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>> This is a view of the earth that you probably not familiar
at looking at all the time,
looking down over the North Pole.
Here you've got the Arctic Ocean,
it's about 14 million square kilometers, and it's surrounded
by land on all of its sides, but then you have these regions
where water can flow in and out in here
through the Bering Strait, into the North Pacific, and then here
through Fram Strait and the Davis Strait
into the North Atlantic.
In the winter, the temperatures across the ocean on average get
down to about minus 30.
And because of these cold temperatures,
the sea waters freeze and it forms a layer
of ice known as sea ice.
And over average, the ice is about 2,
2 and half meters thick,
and below it is kilometers of the ocean.
And in the winter, that ice completely fills the Arctic
basin and even reaches
out through the Bering Strait into the Bering Sea.
Now in the summer, that ice cover starts to retreat
as the temperatures get warmer and in the summer.
The average temperature across the Arctic Ocean is
around 0 degrees, and this video
that you've been watching here shows the summer September ice
extent minimum.
It's from the National Snow and Ice Data Center in the USA,
and some of you might be familiar
within the press every year around September,
you see headlines about we've reached another minimum arctic
sea ice extent, and it's a downward trend
since the satellite records began in 1979.
So, and then you often get kind of speculation
about when the arctic ice cuff is going to be ice-free
in this summer, and whether the Northwest Passage will be open.
And we can go back to PowerPoint now.
The [background noise], this is in the melting and freezing
of the ice [inaudible], that the ice kind of changes.
The ice is also moved around by the wind, it's dynamic.
And what you're looking at here is a video
that I took while I was on an ice company arctic.
And its two icebergs, basically being blown by the wind
and they crush in together, there's actually the sound
that you could hear, just before they lowered the volume,
was the sound of actually the ice [inaudible], the ice pushing
up against each other.
So as the ice is being moved around,
it's forming these ridges and it's thickening dynamically.
The other thing that happens as the ice moved is
that it splits apart, and again this was a picture I took during
an ice camp.
We've gone in for dinner into our mess tent and came out,
kind of-- just as the sun was setting and we were greeted
by this view about 100 meters from where we were camping.
The ice plain we were on had actually split in two,
so we're quite glad it hadn't happened straight on the center
of our camp, but it was an amazing view
and what happens here in the winter, because the warm--
the ocean is a lot warmer than the atmosphere.
It would lose heat to the atmosphere
and then ice-- new ice will form.
So these areas of open water become production areas
for the formation of ice.
So those figures I shared, or that animation I showed you
at the beginning, with the ice extent changing from year
to year, it's changing for 2 reasons,
one because it's melting or it's refreezing,
and the other thing 'cause it's changing dynamically.
So we don't just need to know how the area is changing,
we also really need to know how the ice thickness is changing,
'cause then we can work out how the ice volume maybe changing.
Now sea ice has kind of an important role
in our climate system.
Something that you maybe familiar with it is this--
is the idea of the ice-albedo feedback mechanism.
So albedo is ma-- measure of the amount
of solar radiation that's reflected back in to space.
So sea ice covered by layer
of fresh snow has a very high albedo, about 0.9.
That means it reflects more radiation back into space
than the open water does and absorbs more radiation.
So when you have more [inaudible] from water,
more radiation is absorbed, you get more heating that can go
on to melt more ice and so on.
And of course the converse is true.
When you have more ice cover,
you get more radiation reflected,
and you can get cooling.
But this is isn't the only way the sea ice affects our climate.
It forms on the ocean so it forms a barrier
between the atmosphere and the ocean.
On the open ocean, the winds can free, they can't move the water,
but this isn't the case in the Arctic.
So that's another effect that it can have on,
on our climate system.
The third thing is that when it melts,
it adds fresh water into the ocean.
When it freezes, it add salt into the ocean.
So that can affect the density of the water,
but it's not just sea ice that's an important component
of the fresh water in the Arctic.
Now this diagram here describes a kind
of simple structure of the Arctic Ocean.
The sea ice actually fits in a very cool fresh layer
and that's separated from warm, salty Atlantic waters beneath,
by I think called the halocline.
So "halo" means salty and "cline" means slope.
