SPACE WEATHER INTRODUCTORY COURSE Collaboration of So Solar-Te - - PowerPoint PPT Presentation

SPACE WEATHER INTRODUCTORY COURSE

So Solar-Te Terrestrial Centre of Excellence

Collaboration of

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

SPACE WEATHER

Petra Vanlommel

Overview

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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The source of weather

We are all familiar with terrestrial tropospheric weather. It is what we experience all around us; our atmospheric environment. It may be fine, cloudy, stormy or sunny. It may rain or hail. We know about temperature and pressure and humidity. This is all about weather in the lowest 10 km of our atmosphere. Wikipedia Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the lowest level of the atmosphere, the troposphere, just below the stratosphere. Weather refers to day-to-day temperature and precipitation activity, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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The main source of space weather

As we go out into space, the atmosphere becomes very thin, until by the time we are in space, it has almost vanished. Almost, but not quite. Even in space there are some atoms which are often moving very quickly. Many forms of energy also move through space and it is the interaction of energy and atoms that produces what we refer to as space weather. In particular, space weather is the changes that occur in the space environment. The sun is the source of 'normal' terrestrial weather. It is also the primary (but not the only) source of space weather. Most aspects of space weather afgect us to some

• extent. The more our society becomes dependent on technology and the more we utilize space, the more we are afgected by space weather. Some aspects of space

weather are benevolent, and allow activities not otherwise possible such as long range radio communications. Some aspects are benign but fascinating such as the Aurora, and some are malevolent. Like terrestrial weather, it depends on the situation and the event.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

Title Text

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Image: Siberia 20080801
 J.M.P ., W. G. Wagner and H. Druckmüllerová S T U D Y I N G T H E S U N

Simply by watching it, at special events.

How can we study the Sun - simply by watching it.

in difgerent circumstances, at special events, using a telescope - from 1609 - to magnify Visible light A special event: a solar eclipse. In the past, people thought it was a divine event: the gods interfered and made the sun disappear. Now we know it is the moon that occults the sun. The moon appears to be as big as the Sun.

The total solar eclipse of 1 August 2008, observed from Siberia. 
 What happens:


• visible light from the disc bounces off from plasma in the corona in our direction (Thompson scattering) - refracted light

• the solar disc is a million times brighter than the corona, the light we see during eclipse is always there but swamped in the much brighter direct light

Seeing the corona ‘naturally’ is exceptional on astronomical scales:


• the apparent size of moon and star have to match the distance planet-star

• the moon should have no atmosphere

• the planets atmosphere should be transparant

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

ELECTROMAGNETIC SPECTRUM

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To study an object, we take pictures. A doctor can use an x-ray camera to take a special picture of your bones. In fact, an x-ray picture shows the shadow of your bones which are not transparant for x-rays. The softer parts of your hand are partly transparant for x-rays. These pictures can show doctors parts of your body that they can’t normally see. Each wavelength give other information.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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H-alpha 656.28 nm - rood - 9000 °K C II K 3933.7Å - 393.37 nm - blauw - zichtbaar licht: 780 - 380 nm / 7800- 3800 Angstrom / ROGeGrBIV UV: 380 - 10 nm / 3800 - 100 Angstrom EUV: 100 - 10 nm / 1000 - 100 Angstrom

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

ELECTROMAGNETIC SPECTRUM

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We use many tricks to observe the Sun and its activity. One of them is to look at the Sun using difgerent parts of the light spectrum, thus in difgerent wavelengths. From Earth, with the naked eye, we see the surface of the Sun in white light like this. However, now that I start the movie, you can see how looking at the Sun in other wavelengths from space reveals very difgerent structures and complexity. For this we mainly use extreme ultraviolet wavelengths because we are studying the hot outer region of the Sun, the corona. We see active regions, these are the bright patches, that show up in EUV wavelengths where the sunspots were first seen in white light. We also see the efgects of the sun’s magnetic field in the many loops above these sunspots. Each wavelength shows us difgerent aspects and difgerent layers of the solar atmosphere and by combining them, we try to build a complete picture of the solar activity. Therefore, we have many instruments in space to observe the solar atmosphere. credits: This movie was made combining difgerent observations from the AIA telescope on board the Solar Dynamics Observatory.

The Sun has a hidden part that became only visible at the start of the space age. From the moment, we could inspect the Sun in other wavelengths, the Sun showed its dynamic, explosive and magnetic personality.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Lagen van de zon De zon als magnetische structuur

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

LAYERS

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Photosphere Chromosphere Transition Layer Corona The solar atmosphere are the most outer layers of the Sun from where the sunlight can escape freely, in contrast to the un-transparant inner layers. The solar atmosphere has 4 basic layers Photosphere - chromosphere - transition layer - corona Temperature increases which is sort of strange. Normally you would think that the temperature decreases if you go further away from the heat source. Why is the corona so hot? There is not a clear answer yet. The name photosphere comes from the greek work photon which means ‘light’. The photosphere radiates mostly in visible light which we can see. While the corona radiates in (E)UV and X-rays, all wavelengths which we can’t see with our eyes. That’s why we see the sun as a non-dynamic structure. The coronal loops and dynamic structures in the corona are invisible for us unless we watch it in the EUV using special filters translating the EUV into a picture which we can see.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

LAYERS

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Photosphere Chromosphere Transition Layer Corona But, although the corona is million degrees °K, satellites don’t ‘burn’. This is because it is not dense at all. Compare it with going to a sauna of 90°C and a bath of 90°C. I can take a sauna of 90°C but not a bath of 90°C. The air is the sauna is less dense than the water in the bath.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

POSITIONING

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Solar Equator Solar rotation axis Northern hemisphere Southern hemisphere Solar North Pole Magnetic South Pole positive/outward yellow/white Solar South Pole Magnetic North Pole negative/inward blue/black West East

Before going into more detail of flares (e.m. waves), CME’s and CH’s (solar plasma that moves through space) and SEPs (Solar Energetic Particles)/plasma storms (electrically charged particles that move along magnetic field lines through space), we have to be able to ‘navigate’ on the sun. Two important circles/lines are: the central meridian and the solar equator. You determine positions on the solar surface Solar equatorial plane is not the ecliptic (plane in which the Earth orbits). The earth has a certain heliographic latitude. In summer and winter, the earth looks more on the

• poles. While in spring and autumn, earth is located in the solar equatorial plane.

magnetic reversal - at solar maximum: magnetic north pole becomes the magnetic south pole and reversed. A magnetic cycle of 22 years.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Image: Siberia 20080801
 J.M.P ., W. G. Wagner and H. Druckmüllerová

2015 2008

M A G N E T I S M

An enormous amount of magnetic energy is stored in the Sun. The magnetic field is not only contained in the interior of the Sun but is present every where in space, better said, in the heliosphere. It is the magnetic field that lies at the base of all solar activity. Magnetic signature visible here is at a large length scales. It changes over a period of 11 years. Large spatial and time scale: Solar dipole - visible during a solar eclipse, more pronounced at solar minimum, orientation and geometry vary during the solar cycle.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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2015 2008

Snelle wind Snelle wind Snelle wind Trage wind Trage wind Open magneetveld lijnen Gesloten veldlijnen Heliosferisch stroomvlak

The sun is a gigantic dipole.

