1. Real-time Radiation Storm Forecasting with SOHO/COSTEP
Space Weather Workshop, Boulder, CO, April 29, 2008
Real-time Radiation Storm Forecasting with SOHO/COSTEP
Presenter: Charles P. Holmes1
for
Arik Posner1,2, Bernd Heber3,
Oliver Rother3, and Reinhold Müller-Mellin3
1NASA HQ, SMD Heliophysics Division
2 Southwest Research Institute
3University of Kiel, Germany
Good afternoon, I feel privileged this afternoon to present work led by Dr. Arik Posner. Arik has just begun a 3rd year of service at NASA Headquarters as Heliosphere Discipline Scientist.
This work is a new "Research to Operations" advance in the area of "Real-time Radiation Storm Forecasting." This is a new forecasting method that enables warnings of Solar Energetic Proton impacts with lead times of up to an hour.
We are very interested in this work at NASA HQ for two reasons … because of the potential impact of the new forecasting technique … and also because this work represents the best intentions of NASA's commitment to Space Weather Operational needs. The time from the scientific advance to actual application in an Operations Setting was only eight months … the time since the publication of the Space Weather paper.
Now, since the REAL Team that did this work – which is not me – can't be here today in person, I brought them in as a photograph …. NEXT SLIDE …
OTHER NOTES: Logo at the top represents the central role of the Institute of Experimental and Applied Physics at the University of Kiel

2. COSTEP+ Forcasting Team:
R. Mueller-Mellin COSTEP Operations
O. Rother Real-time Implemen-tation
A. Posner Forecasting Technique
B. Heber COSTEP PI
SOHO/COSTEP 1:1 Model
The analysis work you will see today was led by Arik Posner ... Bernd Heber is to be credited as the PI of the COSTEP instrument … the real-time implementation was led by Oliver Rother … and Reinhold Müller-Mellin is credited for his care of the COSTEP operations. Support is acknowledged from the SOHO Science Operations Center … the CCMC at NASA's Goddard Space Flight Center … and Timo Ero-nen of the University of Turku is also gratefully acknowledged.
Certainly, any mis-steps this afternoon should be credited squarely on me … all admiration for these gentlemen.
The instrument that supplied the critical data for this project, COSTEP on SoHO, is also shown here and labeled … but not this unknown guy in the back … he may not be a co-author but let's assume Andreas Klassen deserves a pat on the back as well.
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Thanks also to SOHO/SOC and CCMC at GSFC and Univ. Turku, Finland

3. NASA Heliophysics Division Objectives
First, let me remind you of the motivation for this work … shown are NASA's Objectives for Heliophysics as described in the 2006 Heliophysics Roadmap and the NASA Science Plan.
This work addresses all three objectives: first, there was the discovery of a physical process associated with the prompt acceleration of energetic electrons and protons at the Sun … this led to a new understanding of how those particles impact our near-Earth system … this, in turn, enabled a new Space Weather prediction technique that went into immediate use to maximize the effectiveness of our astronauts on the International Space Station.
Hitting all three objectives squarely on the nose with one paper … I believe we call that a "Heliophysics 3-point shot“.

4. The Problem: Exposure Risk from Fast-Rising Solar Proton Events
Lower Limit for Acute Radiation Sickness from 1h Exposure
As we know, Solar Particle Events are a major concern for astronauts venturing beyond the Earth’s magnetosphere. This slide shows a graph from the 2005 work of Kim, Hu, and Cucinotta in which they estimate shielding requirements for space explorers exposed to the effects of solar energetic particles.
The exposure profile shows the dose rate that would have been received behind several thicknesses of Al during the course of the "Halloween Storms" of Note the rapid change in the radiation environment that can occur in the matter of minutes or hours. Within even one hour, explorers can be engulfed with particles that cause harmful health effects or simply put the productivity of a mission at risk. Although the inside of a spacecraft or lunar base can be made relatively safe, “Staying Inside” isn't the long-term goal. “Going Outside”, as you may imagine, requires a capability for warning astronauts when such an event is imminent. Advance warning capabilities would allow for higher productivity EVAs without facing the risk of sudden, severe exposure.
The technique presented here allows for up to one hour advance warning before these hazardous protons arrive at 1 AU. And the key … the telltale sign … that a proton event is underway and headed toward you … is an early precursor signal of relativistic electrons … which sounds quite simple in hindsight … NEXT SLIDE …
From Kim, Hu, and Cucinotta, AIAA, 2005