It's a steep density gradient that's controlled by salinity
that separates these 2 very distinct water masses.
Now, I siad the sea ice forms contribution to that fresh water
in the top, but it's not just that.
In the beginning, you saw the map of the Arctic
and it was surrounded by continents.
And as you move in to the summer, these--
the rivers in those continents thaw and the river runoff runs
into the Arctic Ocean, and that provides another source
of fresh water, will also got cha--
changes from fresh water from precipitation and evaporation,
and also exchanges through those outlets that I showed you
into the North Pacific and North Atlantic.
And this diagram here is taken from a paper
and it shows the mean distribution
of that liquid fresh water in the Arctic.
And you'll notice it-- the red colors,
basically show we've got more of that fresh water
and that's predominantly in the Western Arctic.
So here you've got Greenland,
and this is the Canadian archipelago.
This is an area, notice the Canada basin
and it contains the Beaufort Gyre,
which is something I'm going to talk a bit more about later on.
Now we're interested in the storage and distribution
of this fresh water because if it is released even in parts,
it has the potential to disrupt the thermohaline circulation,
which then could have a knock-on effect
to our climate in Northern Europe.
So this slide is basically to summarize UCL's heritage
with working wit the European Space Agency to use satellites
to look at the changes in the Arctic.
This photo here was taken of the remote sensing group
at the Mullard Space Science Laboratory which is also known
as MSSS-- MSSL, and it's part of UCL.
This photo was taken about 20 years ago,
but actually our heritage with this kind of work starts,
even earlier than that, around the early 1980s, 1982 to 1983.
MSSL let us study for the European Space Agency,
looking at the feasibility of using satellites
to monitor changes in the Arctic.
But it wasn't really until the launch
of the Earth remote sensing satellites, which name is ERS1.
That was launched in 1991.
We can use data from 1993 onwards.
It wasn't until those satellites we launched
that we're actually able to have observations over the Arctic.
Previously, the satellites didn't go up that high,
we can actually see-- take data from there,
and it was really work done during this time
by Seymour Laxon who is sitting in the audience here
that pioneered the method that we used to calculate
or estimate sea ice thickness from space.
And I'm going to go on to the next few slides
and describe actually what this technique is
and how we're actually doing it.
So all of those satellites you saw were on the last slide,
and you carry an instrument known as a radar altimeter.
So the first bit of that is radar.
Now radar's a really useful tool for Earth observation.
This diagram here shows the opacity of the atmosphere
to different wavelengths of radiation.
And I'm sure you're all familiar with the idea
that an x-ray can see through your skin
and it can make a map with your bones.
Well, radar can see through our atmosphere.
It can see through the clouds and it can monitor what's going
on at the surface of the earth.
So that's why we use that frequency in Earth observation.
It also doesn't rely on having daylight,
which if you're using sort of an invisible wavelength,
then when it's dark, you're not going to see anything.
So it's useful for getting year-round measurements
over the earth.
Now the second word I mentioned was an altimeter.
Now this slide describes the measurement principle
for an altimeter.
And if you cast your mind back to your school days,
I'm sure you'll remember the relationship speed equals
distance over time, and that's basically what we're doing here.
The altimeter transmits a pulse of radiation, it travels to down
to the surface of the earth, it reflects to the surface,
and travels back up to the satellite.
And we measure the time taken for that pulse of radiation
to travel from the satellite to the earth and back again.
Now we know how fast the radiation is traveling.
We know the time, so from that we can work out the elevation
of the satellite above the surface that we've looking at.
So over the Arctic Ocean, we have the--
those areas of open water, the leads.
So we measure the elevation to the leads,
and then we measure the elevation
to the ice slopes next to them.
And if we take the difference between those measurements;
we can calculate the free board of the ice, so that's the amount
of ice, that sticky arc above the ocean surface.
Now, to kind of simply explain what we do next
to estimate ice thickness from this measurement,
the ice is floating and roughly nine tenths
of the ice is below the water level.
In reality, it's a little bit more complicated from this,
we have to take into consideration things
like the snow depth and density that's sitting on the top
of the ice and how it weights the ice down.
We have to consider the ice density
and the water density as well.