G I G A N T I C D I P O L E

Magnetic field lines have a direction, i.e. you can draw an arrow. A magnetic field line that comes through the solar surface, goes ‘in’ or ‘out’. we have ‘closed’ and ‘open’ magnetic field Iines. Open magnetic field lines goes from the sun into space. An open magnetic field line is positive (pointing away from the sun) or negative (pointing towards the sun). Loops are closed magnetic field lines: a line leaves the sun, bends and turns back into the sun. The Sun is a large magnetic dipole:

• you have positive magnetic field lines leaving the sun and negative magnetic field lines pointing to the sun. It is the solar plasma that moves away from the sun that drags the magnetic field lines into

space creating an open magnetic field structure. Or you can also say that the open magnetic field lines guide the solar plasma into space. This will become clear further one.

• above the equator, these field lines bend and create loops.

This magnetic field that is present in space, we call the Interplanetary Magnetic Field, or IMF. The magnetic field lines are close together near the sun - higher magnetic density. The more you go away from the sun, the fainter the magnetic density becomes.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Active regions are dynamical bundles of huge coronal magnetic loops that resides in sunspots at the photosphere.

L O C A L M A G N E T I C F I E L D S

Magnetic forces are present on the sun in all possible length scales. These magnetic structures vary on difgerent time scales: from minutes, to hours, to days, to years. On a smaller spatial scale, local magnetic field - the magnetic field can have a more complex geometry, multi polar. Active region - magnetic loops in the corona, coronal part of a magnetic structure that appears as a sunspot on the photosphere. On a smaller spatial scale, local magnetic field - the magnetic field can have a more complex geometry, multi polar. Active region - magnetic loops in the corona, coronal part of a magnetic structure that appears as a sunspot on the photosphere.

In het EUV zien we dat die structuren erg dynamisch en beweeglijk zijn. Dit is een filmpje over enkele zonnerotaties. De zon varieert Film over een paar zonnerotaties Actieve gebieden kunnen net zoals zonnevlekken ontstaan, groeien, verdwijnen.

It is the magnetic field that lies at the base of all solar activity: eruptions on a short time scale, up to the phenomenon of the 11 year solar cycle. Magnetic forces are present on the sun in all possible length scales. These magnetic structures vary on difgerent time scales: from minutes, to hours, to days, to years. On a smaller spatial scale, local magnetic field - the magnetic field can have a more complex geometry, multi polar. Active region - magnetic loops in the corona, coronal part of a magnetic structure that appears as a sunspot on the photosphere.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Space climate Space weather

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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The Sun emits energy.

RADIATION PARTICLES + B

The sun is a gigantic ball of energy: magnetic energy, heat, moving plasma, … Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Plasma is the fourth state of matter. When you have solid material and you heat it, it becomes liquid. You keep on meeting it, it becomes a gas. When you still add heat, the atoms split into ions and

• electrons. The gas becomes electrically conductive creating electrical and magnetic field.

This energy is kept inside the Sun but also on its surface and in its atmosphere in magnetic structures like sunspots and magnetic loops, filaments or prominences ready to be released. This energy is expelled, leaves the Sun to outer space in the form of electromagnetic radiation, kinetic, electric and magnetic energy. Note: the solar plasma is hot. The plasma particles bump on each other. These collisions changes their kinetic energy. This change is emitted in the form of thermal radiation, light photons. Once these photons are at the solar surface, they can escape and move freely. Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. You have thermal motion as soon as the temperature is above absolute zero.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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TOTAL SOLAR IRRADIANCE SOLAR WIND

The sun emits continuously energy and creates a space climate that has 2 seasons: a more active and a less active. This seasonal variation is called the solar cycle and takes around 11 years. S PA C E C L I M AT E

The outward flow of solar particles and magnetic fields from the Sun. Typically at 1 AU, solar wind velocities are near 375 km/s and proton and electron densities are near 5 cm-3. The total intensity of the interplanetary magnetic field is nominally 5 nT. TSI, e.m. radiation is not linked to the IMF. It doesn’t follow the magnetic field lines. PROBA2/SWAP, the sun in the EUV However, plasma containing ions and electrons has to follow the magnetic field lines. Or you can also say that the magnetic field lines guide the plasma. The solar wind plasma is glued to the IMF - or the IMF is glued to the plasma. The plasma in the solar wind is considered as a gas, a group of particles behaving and moving in group. You don’t speak about that particular particle in the solar wind, you speak about the solar wind, a whole bunch together. Cartoon Electrically charged particles have to follow the IMF. These electrically charged particles are considered as individuals and behave as individuals. Cartoon Near Earth, the IMF still controls the solar wind and its movement. Much much further away from the Sun, the IMF becomes very weak and doesn’t control the solar wind anymore. But, this is not important for us. At 1AU, the IMF influences the plasma and the plasma the IMF.

About the animated gif: Conceptual animation (not to scale) showing the sun's corona and solar wind. Credits: NASA's Goddard Space Flight Center/Lisa Poje The solar wind is a continuous radial stream of solar plasma that leaves the sun and moves away from it. It fils the space between the planets with solar mass. The solar wind reaches the boundaries of the heliosphere, a magnetic shield around the Sun. In the heliosphere, the Sun sets the rules and you have solar weather. Outside the heliosphere, you have the rest of the galaxy. Earth is in the heliosphere. A nice movie is found on

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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FLARE CME CORONAL HOLE 8 MIN DAYS

T I M E S C A L E S

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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FLARE CME CORONAL HOLE FLARE CME or CLOUD CORONAL HOLE SBC SOLAR ENERGETIC PARTICLES

At a certain moment, energy might be released on a shorter time scale. Space weather is the more sudden change that occur on the Sun or in the space environment.

S PA C E W E AT H E R

Space weather is the changes that occur in the space environment. A Flare is a sudden strong increase of the solar e.m. radiation. The light flash is localised on the solar surface. SDO/AIA A Coronal Mass Ejection is a plasma cloud that is ejected into space. You consider it as a cloud and not as a bunch of individual particles. It is superimposed on the background solar wind. You can see a CME as a complex magnetic bag with difgerent magnetic layers with plasma in it that travels as a tsunami through space. It can go faster/as fast as/slower than the background solar wind. When it is faster, you will see a shock in front of the cloud. This is exactly the same as the shock you see in front of a speed boat. A CME is visible as a white cloud in corona graphic images like the one on the slide. A coronagraph is a telescope that creates an artificial eclipse and makes pictures in the visible light of the region around the sun. SOHO/LASCO C2 (red) and LASCO C3 (blue) A coronal hole is a structure in the solar corona that you see as a black area in the EUV. It looks black because there is less plasma present that radiates in the EUV. The magnetic field lines are open, i.e. fan out into space. There are no magnetic loops above a coronal hole. The solar wind emanating from a CH is faster compared to the usual solar wind. SDO/AIA A particle storm is a bunch of electrically charged particles that are accelerated in the solar atmosphere to very high velocities by a large-scale magnetic eruption often causing a CME and/or solar flare. They follow the IMF They may impact telescopes. They are seen as white stripes and dots: this are particles that fall into the lens and blind the pixel(s). During that particular moment, the telescope can’t see anymore through the impacted pixels. You can say that the dots and stripes represent a sort of in situ measurement. In situ means that you measure a parameter local. Remote sensing means that you look at something from a distance. Near Earth, the IMF still controls the solar wind and its movement. If we would go much much further, the CME magnetic bag with solar plasma would be almost empty (all the solar material is spread

