And now I'd like to introduce the director
of the Geophysical Institute, Bob McCoy to
welcome our speaker.
Like Fritz I'd like to thank you all for coming
out tonight and braving the elements, but
you're in for a real treat.
It's my pleasure to introduce tonight's speaker,
professor Mike Conde.
He talks a little funny.
He's from Australia.
He probably thinks of all of us talk a little
funny so this is this is fair game.
Mark is from Tasmania in Australia you've
got a speech from the University of Adelaide.
And he did his is research is based on lots
of field work studying the aurora over Australia,
over Antarctica.
After graduating he worked as a computer programmer
for the Australian and Artics Division Marine
Science Program and later as a postdoc at
La Trobe University.
In 1993 he came to Alaska to work on an upgrade
and revitalization program for the Poker flat
research range.
If I could give that a plug.
March 9th is the 50th anniversary of the Poker
Flat Research Range.
We're having a celebration at the range at
midnight.
So please come out I think there's buses.
You can ask Fritz later about some of the
details but 50 years is a long time it's the
only university owned rocket range the biggest
rocket range in the world.
It's 50 years old.
This March.
Getting back to Mark, in 2002 he accepted
a joint academic appointment at the University
of Alaska in the College of Natural Science
and Mathematics and also in the Geophysical
Institute.
He is a professor of physics and he's a space
physicist in the Geophysical Institute.
His experimental work focuses on weather and
the Earth's upper atmosphere where he studies
the the ionosphere and upper atmosphere over
Alaska, Antarctica, Norway, and Sweden.
He makes exquisite measurements of airglow
and wind in the upper atmosphere.
He's a rocket scientist so with that I'd like
to welcome Mark.
Well thank you Bob.
Let me see if I can get this presentation
going here.
Excellent.
Alright well I'd like to add my voice to the
thanks for everyone to come out here.
I feel I've been a little bit one upped because
I want to talk about weather in space and
trust Alaska to throw some weather at us and
some weather you can actually touch and feel
and see and to one up my story a little bit.
But that's why we're here in Alaska because
we like that sort of thing.
So what I want to do tonight I want to I want
to tell you a story about- about weather in
space starting with a rather grumpy middle
aged star called the Sun which has a habit
of throwing tantrums every so often and throwing
stuff at the kids including us.
And when that stuff hits our magnetic field
it creates disturbances in the magnetic field
particles rain down on the top of the atmosphere
produce the Aurora and it- in that process
it disturbs the atmosphere itself and drives
changes in wind, changes in temperature things
that we would think of as weather.
And it's not just an academic interest.
It affects spacecraft, it affects orbits,
it affects communication.
And so it's it's something that the United
States and technologically advanced countries
care a lot about.
Furthermore because the aurora is an integral
part of that story and the Aurora occurs over
Alaska hopefully by the end of tonight you
can go out- maybe not tonight- but you can
go out when the sky is clear and look up at
the Aurora and see some of the phenomena that
I'm talking about happening just with your
eyes above you here in Fairbanks Alaska.
So this is my opening slide and the reason
that I've put this up is because as I said
this weather that occurs at the top layer
of the atmosphere which we'll talk about in
a minute, affects spacecraft orbits and one
of the things I'm going to show you is that
it's very difficult to predict when a spacecraft
will actually re-enter the earth's atmosphere
as the orbit decays eventually it comes down.
And that's a really hard prediction to make.
And one of the reasons it's hard to make that
predictions because the weather that disturbs
the atmosphere is unpredictable.
And so this is a picture or just an artist's
impression of a spacecraft reentering the
atmosphere.
And when and where that happens is very heavily
dependent on the story that I'm going to tell
hopefully here tonight.
So I want to give you an outline of where
I'm headed with this talk.
So I want to start off by talking about what
part of the atmosphere I'm going to be talking
about.
I want to tell you a little bit about what
it's like up there.
It's rather different to what is down here
on the ground.
I want to tell you why weather occurs at these
sorts of altitudes.
I want to tell you what the what the weather
is weather including storms, big disturbances
to the atmosphere.
I want to tell you what these storms do when
they're in progress what they look like.
I want to tell you how we study them why we
care about them.
And I want to finish up with saying a little
bit about what we can do about them.
The answer to that is that we can't actually
do much to stop them but we might at least
be able to be warned and understand them.
Alright so to start at the beginning I want
to talk about the portion- the region the
atmosphere that I'm talking about here or
I'm going to be discussing and the atmosphere,
it sort of gradually fades away with height
as you go up it gets thinner and thinner the
pressure drops the density drops.
And there isn't really you know my title was
weather at the top- storms at the top of the
atmosphere there isn't really a defined top
of the atmosphere it just fades away.
But the last sort of wish for the atmosphere
that behaves like what we would think of as
a gas is in this region.
You probably can't read this from 100 kilometers
or 90-100 kilometres and up of vaguely coloured
that yellow I don't know if you can see it
up to four or five hundred kilometres so 100
kilometres about 62 miles.
I'll apologize for using metric units a bit.
That's what we tend to use in science but
62 miles and up something like that.
Is the area that I'll be talking about.
Let's see there's lots of you know as I said
the pressure and density drops and the atmosphere
as you go up it just gets more and more tenuous.
So by the time they're up to here the pressure
is or the pressure on the ground is about
1000 millibars.
Well the time you're up here it's one ten
millionth of a millibar so it's very very
tenuous.