5. New Space Weather Forecasting Tool from Heliophysics Science Program
EVA Abort Command Issued
Solar electrons reach the Earth-moon system about one hour before the solar proton radiation hazard arrives.
This sketch is an artists‘ view of the radiation field in the inner heliosphere ~ten minutes after the release of solar energetic particles from the Sun.
The Posner research has shown that relativistic electrons … electrons traveling at nearly the speed of light …are always present in solar particle eruptions. That is, for prompt events at the Sun, such as a flare, the event appears to accelerate all particles to relativistic energies. Because the electrons travel much faster than the protons, the onset of MeV protons at 1AU is always delayed over the onset of relativistic electrons.
Moreover, it has been found that events maintain coherence to the degree that for an observer sitting at Earth, the rate of increase in electron and proton intensities are correlated and largely determined by the magnetic connection distance from the flare location to the foot point of the observer.
For the event shown in the paper and illustrated here, the relativistic electrons reached 1 AU at the time when the ~30MeV protons were still within 0.2 AU from the flare location. The fast-moving electrons follow the magnetic field ahead of the protons almost instantaneously connecting to L1-based monitoring equipment. The warning electrons can be used as a reliable sign of a pending proton storm ahead. When the electron signal is detected, operational decisions can be made for a proactive response to the pending event … rather than a reactive response to an event already engulfing an explorer.
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New research has shown that electrons traveling at the speed of light are always present in solar particle eruptions. These electrons – traveling much faster than the hazardous solar energetic protons – follow the magnetic lines of force from the Sun to the Earth. Therefore, they can be used as a reliable early warning sign of hazardous radiation ahead.

6. Electron Rise Parameter
Even in the case of the fastest-rising major proton event on record (Jan. 20, 2005), the electron precursor signal was detected minutes in advance.
EVA Abort Complete
SOHO COSTEP:
A one-hour warning has the potential to provide the advanced notice needed for efficient EVA planning.
Here we show the concept twenty minutes to one hour later when the hazardous solar protons have reached the Earth-moon system. Depending on the time necessary for any given operational decision …. such as an EVA abort … the exposure of astronauts to the protons can be reduced substantially with this early warning technique. The average delay time, as you will see in just a few slides, is on the order of an hour. Although more dangerous events can be faster.
In the paper, Posner studied the events listed in the NOAA GOES Proton Event List. This set of events contains all major solar particle events during the years 1996 through 2002, and is also useful because it includes smaller and intermediate size events. He developed and the team implemented an empirically-based forecasting matrix … given a measure of the intensity of the precursor electrons, and how fast the intensity engulfs you, one can predict the approximate intensity of the proton storm coming from behind. As you may see here, slower rising electron events portend a less intense proton event. Such forecast matrices have now been developed – but still require verification - for a range of energy bandpasses for a fairly complete forecast of the pending proton energy spectra.
This work was found to be immediately useful by the Johnson Space Center Space Radiation Analysis Group. These are the folks charged with ensuring that the radiation exposure received by astronauts is within established safety limits. The forecasting model uses real-time data from the SoHO COSTEP instrument and began operational use early this year.
I have to give one caution at this point …the basic premise behind this forecasting technique … that electrons and protons accelerated promptly close to the sun travel to the Earth-Sun system at a rate proportional to their square root mass … is designed for forecasting prompt events that to originate close to the Sun.
As we know though, interplanetary shocks & CMEs also accelerate protons to energies above 10 MeV in large numbers during shock transits between the Sun and the Earth system. Luckily though, the energy spectra for these DELAYED EVENTS can be quite soft and only a few events have been detected beyond 30 MeV. Also these shock-related events tend to rise slowly compared to the PROMPT events and so, until new forecasting techniques are developed for these DELAYED events, actual proton measurements at L1 are usually sufficient to reduce exposure, as the increase in intensity from such events is much more gradual in comparison to the PROMPT events
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OTHER NOTES: The Posner team has noted that a more focused event list tailored for human exploration activities at the moon may be able to predict a lower limit for flux values for protons above 30 MeV.
Electron Intensity
This is an important example of the potential for further rapid transition of SMD Research to SOMD/ESMD Operations – May 2007 to Feb 2008 – this new prediction tool has entered V&V by the JSC/SRAG for future Shuttle, ISS, and CEV operations.
Slow Fast
Electron Rise Parameter
Empirical Forecasting Matrix Translates Solar Electron Data into +1h Proton Hazard Forecast (Posner, Space Weather, 2007)

