Extreme Space Weather Warning System Andrew Fazakerley (1), Chris Arridge (1), Dhiren Kataria (1), Jonny Rae (1), Matthew Stuttard (2) (1) Mullard Space.

Extreme Space Weather Warning System

Andrew Fazakerley(1), Chris Arridge(1), Dhiren Kataria(1), Jonny Rae(1), Matthew Stuttard (2)

(1) Mullard Space Science Laboratory, University College London

(2) Airbus D&S (but this is not an official Airbus presentation!)

SEREN Bz Workshop Abingdon July 2014

Solar wind power input to the magnetosphere/unit area:

P = Vsw BIMF2 µ0 sin4(θ /2)

Perreault and Akasofu 1978

ENLIL vs ACE

Are forecasts adequate?

• Accurate V and B are needed for several types of predictive models of space weather effects

• Random example interval (Oct-Nov 2009)

• Solar wind speed– Incorrectly indicates

speeds over 400 km/s – Peaks at wrong times

• Interplanetary magnetic field– Magnitude badly wrong– Peaks at wrong times– (direction also matters…)

ENLIL

ACE

ENLIL

ACE

1.6

1.4

1.2

1.0

0.8

0.6

B(n

T)

Multi-spacecraft Extreme Space Weather Warning System

Interplanetary Coronal Mass Ejections (ICMEs)

Earth

L5

Sun

L1

Sub-L1

• Possibility of magnetic cloud, which may have prolonged geoeffective B

• ICME can drive geoeffective sheath• SEPs often associated with sheath

Hazard Potential• sudden magnetospheric compression• possible prolonged geoeffective B• radiation belt enhancements

Forecasting needs measurements at• L5: active regions (caution)• L5: Earthward ICME (clear risk)• L1 or Sub-L1: n, V, B test for

geoeffective plasma (alert)

Multi-spacecraft Extreme Space Weather Warning System

Stream Interaction Regions (SIR) and High Speed Streams (HSS)• Prolonged HSS related to radiation belt

enhancements• SIRs can be geoeffective

Hazard Potential• Radiation belts• sudden compression of magnetosphere

Forecasting needs measurements at• L5: near-equatorial coronal holes and

measure fast streams (caution)• L1 or Sub-L1 : n, V, B test for

geoeffective plasma (alert)

Earth

L5

Sun

L1

Sub-L1

Multi-spacecraft Extreme Space Weather Warning System

L5 space weather observatory

Some studies & proposals:

• Akioka et al, J. CRL, 2005• Vourlidas et al., Gopalswamy et al.,

White papers for Heliophysics Decadal Survey 2010

• EASCO Gopalswamy et al., JASTP, 2011

• RESCO, CAS-ESA Workshop 2013• INSTANT, CAS-ESA Workshop 2013• WATCHER, CAS-ESA Workshop 2013

Very long distance communication: 1 AU

L5 Active Region

L5

Time T Time T + 6 days

L1 L1 No Active Regions

Time T Time T + 6 days

Average direction of CMEs that produce Earth-affecting SEPs is best observed from L1

Average direction of geoeffective CMEs (GEO) is well observed from L5

(Gopalswamy et al)

Multi-spacecraft Extreme Space Weather Warning System

Predictive value of L5 solar wind and IMF data for Earth?

ICMEs

• Data from 2 months when STEREO-B (red) was at L5 and ACE (black) was at L1.

• ICMEs from L1 (yellow) and from L5 (blue) based on published ACE/STEREO lists

• few, if any, are seen at both locations

Multi-spacecraft Extreme Space Weather Warning System

Predictive value of L5 solar wind and IMF data for Earth?

SIRs

• Data from 2 months when STEREO-B (green) was at L5 and ACE (black) was at L1.

• STEREO data shifted 5 days.• Velocity profile is quite similar

• SIRs from L1 (yellow) and from L5 (blue) based on published ACE/STEREO lists – only a few overlap

• ICMEs often appear at only one spacecraft

• Most of the enhanced |B| and n events are ICMEs or SIRs

Multi-spacecraft Extreme Space Weather Warning SystemSub-L1

Measure solar wind/IMF near the sun-Earth line significantly earlier than from L1

Distant Retrograde Orbit Scenarios• St Cyr et al, JASTP, 2000• St Cyr et al Decadal Survey 2010• Cranfield MSc Group Project 2012• MSSL study & student projects 2012-4• St Cyr et al Sp W Experts Mtg 2014• Airbus UK informal study, MagAlert, 2014

Non-Keplerian Orbit Scenarios• Solar Sail: Sunjammer (Geostorm)• Ion engine

Heliocentric Ring inside 1 AU• Needs >10 spacecraft…

Multi-spacecraft Extreme Space Weather Warning System

Sub-L1

Distant Retrograde Orbit type mission:

UK studies: revisiting the St Cyr et al. (JASTP, 2000) “Space Weather Diamond” concept and explore feasibility of a UK mission

• launch scenarios • orbits• communications challenges• number of spacecraft• most cost-effective operational

approach

A more sophisticated Concurrent Design Facility study is under discussion C

redi

t. C

Arr

idge

,MS

SL

Credit. MagAlert, Airbus

Multi-spacecraft Extreme Space Weather Warning System

Sub-L1

Sunjammer: state of the art solar sail

• Solar sail– Largest area solar sail, by factor 7: 1,200m2

– Lowest mass solar sail, by factor 10: ~ 50 kg, – Thrust ~ 0.01N

• Small mass spacecraft bus and payload, as well as sail

• Current status– Possible test flight in 2018

• There are limits on how far Sun-ward a sail can get, while sitting near the Sun-Earth line, related to sail mass/unit area

• For Sunjammer the limit is ~ 0.018 AU (2,747,100 km)

• (multiple sails in halo orbit around that distance can improve warning time, in theory, Heiligers and McInnes 2014; but comms issue tough in low mass spacecraft)

Multi-spacecraft Extreme Space Weather Warning System

Extreme Interplanetary Coronal Mass Ejection Event

STEREO-A (Liu et al, Nature Comm, 2014)

• Peak speed at STEREO ~2,246 km/s;

• Average speed ~ 2,150 km/s

• Transit time across 1 AU: ~19 hours

• Peak magnetic field magnitude ~109 nT

• Predicted minimum Dst = -598/1,154 nT, comparable to Carrington Event estimates

• By chance, strongest Bz north, not south

Best possible warning times for n, V, Bz:

• L1 (0.01 AU) 11 min

• Sunjammer (0.018 AU) 20 min

• DRO (0.1 AU) 110 min (~2 hours) (best case)

Multi-spacecraft Extreme Space Weather Warning System

Summary• Concept for operational extreme space weather

warning satellite system• Satellites in different places are complementary• In combination, they could provide a graduated

space weather alert system• Share costs of elements/ops internationally?

Some Possible Discussion Points• Limited information on statistics of 3D spatial

scales, forms of ICME magnetic clouds: DRO constellation data would improve stats and models

• Even non-MC ICMEs can drive a geoeffective sheath (piled up solar wind)

• How does prediction effectiveness of in situ data fall with increasing distance away from the Sun-Earth line? how does this vary with heliocentric distance? scale of solar wind structure?

Earth

L5

Sun

L1

Sub-L1