Another thing that helps you think about what's
going on here is this quantity which which
scientists call the mean free path and that
is if you are an atom or a molecule of the
air you collide into other atoms and molecules
frequently in the room here when an atom or
a molecule collides with another one it gets
to go.
I think what is it a few tens of nanometers
so maybe a thousandth of a micron something
like that.
I'm sorry- A tenth or a hundredth of a micron,
a very short distance before it will collide
with another one.
By the time you go up to 500 kilometres altitude
the air molecules can travel 100 kilometres
between collisions.
So that tells you that the gas can't really
communicate amongst itself very much because
it you know they're not colliding the molecules
are not colliding into each other very much.
That's not to say they're rare.
There's still an awful lot of them.
As you'll see there's trillions per cubic
meter.
But they're so small they don't collide much.
When you get to the top of this region you
enter what's called the spray region.
I don't know if people have seen you know
state lottery machines and things will they
have a whole bunch of balls in a big chamber
and they blow air in them and all the balls
bounce around and up at the top you see little
balls bouncing along the surface.
That's pretty much what happens at the top
of the atmosphere.
Well the very last of these particles they
experience a collision and they just sort
of go off on a ballistic trajectory and come
down again.
And they.
And so they follow these sort of parabolic
trajectories there is that it's called the
spray region because it's like they're being
sprayed up and dropping down again.
So very different and lots of other properties
that I won't discuss but all the properties
are completely different.
One other thing I'll comment is that the chemical
species separate out according to their weight
here.
But very surprisingly this curve here is the
temperature.
And there's a big increase in temperature
so down here on the ground it gets cooler
with altitude until you get to the top of
the what's called the troposphere that then
warms up in the stratosphere because of ozone
continues cooling and once you get past the
ozone.
But here it gets very hot.
The reason for that is ultraviolet light from
the sun heats the top of the atmosphere.
And because it's so hot more than 1000 Kelvins
at the very top of the atmosphere we call
this the thermosphere thermo being heat.
All right.
Next question is everybody knows from watching
science fiction movies or something if you
open the door of the airlock all the gas escapes
and disappears.
Well here's the top of the atmosphere here
is empty space it's a vacuum.
Why doesn't Earth's atmosphere just all escape
off into space.
Fair question and the answer is actually pretty
simple and the answer is our atmosphere is
held and trapped around our planet by gravity
and the way to think about.
I talked about that spray region I said these
things head up and big parabolic ballistic
arcs.
You can ask how fast does an air molecule
have to go in order to be able to escape and
get out into space.
Turns out it has to be going at about 11 kilometres
per second.
That's pretty fast.
That'll get you across Alaska- what's alaska
Alaska 1000- that'll get you across Alaska
in 100 seconds.
The atmosphere just isn't hot enough for the
gas to be moving that fast.
So sure these things can they can they can
bounce up but they always fall back down again
there's not enough energy for them to escape
and get away from our gravity.
And the way scientist think about this they
think well occasionally one of them actually
does manage to get away.
And if you total it all up how long would
it take.
At the rate that these very occasional ones
do manage to escape.
How long will it take for Earth to lose its
atmosphere.
The answer is tens or hundreds of billions
of years.
So our atmosphere is not going anywhere in
it certainly not in our lifetime and probably
not in the lifetime of the solar system it's
very stable.
However that's the most of it.
There are actually just little hydrogen atoms
up there.
Hydrogen is so light that hydrogen actually
is lost easily.
The only reason that it's that you cannot
find any hydrogen up there is that it's constantly
replaced from oceans below.
That's by the way.
All right.
So I talked about storms at the edge of space.
What do I mean by the edge of space.
I looked round for some definitions I found
that the Red Bull Company that makes soda,
they had an idea of what they meant by the
edge of space and I got a little clip from
one of their promos here if I can drive my
cursor around.
Hopefully it'll play- [video narrator:] A
mission to the edge of space.
Felix an Austrian base jumper is aiming to
break the world freefall record by jumping
from a 120,000 feet above the Earth's surface.
So according to Red Bull the edge of space
is at 128000 feet or 40 kilometres that's
in the stratosphere the atmosphere still looks
very atmospheric at that height.
So I don't much like that definition for the
edge of space.
If you look around for what people would call
where space begins a very common definition
is this thing called the Karman line, and
it was invented by aeronautical engineer and
he said well the air gets less and it gets
more and more tenuous as you go up less and
less thick it gets harder and harder for an
aircraft to fly because there's less air to
support it.
So the only way an aircraft can remain flying
is to go faster and faster as you go up and
eventually when you get to about 100 kilometres
altitude for a typical aircraft the atmosphere
has become so thin that the speed it would
have to be going at would be faster than the
escape speed- so faster than orbital speed
around Earth and so it would not remain close
to Earth it would it would escape.
And so basically no form of conventional aerodynamic
flight is possible above about 100 kilometers
by that sort of thinking are all sorts of
other things change at this altitude 62 miles.
So that's a pretty good definition of the
start of space.
You could also say when does the atmosphere
stop behaving like a fluid when do collisions
stop being important.
That's around 500 kilometres but there's really
no hard edge.
So I'm using a little bit of- what's the word
being a little bit loose with language when
I talk about the edge of space here.
I don't know how much you can see of this
but this is another really good way to think
about when you're in space and that is if
I put a satellite up there as the satellite
flies it experiences a little bit of drag
moving through the atmosphere and it gradually
loses height and falls down.
So the question is how high do you have to
be in order for your spacecraft to not fall
down and there is not one simple answer to
that either because it's really the answer
is how long do you want to stay up there.
