Rodney Viereck
NOAA Space Environment Center
Boulder Colorado
An introduction to Space Weather
• What is it?
• Where does it come from?
• What does it do?

Space Weather:
Space Weather refers to changes in the space environment near Earth
Sun
Sun:
• Energy ( 386 Billion Billion MegaWatts) released in the form of…
• Light
• Particles (electrons and protons)
• Magnetic Field
• Activity Cycles
• 27 Days (solar rotation)
• ~100 Days Active Region Development
• 11 years
• 22 years
• 88 years
Earth

Space weather events are usually initiated by a solar flare or a coronal mass ejection
During a solar flare, the x-ray irradiance can increase by several orders of magnitude in just a few minutes

Space Weather:
Space Weather refers to changes in the space environment near Earth
Sun
Interplanetary Space
Interplanetary Space:
• Solar Wind
•Constant outflow from the sun
•Electrons and protons
• Disturbances from the sun produce waves and shocks in the solar wind
Earth

– Density
• 1 to 100 particles per cm 3
– Speed
• 200 to 800 km/sec

Space Weather:
Space Weather refers to changes in the space environment near Earth
Sun
Interplanetary Space
Magnetosphere:
• Created by Earth’s magnetic field
• Deformed by the Solar Wind
• Particles (electrons and protons) trapped on magnetic field lines
Magnetosphere
Earth

Field

Space Weather:
Space Weather refers to changes in the space environment near Earth
Sun
Interplanetary Space
Magnetosphere
Ionosphere
Earth
Ionosphere:
• Layer of electrons at the top of the atmosphere (100 – 300 km up)
• Formed when extreme ultraviolet light from the sun hits Earth’s Atmosphere
• Strongly affected by changes in the magnetosphere
• Critical in the reflection and transmission of radio waves

– Electrons and
Protons collide with the atmosphere
– The collisions excite atoms and molecules to produce the aurora

• Solar Flare: An eruption on the sun that emits light (UV and x-rays) and often particles (electrons and protons).
• CME (Coronal Mass Ejection): A disturbance in the solar wind caused by an eruption on the sun.
• Solar Wind : The outward flow of electrons, protons, and magnetic field from the sun.
• Energetic Particles: electrons and protons that have been accelerated to high speeds.
• Geomagnetic Storm: The disturbance in the near-Earth particles and magnetic fields that can upset technological systems and creates aurora.
• Radiation Storm: A large flux of solar energetic protons as measured near Earth.
• Radio Blackout: An enhancement in the lower ionosphere as a result of large x-ray flares.

1. Solar Flare (x-ray)
2. Shock (energetic particles)
3. Corornal Mass Ejection (particles and fields)
hours

1.Radio Blackouts
– Solar Flares send out x- rays
– Arrive at Earth in 8 minutes
– Modify the ionosphere
– Disrupt HF radio communication
– Impacts:
• Airline communication
• HF radio operators
• DoD Communications
• Satellite Communications
2.Radiation Storms
– Solar Flares and Coronal
Mass Ejections (CMEs) send out Energetic
Particles
– Arrive at Earth in 15 minutes to 24 hours
– Modify the high latitude ionosphere
– Disrupt HF radio communication
– Impacts:
• Airline communication
• HF radio operators
• DoD Communications
– Ionizing radiation penetrates into the atmosphere
– Impacts:
• Astronauts (radiation)
• Satellite failures
3.Geomagnetic Storms
– Coronal Mass Ejections
(CMEs) send out Magnetic
Clouds
– Arrive at Earth in 1-4 days
– Accelerate particles within the magnetosphere and into the ionosphere
– Impacts:
• HF radio communication
• Radio Navigation (GPS)
• Electric Power Grids
• Increased Satellite Drag
• Aurora

•The Sun
• Rotates every 27 days
• Has an 11-year cycle of activity
•Flares produce large amounts of x-rays and extreme ultraviolet light but not much visible light
The sun in X-rays
From GOES 12
An Erupting Prominence
A Solar Flare
Image from NASA TRACE Satellite
Image from NASA SOHO Satellite

• Visible light (small slow changes)
– Most of the energy output
– Impacts climate
• UV light (medium slow changes)
– Affects ozone production and loss
• EUV light (large changes)
– Affects radio communication
– Affects navigation
– Affects satellite orbits
• X-ray light (Can change by a factor of 1000 in five minutes)
– Affects radio communication
X-Ray Flare
Variability
(minutes)
Solar spectrum
Solar variability
Atmospheric penetration
Lean

Effect of Solar X-rays on D-Region and HF Propagation.
• D-Re gion Abs orption Product bas e d on GOES X-Ray
– The map shows regions affected by the increased D-region ionization resulting
TJFR

(Coronal Mass Ejections)
• While Solar flares send out light
(mostly x-rays)
• CMEs produce…
– Energetic particles
– Magnetic structures
Propagate away from the sun but their paths are modified by the background solar wind and the sun’s magnetic field.
Image from NASA SOHO Satellite
Image from NASA SOHO Satellite

What happens when a CME hits Earth?
1. Solar wind is deflected around Earth
2. Deflected solar wind drags Earth’s magnetic field with it
3. Magnetic field lines “reconnect” and accelerate particles
4. Accelerated particles follow field lines to Earth
Aurora is produced when particles hit Earth’s atmosphere
2. Deflected solar wind drags Earth’s magnetic field with it
1. Solar wind is deflected around Earth
Aurora
4. Accelerated particles follow field lines to Earth
Inner
Belt
Outer
Radiation
Belt
3. Magnetic field lines
“reconnect” and accelerate particles

Energetic Particle Effects
• Systems affected
– Spacecraft electronics
• Surface Charging and Discharge
• Single Event Upsets
• Deep Dielectric Charging
– Spacecraft imaging and attitude systems
SOHO Satellite Image
Degradation
Spacecraft Surface Charging (NASA animation)
Polar Satellite Image Degradation

Energetic Particles Effects
Health Hazards from
Energetic Particles
• Humans in space
– Space Shuttle,
International Space
Station, missions to
Mars
• Crew/Passengers in high- flying jets
– Concorde carries radiation detectors
– Passengers and crew may receive radiation doses equivalent to many chest X rays.