But that basically describes the principle of the measurement
and what were looking at.
Now, as I said today, I want
to present you our most recent results,
and I don't really have time to go into what we've looked
in the past, and though Seymour and myself had looked
at how the Arctic ice thickness has been changing,
but today just going to take the measurements over the ocean,
and this was actually started a couple of years ago
when we started looking at these ocean graphic measurements
on their own, and we noticed something was going on.
Now this is a video that's being made using our data.
The reds mean that the sea surface height is getting
higher, and we were looking at data between 1995 and 2010,
and what we could see is the sea surface height getting higher
and higher.
This area is in the Western Arctic, that area I pointed
out to you earlier where you get the largest storage
of fresh water.
So obviously after seeing this in the--
our data, we wanted to find out what was going on.
So our first port of call was to get and actually have a look
in the literature, and see what other people had been observing.
Now this figure here is from some work by [inaudible]
and what they've done is taken in situ measurements,
say measurements that should be made for being
on the Arctic Ocean, so from a ship or being in ice kind
of pool having a mooring floating around
or buoy floating around.
And here we've got data from 1992 to 1999.
There's some very small black dot from this plot
which actually show where the data are.
It's only data during the summer,
and that's because there's--
well there's not many measurements during kind
of Arctic winters, it's difficult to get
up to the Arctic when it's dark and it's so cold to actually
in situ observations, which is why satellites are really useful
because they can write kind
of a large scale view all year-round of what's going on.
So they collected measurements during the 1990s, and this group
of scientists then compared
that to measurements during the summer between 2006 and 2008,
and what you see when you just look at these two graphs,
this shows the amount of fresh water, and you can see here on,
here's the color scales,
so you're getting more fresh water in those later years.
This part here shows the difference between the two,
and when they added this up over the whole of the Arctic,
they got a number that was 8,400 cubic kilometers.
Now let's give you an idea of how much that was.
The figures I showed earlier with the fresh water
in the top layer of the Arctic Ocean, that contains
about 70,000 or just over 70,000 cubic kilometers.
If you are to amount all the sea ice, that would add
about 10,000 cubic kilometers.
So that number's kind of similar to the amount you'd have in all
of the sea ice, but it wasn't any of these guys
that as they always say, seen a change
in the fresh water storage.
This was another study done by some scientists,
and they had a hydrographic survey that took place in April
and March 2008, and they compared that to a climatology,
so a climatology just means like an average state,
and that average state was collected from or made
up from data collected between, I think, 1950s to the 1980s,
and there was another study
and they had 4 moorings again situated in the Western Arctic,
and they saw an increase in the fresh water during the Northeast
as well when they compare that back to the climatology,
I think, that was collected during 1950s.
So all of these data was pointing towards this,
they kind of snapped shots in time showing us
that something is changing in the Arctic,
the freshwater storage is changing.
Next thing a lot of these papers did was they used the models
to go and have a look at what was controlling that storage
of fresh water, and what these models told them was
that the wind was having an effect
on that storage and distribution.
Now this diagram here shows you what happens when the wind blows
on the ocean, so the thick, blue--
white arrows, that's the wind,
the thick blue arrows describe the average movement
of the wind-driven layer,
and thin blue arrows show the directions
of the surface current.
Now you might notice when you're looking at this figure,
the direction of the wind-driven layer,
the way of water is moving, is that right angle is to the way
that wind is blowing, and this was first spotted
by a Norwegian explorer and scientist Nansen and,
in the 1890s, Nansen decided he wanted to reach the North Pole
and he-- the way to do this was to sail his ship
which was called the "Fram," around kind of the Russian side
of the Arctic and let the Fram freeze into the ice
and then drift with the ice
and then hopefully the ice drift would take him
to the North Pole, so Nansen embarked on his voyage
and he would stay with his ship
for about a year while it was frozen into Arctic ice bank.
As they were drifting,
he noticed that the ice didn't drift
in the same direction as the wind.
It drifted kind of an angle 20 to 40 degrees to the side of it,
and when he finally returned from this kind
of epic adventure, he got back and explained what he'd seen
to other scientists and Ekman who I think was a Ph.D. student
at the time, came up with his theory of wind-driven currents
to explain the motion of the water in response
to the winds blowing on them.