So this is a plot mostly Soviet spacecraft
debris and on the x axis of this plot we have
altitude.
So I don't know if you can read it but this
is 250 kilometres here.
This is 190 kilometres and this is 300 kilometres
so basically 200 to 300 kilometres on this
axis and on this axis is the number of days
that these things actually remained in orbit.
So if you look at the main curve here at 250
kilometres things fell out of orbit in less
than five days.
Now the length of time you stay in orbit depends
a little bit on how dense you are it depends
how much drag you've got.
So there's some variability here.
But you know if you want to be in orbit for
years you have to be well above 300 kilometres
probably more like 400 kilometres if you want
something to stay up there for years and function
as a long term spacecraft as spacecraft start
to come down.
You know they encounter thicker and thicker
atmosphere as they come down and their lifetime
gets shorter and shorter and shorter until
below about 200 kilometres it's game over.
You know you only get a few orbits after that
and then the spacecraft re-enters.
So where can a spacecraft continue to orbit.
I would say 350 kilometres and above is a
good starting point the space station flies
370-380 and has to be boosted periodically
because it's losing height.
All right.
So what are we.
What have we got.
We've got a very tenuous atmosphere.
Collisions are rare a mean free path is really
long.
Is it even if it isn't even a gas because
it's it makes sense to talk about wind when
the gas is so thin.
Well the answer is yes at least up to four
or five hundred kilometres.
And I can show that to you just before I play
this video I'll tell you what it is.
This is a view of the sky taken from Toolik
in Alaska which is up north of the Brooks
Range.
On the haul road up to Prudhoe Bay.
This was this video was taken during a rocket
mission that we conducted in 2003 called Hex.
And what you'll see you'll see a rocket pass-
this is stars in the background and this as
Aurora this sort of background here.
You'll see a rocket pass across the field
of view and it's releasing clouds of gas that
you can see as it goes through little little
puffs of gas.
You'll see a bunch of little puffs and you
will see those puffs moving up the screen
because they're moving with the wind.
Now this rockets at 150 kilometres altitude.
So there it is as far across the air these
are the gas clouds it releases and we can
see them moving across.
With respect to the stars.
So those gas clouds are telling us what the
wind is doing 150 kilometres up which is you
know a spacecraft there wouldn't last long
but it's pretty much in space.
There's a satellite passing through the field
of view here as well.
So yes there's a gas there and yes there is
wind at like wind and it'll push things around
just like the wind does, even though it's
very tenuous.
If I can move to the next slide- this is another
interesting thing.
This is two rockets launched from Poker flat
shortly after each other.
You're looking up from below you can see the
rocket heading up and you can see a trail
of gas released.
I'll try and stop this part way through because
there's a very interesting point that this
shows- if I stop it about there- what you
can see is you can see all these billows and
you know structure in that this is a continuous
trail of gas released by the rocket.
It's all it's turbulent.
Same sort of thing you experience in an aircraft
turbulence here but then eventually somewhere
a bit above 100 kilometres everything goes
smooth and clean in the turbulence stops.
That's because the atmosphere is becoming
so thin that the mean free path is bigger
than the size of the turbulence and the atmosphere
just can't sustain the turbulence anymore.
So above 100 maybe 110 kilometres there's
no turbulence in the atmosphere anymore unlike
down on the ground here.
All right.
So there is wind and we can see it by releasing
a chemical.
Why does it blow.
What causes the wind to blow.
Well there's basically two things that drive
the wind at these altitudes.
One is the same thing that drives the wind
down here on the ground.
And that is a difference in pressure.
The main reason you you have winds.
At ground level is you got high and low pressure
systems in close proximity.
When there's a pressure difference that causes
the wind to move.
That plays out differently at this altitude
though this is meant to be.
This is obviously a view of the earth.
I'm imagining this as the day daylit sun-
sunlit side of the earth.
And this point here is directly beneath the
sun this is where the sun's directly overhead.
The sun heats Earth's atmosphere on the day
side creates a high pressure but unlike down
on the ground there on the ground that the
wind blows around the high and low pressure
systems they circulate like vortices the atmosphere
is different up here.
The wind just blows directly away from the
high pressure around the earth and towards
the low pressure on the nightside.
That's the basic solar driven circulation
of the atmosphere up here we call it the solar
diurnal tide.
Now on top of that you can see these two vortices
here counter rotating vortices.
They are driven by essentially the same process
that causes the aurora.
So the aurora is just one thing that you can
see it's if you imagine that the atmosphere
is like a big cathode ray tube.
When particles hit it you see that you see
where the particles are impacting the atmosphere
but that's just one signature of a whole structure
that extends out into space.
And what that does associated with the Aurora
there are electric fields that are created
by the by the interaction of the solar wind
and the Earth's magnetic field.
A portion of the upper atmosphere is not neutral
particles not neutral atoms and molecules
but ions they've had a charge removed their
ions they move as a result of these electric
fields and they move in these circ- sorry
counter rotating vortices like that.
When these ions bump into the atmosphere that
they're embedded in they stir it up just like
a big stirring stick causing the atmosphere
to circulate like this.
And the whole story of this weather that occurs
in the atmosphere is this- this is the thing
that disturbs what would otherwise be a fairly
simple day to night winds flow caused by the
sun.
This is quite dynamic changes in size it changes
in intensity and changes the amount by which
the atmosphere is stirred up.
And that's what drives these things we're
calling storms as the changing input from.
The processes that cause Aurora.
And I can- you don't have to believe me I
can actually show you this in a movie.
