good evening everybody. So one of the things we do at NASA and Earth science
using the unique vantage point of space is explore and that exploration leads to
discoveries and those discoveries lead to research to understand and protect
our home planet for societal benefit, okay, now we can explore the Earth
spatially in this case the combined land and ocean biosphere together and that's
basically looking at Earth's primary producers and what's really interesting
is that in just a single global composite we can actually see all of
this dimension in the ocean biosphere in the terrestrial biosphere, next slide
actually using a series of images or information allows us to not only
explore in the spatial dimension but in time and we can use this information to
identify long-term trends now this is kind of unprecedented so what you're
looking at is the combined global land and ocean biosphere and it's like
watching the Earth breathe in Earth's primary producers now missions like
Terra and sensors like MODIS are celebrating a 20-year anniversary or a
20 year time series and what that does is opens the door into looking at
decadal changes in our earth system so that's truly unique, now traditionally
what we use is passive ocean color radiometry which is what you're seeing
here to actually look at the ocean biosphere and this is only one piece of
the puzzle what passive ocean color has done is absolutely revolutionize our
understanding of the ocean ecology and Earth's carbon cycle in general, but if
we really want to open new doors then we have to push the boundaries
scientifically and in engineering and actually use some new scientific
approaches and looking at things like our ocean biosphere and so one of the
limitations I think of ocean color remote sensing is
that our scientists actually think it's incredibly valuable and critical for
studying climate variability and change however
it has to be used during the daytime it can't be used at low solar elevation
angles and it has to be used in a cloud free environment now what you can lump
on top of that is actually it has some depth integrated challenges it can only
see you the first optical depth in the ocean and in addition it's got some
challenges when you have heavy aerosol loading however there are technologies
that we can use when coupled with passive ocean color remote sensing
absolutely revolutionize our view of the ocean, next slide,
LIDAR is one of them okay that stands for Light Detection and Ranging and in
2006 NASA and CNES together launched the mission known as Calypso as
a Cloud-Aerosol LIDAR and the main sensor onboard it of it CALIOP has
orthogonal polarization and so this has been Calypso has a, sorry it's supposed
to be the Calypso animation, sorry you guys, just back up one so what you're
actually, so Calypso has been reliably providing global views of our earth for
over 13 years now what's absolutely revolutionary about it is that it can
penetrate up to three optical depths in the ocean okay so where is passive ocean
color can only go the first optical depth
however LIDAR data such as that from CALIOP can only see a limited spatial
resolution has about a 16 day revisit where as passive ocean color remote
sensing can cover the earth in about two days taken together however they provide
unprecedented scientific benefit for looking at things like dynamics in
Earth's biosphere specifically in the ocean, so we're going to talk about that
in just a minute I just want to also point out that studies of LIDAR have
used have been used on both ships and on aircraft and what they do is they use
unique properties like the backscatter coefficient the vertical attenuation
coefficient to look at things like phytoplankton properties, zooplankton and
even fish stocks and this is important, very important properties of the ocean
when we're talking about commercial viability in economics, so the other
thing about LIDAR is that is not limited by some of the things
that limit ocean color remote sensing you can use it day or night it can deal
with considerably heavy aerosol loads as well as thin clouds you don't have to
worry about low solar elevation angles which I'm going to show you in a minute
and as I said it can penetrate up to three optical depths, so this can be
absolutely revolutionary and looking at our ocean now remember I'm going to show
you CALIOP data in just a minute and
remember that was not created to look at the ocean it is an aerosol based sensor
okay but it can give us unprecedented views of our ocean system, next slide, so
in 2013 what we did is we had the first global view of plankton in the ocean not
phytoplankton not primary producers but actually secondary producers from a
space-based LIDAR and we took this unprecedented information and we
estimated phytoplankton carbon and particulate organic carbon at least to
ocean carbon properties together were derived directly from the calliope base
back scattering by particles now remember this was just a
proof-of-concept study, right this system was not created to produce anything in
the ocean and yet here we are and so what we, what we know from moving forward
is that we can see into the ocean and tell something about Earth's biosphere
now that's not where it stops, next slide, so I already mentioned that the sensor
can function or we can get data in the ocean at low solar elevation angles and
basically what that means is that about 81 degrees north and south we can
actually collect data where is on the left hand side you see MODIS which is
passive rate radiometry and what you're seeing is that we don't have a lot of
coverage whereas CALIOP on the right hand side
actually does so what this study was able to do this was part of the the
NAMES project the North Atlantic Aerosol and Marine Ecosystem Study they actually
looked at CALIOP data at high latitude and used a combination of the vertical
