace the current explanation of effects with risk-informed action statements
Improve navigability of SWPC website
Provide a clear web interface for learning about the scales and their effects

Improve Communication

Improve the communication of the scales

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What we heard: Provide Geographic Specificity

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Geographic Specificity

Provide grid operators and surveyors region-specific information about space weather effects, particularly geomagnetic induced currents and local magnetic fields
Provide airline operators charged particle information at various latitudes, longitudes, and altitudes
Offer more specific radio frequencies to emergency managers in different regions

Incorporate geographic specificity in the scales

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What we heard: Include Uncertainty

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Geographic Specificity

Explore how to quantify and communicate the confidence of forecasts
Use disclaimers to help manage users’ expectations
Present uncertainty information graphically
Qualify the extent of measurement and model uncertainty

Include uncertainty information with the scales, especially in forecasts

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What we heard: Expand or Contract Scale Levels

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Geographic Specificity

Expand the Scale Levels

Distinguish between high and low G5 storms so users can differentiate between Carrington- and non-Carrington-level events
Expand G5 into additional levels to gain more granularity

Contract the Scale Levels

Alter scale forecasts so as to not imply a level of precision in forecasting that the science cannot support
Forecast to a 3-point scale where phenomena are classified as minor, moderate, or strong may be more feasible

Expand or Contract Levels

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What we heard: Align the Scales on Impacts to Users

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Geographic Specificity

Base the scale qualifiers, such as “extreme”, on the effects and not the storm magnitude
Align scale threshold with potential effects instead of the measurements of phenomena

Better align scales with space weather effects

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New Scales Suggestions

Geoelectric field

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Ionospheric scintillation

Dosimetry

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Next Steps: Year-2 SWS Revisions

The Year-2 goal is to evaluate the various SWS revision options, determine feasibility, timeline, and resources for a path forward
In the coming year, STPI plans to

Share findings and gather feedback on options from Year 1 study with communities at

American Meteorological Society (AMS) Annual Meeting (Jan 2025)
International Space Weather Action Teams (ISWAT) Annual Meeting (Feb 2025)
NOAA’s Annual Space Weather Week Meeting (Mar 2025)

Engage with SWORM, FTAC and SWAG
Deliver a memo to SWPC with a suggested implementation plan to consider in late 2025

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Thank you for your time!

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For more information contact the STPI team at: SWx-SWS@ida.org

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Backup Slides

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We facilitated input from nearly 500 people through over 170 engagements.

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Types of engagements	Number of engagements	Number of participants
Interviews	60	171
Sector-specific interviews	58	149
Space Weather Advisory Group Meeting	1	12
Fast Track Action Committee participants	1	10
Request for Information (RFI)	81	81
Survey	25	25
Domestic Group Engagements	2	130
American Meteorologic Society Meeting	1	30
Space Weather Week Panel Discussion	1	100
International Group Engagements	4	76
Asia-Pacific Region (Australia)	1	19
Asia-Pacific Region (Korea / COSPAR)	1	20
European Region (Ireland)	1	25
Americas Region (Brazilian Embassy in Washington, D.C)	1	12
TOTALS	172	483

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Scales Project Background

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We addressed five fundamental questions.

What scales are currently being used and how are they being used? (Current state)
What is the value (benefits) of the current scales? (Usefulness of the scales)
What are the challenges (gaps) of the current scales? (Challenges of the scales)
How should the scales change, if at all, to meet the needs of stakeholders? (Proposed changes to address challenges)
What phenomenon should be captured by potential new scales? (New scales)

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Methods

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We sought input from users from a number of sectors affected by space weather.

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Aviation

Communications

Emergency Management

Satellites

Power Grid

GNSS

Human Space Flight

Space Domain Awareness

Tourism (Aurora)

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We employed multiple methods to collect data for answering our research questions.