This is another complicated slide I apologize
for some of these slides being a bit complicated
but this is a picture of Alaska here in the
middle is a colored circle.
That is the region that is viewed by a camera
at Poker Flat, an all sky camera looking up
into the sky.
There's a couple of different colors here
there's green yellow and red the green is
showing the brightness of the structures we're
looking up there or in this case twilight.
The red and blue showing temperature.
We won't worry about that too much in the
background you can see these yellow arrows
these yellow arrows are measured by our network
of radars across Alaska and around Alaska.
These yellow arrows are showing where the
ions are moving.
They're essentially showing this pattern here
caused by the ions.
The white arrows are the wind.
I'll show you later how we measure the wind
and what you can see even before I start this
playing.
You can see that the ions moving like this
have imposed their will on the background
atmosphere and caused the atmosphere to flow
along with them.
If these weren't doing that the atmosphere
would be flowing in the other direction pushed
by the sun.
This is right around sunset.
The wind would be blowing eastward were it
not for the motion of the ions.
So I play this video and comment and a few
things.
So you can see the ions you know changing
they're very dynamic.
They change their flow the ion motion has
become weaker the winds have become weaker
there's less ion motion pushing winds around
at the moment.
I've still got the sun down here affecting
these.
This portion now here's the Aurora.
The aurora is getting brighter, here's Fairbanks
here.
So the aurora is just moving south over Fairbanks
these are more ion motions measured with a
different instrument a different radar.
The Aurora is now getting quite active.
We got quite strong wind blowing to the west.
The ions are starting to get a bit confused
in which direction they want to go and shortly
they'll change there instead of blowing this
way they'll start to flow down here and shortly
afterwards you'll see the winds react to that
so the ions are starting to turn their motion
here.
And now you can see the winds responding.
The ions have changed their mind about where
they want to go and the winds are picking
of a following suit with some delay.
It takes a while for the ions to stir up the
winds and towards the end of this video you'll
see the aurora get quite active.
And you'll see the winds really pick up.
So the aurora is starting to pick up here
now.
It should get even this blue color tells me
the aurora is really quite energetic and the
winds are blowing now southward and they're
really quite strong look at them picking up
here.
This is all driven by the Aurora moving the
air around at the top of the atmosphere.
I think that went back to the beginning so
I'll go on to the next slide.
So the point of that was just was to try and
convince you that motion of the ions associated
with the Aurora pushes the wind around.
So the Aurora and the ions pushes the wind.
Where does the Aurora occur.
Well we all know from Fairbanks that you see
aurora over Fairbanks but we can only see
a little piece of the Aurora from here we
can't see the whole structure.
If you go out into space and look down from
well above the Earth you can paint in the
whole complete edifice that is the Aurora
at any given time.
This particular image is actually not a single
snapshot in time this was taken by a spacecraft
called TIMED and it was a low orbiting spacecraft
and it actually took swaths it would orbit
across and see a swath of the earth.
And so what I've done here to make this image
is I've built up I think it's about 11 or
12 or 13 orbits here where we've merged and
stitched them together to produce a continuous
view of the Aurora.
And what do you see.
Well you see that the Aurora exists in an
oval shaped region like this.
It's centred on the magnetic pole which is
here somewhere and it passes pretty much smack
bang over Alaska.
This is why Alaska matters in this story because
Alaska is right where the action is for stirring
up storms and wind in the- at the top of our
atmosphere.
Again another busy slide I apologize for that.
But I think the point is simple enough and
the purpose of this slide is to answer the
question why is Alaska or why and what is
it about this region that makes- why does
the aurora occur here why doesn't it occur
down here.
Why doesn't it occur up there why this ring
that looks like that.
I'm attempting to answer that here.
So what is the Aurora.
The Aurora are particles from space heading
down the Earth's magnetic field until they
hit the top of the atmosphere and causing
the atmosphere to glow.
So if you're going to have Aurora you need
two things you need a magnetic field to guide
the particles down and you need a source of
particles to create the aurora.
Now these particles only travel along these
magnetic field lines.
They don't tend to travel across the magnetic
field lines.
So if you're down here at mid latitudes or
lower altitudes the magnetic field lines that
could provide you with some or all particles.
They just don't go very far out into space.
They don't get far enough out to reach any
sort of a reservoir of material that would
supply the particles to produce the aurora.
Conversely if you go to really high latitudes
these lines go well out into space it turns
out you've got to know where the particles
are coming from where is the reservoir of
material that feeds the Aurora where it is
it's in this region here behind the earth
the sun's here the sun is blowing blowing
across here.
So the sun is on the left of this picture
behind the earth is this big long structure
called the plasma sheet.
Material accumulates there it's actually squeezed
into a sheet in this region here by the magnetic
field.
And then if you follow these field lines down
they sort of produce two funnels or horns
that come down and hit the earth at that sort
of high latitudes but not not at the poles
and not at the equator but in a ring that
runs around here.
These are the field lines that map out to
the reservoir- the place where you can get
material to produce an aurora from.
So that's why the aurora occurs over Alaska
and in a ring that includes you know the Arctic
regions.
Same thing happens in the Antarctic.
There's a mirror image down here or roughly
mirror image down here.
And that's why it matters to us.
So what have we got.
We've got tides.
We've got something that can disturb the winds.
The question is how blustery is this weather
it is it is it once in a while you get a storm
or is it always going all over the place.
Well the source of the material in that plasma
sheet it comes from a few different places
but the source of the activity at least is
the sun and here this is a video actually
before I play the video I'll tell you what
you're looking at.
