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>> We're trying to understand the global carbon cycle,
and we're trying to understand climate change and the effect
that climate change might have on our planet in the future.
>> The main question we're trying
to answer here is how much carbon is stored
in the forest ecosystems.
We understand very well what's happening in the atmosphere
and the oceans but not so much forested sites.
>> And when it comes to forest structure in particular,
there is a huge hole over Africa.
We don't have the data that we need anywhere in Africa.
>> The one element that's missing is us being able
to map the vertical structure of forests.
When you look at an image, you can tell there's forest there,
you can tell it's green, but we don't know how tall it is.
If we can tell how tall it is, then that's a very good proxy
for how much it weighs and with that you can infer biomass
and with that you can infer carbon.
>> NASA has a few upcoming missions to look at this,
and so does the European Space Agency.
We have lots of different things we're putting in space,
but one of the main goals of all of these missions is
to count how much carbon is stored in the earth's forests.
So how we do that is essentially measure how big the trees are.
Especially here in the tropics, most of the carbon is stored
in the tree trunks and above the ground,
so we're measuring how fat the trees are, how tall they are,
and then comparing that to our spaceborne measurements.
>> 51.3.
>> The picture is degraded,
but it shows the carbon cycling of the forest.
The sun and the light would actually shine on this forest
and they absorb the carbon from the atmosphere,
from the photosynthetic activities, and they grow.
So as the forest grows,
we capture more carbon from the atmosphere.
So the forests are extremely important
for global carbon cycle and climate change because we --
by having the forest, we mitigate part
of the carbon we put in the atmosphere
from our cars and our factories.
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>> There is a very big effort
to integrate the remote sensing imagery with ground data.
What we can get from remote sensing is the vertical
structure of the forest, but we need people on the ground to tie
that information to biomass.
The biomass is what we're really after.
And with ground plots, we can make that connection
between a height in the particular plot and the biomass.
>> So when we are looking at the forest,
we are very much interested in this trip to look
at the structure of the forest.
The trees have irregular shape, but the volume of the trees
and the size of the trees is extremely important for us
because that tells us what would be the mass of the forest.
So if we measure the diameter of the trees and tree height
and know the wood density of the trees, we get an estimate
of the mass of the tree, and almost half
of the mass is carbon.
So by measuring the size, we actually get an estimate
of the carbon in the forest, and that helps us a lot
to use our measurements from the airborne sensors
and from the satellites to calibrate
with that carbon on the ground.
>> The mangroves in Gabon are one
of the tallest mangroves in the world.
We are interested to know how the water circulates
within this ecosystem, how it comes in and out of the system.
So once we understand the hydrology of these systems,
it helps us also understand how these ecosystem really work.
And what drives their productivity.
These mangroves are some
of the most productive ecosystems on earth.
They stock a huge amount of carbon, of which most
of it is located and captured in the soils.
The advantage of the airborne campaign
over any other observations, like spaceborne observations,
is with airborne you can go wherever you want,
whenever you want.
You can have almost real time and designated campaign just
to observe a given phenomenon, like this one here,
which is a mangrove ecosystem.
What happens in these systems, which are driven by hydrology,
is that you have tidal impact that comes in and out
of these ecosystems twice a day.
It's extremely dynamic.
>> So you see where the roots are dark,
that's how high the tide goes.
>> And you can only monitor this kind of ecosystem
with airborne sensors.
The spaceborne sensors have repeat pass periods in the order
of weeks to months,
so the airborne campaign is optimum for that.
In particular, the UAVSAR, we are not only using it to try
to estimate forest canopy height
but we are also developing this new technique whereby we can
measure water level with repeat pass interferometry.
So we cover the same area during a full tidal cycle
as the water rises and retreats from the ecosystem,
and the UAVSAR can actually give you this sort of measurement.
We will be able to measure the relative change in height
of the water within the ecosystems.
And here we're setting up probes in these systems
that will be used in the validation of the data sets
and the measurement from the UAVSAR.
>> We use these data to get a feeling
for what the radar images, the final product,
is going to look like, and we also provide these images
to researchers on the ground so they can decide where to go
to do their field work.
This is a region that's very hard to do field work at,
so the researchers have to be smart about deciding a place
to establish their field plots.
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We want to map forest biomass globally,
and the ultimate goal is to tie that into the carbon cycles.
It's important to understand how that changes in space
and in time, because this will have consequences
for management and policy.
And in order to do that, we need to see what the biomass is
in different places of the world and how forests respond
to changes in climate and changes in management.
>> And now that we're, you know, very interested
in doing carbon accounting, we've also found
that mangroves store large amounts of carbon,
not only in the trees, and these trees here in Gabon are huge,
so they have a lot of carbon in their trunks and their
above ground biomass, but there's also a lot
of carbon that's stored in the soils here.
It's really, I think, important to be able to try to account
for that, so that we can continue protecting them
and just get a better understanding
of these ecosystems.
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