7. Forecasting Results Also: Combined Models Posner / Townsend
space radiation analysis group
Lyndon B. Johnson Space Center
AW AW FW AW FW+AW FW
CLICK THE MOVIE!!!!
The Posner team is continuing work to sharpen their technique and are now looking at how this new information, combined with the results from other models, might yield a third useful set of information.
The work thus far gives us a continuous characterization of the particle intensity likely to come … operationally however, we would also have an outlook of the cumulative exposure [total dose] from any given SPE event or series of events. The most obvious case to work on is a scenario like the 2003 Halloween Storm series. It is thought that a combination of the Posner technique with a Bayesian approach, such as that currently under development by Larry Townsend of the UNIVERSITY OF TENNESSEE, might lead to achieving this goal.
The graph shows the flux of radiation protons from 16 TO 40 MeV … the movie is showing how the area under the curve may be used as an approximation to the cumulative flux. Shown in RED are the observations we are trying to predict …. BLACK is the forecast as it currently performs …. the BLUE symbols are the WARNINGS issued by the software. Note that some are labeled AW for ADVANCE WARNING …. and FW for FALSE WARNING.
Let's zoom in to this event … right here … and look at the local rise time … NEXT SLIDE …

8. Zoom into 16-40 MeV Proton Forecast
Black: Forecast Red: Observations Blue: Hazard Warnings
Here: ~20 Minutes Warning with
Intensity-Time Profile Prediction
We have the same basic plot format here as for the previous slide …particle flux as a function of time, a few hours in this case … the data points themselves may be difficult to see from your position but hopefully you can see the overall trend … observed particle fluxes in RED, measurements of MeV protons … in BLACK is what the SW operators would have seen had they been running the Posner model at that time … with the BLUE dots representing the ADVANCE WARNING signals … the number of which, here, would attract the appropriate amount of attention, I would imagine.
For this particular event … an ~20 minutes warning time would have been given …. with a pretty realistic forecast of the particle flux to come ….
So they did pretty well with this event … how about others? and what's up with those FALSE WARNINGS?
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Posner, Space Weather, May 2007