You're looking at the sun from space taken
from a spacecraft the sun itself is this white
circle here.
This is a camera looking directly at the sun
an incredibly sensitive camera looking directly
at the sun if it looked directly at the sun
it would be at least blinded and probably
destroyed by the bright light from the sun.
So what they do is they put a metal disk in
front of it which is this dark dark thing
here.
And in a rather crude fashion to keep the
disc in place there's a stick running in here.
It's on the it's on the it's a disc on the
end of a stick that's in the way of the sun.
It's sort of done it.
They've tried to blur the stick out here but
you can still see that it's there.
So the sun is behind this discus this is rather
a high stakes instrument if they get it wrong
and it wanders around so that the sun peeps
out from behind this thing it would probably
be game over.
With the sun so bright you block it.
Now you can turn the sensitivity of a camera
way up.
You're Above the atmosphere so there is no
light from the atmosphere you're looking at
the blackness of space with that high gain
high sensitivity.
Now you can see streamers coming out from
the sun this is the atmosphere of the sun
streaming away from the sun but it's not-
doesn't look like that this is what it really
looks like.
This is what you're seeing here is an actual
view of what we call the solar wind.
This is material leaving the sun all the time
and punctuated and in amongst that are these
enormous explosions.
There are things that occur on the surface
of the sun called solar flares when a flare
goes off it causes an eruption and it just
spits a big bunch of material into space.
A large cloud that spreads out over a fills
the solar system pretty much or half the solar
system one side you can also see there's some
persistent streamers coming out of here things
that are not that eruptive.
They last for a while.
Why are they there.
Well it turns out this atmosphere of the sun's
a bit leaky gets big holes in it that are
called coronal holes.
So as well as the explosions producing big
clouds of material coming out eruptively there
are these sort of persistent holes in the
atmosphere where material is leaking out all
the time.
The combination of these two things either
an either an explosive eruption or a stream
it's a bit like being downstream of a firehose,
a stream coming from the sun.
Either of those when they hit the earth they
cause a disturbance and produce bright aurora
all sorts of disruptions to power grids communications
and satellites and all sorts of things we're
talking about.
I should mention by the way these storms affect
a lot more than just the wind and the temperature
in the upper atmosphere.
They affect a whole bunch of things but I'm
focusing on their effect on the atmosphere
itself.
So two reasons why we get you know dramatic
changes in levels of activity one is because
of an eruption and one is we might get hit
by one of these streams- these things here
are these persistent streams coming out from
the sun.
Alright.
This is an animation I think produced by NASA
and what is showing here is that there is
an eruption from the sun.
Here's our poor little earth.
You can see how big this front of material
that is erupted from the sun is when it hits
the earth.
It disrupts our magnetic field the magnetic
fields of this comet shape you see a big wave
passing down the magnetic field the magnetic
field becomes compressed fields the electric
and magnetic fields are perturbed particles
move around and ultimately rain down on the
earth.
It's a little bit hard to see what's going
on here but the main point of this video is
to just see that huge cloud of material.
You know this shock front coming out from
the sun this enormous cloud of material that
strikes the earth it takes about two to three
days to get from the sun to the earth to produce
this.
Disruption that we experience.
So when it gets here what does it do.
Well this is a very famous sequence in our
area of study.
This was taken in the early 80s by one of
our colleagues up in the Geophysical Institute
John Craven and he was at the time working
at the University of Iowa with other colleagues.
This is taken by a spacecraft called dynamics
explorer 2 and it was one of the first spacecraft
to give a really good you know large scale
picture of what the aurora is doing.
Here's a picture of what the Aurora looked
like seen by the spacecraft.
And then there's a sequence here.
These are 12 minutes apart.
You can see there's an auroral oval which
is relatively quiet a little bit of activity
here.
It's not very- not all that bright.
Somewhere about here things start to brighten
up and then all of a sudden the Aurora gets
much brighter fills in here.
Activity has increased very dramatically.
Now this is not quite the same process as
what I showed you before this is actually
what's called a sub storm.
This is the Aurora.
This is the Earth's magnetic field and the
plasma contained in it becoming unstable in
and of itself and dumping a bunch of stuff
down on Earth.
So this particular event doesn't need a shot
from the sun but it's the same general idea.
The Aurora goes from being quiet to being
very active in a short space of time and causing
lots and lots of disruption.
And so this particular one would have happened
regardless of what the sun did because the
whole system just became unstable.
That happens commonly if you go outside at
night at 10 11 12 o'clock at night sometimes
you'll see an auroral arc sitting there and
it'll move gradually south all of a sudden
it'll bright and suddenly and for half an
hour the sky will be filled with what some
of my colleagues called Hollywood Aurora,
super bright colourful fast moving aurora.
That's what that same thing looks like if
you look down at the whole system from space.
Alright so the sun disrupts the upper atmosphere.
What are some what are the effects while this
is two days of measurements taken with our
instruments.
This is taken from McMurdo Station in Antarctica
and it's looking at an altitude of about 240
kilometres not just plotting temperature as
a function of time.
Let's see this is 700 Kelvins 800 Kelvin 900
Kelvins.
The atmosphere's sitting around 800 Kelvins
that's about what you'd expect for this altitude
that's hot but that's what you'd expect.
Then all of a sudden the sun heating up and
then it heated really dramatically at the
end of this day so dramatically it went off
scale on this plot and it stayed off scale
I've got no idea what it did up here I could
probably find out if I replotted it but there
are routine things- it's off scale and it
wasn't for you know 18 hours later or something
that it gradually started to recover and come
down.