• ver an immense volume) and the magnetic bag would have evaporated. But, this doesn’t matter for us. We are at 1AU and at 1AU the IMF and solar plasma make space weather in a normal way, in an

extreme way.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

RADIO BLACKOUT

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GEOMAGNETIC STORM SOLAR RADIATION STORM

The Earth and its environment reacts on these space weather events. The solar storms that impact earth are called ‘radio blackout’, ‘geomagnetic storm’ or ‘solar radiation storm’. S PA C E W E AT H E R

Impact on Earth environment according to the NOAA space weather scales Radio blackout Impact on navigation & radio communication Afgects communications, and on rare occasions GNSS navigation. Daylight side impact only. May last from a few minutes to a few hours and are much shorter duration than geomagnetic storms. Geomagnetic storm Radio communication, HF and LF Satellite operations Power systems, e.g. GIC Aurora —> afgect communication and GNSS navigation in the HNH and HSH regions and sometimes include MNH and MSH regions. EQN and EQS may be afgected during the worst storms. Solar radiation storm Biological impact Satellite operations HF communication in the polar regions - degradation or black out (PCA) Navigation

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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FLARE CME CORONAL HOLE STORM 8 MIN HOURS - DAYS HOUR

T I M E S C A L E S

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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B I O L O G I C A L L I V E I S P R O T E C T E D

The Earth atmosphere protects human and biological live against solar e.m. radiation. The Earth magnetic field protects human and biological live against the solar wind.

The earth magnetic field guides the solar protons that reach the Earth’s magnetosphere and ionosphere towards the poles. The earth atmosphere is not blown away by the solar wind thanks to the magnetosphere.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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SOLAR EVENT How is it MEASURED? IMPACT on EARTH

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

SOLAR ENERGETIC PARTICLES

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FLARE CME CORONAL HOLE FLARE CME or CLOUD CORONAL HOLE SBC

Space weather is the changes that occur in the space environment. A Flare is a sudden strong increase of the solar e.m. radiation. The light flash is localised on the solar surface. SDO/AIA A Coronal Mass Ejection is a plasma cloud that is ejected into space. You consider it as a cloud and not as a bunch of individual particles. It is superimposed on the background solar wind. You can see a CME as a complex magnetic bag with difgerent magnetic layers with plasma in it that travels as a tsunami through space. It can go faster/as fast as/slower than the background solar wind. When it is faster, you will see a shock in front of the cloud. This is exactly the same as the shock you see in front of a speed boat. A CME is visible as a white cloud in corona graphic images like the one on the slide. A coronagraph is a telescope that creates an artificial eclipse and makes pictures in the visible light of the region around the sun. SOHO/LASCO C2 (red) and LASCO C3 (blue) A coronal hole is a structure in the solar corona that you see as a black area in the EUV. It looks black because there is less plasma present that radiates in the EUV. The magnetic field lines are open, i.e. fan out into space. There are no magnetic loops above a coronal hole. The solar wind emanating from a CH is faster compared to the usual solar wind. SDO/AIA A particle storm is a bunch of electrically charged particles that circle around the IMF lines into space. They may impact telescopes. They are seen as white stripes and dots: this are particles that fall into the lens and blind the pixel(s). During that particular moment, the telescope can’t see anymore through the impacted pixels. You can say that the dots and stripes represent a sort of in situ measurement. In situ means that you measure a parameter local. Remote sensing means that you look at something from a distance. Near Earth, the IMF still controls the solar wind and its movement. If we would go much much further, the CME magnetic bag with solar plasma would be almost empty (all the solar material is spread

• ver an immense volume) and the magnetic bag would have evaporated. But, this doesn’t matter for us. We are at 1AU and at 1AU the IMF and solar plasma make space weather in a normal way, in an

extreme way.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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FLARE FLARE Radio blackout

A Flare is a sudden increase of the solar e.m. radiation. The light flash is localised on the solar surface. In these images, the flare is visible in the EUV: in that particular wavelength, the e.m. radiation increased suddenly. The plasma on that spot started to radiate very intense in the EUV. A short time, pixels that see the flare are overexposed and blinded. You see a vertical flash in the top/left. It is vertical because the pixels are read out in this direction.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

DE ZON IS VARIABEL

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L O C A L M A G N E T I C F I E L D S

A sunspot is a bundle of intense magnetic field that points through the photosphere. A sunspot appears black because the temperature is cooler compared to its surroundings.

A sunspot is a black spot on the surface of the sun when seen in the visible light. We see the sun rotating and sunspots rotating with it. The form of a sunspot can change.

Vlekkengroepen zijn plaatsen waar de onderliggende intense magneetvelden de dunne laag van de fotosfeer doorboort.

• Ze hebben een dipolaire globale structuur die overeenkomt met het voetstuk van het magnetisch gewelf dat zich tot hoog tot in de zonneatmosfeer
• ntwikkelt. De dipool is steeds oost-west georiënteerd.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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A flare is a light flash near an active region. A volume of plasma is suddenly heated and therefore lights up.

S O L A R F L A R E S Flare

Een zonnevlam bestaat uit een brutale en kortstondige verhitting van een beperkt plasmavolume van de zonneatmosfeer, dat tot minstens 107 K wordt

• verhit. Deze verhitting is een gevolg van een snelle herschikking of reorganisatie van het magneetveld.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Flare X - R AY F L U X

A flare is identified by its x-ray flux. Flares are put into logaritmisch categories.

GOES satellite, geostationary http://www.swpc.noaa.gov/products/goes-x-ray-flux This graph was made on the fly with stafg, a solar time lines viewer: http://stafg.oma.be During a flare, magnetic energy is transformed into e.m. waves. GOES measures the full disk e.m. radiation (Energy per second per square meter) in a particular X-ray wavelength every minute. The more intense, the higher the curve. Flares are put into X-ray flux categories. The X-ray flux is measured by GOES (meteo-satellites of NOAA). The classes are based on the enlargement factor of the X-flux in the spectral range 1 to 8 Å - logarithmic. This enlargement factor can go up to 10 000, typically between 10 and 100.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Flare N O A A S PA C E W E AT H E R S C A L E S

The impact of a flare depends on the intensity of the x-ray flux.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

FLARE CATEGORIES

X-ray output

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R2 R1 R3 R4 R5 Flare F L A R E C AT E G O R I E S & S W S C A L E S GOES satellite, geostationary http://www.swpc.noaa.gov/products/goes-x-ray-flux This graph was made on the fly with stafg, a solar time lines viewer: http://stafg.oma.be During a flare, magnetic energy is transformed into e.m. waves. GOES measures the full disk e.m. radiation (Energy per second per square meter) in a particular X-ray wavelength every minute. The more intense, the higher the curve. Flares are put into X-ray flux categories. The X-ray flux is measured by GOES (meteo-satellites of NOAA). The classes are based on the enlargement factor of the X-flux in the spectral range 1 to 8 Å - logarithmic. This enlargement factor can go up to 10 000, typically between 10 and 100.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Impacts

Flare

Global Navigation Satellite System How the ionosphere behaves has an impact on HF communication and navigation Ionospheric storms primarily afgect the equatorial regions but can also extend into the middle latitudes and afgect GNSS navigation.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