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Interviews

Group Discussions

Review of peer-reviewed and grey literature

Request for Information

Survey

NSTC Space Weather Operations, Mitigations and Research Subcommittee

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The study had limitations:

Study results cannot be used to make inferences about the entire space weather stakeholder population.

We did not randomly sample the entire stakeholder population, but reached out to individuals who were known or suggested to STPI
Not all industries and sectors responded with equal enthusiasm

In some instances, we captured remarks by users who indicated an inaccurate understanding of the scales in order to represent their true needs.

The goal of the study was to understand how users rely on the scales and what they would like to change, irrespective of the feasibility of those changes

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We clarified remarks by users who indicated a flawed understanding of the scales in order to represent their true needs.

The global reach, and diversity of effects, of space weather means that stakeholders are from a wide-ranging group, with a variety of technical knowledge and understanding of the scales and space weather phenomena

Our mission was to understand how they use the and what they would like to see changed, irrespective of the its feasibility

Aviation satellite, power grid, and emergency management engaged more than other sectors

There was little input from the rail or drilling communities

The global reach, and diversity of effects, of space weather means that stakeholders are from a wide-ranging group, with a variety of technical knowledge and understanding of the scales and space weather phenomena

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Findings

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What we heard: How do you use the scales?

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What we heard: How are the scales useful?

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What we heard: How should the scales improve? - Communication

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The Science and Technology Policy Institute (STPI) is assisting the Space Weather Prediction Center (SWPC) in revising the space weather scales through:

Stakeholder engagement, which captured

challenges users face when employing the scales
improvements suggested by users

Literature review, which collected

Theories of best practice in risk communication, with a focus on natural hazards

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Stakeholders suggested improving the communication of the space weather scales to increase user comprehension.

“It’s really hard to use much of the information usefully. It’s confusing.”

“The science needs to be translated into something they can understand.”

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Most recommended changes to the Space Weather Scales

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Scales are not the be-all and end-all of natural hazard communication tactics.

Currently we use a 5-point scale for space weather as well as tornadoes and hurricanes.
There is no global consensus on the ideal number of levels for natural hazard scales.

12-point tsunami scale
10-point earthquake scale

Communicating about hurricanes using the Saffir Simpson scale has created challenges in prompting community preparedness.

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1 2 3 4 5

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Many SWPC products do not tailor messaging for the intended audience or use plain language.

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The National Weather Service uses Impact-based Decisions Support Services (IDSS) to communicate hazard information to the public.

IDSS is the “provision of relevant information and interpretative services that enable partners to prepare for and respond to extreme weather, water, and climate events for the protection of lives and livelihoods.”

IDSS is supposed to help the NWS “to ensure a planned, coordinated, and effective preparedness and response effort.”

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Scientific literature suggests that risk preparedness is the result of interplay between many factors including risk perception and personal experience and values.

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Risk Perception

Contextual Experience

Risk Preparedness

Risk Communication

Trusted Messenger

Risk Tolerability

Can I take Effective Action?

Visualization author’s own, based on literature review

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The literature also says that probability information, if presented appropriately, can allow average people to make better decisions.

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Source: NOAA SWPC Website

Some studies have shown that users prefer also to see uncertainty information so they can make their own evaluation of risk.

For example providing error information (+/- 0.2)

Studies have also shown that providing probability information as shown on the left can help improve users understanding of forecasts.

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One way to encourage decision making and help users understand the risks of space weather is to provide impact information.

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Risk preparedness is strongly correlated with belief that one can take effective actions to mitigate the risk (i.e. that you can prepare and that your preparation will mitigate risks)
Some stakeholders in the space weather community struggle to understand what the impacts of space weather are on their systems and consequently struggle to take appropriate mitigation steps.

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In summary, suggested best practices are:

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Explain space weather forecasts and circumstances in the context of system impact and action.

Tailor communication content to the intended audience.

Communicate both the probability and uncertainty of forecasts.

Incorporate lessons from risk and hazard communication theory going forward.

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