This is a big increase in temperatures for
400-500 Kelvins heating lasting for more than
a day.
That really disrupts the atmosphere.
You know it's it's changed the temperature
by 50 percent.
It's a big disruption and it last- in this
case lasted for a day or so.
Uhp- I'm doing what I need to do here.
Well maybe that previous- maybe this was just
a you know a one off thing a special rare
event.
Not really.
There's a lot on this slide I just want to
focus on the top panel here.
This is data from 2012 fall to 2013 spring.
So it's a whole winter season of measurements
again taken from Toolik Lake up north of the
Brooks Range it's showing temperature and
the black points here are the temperature
that was measured by our instrument at Toolik
lake.
You can see a seasonal effect it's where-
you know as we went into winter it cooled
down a bit.
This is 800 Kelvins here it was maybe 900
1000 in fall and back again in spring.
So a seasonal effect here there's other bumps
here caused by that- The sun rotates and sometimes
the sun's a little bit more active than the
other times and then when those active parts
of the Sun pass in our field of view it warms
up things up so there's a bunch of ups and
downs here caused by just the background effects
of the sun.
But look at these spikes here and here and
here and here and here these are the storms
I'm talking about and you can see how often
they're occurring they're occurring you know
once a month or something.
Not predictably in time sometimes you'll get
two or three of them in a month sometimes
it will go for a relatively long period without
seeing them but you know they are common events
and they're large disruptions in temperature.
And as you'll see large disruptions in wind.
I'm gonna skip this slide.
So talking about temperature, what about wind.
Well this is again a busy slide I apologize
for that this is four days in March of 2013.
You can barely see it.
There's wind arrows here and there's temperature
in the background.
This is a slightly active day but this is
a storm day see you know these are two quiet
days that follow.
This is what the wind looks like on a quiet
day.
You can see how it disrupted the wind was
on those on the day of this storm here.
This is the vertical component of the wind
just the up and down the atmosphere moving
up and down.
Right now a few waves waves in the atmosphere
common here big oscillations during the storm
and then much quieter again after the storm.
So you know winds both horizontal winds blowing
across Alaska and vertical winds and a few
other things that I haven't time to discuss.
All disturbed during this storm day.
The storms happen you know every month or
so.
And they're big.
All right.
What do the winds do.
Well I've got another video to show you here.
What it what this is showing you is winds
measured over Alaska with our instrumentation
at about 250 kilometres altitude that's up
there almost high enough for it to be where
the spacecraft are and if you know the winds
you know what the winds are doing at the height
of the spacecraft you'll see all sky camera
views in the background these arrows are showing
the wind what I've done with these little
colored spots this will become obvious in
a minute.
Imagine if you release a plume of smoke into
this wind field you could follow where that
smoke goes and you can see what effect the
wind would have on how things are carried
around.
It turns out when the aurora is active it
modifies the chemistry of the atmosphere it
changes the actual chemical composition of
the atmosphere and then the wind takes those
modified air parcels and moves them somewhere.
If you're downwind of us you'll have different
air passing over you than you would normally
experience.
So you'd like to know what the wind does to
that modified air.
So let's have a look.
So you can see these smoke plumes being released
into the wind field is done computationally
by a computer wind blowing to the west is
transporting things.
Now the aurora's picked up look at that the
wind turned around.
Now these trails that the smoke plumes are
producing have completely changed direction.
Look at this tangled mess here.
Imagine you're a forecaster and you're trying
to predict where things are going to go.
You know good luck with that and you can just
see how strong this flow has become in response
to that Aurora.
Now at least it's relatively clean.
But during that transition when the storm
is starting the flow fields become a little
bit.
This is what we saw earlier the flow to the
east here to the west.
But this transition here produces incredibly
complicated.
Transport trajectories.
But you already knew this anyone has mixed
paint knows that stirring up a fluid mixes
things up, but you don't sort of think of
it as happening in the upper atmosphere many
more from us.
All right I'm heading on to the why do we
care about this part of the story.
And this is this.
This slide is- It might look a little dull
here but this is- really speaks to the heart
of why the United States and other nations
care about this and why they're willing to
invest a lot of effort in it.
What this is showing this is showing about
a year of data.
And if we just look at the top slide here
it's actually showing the density of the atmosphere
at 400 kilometres that's the density that's
pounds per cubic foot if you like or kilograms
per cubic metres it's the mass density of
the atmosphere and let's see the blue curve
are actual measurements from spacecraft.
You can see these oscillations that's caused
by the sun rotating.
You can see this sort of trend that's a seasonal
trend.
But look at these big spikes here the density
of the atmosphere increased and it increased
a lot you know from foot doubled during this
period here.
What does that mean.
I have a colleague a University of New Hampshire
who says that means that all the spacecraft
hit a speed bump.
You know all of a sudden they're flying along
through nice thin air and wham you know the
density goes way up.
They're just slowed down and retarded by this
this speed bump that's been produced as a
result of a storm that affects the orbit that
affects where they're going to go.
Making this too hard we do this- I'm going
to skip the slide because it's too much on
it.
Here's the story so you can go online you
can.
NASA provides tools for predicting spacecraft
orbits so what I did is I just created a pretend
imaginary spacecraft.
I set it into orbit at 300 kilometres altitude.
I chose a period of time.
I knew there was a bit of activity on the
storm front this is 2003.
I just let this spacecraft orbit for a while.
So this is about a month of time.