SOLAR ENERGETIC PARTICLES

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FLARE CME CORONAL HOLE FLARE CME or CLOUD CORONAL HOLE SBC

Space weather is the changes that occur in the space environment. A Flare is a sudden strong increase of the solar e.m. radiation. The light flash is localised on the solar surface. SDO/AIA A Coronal Mass Ejection is a plasma cloud that is ejected into space. You consider it as a cloud and not as a bunch of individual particles. It is superimposed on the background solar wind. You can see a CME as a complex magnetic bag with difgerent magnetic layers with plasma in it that travels as a tsunami through space. It can go faster/as fast as/slower than the background solar wind. When it is faster, you will see a shock in front of the cloud. This is exactly the same as the shock you see in front of a speed boat. A CME is visible as a white cloud in corona graphic images like the one on the slide. A coronagraph is a telescope that creates an artificial eclipse and makes pictures in the visible light of the region around the sun. SOHO/LASCO C2 (red) and LASCO C3 (blue) A coronal hole is a structure in the solar corona that you see as a black area in the EUV. It looks black because there is less plasma present that radiates in the EUV. The magnetic field lines are open, i.e. fan out into space. There are no magnetic loops above a coronal hole. The solar wind emanating from a CH is faster compared to the usual solar wind. SDO/AIA A particle storm is a bunch of electrically charged particles that circle around the IMF lines into space. They may impact telescopes. They are seen as white stripes and dots: this are particles that fall into the lens and blind the pixel(s). During that particular moment, the telescope can’t see anymore through the impacted pixels. You can say that the dots and stripes represent a sort of in situ measurement. In situ means that you measure a parameter local. Remote sensing means that you look at something from a distance. Near Earth, the IMF still controls the solar wind and its movement. If we would go much much further, the CME magnetic bag with solar plasma would be almost empty (all the solar material is spread

• ver an immense volume) and the magnetic bag would have evaporated. But, this doesn’t matter for us. We are at 1AU and at 1AU the IMF and solar plasma make space weather in a normal way, in an

extreme way.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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CME CORONAL HOLE CME or CLOUD CORONAL HOLE SBC Geomagnetic storm

Space weather is the changes that occur in the space environment. A Flare is a sudden strong increase of the solar e.m. radiation. The light flash is localised on the solar surface. SDO/AIA A Coronal Mass Ejection is a plasma cloud that is ejected into space. You consider it as a cloud and not as a bunch of individual particles. It is superimposed on the background solar wind. You can see a CME as a complex magnetic bag with difgerent magnetic layers with plasma in it that travels as a tsunami through space. It can go faster/as fast as/slower than the background solar wind. When it is faster, you will see a shock in front of the cloud. This is exactly the same as the shock you see in front of a speed boat. A CME is visible as a white cloud in corona graphic images like the one on the slide. A coronagraph is a telescope that creates an artificial eclipse and makes pictures in the visible light of the region around the sun. SOHO/LASCO C2 (red) and LASCO C3 (blue) A coronal hole is a structure in the solar corona that you see as a black area in the EUV. It looks black because there is less plasma present that radiates in the EUV. The magnetic field lines are open, i.e. fan out into space. There are no magnetic loops above a coronal hole. The solar wind emanating from a CH is faster compared to the usual solar wind. SDO/AIA A particle storm is a bunch of electrically charged particles that circle around the IMF lines into space. They may impact telescopes. They are seen as white stripes and dots: this are particles that fall into the lens and blind the pixel(s). During that particular moment, the telescope can’t see anymore through the impacted pixels. You can say that the dots and stripes represent a sort of in situ measurement. In situ means that you measure a parameter local. Remote sensing means that you look at something from a distance. Near Earth, the IMF still controls the solar wind and its movement. If we would go much much further, the CME magnetic bag with solar plasma would be almost empty (all the solar material is spread

• ver an immense volume) and the magnetic bag would have evaporated. But, this doesn’t matter for us. We are at 1AU and at 1AU the IMF and solar plasma make space weather in a normal way, in an

extreme way.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Solar wind = Interplanetary Magnetic Field + Plasma

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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2015 2008

M A G N E T I S M

An enormous amount of magnetic energy is stored in the Sun. The magnetic field is not only contained in the interior of the Sun but is present every where in space, better said, in the heliosphere.

The solar wind carries out solar material and solar magnetic field. The solar material and magnetic field becomes less dense the further away from the Sun.

I N T E R P L A N E TA RY M A G N E T I C F I E L D

Near Earth, the IMF still controls the solar wind and its movement. If we would go much much further, the CME magnetic bag with solar plasma would be almost empty (all the solar material is spread

• ver an immense volume) and the magnetic bag would have evaporated. But, this doesn’t matter for us. We are at 1AU and at 1AU the IMF and solar plasma make space weather in a normal way, in an

extreme way.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Mass + B

The IMF can couple with the magnetic field of Earth. This coupling is stronger when the IMF is opposite to the magnetic field of Earth.

I R E C O N N E C T I O N This is the earths magnetosphere. The sun is somewhere far away in the right top corner. The earth is a giant dipole - similar as the sun. Except, the solar magnetic dipole field reverses every 11 year. The Earths magnetic poles don’t. They are already for ages like this. The part of the earths dipole facing the sun/solar wind is pushed more together, while the part behind the earth is stretched and forms a tail. In front of the magnetic structure, you have a shock. This is a structure similar like a shock in front of a speed boat that moves very fast over water: the water waves that the moving boat initiate are slower compared to the speed of the boat. The boat is super-water wave. When a plane is super-sonic, there is also a shock in front of it. The pressure waves that the moving plane creates move much slower than the plane. In the case of a speed boat, the boat moves through the water. In our case, it is the solar wind that blows over the earth. It is just a matter of reference, but the result is the same: a shock. A magnetic field is imbedded in the solar wind. This magnetic field can interact with the magnetic field of the earth at the boundaries of the earth magnetosphere. This interaction is called reconnection. It happens when 2 magnetic regions are confronted with each other. The blue magnetic field lines are imbedded in the solar wind. The red magnetic field lines represent the earth magnetosphere. The blue and the red magnetic region have to face each other. Opposite magnetic field lines can reconnect easily and ‘open’. This causes geomagnetic storms. Magnetic field lines in the same direction interact less. Therefore, it is very important to know how strong the 0.3 T - solar sunspot 5mT - strength of a typical refrigerator magnet 31.869 µT (3.1 × 10−5 T) – strength of Earth's magnetic field at 0° latitude (North/South), 0° longitude (west/east)

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PARKER SPIRAL

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Left: This is a view of the global IMF in the solar equatorial plane. Right: The IMF and our space is 3D. You have at a particular latitude also IMF lines coming out. Also these lines bend because of the solar rotation. All IMF lines at a particular latitude form a magnetic coin. The solar equatorial plane is a flat cone :) This is the ideal IMF. left: It has no component perpendicular on the solar equatorial plane. right: it has no component perpendicular to the surface of the magnetic cone. The frozen-flux theorem: IMF and plasma are glued. The food points of the magnetic field lines are attached to the sun. At the same time, the plasma of the solar wind on the further distance is glued to that same magnetic field line. When the sun rotates, the IMF is forced to bend.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

SOLAR WIND MEASUREMENTS

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This are in situ solar wind measurements done by the NOAA DSCOVR satellite http://www.swpc.noaa.gov/products/real-time-solar-wind This satellite is located at the Lagrangian point L1: in between the earth and the sun. When the earth moves around the sun, L1 follows. We call L1 one hour upstream of

• earth. This refers to the solar wind. It takes the solar wind from that point roughly 1 hour to reach the magnetosphere of the earth.