9. 24 Proton Events beyond Threshold
Archived Data Stats
24 Proton Events beyond Threshold
10/11 Prompt Events Forecast (91%) with 122 min average warning time
9/13 Delayed Events Forecast (69%)
Overall: 79%, 195 min average warning time
13 False Warning Series (10 from Decreases)
Since the original paper was published, the Posner team has been compiling a longer-term statistical database to further sharpen the statisticss. The Posner paper is based on the first eleven months of 2003 … here they have expanded their statistical basis to several years.
In general, the technique has gotten to the stage of refinement that for the 24 proton events that should have triggered a warning … 10 of the 11 PROMPT SPE events were well predicted with warning times that averaged 122 min (but strong events have much shorter advance warnings) … and 9 of 13 DELAYED SPE events were predicted …. which is pretty good considering that the technique isn't well applicable for the delayed events.
There were 13 False Warnings sprinkled in there however, Most false warnings … if we had examined them more closely during the previous slide that slowed some examples … originate from the flux decrease at the tail end of SPE events due to limitations in the geometric factor of the instrument … there are statistical intensity variations. The false warnings appear to be an instrumental effect of the science instrument doing the monitoring.
For the time being, until there is appropriate monitoring instrumentation available, most of the FALSE WARNING can be easily be ruled out by requiring that there was also flaring activity at the Sun. An operational forecasting instrument would have geometric factor requirements to offset this problem … NEXT SLIDE …
ADDITIONAL NOTE: Note that the larger advance warning times are strongly influenced by weaker events with less critical maximum intensities. The most dangerous events leave us with much shorter (<1 hour) advance warning times (January 20, 2005: minutes).
SOHO COSTEP

10. Real-Time Data Feb. 7-Apr. 23, 2008
In Place for 76.2 Days
Live: 33.3 Days (43.7%; Main Limitation: SOHO DSN Downlink)
0 Proton Events beyond Threshold
1 False Warning (April 7, Radio Frequency Interference?)
1 Software Glitch (April 18, 60 Forecast Hrs Lost)
Single False Warning
I mentioned earlier that the forecasting software has been in operational use at the Johnson Space Center SRAG since February … how is it doing there?
This summary plot summaries the performance from February until last week. The forecast data is shown across the middle, a more magnified view of the same data and the fluctuations toward the bottom. Note that forecast flux is 4 orders of magnitude below alert threshold … the sun hasn't really done much since February … there was a single, one-minute non-exciting FALSE WARNING in April … due to radio frequency interference … whatever … we're still waiting for a good operational validation of the warning system .. stay turned for that as the new solar cycle decides to "rev up". More details will be forthcoming at Spring AGU … you'll want to visit with Arik Posner at Session SH41A on May 29.
You'll also note that there are some gaps in the real time coverage …There is NO OTHER INSTRUMENT in the solar wind near Earth with the near real-time capabilities to monitor the important energy ranges of the precursor electrons.
This GLITCH was classified as a "weekend problem" … something in the line of data flow stopped … it was a weekend … I'm told there was an apartment renovation involved … that's the less fortunate side of "Research to Operations" I would guess. … NEXT SLIDE …
Glitch
SOHO COSTEP

11. http://www-etph. physik. uni-kiel
In case you'd like to see the same real-time information as our Johnson Space Center folks, here's a link to the real-time forecast page at the University of Kiel. The real-time forecast on this web site is updated every minute … this is the information from the day that Arik handed over his talk to me. Still looks dull ...
Here's another caution I'll give … we're getting near-continuous real-time coverage on SOHO only during MDI campaigns. The COSTEP data comes down in 1-minute packets and, in general, three consecutive packets are used to compile one complete 1-minute forecast record … it’s a "moving boxcar" approach … the data processing takes less than 10s. The SoHO mission is scheduled, nominally, to provide significant (~12-16 hours/day) real-time coverage only until the middle of 2009 … that is, until the end of cross-calibration with SDO. After that, we may only have 2-4 hours of coverage per day.
We have a great new technique, but the monitoring equipment for future use looks to need some attention.
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QUESTION: How often and how long are the MDI campaigns?
I think twice a year for two months. Plus the overlap with SDO will likely require additional campaigning.

12. Summary First SPE Ion Intensity-Time Profile Forecasts
Forecasting Successful because SPE Electron and Proton Acceleration & Transport Closely Linked
4.5 Year Verification Highly Successful for Prompt SPEs
Implementation with SOHO Complete, on Console at JSC/SRAG since Launch of STS-122, February 2008
URL:
Not Designed to Forecast Slow-rising (“Delayed”) Events: Nowcasting
Flux Decrease FW Problem to be Addressed: no Flares!
Solar Particle Event