Spacecraft initially at 300 kilometres its
altitude drops over time and eventually it
comes down and re-enters the atmosphere.
You can actually see a little bit more clearly
if instead of plotting the height that the
spacecraft's at you plot how many kilometres
height does it lose per day starting off it
didn't lose very much but as it gets lower
and lower and lower it loses more and more
height and eventually as it gets down here
it's losing height really rapidly.
This plot is showing the mass density that
kilograms per cubic meter or pounds per cubic
foot if you like of atmosphere for that same
period.
These two curves look identical.
Pretty much so the rate of decay of the orbit
is determined by the mass density the mass
density is determined by the weather.
These bumps here these little wiggles are
caused by storms.
It doesn't look like much but when you add
up their effect it means it changes when the
spacecraft re-enters by days many many days.
So how hard is it.
You know you've got a big spacecraft up there.
There's been- not in the last couple of years
but four or five years ago there were a couple
of really big ones that reentered ones where
there were pieces of the spacecraft that could
come down and impact a city or an orphanage
or something you don't want to hit.
So you'd like to be able to warn people if
this thing is going to come down you know.
Is it going to come out on top of you.
The answer is we just can't tell.
We can't tell where these things are going
to come down this is a prediction by the Aerospace
Corporation the best in the business for predicting
where these reentries will occur.
This particular one I think was an upper stage
of Soviet rocket or something there on the
14th of July 2003.
They were predicting that this rocket stage
would re-enter the atmosphere on the 17th
of July.
Three days later.
But how.
Big was the uncertainty in when it would re-enter.
It was 21 hours.
Now it takes 90 minutes to do one orbit of
the earth and the spacecraft and see how these
are successive orbits.
So you know a 21 hour uncertainty plus or
minus 21 hours is why 21 hours it was literally
42 hours a window 42 hours long.
That means the whole earth is you know, they
can't localize it anywhere even three days
ahead.
So you know good luck getting out of the way
because you're not going to get any warning.
So reentry is difficult.
Again this is a busy slide that I will say
something about this one.
The other part of the story is if you're a
spacecraft operator today and your spacecraft
is in what's called low Earth orbit you know
four five six hundred kilometres roughly once
a day you have to worry about.
You'll get a notification saying there's a
piece of space debris there's a you know a
hatch cover or a battery or a fuel tank you
know, a rocket stage that's going to come
close to your spacecraft and you need to think
about whether you need to do a little maneuver
to have to avoid the chance that you might
hit it.
This happens all the time in 2007 the operators
of the iridium spacecraft constellation the
satellite phone system 400 times a week.
They had to at least think about whether there
was a hazard to the one of their spacecraft
400 times a week.
And the thing that really brought this into
focus happened in 2009 when two full sized
spacecraft collided in orbit.
One was one of these Iridium spacecraft it
was still operating it was being used to rout
phone calls at the time.
And it ran into a disused Soviet surveillance
spacecraft 42000 kilometre an hour collision.
Happened at 799 kilometres and happened over
Siberia.
The fact that they collided is not the issue.
What was the issue was that they knew in advance
that these two things were going to come close
and they looked at it and they said oh we're
okay they're going to miss.
We don't need to do any sort of correction
and they were wrong.
And then the satellites collided.
So in the days before this there was a forecast
that said they might get as close as 117 meters.
That's pretty uncomfortable I wouldn't wanna
be an astronaut on one of these if that was
all you had.
But in the subsequent days they they said,
oh now it's looking better and yeah we're
going to miss by kilometre a bit more.
We should be okay.
But they were wrong and they and the spacecraft
actually collided.
I'll show you a video and second.
Why were they wrong.
They were wrong because they couldn't predict
the effects of space weather that were changing
the orbits top dynamically to know.
Now this matters because it now what it means
is if you've got an error of a few hundred
meters or if you're only sure that you're
going to miss by few meters you better put
a bit more distance between you and the hazard
and you actually have to put a lot.
Because if you only do a little correction
you know you might actually have made it worse.
You actually have to do a large correction
to be absolutely sure that you're not going
to collide and that costs fuel and that's
expensive for the operators.
So this is the simulator it's a company called
Analytical Graphics.
They do a lot of orbital prediction stuff
after the- when everyone knew that the collision
occurred.
Said we'd better go back and have a look at
this and so they simulated it to see what
actually happened.
And this is what they as more of a PR thing
but this is what they came up with.
So this is the Iridium spacecraft.
It collides with this cosmos.
Soviet satellite roughly 90 degrees to each
other.
They collided produce two clouds of debris
that were tracked.
Large numbers of a well large numbers of trackable
objects and then a whole cloud of things that
are too small to track those debris clouds
went on and circled the Earth you'll see in
a minute it looks fairly bad at the moment
it looks like ah they got these nasty clouds
of debris and they are but in a second this
video I'll show you all the other stuff that
Norad and others are tracking.
You'll see while it's an addition, but look
at all the other stuff that's up there you
know.
So this is a problem because as I said these
close encounters with debris are so frequent
now if there's a scenario called the Kessler
syndrome where a collision like this could
occur would produce some debris that would
cause another hit another spacecraft cause
more debris and you can get a chain reaction.
We're not quite at the point where that's
the chain reaction will take off but we're
getting close.
So space debris and tracking it is a big big
issue for spacecraft operators alright on
I'm getting a little low on my time here so
I'll try and speed up a little bit.
How do we track these storms.
We have instruments on the ground this is
our instrument at Toolik lake it's a photograph
of the instrument.
We have four of these across Alaska and a
couple in Antarctica and various other instruments
that support them.