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COORDINATE SYSTEM

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GSE: Geocentric Solar Ecliptic system. This has its X-axis pointing from the Earth toward the Sun and its Y-axis is chosen to be in the ecliptic plane pointing towards dusk (thus opposing planetary motion). Its Z-axis is parallel to the ecliptic pole. Relative to an inertial system this system has a yearly rotation.

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IMF POLARITY

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for 400 km/s ϕ ~ 315° for 400 km/s ϕ ~ 135°

This is the IMF in the solar equatorial plane. Check slide 35

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EXTREME FAST

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ϕ = 180°

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EXTREME FAST

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ϕ = 0° ϕ = 360°

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SOLAR WIND IS RADIAL & IMF BENDS?

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SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

SOLAR WIND VARIATIONS

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Non-eruptive Coronal Hole Sector Boundary Crossing Eruptive Coronal Mass Ejection

The variations in the solar wind introduce space weather events. CME - suddenly, a mass is ejected into space. A CME is an eruptive event. You can have filament eruptions or plasma ejections associated with flares. We come back to this. A CH is not eruptive. A CH is present, it doesn’t pop up suddenly. A CH can of course slowly appear or disappear, become bigger, become smaller but not on time scale of a few minutes. It is also not the case that a CH ejects material and a little bit later, not any more. The solar wind continuously emanated from a CH. A sector boundary crossing is also not eruptive.

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SECTOR BOUNDARY CROSSING

Heliospheric current sheet

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Snelle wind Snelle wind Snelle wind Trage wind Trage wind Open magneetveld lijnen Gesloten veldlijnen Heliosferisch stroomvlak

The heliospheric current sheet is a layer between regions with opposite magnetic field lines. The heliospheric current sheet is in a perfect world a flat sheet, perpendicular on the dipole axis of the Sun. The dipole axis is not the same as the solar rotation axis. The heliospheric current sheet is therefore not the same plane at the solar equatorial plane. And there is also the third plane: the ecliptic plane. This is plane in which the earth orbits the sun.

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SECTOR BOUNDARY CROSSING

Ballerina Skirt

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Neither the solar rotation axis nor the efgective dipole axis are perpendicular to the ecliptic plane. Accordingly, the Sun's rotation causes the heliospheric current sheet to move up and down at a fixed observer's position, with associated changes in the plasma density and the direction (towards/away) of the magnetic field. This wavy pattern

• f the current sheet is sometimes referred to as the “ballerina skirt" .

In this picture, you see 2 waves. There can be more.

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SECTOR BOUNDARY CROSSING

Magnetic sectors

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Cravens, 1997 distinct, long-lasting intervals of uniform solar wind field direction exist, called ``sectors'' Going from one sector to another, changes in the plasma density and the direction (towards/away) of the magnetic field occur. When you pass from one sector to another sector, the density and Bz of the solar wind measured at the L1 point by ACE or DSCVR can change and have a geomagnetic

• impact. But in general, sector boundary crossings do not do much.

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CORONAL HOLE

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• pen field structure, source of fast solar wind

non eruptive radial - plasma leaving when it is at the central meridian, reaches Earth What is important determining when and how strong the impact of a CH will be:

• The heliographic latitude of earth
• The latitude of the CH on the solar disk: the part of a CH with a low latitude is important. Polar coronal holes have only an impact when they extent to lower latitudes.
• It is the material that leave at the central meridian that will reach earth. You have to guess how fast the solar wind is. Calculate the time the material needs to cross the

distance 1AU and you have an estimate of the arrival time of the CH wind near Earth. at the central meridian

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

WHAT HAPPENS WHEN FAST CATCHES SLOW?

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Top View

What happens when fast catches slow solar wind material?

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SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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Interaction Region Rotates together with the Sun Co-rotating Interaction Region

Continuous process - the source of the fast particles, i.e. stays present. When fast solar-wind streams, emanating from coronal holes, interact with slow streams, they can produce Co-rotating Interaction Regions in interplanetary space. The magnetic fields of the slow streams in the solar wind are more curved due to the lower speeds, and the fields of the fast streams are more radial because of their higher

• speeds. Intense magnetic fields can be produced at the interface (IF) between the fast and slow streams in the solar wind. The Co-rotating Interaction Regions are

bounded by a forward shock (FS) and a reverse shock (RS). One reason why two shocks are eventually formed at a CIR is due to symmetry about the pressure enhancement caused by compression and entraining of the slow wind ahead of the fast stream (Figure 10.9 [Gosling, 1996]): shocks are driven away from the pressure increase in both directions, resulting in a so-called \Forward-Reverse shock pair" in which the forward shock propagates away from the Sun while the reverse shock propagates towards the Sun but is carried out with the solar wind flow. http://www.boulder.swri.edu/~deforest/Movies.html

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• Co-rotating structure
• Radial!
• No extra mass-flux

Coronal Hole

The Dst is a geomagnetic index which monitors the world wide magnetic storm level. It is constructed by averaging the horizontal component of the geomagnetic field from mid-latitude and equatorial magnetograms from all over the world. Negative Dst values indicate a magnetic storm is in progress, the more negative Dst is the more intense the magnetic storm. The negative deflections in the Dst index are caused by the storm time ring current which flows around the Earth from east to west in the equatorial plane. The ring current results from the differential gradient and curvature drifts of electrons and protons in the near Earth region and its strength is coupled to the solar wind conditions. Only when there is an eastward electric field in the solar wind which corresponds to a southward interplanetary magnetic field (IMF) is there any significant ring current injection resulting in a negative change to the Dst index. Thus, by knowing the solar wind conditions and the form of the coupling function between solar wind and ring current, an estimate of the Dst index can be made. The Auroral Electrojet Index, AE, is designed to provide a global, quantitative measure of auroral zone magnetic activity produced by enhanced Ionospheric currents flowing below and within the auroral oval.

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Coronal hole at L1

The Dst is a geomagnetic index which monitors the world wide magnetic storm level. It is constructed by averaging the horizontal component of the geomagnetic field from mid-latitude and equatorial magnetograms from all over the world. Negative Dst values indicate a magnetic storm is in progress, the more negative Dst is the more intense the magnetic storm. The negative deflections in the Dst index are caused by the storm time ring current which flows around the Earth from east to west in the equatorial plane. The ring current results from the differential gradient and curvature drifts of electrons and protons in the near Earth region and its strength is coupled to the solar wind conditions. Only when there is an eastward electric field in the solar wind which corresponds to a southward interplanetary magnetic field (IMF) is there any significant ring current injection resulting in a negative change to the Dst index. Thus, by knowing the solar wind conditions and the form of the coupling function between solar wind and ring current, an estimate of the Dst index can be made. The Auroral Electrojet Index, AE, is designed to provide a global, quantitative measure of auroral zone magnetic activity produced by enhanced Ionospheric currents flowing below and within the auroral oval.