attenuation coefficient and the back scattering by particles to detail what
was going on ecologically in the
shit what they were able to determine looking specifically at predator-prey
interactions was that in the Northern Hemisphere basically at the northern
polar, subpolar waters the ecosystem dynamics were driving what was happening
in the phytoplankton and in the plankton in the ocean whereas in the Southern
Hemisphere it was actually the ocean ice dynamics that were driving what was
happening in the predator-prey interactions and this was unprecedented
and impossible without using the LIDAR in the ocean, so let's take things just a
little bit further, next slide, now the other thing that the NAMES team did
going out specifically looking at a number of objectives, one of them was
what's driving phytoplankton blooms in the ocean and you might be saying why
should I care, well as primary producers they're consumed by secondary producers
and fish and if you know anything about fisheries just taking that one economic
aspect of the ocean it's more than a trillion dollar economy worldwide okay
so they did a transect in ships and with an aircraft flying overhead with a LIDAR
going from about 35 degrees north and straight northward although this is I
think they had some Wiggles in there but what I want you to notice is that they
were able to detail oligotrophic waters which means they're almost devoid of
nutrients are very low nutrients which are makes it very difficult to support
phytoplankton and plankton in general they went straight through a
phytoplankton bloom which you're actually seeing in the vertical
attenuation coefficient so this is the LIDAR showing this and then they went
into Mesa trophic conditions where they have low productivity but some going on
now let's zoom in on this a little bit, next slide, and take a look at the eddy
that they went through so if you look at the top panel first you're looking at
the back scattering by particles derived from the CALIOP sensor okay and what
you're seeing as you travel across is the evidence of the eddy right here of
the physics driving the biology now how do we know the physics are driving the
biology most physical oceanographers will tell you everybody knows that but
we're going to actually detail this with a LIDAR remember you're looking
at the back scattering by particle data from a LIDAR not actually any ocean
physics measurements if you look now on the bottom panel and what the team knew
actually first on the top is that some dynamics were going on in that Eddy and
they knew this because on the ship they had a flow-through system that told them
they had a high concentration of phytoplankton in that area so what they
did is they decide to look at the depolarization ratio relative to the
back scattering by particles and what that does is it tells you something
about cell size and what's actually in the in the water and this was confirmed
with instruments on the ship but when they pass through the Eddy what you can
see is a very strong signal here and this depolarization to backscattering
ratio actually enabled them to detail, confirmed by the ship based measurements
that they had different groups of phytoplankton there that becomes very
important when you talk about biodiversity in the ocean and let this
sink in a minute people because this is kind of mind-blowing we're using a LIDAR
that was not created to look in the ocean to actually detail community
structure which is not even something we can do for passive ocean color yet okay
so let's go further, next slide, okay so this is sort of the
like ultimate punch line what you're seeing here is the largest animal
migration on the face of the planet and it happens every day, okay, so we are
looking at what's called dial migration zooplankton are secondary producers
people have heard of phytoplankton these are actually zooplankton and what they
do is they might greet every single day approximately 200 meters to the surface
to feed on phytoplankton, phytoplankton are primary producers they go up to the
surface they need sunlight to actually go through photosynthesis they take up
carbon dioxide zooplankton consume them and they excrete whatever they
excrete and that carbon goes to the deep ocean a lot of it permanently so what
you're seeing is a conveyor belt of carbon, now what this actually is is the
global climate illogical signal of vertically migrating animals in a
normalized differential ratio, now does that mean basically there are
day/night differences in back scattering by particles and this tells us something
about vertically migrating animals in the ocean, okay so you're seeing that
conveyor belt of carbon and where the zooplankton tend to go is in clear
waters, okay, that's because there are less visual
predators there this is a little bit counter to intuitive because you could
think they would be found in highly productive waters where there are a lot
of phytoplankton that they can eat so ecologically what you're seeing actually
makes sense, okay, and if you look between the two yellow lines that's basically
the permanently stratified ocean, so where we're seeing the high signal for
the phyto, for the zooplankton and and the lower signal actually corresponds
significantly to what we would expect ecologically so last slide that's kind
of mind-blowing people, that we can't do that with ships but we can do it with a
LIDAR so the future of LIDAR where is it going
we have never built a LIDAR for the ocean no one has and clearly what this
tells us is this with the minor modification to future LIDAR that are
being planned for the atmosphere or not we could actually detail the profiles of
ocean particles in the ocean and what these figures have actually shown is
that we've got the first ever view of vertically migrating zooplankton on a
global scale which is unprecedented thank you