So the average movement of that wind-driven layer is known
as the Ekman transport of water, and so you can see
in this situation here
where we've got anticyclonic circulation,
so there's winds blowing around in a clockwise direction
and you've got the water converging into the center
of the anticyclone, and that's making the water pile up
and that changes the sea surface height.
So that's that sea surface height here,
and that's something we can measure using our satellites.
On the other side, when you've got a more cyclonic circulation
system, you've got the opposite thing happening.
You've got the sea surface height lowering in the center
and then raising at the edges, and what the climate models
or the Arctic Ocean models showed was
that when you had the more anticyclonic circulation
where it seems fresh water was stored,
and then when you had more cyclonic
that fresh water was pushed to the margins
of that circular Arctic basin,
where it can be more readily released to the North Atlantic.
So what we can do now is take our sea surface height data,
and we can take some wind data,
and these 2 figures here show you this one here,
A is the trend in the sea surface height, so again that's
that Western Arctic, that's the Beaufort Gyre,
and this is a trend, so it's how the sea surface height is
changing through time, and what's happening here is
that you're getting an increasing domain of that gyre
and the center point's increasing height faster
than bits around the edges.
Now when you look at the other plot of what the wind is doing,
they're more blue, they're more negative,
means that the winds are becoming more anticyclonic,
so we've got, as we would expect
from what the models are predicting,
we've got the evidence for the sea surface height domain
and the winds becoming more anticyclonic, and then we--
when we [inaudible] the surface height data
and we did our calculations, we worked out that the change
in sea surface height due to, we'll say,
the change in the fresh water content due to the change
in sea surface height, was about 8,000 cubic kilometers,
so that fits in very well with what's been seen
in the in situ observations.
However, I wanted to look at this
in a little bit more detail, so I decided just to take
that Western Arctic region and average over it
on a year-by-year basis, and then look at how that rise
in the sea surface actually happened
on a year-to-year basis, and this is what you're looking
at on this graph here.
Now it's quite a lot to take in on this graph.
On the axis here, we have the sea surface height and that's
in pink, and then this side here we have the wind,
and that's in blue, and as the wind becomes--
as the trend here becomes more negative,
you get increasing anticyclonicity,
and what was really striking about this plot when we looked
to them, what surprised us a bit was,
it looks like there's 2 types of behavior going on here.
Now in the second half of our time period,
it looks like the relationship we'd expect, the wind is going
that way and sea surface height is going that way.
That's not just obvious in the first half of the time period.
I'll just clean up the graph a bit so it might make it,
kind of even more clear, so the obvious question
to us all is why is this happening?
Why are we not seeing this expected relationship
that we've kind of got the over--
evidence but when we look on a year-to year-basis,
it's not quite as simple as that, and there are a number
of different reasons you can think about.
Ekman transport and changes
in that Ekman transport aren't the only things
that control these storage of fresh water.
You could think about other things like kind
of [inaudible] water coming
in from the sides or changes in mixing.
But another, I think, quite interesting question is,
are changes in the ice cover affecting how the winds kind
of stir up the ocean?
Now earlier in the lecture,
I described to you how the Arctic sea ice forms a barrier
the atmosphere and the ocean, so that affects the transfer
of momentum between the atmosphere,
atmosphere in the ocean so it's peaceful that changes
in the sea ice cover could affect that transfer,
and then maybe towards the latter half of our time period,
the wind is becoming more efficient to spinning
up the ocean, and now there is actually other things
in the scientific literature that could also point
to this kind of change in the ice cover.
And there's the research done by a guy called Rampal who's looked
at the ice deformation rate so and how often you get things
like the leads forming and the ice cover,
how easy it is to move around.
And he's seen that during the year, during that latter half
of the time period that the deformation rate increased
and that implies that the mechanical strength
of the ice decreased, which sort of changed it's response
to the winds and the ocean currents.
So maybe there is something going on here,
and I think there's other another paper that was published
at the end of last year by a guy called Spreen,
who looked at changing ice velocities over the Arctic,
and talked about how the ice velocity can be fully explained
with what the wind was doing.