• The particles collide with the atmosphere and produce the Aurora and currents in the ionosphere
• As geomagnetic activity increases, the aurora gets brighter, more active, and moves away from the polar regions.
– Electric Power is affected
– Navigation Systems are affected
– Radio Communications are affected
Image from NASA IMAGE Satellite

Geomagnetic Storm Effects
March 1989
Hydro Quebec Loses Electric Power for 9 Hours
Electric Power
Transformer
Transformer Damage

• The particles spiral down the magnetic filed lines and collide with the atmosphere to produce the aurora.
• Colors indicate the atoms or molecules that are excited by the incoming particles

Photo by Jan Curtis, http://www.geo.mtu.edu/weather/aurora Geomagnetic Storm Effects
• Intensity and location of the aurora depend on strength of storm
• Best time to view is around midnight
• No guarantee that aurora will occur
G1
G3
G5

• Disrupt Radio Communications • Impact Electric Power Systems
• Disrupt Radio Navigations
• Impact Satellites

starts at the sun and end up at Earth
– Solar Flare
• Light
• Particles
• CME
– Magnetosphere
• Deflects the solar wind
• Responds to the disturbance
• Accelerates particles
– Ionosphere
• Accelerated particles collide with the atmosphere producing the aurora
NASA Animation

Timing and Consequences
• At T = 0, A Flare and CME
Erupts on the Sun
• 8 Minutes later: First blast of
EUV and X-Ray light increases the ionospheric density
– Radio transmissions are lost
• 30 min. to 24 hrs. later:
Energetic Particles Arrive
– Astronauts are at risk
– Satellites are at risk
– High altitude aircraft crew are at risk
• 1 to 4 Days Later: CME Arrives and energizes the magnetosphere and ionosphere
– Electric Power is affected
– Navigation Systems are affected
– Radio Communications are affected
Movie from NASA SOHO Satellite

• The Size of Flare or CME
– Big solar events tend to make big storms
• The Location of the flare site on the SUN
– If it is directed at Earth, it is more likely to make a storm
– If it toward the west side of the sun, the particles will arrive sooner
• The Direction of the
Magnetic Field in the CME
– If the interplanetary magnetic field is southward, then there will likely be a big storm
Note, there does not have to be a solar flare or CME to create a geomagnetic storm

– Geomagnetic Storms
(CMEs)
– Solar Radiation Storms
(Particle Events)
– Radio Blackouts
(Solar Flares)
Combs
Rabin

Radiation Storms
1-4 per month at max
Geomagnetic Storms
3-5 per month at max
Radio Blackouts
50-100 per month at max
Sunspot Number
11-year cycle
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Year

• Sunspots have been recorded for the last 400 years
• Note that there were no sunspots for nearly 60 years after 1640
• During the same period, it was very cold in Europe.
This is a period called “The Little Ice Age”
• Is there a Connection?
• Recent studies say there may be
Solar
Minimum
Solar Maximum

• The sun is the primary engine for weather and the climate
• Very large climate changes (Ice ages) are known to be caused by changes in insolation (amount and distribution of sunlight)
• The sun is likely responsible for some of the climate change… up to
1960s… but not the rapid increase in temperatures since then.
NCAR Climate Model
Ammann: SORCE 2003

NASA STEREO
• Events are observed on and near the sun
•
No measurements until the Particles or CMEs
(Ahead) are 99% of the way to Earth
•
This provides only 30 minutes lead time for
CMEs and no lead time for other events
NASA STEREO
(Behind)
• SOHO
– Solar EUV Images
– Solar Corona
(CMEs)
• GOES
– Energetic Particles
– Magnetic Field
– Solar X-ray Flux
– Solar X-Ray Images
NASA SOHO
• ACE
– Solar wind composition, speed, and direction
NASA ACE
– Magnetic field strength and direction
NOAA GOES
• STEREO
– CME Direction and
Shape
– Solar wind composition, speed, and direction
– Magnetic field strength and direction
• POES
– High Energy
Particles
– Total Energy
Deposition
– Solar UV Flux
NOAA POES

• Space Weather Storms come in three main categories
• Each category originates from different physical processes
• Each category arrives at a different speed
• Each category affects different users and technologies
Space
Weather
Event
Radio Blackouts
Bursts of X-ray and
EUV radiation
Radiation Storms
Energetic Particles
(electrons and protons)
Geomagnetic
Storms
When the CME reaches Earth
Arrival
Time
8 minutes
Systems Radio Comm.
Affected Airlines
15 min. to 24 hrs. 1 to 4 days
Satellites
Astronauts
Radio Comm.
Power Companies
Radio Comm.
Navigation (GPS)
Satellite Drag