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Coronal hole at L1

This is the solar wind measured by the satellite ACE at L1. On Aug 4, an interaction region of a slow and fast solar wind arrived near Earth. This interaction region is indicated in the ACE graphs with white dotted lines in the figure below, denoting the beginning and the end of this particular solar wind event. The magnetic field became much stronger as there is a clear bump in the white curve in the top panel. The plasma is also more compressed in such a region where the slow and fast wind interact. The blue dotted line is the so-called stream interface. It is a rather abrupt transition where the solar wind speed increases suddenly and the plasma becomes hotter and less dense. The magnetic field rotated from the sector where the magnetic field points towards the Sun (Phi = 0° or 360°) to a sector with the magnetic field pointing outwards (Phi = 180°). A rotation is however atypical for this sort of solar wind structures. In normal circumstances - if you could ever speak about normal circumstances in space weather physics - the Phi-parameter fluctuates. In the interaction region, it seems that the magnetic field has diffjculties with choosing a clear pointing direction. Characteristics

• High speed
• Increasing V profile
• High temperature
• High B (normally below 20nT) - high variability
• Stream interface: compression, highest values of everything (except speed)
• Shocks (not very often at 1AU)
• CH at ~40W on the Sun
• The high speed part can also be geoefgective if V is > 600 and Bz <-5nT

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

CME

A new, discrete, bright white light feature in the coronograph field-of-view with a predominantly, radial outward velocity.

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Eruptive - transient

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Mass + B Transient: only lasting for a short time Low density, but enormous and therefore massive. CME is large: compare its size with the size of the sun.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

A CARTOON OF A CME

Magnetic twisted structure that stays linked with the Sun.

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It pushes and deforms the IMF.

A Coronal Mass Ejection is a plasma cloud that is ejected into space. You consider it as a cloud and not as a bunch of individual particles. It is superimposed on the background solar wind. You can see a CME as a complex magnetic bag with difgerent magnetic layers with plasma in it that travels as a tsunami through space. It can go faster/as fast as/slower than the background solar wind. When it is faster, you will see a shock in front of the cloud. This is exactly the same as the shock you see in front of a speed boat.

CME’s zijn plasma-blobs die uit de zonneatmosfeer ontsnappen. Het is een magnetische plasmastructuur in de zonnewind die zich een weg baant door het interplanetair magnetisch veld en die wordt beïnvloed door de zonnewind. Bekijk het als een magnetische/plastieken tas gevuld met plasma. De tas wordt beïnvloed door de omringende zonnewind en kan deze versnellen of vertragen. Als de tas trager gaat dan de zonnewind, wordt deze versneld door de zonnewind. Als de tas sneller gaat dan de zonnewind, heeft de zonnewind een vertragend efgect. Als je ver genoeg van de zon zou gaan staan, zal je geen plotse sprong in in situ plasma-snelheid meer waarnemen. De tas is ook niet ‘dicht’: plasma kan erin en kan eruit zodat uiteindelijk ook het dichtheidsprofiel vlak wordt. Het wordt dan een magnetische tas zonder speciale inhoud. De natuur heeft de neiging om alles te egaliseren. Op 1AU is dit dikwijls nog niet het geval. CME’s en de zonnewind versnellen tussen 1 en 5-10 zonneradii. De zonnewind versnelt in de lage corona van 20 km/s tot 200 - 800 km/s. Er zijn idd al CME’s waargenomen met snelheden minder dan 100 km/s. Dikwijls zijn dit kleine plasma structuren die je ziet vertrekken, maar uiteindelijk worden deze toch versneld tot de snelheid van de zonnewind. Een trage CME kan een efgect hebben op de magnetosfeer, niet zozeer omwille van de plasma- en kinetische druk maar eerder doordat de magnetische zak koppelt met het aardmagnetisch veld. Maar meestal heeft een trage en lichte CME geen sterke magnetische tas. Denk aan de analogie met een plastiek winkeltasje: voor weinig heb je geen sterke, grote tas nodig, voor heel veel en zware dingen heb je een grote, sterke tas nodig. Smak je een grote, zware tas ergens tegen, is het efgect groter dan dat je een klein onnozel plastiek tasje met zo goed als niks in ergens tegenaan gooit (ver zal je in het laatste geval zelfs niet kunnen gooien).

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SOHO / LASCO c2

CORONAL MASS EJECTION

running difference

Mass + B CMEs cause the most extreme geomagnetic storms. Therefore, there is great interest in understanding the properties of CMEs, especially when they have a halo signature around the solar disk that indicates the CME is aimed at Earth. Furthermore, if the CME results in a magnetic cloud with a strong and out of ecliptic magnetic field,forecasts are likely for strong to extreme storms.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

HALO CME

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Mass + B

CMEs cause the most extreme geomagnetic storms. Therefore, there is great interest in understanding the properties of CMEs, especially when they have a halo signature around the solar disk that indicates the CME is aimed at Earth. Furthermore, if the CME results in a magnetic cloud with a strong and out of ecliptic magnetic field,forecasts are likely for strong to extreme storms.

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GEOMAGNETIC STORM

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Mass + B

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GEOMAGNETIC STORM

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Mass + B

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Mass + B N O A A S PA C E W E AT H E R S C A L E S

The effect of a geomagnetic storm depends on how strong the geomagnetic field is disturbed. This is described by an index K.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

GEOMAGNETIC STORM

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G1 G2 G3 G4 G5 Mass + B

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IMPACT

Malmö Blackout - Oct 30, 2004

• About 50 000 customer were without electricity in Malmö,

Sweden for 20-50 minutes

• First known power grid blackout due to GIC in Europe
• An overcurrent relay was too sensitive to the third harmonic of

50 hZ. It has been replaced by a less sensitive relay later.

Mass + B

• GIC
• GNSS
• Aurora
• Drag on satellites

Global Navigation Satellite System

September 2, 1859, disruption of telegraph service. One of the best-known examples of space weather events is the collapse of the Hydro-Québec power network on March 13, 1989 due to geomagnetically induced currents (GICs). Caused by a transformer failure, this event led to a general blackout that lasted more than 9 hours and affected over 6 million people. The geomagnetic storm causing this event was itself the result of a CME ejected from the sun on March 9, 1989.

Galaxy 15 is an American telecommunications satellite which is owned by Intelsat. It was launched for and originally operated by PanAmSat, and was subsequently transferred to Intelsat when the two companies merged in 2006. It was originally positioned in geostationary orbit at a longitude of 133° West, from where it was used to provide communication services to North America. In April 2010, Intelsat lost control of the satellite, and it began to drift away from its orbital slot, with the potential to cause disruption to other satellites in its path. 3 april : B7 zonnevlam, CME-flank kan eventueel langs de aarde afschampen 5 april : K=5,6 — Galaxy 15 anomaly near equinox en op moment net aan middernacht kant aarde, langs de kant van zonsopkomst (dawn) On 27 December 2010, Intelsat reported that the satellite had rebooted as per design and the command unit was responding to commands again. In addition, the satellite had been secured in safe mode and the potential for interference issues from Galaxy 15 had ceased.[1] [2] On 14 January 2011 the satellite was located near 93° west,[3][4] where further testing is scheduled to be performed.[5] On March 18, 2011, Galaxy 15 has been re-certified from the FAA and is now sending GPS signal corrections. Intelsat repositioned Galaxy 15 back to its original location on April 4, 2011.[6][dated info]