So I think there's other evidence that kind
of points towards perhaps something's going on here,
and in the future, this is a question I intend to go
and investigate further.
[Inaudible] and I'm being quite speculous here about the reasons
for that disparity I showed you in our last data report,
but I think it's a very interesting question.
And it's not just because it's the controls in the storage
and distribution of fresh water.
Now if you cast your mind back
to that schematic I showed you earlier, I showed you how the--
that cool fresh layer where the sea ice forms is separated
from the warm salty water, Atlantic water.
Now that warm salty water contains enough heat to melt all
of the Arctic sea ice in 4 years,
if it could get brought up to the surface.
So I think another question from this research is that,
if you've got a changing coupling between the atmosphere
and the ocean [inaudible] change in the ice cover,
could you increase the turbulent mixing in the ocean,
could you bring more of that heat up, and then could
that be another feedback to the ice [inaudible]?
And I think these are really interesting questions
that we can go on to look at with the satellite data
in the new observations from the CryoSat.
So now we're going to move on to CryoSat.
So in 1999, the European Space Agency put
out a quarter scientists and asked them to come
up with ideas, the satellites,
satellites that would monitor our environment or satellites
that could help tell us more about planet change.
And at UCO, a proposal was put forward
for a satellite called CryoSat.
It was led by Professor Duncan Wingham
and it also involved Seymour Laxon,
and they designed a satellite that would be dedicated
to monitoring the Polar Regions.
Everything I've shown you before from the ERS satellite
and MVSAT satellites which is work that I've been working
on previously, has been done with satellites that when sort
of optimized for looking at the Arctic or the Antarctic.
You may have notice in those plots I showed you,
showing the trends, there's a hole in the center
and that's not 'cause there's nothing there.
It's because the satellites don't monitor that high.
And CryoSat was different
because its orbit was different to those satellites.
It's designed to fill in that hole.
It goes all the way up to 88 degrees and it's a little bit--
it's also designed so it has a densest number
of sampling points in the Polar Regions.
But it's not just that that quite makes CryoSat different.
It carries an enhanced radar altimeter.
I'm not going to go into the details of how that works
but basically, it's processing
or the way it works it has the effect
of reducing the footprint on the ground.
Now by footprint, what I mean is if you imagine you had a torch,
so your torch has quite a small bit of like coming from here,
if I was to shine it at that wall,
you'd have a much larger area illuminated
on the wall 'cause the beam was diverging.
So if you imagine a satellite in space, it's transmitting a pulse
of radiation, but that diverges and when it reaches the ground,
the area that it's illuminating on a convention
or a territory is the order of kilometers.
However CryoSat employees enhance processing techniques
that reduces that area of illumination on the ground
to 300 meters and it's a cross track.
And that means that we get a better resolution
of measurement.
It should make it easier for us to pick
out those leads in the sea ice cover.
But it's not only that that it does.
It takes multiple shots, multiple looks at the same point
on the ground, so that means we can average all of those looks
to reduce the noise in our data.
And another advantage CryoSat-2 has is that when it's passing
over the ice sheets over Antarctica and Greenland,
it can measure the slope of the edges and that's where a lot
of the ice mass is lost.
So CryoSat-2 followed CryoSat-1 and I just finished my PhD
in 2005, and my first job as a post-doc was
to actually test the sea ice processing chain.
And in 2005, a group of us went to the one
of the European Space Agency bases to sit in a room
and watch the launch event live and watch the satellite go
up into space and this photo really is the last view
that we had of that satellite.
It was launched and we sat there--
this is us kind of sitting
in the room looking a little bit worried, and we waited
for about 15 minutes, after that time you expect the satellite
to send a signal back down to Earth to tell you
that it's in the orbit.
It's where it should be.
But that didn't happen.
So we waited another hour and still, still nothing
from the satellite and so by that point, of course,
through getting a bit worried,
and eventually I actually got a text from one
of my friends saying, "I'm sorry about your satellite."
And so they have-- they had somehow found out before I did,
but actually it had exploded on launch and when it was passing
over the Arctic actually.
But the European Space Agency quickly agreed
to build another version of the satellite, and in April 2010,
again we went to a European Space Agency base
and we were probably a little bit more nervous this time
after what had happened last time.