This is a photograph of the- this is the hut
that the instrument is in a Toolik lake this
is another instrument that's currently at
Eagle in Alaska.
This is Greg our machine shop supervisor building
an instrument to go to McMurdo in Antarctica
and the instruments look at the sky through
a fisheye lens.
So this is the- this little lens on the top
there is how they look up at the sky.
Just very quickly say the instruments measure
the brightness of their aurora that's this
green band.
They measure the temperature which are these
blue through red colors and you can see the
temperature changes near the Aurora and they
measure the wind which are these yellow arrows
here.
I don't have time to explain this in more
detail.
A single instrument gives you a reasonable
look at the winds.
You do much better if you have several of
them together and we actually have four of
these in Alaska now one at Kaktovik one at
Toolik lake, one at Poker Flat and one at
Eagle.
And by having them work together we can get
a much better view of the Aurora.
I can't say much about this except this is
a status display that we have out of the rocket
range that takes our window or takes our camera
data it takes radar data it takes magnetometer
data and spacecraft data and brings it all
together and provides us with a sort of a
situational awareness now-cast display that
we use to decide weather conditions are what
we want for launching rockets.
I will play this movie.
This is bringing the winds which are measured
in white you've seen before the yellow arrows
the ion motion and a whole bunch of other
stuff together.
I'll just play this movie and try and so a
little bit about it as it's playing the spacecraft
images as the spacecraft move over they are
drawing in swaths of what they're seeing,
ground based all sky cameras, ion motion here
from the radars.
And you can see the winds that are being pushed
around by the ions here.
So we can bring all this together.
There's a bunch of other stuff that we measure
vertical winds and properties of the wind
field.
We can bring all this together and produce
a really nice view of what's happening weather
wise across Alaska.
I'll let this play for just a couple more
minutes.
You know here's the aurora this is aurora
south of Fairbanks.
This is obviously an active night look at
how active the aurora is.
So the aurora became active and you see the
wind changing in response to that.
This is again showing you that the Aurora-
when the aurora is active it affects the winds.
I think I can probably jump ahead now to something
like this.
So what I've got is just a couple of minutes
here I want to finish off by saying I said
the last thing I want to just say was What
can we do about this.
Well the answer is nothing in the sense that
we can't stop the storms from happening.
But what we can do is we can do a better job
of predicting when they're going to happen
and what they will do and how do we do that.
Well the Naval Research Laboratory in Washington
D.C. accumulates observations from everybody
who's got them.
Any data they've got and they put it into
a big computer model which is essentially
a summary of all the weather that's been seen
and I use that to predict what the wind will
look like this is these are some predictions
of the wind that are produced by that model.
That's not the point here the point is what
data go into it.
Well this blue horseshoe here and here are
all our measurements from Alaska.
Now they're not all out there.
They're our measurements from Alaska that
we gave to the Naval Research Labs and I'm
very proud of the fact that we gave them a
bunch of data to put into this model that
we gave.
It turned out we had so much data that they
could only use 2.5 percent of what we gave
them.
They had to throw all the rest away because
if they put all our data in it would have
overwhelmed everything else.
So all these other points here are from other
you know they're from spacecraft and other
institutions other measurements.
But here in Alaska as I said this is this
is our contribution the blue stuff.
This is an operational model this is what
the forecasters use to tell them how their
spacecraft are going to behave.
This is our data from Alaska going into it.
And as I said by far we are the biggest contributor
of data to that model.
I'll just finish by saying you know these
storms I've sort of talked about how they
look to us here in Alaska.
You know they're driven by the aurora, the
aurora is occurring over Alaska but those
air parcels they don't just stay over Alaska
they move they cover the whole globe really.
We've got nice instruments here but really
you'd like to know what's happening across
all across here and further on down over the
lower 48 of the US where there's so much of
the population is.
So our community is talking about trying to
build a- Take what we have here in Alaska
and you know multiply it many times over.
These instruments only work at night.
You can only see the aurora at night you got
to see the dim light and so you don't get
any information during the day but then as
the nighttime pass through what's shown here
is imagine having instruments like the ones
I've been showing you all across Canada and
over down over the main part of the US here.
What would you see.
So they've taken a computer model of a storm
and imagined what we would see if we were
observing it during the storm you can see
how complicated this wind flow is.
There's all sorts of stuff going on lots and
lots of flow here.
So our community is working now on ideas for
how we could fund and build something like
this which would let us see really what the
story looks like for the whole US and not
just for Alaska.
So with that I will give you a summary and
stop.
So let's see the main points I want to take
away from this are there's this region we
call the thermosphere.
It's the outer layer of our atmosphere 100
kilometres and up.
It's tenuous.
It doesn't act all that much like the air
in the room here but it does still experience
weather.
Not a very familiar form of weather but it
experiences weather.
The weather is driven by eruptive emissions
from the sun and that frequently produces
these large storms.
There's lots of other effects of the storms
that haven't even touched on.
I've just talked about how the sun upsets
the top layer of our atmosphere the effects
on the atmosphere effects lots and lots of
technical technological aspects of our society.
But very particularly they affect spacecraft
orbits whether the spacecraft are going to
have encounters with debris, reentry, those
sorts of things.
Geophysical Institute has an active program
to monitor and understand the storms using
both the ground based instruments I've spoken
about here and also sounding rockets which
I haven't spoken about.
And our near term goal is to expand the monitoring
network to include sites in Canada and the
lower 48 of the US.
So I'll leave you with that and take questions.