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

SOLAR ENERGETIC PARTICLES

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FLARE CME CORONAL HOLE FLARE CME or CLOUD CORONAL HOLE SBC

Space weather is the changes that occur in the space environment. A Flare is a sudden strong increase of the solar e.m. radiation. The light flash is localised on the solar surface. SDO/AIA A Coronal Mass Ejection is a plasma cloud that is ejected into space. You consider it as a cloud and not as a bunch of individual particles. It is superimposed on the background solar wind. You can see a CME as a complex magnetic bag with difgerent magnetic layers with plasma in it that travels as a tsunami through space. It can go faster/as fast as/slower than the background solar wind. When it is faster, you will see a shock in front of the cloud. This is exactly the same as the shock you see in front of a speed boat. A CME is visible as a white cloud in corona graphic images like the one on the slide. A coronagraph is a telescope that creates an artificial eclipse and makes pictures in the visible light of the region around the sun. SOHO/LASCO C2 (red) and LASCO C3 (blue) A coronal hole is a structure in the solar corona that you see as a black area in the EUV. It looks black because there is less plasma present that radiates in the EUV. The magnetic field lines are open, i.e. fan out into space. There are no magnetic loops above a coronal hole. The solar wind emanating from a CH is faster compared to the usual solar wind. SDO/AIA A particle storm is a bunch of electrically charged particles that circle around the IMF lines into space. They may impact telescopes. They are seen as white stripes and dots: this are particles that fall into the lens and blind the pixel(s). During that particular moment, the telescope can’t see anymore through the impacted pixels. You can say that the dots and stripes represent a sort of in situ measurement. In situ means that you measure a parameter local. Remote sensing means that you look at something from a distance. Near Earth, the IMF still controls the solar wind and its movement. If we would go much much further, the CME magnetic bag with solar plasma would be almost empty (all the solar material is spread

• ver an immense volume) and the magnetic bag would have evaporated. But, this doesn’t matter for us. We are at 1AU and at 1AU the IMF and solar plasma make space weather in a normal way, in an

extreme way.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

SEP Solar radiation storm

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Space weather is the changes that occur in the space environment. A Flare is a sudden strong increase of the solar e.m. radiation. The light flash is localised on the solar surface. SDO/AIA A Coronal Mass Ejection is a plasma cloud that is ejected into space. You consider it as a cloud and not as a bunch of individual particles. It is superimposed on the background solar wind. You can see a CME as a complex magnetic bag with difgerent magnetic layers with plasma in it that travels as a tsunami through space. It can go faster/as fast as/slower than the background solar wind. When it is faster, you will see a shock in front of the cloud. This is exactly the same as the shock you see in front of a speed boat. A CME is visible as a white cloud in corona graphic images like the one on the slide. A coronagraph is a telescope that creates an artificial eclipse and makes pictures in the visible light of the region around the sun. SOHO/LASCO C2 (red) and LASCO C3 (blue) A coronal hole is a structure in the solar corona that you see as a black area in the EUV. It looks black because there is less plasma present that radiates in the EUV. The magnetic field lines are open, i.e. fan out into space. There are no magnetic loops above a coronal hole. The solar wind emanating from a CH is faster compared to the usual solar wind. SDO/AIA A particle storm is a bunch of electrically charged particles that circle around the IMF lines into space. They may impact telescopes. They are seen as white stripes and dots: this are particles that fall into the lens and blind the pixel(s). During that particular moment, the telescope can’t see anymore through the impacted pixels. You can say that the dots and stripes represent a sort of in situ measurement. In situ means that you measure a parameter local. Remote sensing means that you look at something from a distance. Near Earth, the IMF still controls the solar wind and its movement. If we would go much much further, the CME magnetic bag with solar plasma would be almost empty (all the solar material is spread

• ver an immense volume) and the magnetic bag would have evaporated. But, this doesn’t matter for us. We are at 1AU and at 1AU the IMF and solar plasma make space weather in a normal way, in an

extreme way.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

HOUR

SOLAR ENERGETIC PARTICLES

73 Electrically charged particles that are ejected by the Sun. They spiral around magnetic field lines. They are ejected during an flare or CME event. The solar event accelerates the particles. Solar radiation storms occur when a large-scale magnetic eruption, often causing a coronal mass ejection and associated solar flare, accelerates charged particles in the solar atmosphere to very high velocities. The most important particles are protons which can get accelerated to 1/3 the speed of light or 100,000 km/sec. At these speeds, the protons can traverse the 150 million km from sun to Earth in just 30 minutes. When they reach Earth, the fast moving protons penetrate the magnetosphere that shields Earth from lower energy charged particles. Once inside the magnetosphere, the particles are guided down the magnetic field lines such that they penetrate the atmosphere near the north and south poles.

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Particles N O A A S PA C E W E AT H E R S C A L E S

The impact energetic particles depends on the flux of the stream of particles.

NOAA categorizes Solar Radiation Storms using the NOAA Space Weather Scale on a scale from S1 - S5. The scale is based on measurements of energetic protons taken by the GOES satellite in geosynchronous

• rbit. The start of a Solar Radiation Storm is defined as the time when the flux of protons at energies ≥ 10 MeV equals or exceeds 10 proton flux units (1 pfu = 1 particle*cm-2*s-1*ster-1). The end of a Solar

Radiation Storm is defined as the last time when the flux of ≥ 10 MeV protons is measured at or above 10 pfu. This definition allows multiple injections from flares and interplanetary shocks to be encompassed by a single Solar Radiation Storm. A Solar Radiation Storm can persist for time periods ranging from hours to days.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

PROTON FLUX NOW

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Particles

Steradiaal is een dimensieloze eenheid, de 3D versie van de 2D radiaal. Radiaal is de eenheid voor hoek en legt de link tussen hoek en een booglengte. De radiaal is de SI-eenheid voor hoek. Eén radiaal is gedefinieerd als de grootte van een middelpuntshoek van een cirkel waarvan de lengte van de boog gelijk is aan de lengte van de straal (radius). Steradiaal is de eenheid voor ruimtehoek en legt de link tussen ruimtehoek en boloppervlak. Wanneer men op een boloppervlak met een straal van 1 m een figuur (van willekeurige vorm) tekent met een oppervlakte van 1 m², heeft deze figuur (vanuit het middelpunt van de bol) een ruimtehoek van 1 steradiaal. In het geval van een cirkel Booglengte = hoek * straal SI eenheid van lengte is meter. Met hoek in radiaal, dimensieloos De hoek van een hele cirkel is 2*pi, de omtrek van een cirkel met straal r is 2*pi*r In het geval van een sfeer Boloppervlak = ruimtehoek * straal^2 SI eenheid van oppervlak is m^2 Met ruimtehoek in steradiaal, dimensieloos De ruimtehoek van een hele sfeer is 4*pi, het oppervlak van een sfeer met straal r is 4*pi*r^2 Het woord rad of sr wordt veelal niet vermeld: 180 graden komt overeen met pi rad, men zegt gewoon pi. Hetzelfde voor steradiaal: in de definitie voor proton flux kan je het woord steradiaal weglaten. Flux is ‘iets’ doorheen een oppervlak - alles in SI eenheden. bv magnetische flux: aantal veldlijnen die doorheen een oppervlak prikken. Als het ‘iets’ beweegt, vloeit, spreek je die grootheid per seconde doorheen oppervlak, een debiet. Bv debiet van een rivier : volume water dat per seconde doorheen m^2-oppervlak vloeit. Het woord steradiaal staat er niet bij omdat de proton flux niet perse isotoop hoeft te zijn. Het staat erbij omdat de proton-flux een richting heeft, je neemt alle protonen die in de ‘kegel' zitten gedefinieerd door de ruimtehoek (let op: je hebt alleen een echte kegel als de ‘doorsnede' van je ruimtehoek met een bol een cirkel is - weet niet goed hoe ik dit duidelijk moet zeggen). De punt van de kegel is de zon. Dat de punt van de kegel de zon is, moet je kaderen in de betekenis van het woord flux. Want er kunnen evengoed protonen op het meetinstrument invallen die niet uit de kegel komen met punt op de zon. In LASCO beelden zie je soms strepen naast de witte stippen die protonen voorstellen. De strepen zijn protonen die langs de detector ‘scheren’ en een hele rits pixels aandoen.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

PROTON FLUX BY GOES

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S1 S2 S3 Particles

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PROTON FLUX BY GOES

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S S S Particles

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PROTON STORM

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Particles

Electrically charged particles that are ejected by the Sun. They spiral around magnetic field lines. They are ejected during an flare or CME event. The solar event accelerates the particles.