But I think you can probably see by the smiling faces
in this photo that actually this launch went well
and we are all absolutely delighted.
A few of those faces are from that photograph I showed you
from [inaudible] MSSO 20 years ago, Richard Francis was there
who was-- he now was European Space Agency's,
the mission manager for CryoSat, Duncan Wingham
who led the proposal, and so obviously we were all delighted
that that, it had gone well this time.
So following the launch at CryoSat,
it hasn't all stopped there.
UCL is still very involved with the way it was going on.
Not only will we be looking at the data and analyzing it
to look at how the Arctic and Antarctica is changing,
but we're also kind of making sure
that we really understand the data,
and part of that is validating our measurements
over the Arctic sea ice.
Now in April last year, myself, Seymour and [inaudible],
who is a PhD student in CPOM all went up to the Arctic
to actually take a radar and go
and investigate how the radar was penetrating
into the snow and ice cover.
And it was quite a complicated experiment, and what we wanted
to do was to be able to sample different ice types.
Now this part here is data from a guy called Christian Haas
and he was also heavily involved in organizing and participating
and designing this field experiment and he's
at the University of Alberta.
So this is data from an instrument called
electromagnetic bird.
It basically looks like a missile and it is towed
from an aircraft and it's tired so as it flies about 10 meters
above the ice and it transmits the signal
that then can be processed then from that week in
and measure the ice thickness from an aircraft.
And that's what this is, this is transects of an aircraft flying
out over the Arctic ice cover,
and the color codes show the thickness.
So you can see here it's thickened near the case.
This is Greenland, this is the Canadian Archipelago,
and if you fly out, it gets a bit thinner, and what we wanted
to do is sample that gradient and thickness.
So to do that, we had to get ourselves
up to a place called Alert, which is, sorry [inaudible],
she's about here, and it's a Canadian military base and then
from there, we got on to a small aircraft and we flew
out into the Arctic Ocean where we landed on the ocean
and on the frozen, on the ice, on the frozen ocean and got
to lock it out then did our experiments with our radar,
we did the ground surveys back in the plane
and then back to the base.
And we set up 2 sites, a North and South site on the ice
and a base as well on the ice
that was land far after the coast.
The other part of this experiment is
that it's difficult to take measurements that you make
on the ground, say, you got a radar and you're just looking
at the ground, it's maybe [inaudible] meters square
to something that you're observing from space
because of the different scales.
So another really important part of this field experiment was
to use aircraft to tie in the ground measurements
that we're making on the ground to the measurement
that CryoSat was making.
So not only did we have us on the ground,
we had aircraft flying over us
and then CryoSat flying over them.
So logistically, it was quite a big organization thing and a lot
of that organized by the European Space Agency.
So this Alert, you can't get a commercial flight there.
We had fly up and in with sort of [inaudible] aircraft
and you can see us all kind of packed into the aircraft,
with all our kits in the front,
and it's the [inaudible] most place on earth
where people actually live.
We're really dependent on weather when we do this.
We can't land on the ice if the visibility is poor.
Remember no one's been to where we're flying to before this.
No runway, and there has to be an instant
of them losing a plane through the ice before as well.
So the pilots need to make sure they can actually see what's
going on.
They can see if there's any lumps and bumps.
So this is Troy, our pilot.
He's kind of-- looking at the weather reports everyday
to see if we could fly.
On the days that we couldn't fly, we put everything,
all [inaudible] and went down to the ice that was grounded
to the coast and-- and kind of practice experiments as often,
experiments like that.
And we do spend time in the warehouses setting up our kit.
And these are polar bear tracks which I'm very glad to say
that we didn't actually see the bear
that made them 'cause it's something I particularly want
to come in to place contact with.
And but these little tracks next to it,
we're not quite sure what they were either.
Either it's this one or it was stalking something,
one of the team.
So when we finally could make it out and we set up two sites
in the ice, north and south site, we put out things
that like this bright orange tarpaulins
and bin bags for [inaudible].
So the aircraft, when they fly over, would have a target.
What is-- aircrafts are trying to hit these things,
they're called corner reflectors
and they provide a very bright target for the aircraft,
but they're difficult to spot when you're flying.
