Living with our star Henrik Lundstedt Swedish Institute

Living with our star Henrik Lundstedt Swedish Institute of Space Physics www. lund. irf. se The Sun drives a space weather, that influences the atmosphere, technological systems and us. Our society has become more susceptible to these effects. We therefore need to start learning how to live with our star! I will tell how!

Outline • • How and why does the Sun vary? How does the Earth respond? What are the impacts on life and society? How can we forecast it? What services exist? Teach space weather. Today’s space weather.

The Sun Diameter: 1 390 000 km (109 x Earth) Mass: 1. 99 x 1030 kg (330 000 x Earth) Density: Core 151 x 103 kg/m-3 Average 1. 41 x 103 kg/m -3 The Sun consits of: H (≈ 90%) Helium (≈ 10%) C, N, O ( ≈ 0. 1%) Temperature: Core 15 million Photosphere 5800 K Chromosphere 4300104 K Corona 1 -30 million K 4 protons --> He + 2 positrons + 2 neutrinos + 2 fotons (26. 2 Me. V)

Xspace from UCLA

Magnetohydrodynamic (MHD) approximation Induction equation Equation of continuity Equation of motion Maxwell’ equations and Ohm’s law give the induction equation. We need to observe V and B.

Solar observations • Where do we observe the Sun? • How do we observe the solar rotation and oscillations? • How do we observe the solar magnetic field?

Solar observations in California Mount Wilson Observatory Big Bear Solar Observatory Wilcox Solar Observatory Internet-accessible robotic solar telescope in Livermore

Solar observations with the Swedish solar telescope on La Palma

SOHO has given us a totally new picture of the Sun- always active • Solar Heliospheric Observatory was launched on December 2, 1995 • SOHO carries three instruments observing the solar interior, six the solar corona and three the solar wind

How do we observe the solar rotation and oscillation?

Dopplergram shows the solar rotation

Dopplergrams show the solar oscillations

The oscillations reveal solar interior

How do we observe the solar magnetic field?

When the solar magnetic field emerges thru the solar suface sunspots appear

MDI/SOHO reveals the interior MDI shows how the dynamo changes Sunspots are footpoints of emerging magnetic flux tubes MDI shows how magnetic elements form sunspots

Sunspots observed on solar surface Schwabe found the 11 - year sunspot solar cycle. R = k(10 g + f) The two peaks of solar activity, 1. 3 years separated!

At solar maximum 100 times brighter X-ray emission and 0. 1 % brighter in visible

Coronal mass ejections

CMEs cause the most severe space weather effects • Halo CMEs are most geoeffective • Mass: 5 -50 billion tons • Frequency: 3. 5/day (max), 0. 2/day (min) • Speed: 200 -2000 km/s

Solar flares and sun quakes

The source of the fast solar wind

Earth’s response • • Geomagnetic disturbances Aurora Ionospheric disturbances Climate and weather changes

Earth’s magnetosphere and current systems

Aurora oval

Aurora during severe solar storms Aurora was observed in Italy 6 -7 April and on July 15 -16, 2000! The aurora observed in Stockholm

Solar activity and North Atlantic Oscillation Index

North Atlantic Oscillation and solar wind activity The NAO response on increased solar wind E, one month later! That makes forecasts one month ahead possible. 11 års, 1. 3 variations are seen both in solar wind and NAO.

Impacts on life and society • Human radiation exposure (space station, space exploration (Mars), high altitude flights) • Impacts on technology (space systems (satellites), communications, navigation, terrestrial systems (electric power grids)) • Terrestrial climate

Satellite anomalies of July 14 -16, 2000 event The proton event caused problems for ACE, SOHO, Ørsted, Japanese X-ray satellite, star trackers on board commercial satellites. Proton flux (pfu) > 10 Me. V, 24000 pfu (July 15, 12. 30 UT). Third largest! Largest 43 000 pfu, (March 24, 1991). Second 40 000 pfu (October 20, 1989). Today IRF-Lund has real-time neural networks forecasts of satellite anomalies one day in advance (ESA project SAAPS). The work has been in collaboration with Swedish satellite operators (ESRANGE).

Solar proton events are dangerous to man in space Mars Between Apollo 16 and 17 a proton event occurred, which should have been deadly to the astronautes within 10 hours (i. e. above 4000 m. Sv).

Radiation risks and aviation The radiation exposure is doubled every 2. 2 km. Solar flares can increase the radiation by 20 -30 times. The intensive solar flare of April 2, 2001, which caused major communication problems also made Continental Airlines to change their route between Hong Kong and New York. Pilots get cancer more often than average. New EU law: Pregnant (aircrew) should not be exposed to more than 1 (1 -6) millisievert/year IRF-Lund collaborates with the Swedish Radiation Protection Institute and Medical University in Stockholm to develop forecasts of radiation doses for Aviation Industry.

Power systems and pipeline systems are effected at times of geomagnetic storms This severe electrojet caused the failure of Quebec’s power system March 13 -14, One of the generators of OKG’s 1989. (Sydkraft’s) nuclear plants was heated due to the geomagnetically induced current in March 13 -14 1989. Measured (Syd. Gas) geomagnetically induced disturbance at time of the Nordic GIC meeting in Lund September 23 -24, 1999. We in Lund have collaborated with the Swedish power industry during more than twenty years. Today we have real-time neural network forecasts of local GICs, based on ACE solar wind and warnings based on SOHO (LASCO and MDI) data.

Forecasts • Forecasting is a central problem within science • Forecasts based on knowledge-based neural model (KBNM) have been most succesful • Why not teach students how to forecast and model with KBNM?

Workshops arranged by us Workshops on ”Artificial Intelligence Applications in Solar-Terrestrial Physics” were held in Lund 1993 and 1997.

Artificial neural networks The basic element of every ANN is an artificial neuron or simply a neuron (which is an abstract model of a biological neuron (nerve cell)).

Download Lund Dst model in Java The ARMA filter is obtained by adding auto-regressive terms to a MA filter. The partial recurrent network (Elman) becomes identical to a linear ARMA filter if it is assigned linear activations functions.

Test Dst forecasts

Space weather service • • • Real-time solar data International Space Environment Service (ISES) 11 Regional Warning Centers (RWC) RWC-Sweden in Lund H. Lundstedt Deputy Director

Real-time forecasts and warnings based on KBN Solar input data Solar observations with SOHO make warnings 1 -3 days ahead possible. Solar wind observations with ACE make accurate forecasts 1 -3 hours ahead possible.

ESA/Lund Space Weather Forecast Service

Near and farside solar activity from MDI/SOHO observations

Latest information on arrival of halo CME at L 1

Latest info on forecasts of satellite anomalies (SAAPS)

Latest information on forecasts of Kp, Dst, AE and GIC

Regional Warning Centers RWC-Sweden in Lund

Forecasts of aurora as SMS, voice messages or WAP service

Teach space weather • Web sites (SOHO Explore links, Lund Space Weather Center) • Software packages (Xspace, Lund Dst-model in Java or Matlab • Books • CD-ROM ”SOHO - Explore the Sun”

Where to learn more?

Today’s Space Weather

Stanford collaboration

Space weather effects on technological systems

Artificial Neural networks The basic element of every ANN is an artificial neuron or simply a neuron (which is an abstract model of a biological neuron (nerve cell)). The neuron receives signals (information) from other nerve cells thru the dendrites. The axons take information away from the neuron. The output of the neuron is y=f(Swixi), with x as input vector. The value y is the state of the neuron. If f=sgn the state of the neuron is (+1, -1).

User of NAO forecasts Proton events give positive NAO within days! A User: Power sytem operators