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IMPACT

Particles

• Polar flights
• Astronauts
• Electronics
• Satellites: anomalies/loss

Solar Radiation Storms cause several impacts near Earth. When energetic protons collide with satellites or humans in space, they can penetrate deep into the object that they collide with and cause damage to electronic circuits or biological DNA. During Solar Radiation Storms at the S2 or higher level passengers and crew in high flying aircraft at high latitudes may be exposed to radiation risk. When the energetic protons collide with the atmosphere, they ionize the atoms and molecules thus creating free electrons. These electrons create a layer near the bottom of the ionosphere that can absorb High Frequency (HF) radio waves making radio communication difficult or impossible. (from https://www.swpc.noaa.gov/phenomena/solar-radiation-storm) Today, airlines fly over 7,500 polar routes per year. These routes take aircraft to latitudes where satellite communication cannot be used, and flight crews must rely instead on high-frequency (HF) radio to maintain communication with air traffic control, as required by federal regulation. During certain space weather events, solar energetic particles spiral down geomagnetic field lines in the polar regions, where they increase the density of ionized gas, which in turn affects the propagation of radio waves and can result in radio blackouts. These events can last for several days, during which time aircraft must be diverted to latitudes where satellite communications can be used. dodelijke stormen No large Solar Energetic Particles events have happened during a manned space mission. However, such a large event happened on August 7, 1972, between the Apollo 16 and Apollo 17 lunar missions. The dose of particles would have hit an astronaut outside of Earth's protective magnetic field, had this event happened during one of these missions, the effects could have been life threatening.

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SOLAR EVENT How is it MEASURED? IMPACT on EARTH

SOLAR RADIO BURST IONOSPHERIC STORMS

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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S O L A R R A D I O B U R S T S

SRB are produced by energetic electrons accelerated by solar eruptive events, like flares, filament eruptions, coronal mass ejections. Their radial signature - how it looks like in a spectrogram - tells something about the fate of these electrons.

These bursts are triggered by a solar event. Signature of presence of a CME, flare ****************** Detected by measuring e.m. waves in the radio wavelength Type II, III and IV are important for space weather. We can measure the solar e.m. radio output and put it into a spectrogram. At low frequencies, 5 types of radio wave bursts are seen, each with a unique signature in frequency and time. Mind the orientation of the vertical axis! Other figures may have a reversed direction. As the frequency is proportional to the square root of the density, and the density decreases with increasing distance from the Sun, a decreasing frequency means locations higher up in the solar atmosphere. The ionospheric cut-ofg frequency is around 15MHz (due to too low frequency and so reflected by ionosphere). In order to observe radio disturbances below this frequency, one has to use satellites (above the earth atmosphere) such as STEREO/SWAVES or WIND. Radio bursts at low frequencies (< 15 MHz) are of particular interest because they are associated with energetic CMEs that travel far into the interplanetary (IP) medium and afgect Earth’s space environment if Earth-directed. Low frequency radio emission needs to be observed from space because of the ionospheric cutofg. Example: https://stereo-ssc.nascom.nasa.gov/browse/2017/01/16/insitu.shtml Coronal Mass Ejections and solar radio emissions, N. Gopalswamy http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.708.626&rep=rep1&type=pdf Gopalswamy: The three most relevant to space weather radio burst types are type II, III, and IV. Three types of low-frequency non-thermal radio bursts are associated with coronal mass ejections (CMEs): Type III bursts due to accelerated electrons propagating along open magnetic field lines, type II bursts due to electrons accelerated in shocks, and type IV bursts due to electrons trapped in post-eruption arcades behind CMEs. [Radio burst type II, III, and IV are also the only ones that ever get mentioned in the Ursigrams. ] ************** A type II burst is caused by a shock that triggers the local plasma to emit radio waves. While most of the interplanetary shocks are CME-driven, coronal shock waves can be attributed to solar flares, CMEs, or some combination of these two phenomena. Since the acceleration phase of the CME and the flare impulsive phase are usually closely synchronized, it is hard to distinguish between the flare energy-release efgects and the CME

• expansion. Due to this problem the origin of the coronal shocks, i.e. metric type II bursts, still remains unresolved.

Type II

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• Type I: trapped in loops above A.R.
• Type II: accelerated by shock waves
• Type III: beams accelerated along
• pen magnetic field lines
• Type IV: trapped in post-flare loops

We distinguish between 5 types of solar radio bursts. Not all types are present during an event.

S O L A R R A D I O B U R S T S

Signature of presence of a CME, flare

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Impact of SRB itself GPS station Signal/noise - signal is from the satellite. GPS receivers are designed to be sensible to the signal above them, not at the horizon. When there is a strong radio burst - in the typical GPS frequencies - the noise increases. GPS receiver ontvangt signalen die niet van een satelliet komen maar van de Zon. De GPS ontvanger maakt geen onderscheid tussen solar noise en satelliet signaal. Radar interference Radars are monitoring the planes near the horizon - descending and ascending planes SRB can impact HF communication (no feedback from industry) and navigation

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

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IONOSPHERE Exists because of ionising solar e.m. radiation

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Our atmosphere protects us against harmful solar light. This ionising solar light can penetrate only until a certain height.

T R A N S PA R E N C Y O F E A R T H AT M O S P H E R E

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IONOSPHERE

The ionosphere (/aɪˈɒnəˌsfɪər/[1][2]) is the ionized part of Earth's upper atmosphere, from about 60 km (37 mi) to 1,000 km (620 mi) altitude, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth.[3] The Total Electron Content (TEC) is the integrated total number of electrons present along a path between a radio transmitter and receiver.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

RADIO WAVES

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RADIO WAVES

The ionosphere has the ability to reflect radio waves. If the degree of ionisation would be zero, no radio waves would be reflected and all would pass. Ionisation can change over time. Ionisation is not the same everywhere. HF goes through LF are reflected During the night, the ionisation decreases - the skill to reflect drops. —> only LF goes through —> Maximum Usable Frequency, MUF decreases.

SWIC 2018 – collaboration between STCE, Koninklijke luchtmacht and KNMI

IONOSPHERIC STORMS

Body Level One !

How the ionosphere behaves has an impact on HF communication and navigation Ionospheric storms primarily afgect the equatorial regions but can also extend into the middle latitudes and afgect GNSS navigation.

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