So putting things like this light bin bags,
just provides a simple target for them.
And here, one of our colleagues is also drilling through the ice
that we landed on to see how thick it was,
it was about 1.8 inches I think here.
And then as I mentioned, we also had the [inaudible] flights.
NASA, NASA had a plane up in the arctic during the time we're
there so they overflew as well
as the European Space Agency plane.
And around the lair as well, there's a pack of wolves,
they're-- are quite tame really and they pose very nicely
for photographs like this.
Well, the one other one was basically licking anything
that you'd left on the ground and hope
for finding food in there.
And this is our experiment site from the air,
so we try [inaudible] almost about 500 to a kilometer apart.
We've have 500 meters.
So we come-- so we tag these corner reflectors
and then we do dense snow surveys around them.
That graph that you see on this slide shows them,
our snow survey and shows how the snow varies
and we take our radar, we take measurements there.
We dig snow pits, we look at density, and we'll collate
in all these data so we can better understand how the radar
penetrates through the snow, which will depend
on the snow characteristics.
And this is just another going kind of shot,
I think that Rosie took and just showing our experiment site
and just after we've made all our survey lines,
and this is another shot of us showing, this is actually,
this a ridge, so that's when the ice is being pushed together,
and you're getting that dynamic thickening
and if you actually want to read a bit more about this experiment
and there's some blogs up at the European Space Agency web site.
And what I actually thought I'd show you next is,
it's going too advanced.
This is a video that shows you actually what it's like to land
on the ice, I think it's got sound on it as well.
[ Silence ]
The pilot would have done a couple of laps to check
that it looked okay before for he actually went in to land.
[ Noise ]
[Inaudible Remark]
[ Noise ]
So once the aircraft has landed, it will taxi around for a bit
to it actually flattened the snow
down to make sure we can take off again and also to make sure
that the skis don't freeze to the snow
and ice 'cause they quite warm once you come into land.
And then these next few shots might just give you an idea
of what it's like to be on the ice.
It shows the aircraft flying over the top of us.
You could put the sound back up.
[ Noise ]
[ Music ]
So just to summarize kind of what I've shown you today,
hopefully I've kind of introduced
to you UCL's highly long heritage with working
with the European Space Agency to use satellites
to monitor changes in the arctic, not only the Arctic
but the Antarctic as well.
And more recently, the research that are--
most recent discovery is
that it's not only the ice cover that's changing.
We're also being able observe changes
to the ocean's circulations
and that's revealing some interesting questions I think,
which is definitely something that I tend to look
into the future and try
to understand a bit better the physics
of actually what's going on.
I think UCL's involvement with CryoSat-2 is what hopefully,
you've se-- caught a glimpse of that by naming the full extent
of our involvement and there're numerous people
in our research group working very hard on looking at data
in CryoSat, and the map that's faded
out in the background here shows the ice thickness
for April 2011, and Seymour is hoping by April this year
that we should be able to have the first estimate of ice volume
since 2008, and that's should hopefully give us some
information about whether the volume
of the ice covering the ocean has been changing
over the recent years as well as the extent.
So, I'd like to thank you very much for your attention.
[ Applause ]
>> Thank you so much Katharine for such an exciting talk.
I think we have time for maybe one question, if anyone has any?
It's good.
Just run down the front and if you cold just wait for the mic
so they can hear you online.
>> I have one elementary question.
>> Okay.
>> Which is something that crops up whenever people talk
about the Arctic and or the Antarctic,
they talk about the West Arctic and one doesn't know
which direction is west when one is so close to the North Pole.
How is it related to the grand Meridian?
>> So when I talked about the West Arctic
and I would put [inaudible]
and moving towards Canada as-- as west.
That's-- that's how I think about it or how,
we don't typically describe it, and then east would be round,
kind of Russian and Siberian side.
>> Okay, I'm afraid that is all we've got time for today.
I want to thank you all for coming,
and I hope you could make some events this term and I would
like you to join me and thanking Dr. Katharine Giles.
[ Applause ]
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Exploring the Arctic from Space (17 Jan 2012)

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Amy.Lin 2018 年 11 月 20 日 に公開
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