okay, good morning,
um i'm sorry for the technical issues
about
the live stream to the youtube. um if
anybody on the youtube channel, please
leave a message over there, said you
know, we cannot live stream
youtube today but uh thank you.  welcome
again to this world large river and the
delta system source to sink webinar
series.  so today we
invite Irina overeem
from university of colorado boulder to
give a talk about
the greenland sediment flux.  before
i introduce irina i would like to
mention
next week, our next webinar
so Wednesday and also next week Friday
next week, starting from next week to
December
we will have two talks per per week
so please mark your calendar so next
Wednesday we will have Jaap Nienhuis
from Utrechet university he will talk
about the global view of the
river data methodology and also from the
source to sink,  point of view.
and also next friday we have another
very
interesting talk from Uri Schatner from the university of haifa
israel
he will talk about the Nile river derived
sediment
from the source to sink the routing
system and all that way along shore
transport
along the eastern mediterranean sea
will be a very very interesting talk so
um please come back next wednesday
and next friday at the same time
okay um Irina
as you can see here, she graduated
from uh Wageningen university in netherlands
and also get a master from wageningen
and also phd 2002 from delft university
now is associate professor at the
university of boulder
uh university of colorado at the boulder
so
i believe it's just a 7 a.m for her so
thank you very much uh
willing to give us a very interesting
talk. so,  Irina
oh you can go ahead you can start to
share
thank you paul for like getting us all
together in this like source to sing
seminar series
um it it's been like such a pleasure to
see like how many people stepped up and
are like giving talks etc
i i'm not gonna make all of them but
um i hope to like cherry-pick a little
bit and like see a bunch of you guys's
newest and latest and greatest talks in
the future too
so what i'll be talking about today
um are these studies that we're doing in
greenland
and i mean in general like for those of
you who don't
know me i see some familiar names like i
know some people
know this um i work on river coastal
processes
deltas in uh specifically um
in general i ask the questions like how
do these
or how do like sedimentary systems get
perturbed how do they
change with environmental changes how
does that impact sediment fluxes
and morphology of the systems um
generally time scale of like post
glacial
is what is the longest that you'll like
hear about in this talk
um and then in greenland we also work on
the modern system quite a bit
and so in general when you're looking at
like a source to sink system
and you're trying to look at like do i
have a signal in my upstream basin and
do i find it back in my like downstream
far downstream sink um then it's good if
that signal in the upstream based on
it's large
right and so one of the places where
signals of change are large
at the moment is in the arctic regions
where climate change is just so much
more amplified compared to like global
climate change and so i've been
fascinated with thinking about arctic
systems and modern arctic systems
to see some of the questions that
sometimes we tackle in on a little bit
longer time skills as well
um this photo
is um sort of
um symbolic of like the high
sediment loads that um get transported
in these systems
but always seasons are very short
right so like yes there's like this
activity that is associated with like
the summer season and the few months
that there's really like large melt
going on etc
but also remind remind like everyone
that like the system is quiet
um for like a long term of the season
too
so i'll um start with like a little bit
longer time skill which is sort of post
Holence
or like holocene and post glacial
sedimentation rates that we studied
um earlier like that is a little bit
older work
um that i did with colleagues in delft
and um
a little bit with uh university of
colorado also
but then we uh moved to like more modern
sediment loads and
that part is what provoked the title of
this talk
modern sediment fluxes from greenland um
i'll also talk
about work that mata bendix is the lead
on she's a
postdoc in our group funded
from denmark uh and has been visiting
with us now back with the kovit
in denmark um and she works on the
deltaic and the they'll take systems and
the progradation rates on
deltas there and just a quick
peek for to like be informative to
people and sort of let
you know what goes on in the lab in
general like what are our next steps
what are the projects that we're working
on now
that we don't have like so much out in
the literature yet
modern greenland used to be a white spot
on the map for a long time
and um there's there's sort of two
papers that came out in the time that
i've been starting to think about
greenland and like the magnitudes of
modern
sediment fluxes from greenland that
made me thought even harder about this
problem and like
understand the relevance of this in like
a more global
climate story as well and so one is
uh came out of like woods hall uh where
this group uh of maya bhatia uh
sampled for iron and
showed that um there's a bioavailable
iron
that travels with suspended sediment
loads
um and casted this hypothesis that it
potentially would be
a um limited
nutrient that normally is limiting in
the ocean system and that would be now
newly supplied to the ocean system and
thus make like sort of an impact on like
phytoplankton balloons etc
and we'll see this later back in the
talk to you about
a similar timing there was this
paper um where people put together like
more source to sync studies of fjords
and sequestration in fjords and how much
carbon gets captured
when you like have all these deposits
coming out of glacial systems
um and with the idea that in general
these sediment fluxes are large these
fjords fill up
quickly but with that there's also
carbon storage
and to me that was like a little known
intuitive from like greenlandic fluxes
because we
mostly see like very low um
organic matter contents um but it
definitely was thought provoking for
like how do these systems
play out and so we set out um
thinking about magnitudes of modern
fluxes but then also some of the
um sink and trapping into the fjords
so just to give you a quick tour of the
sedimentary environment i think many
people are
um used to looking at like maybe big
asian deltas or like
huge tidal flats somewhere or whatever
um
so greenland has these very short source
to sink systems
like the source is at the ice cap
um where melt water drains
off the glacial system um and then
in general like the pathway of through
the terrestrial
is orders of like tens of kilometers or
so
um with some exceptions sometimes
there's big pro-glacial legs i won't
talk
much about those um today
but then the sediment gets through the
terrestrial system and comes into the
marine system and that's generally in
big fjord systems
and so there it's a little bit different
from um
huge shells because there's this trap of
the fjord systems in between
so you can see this river mount plume um
sort of going into like a um this is
near
illusion in western greenland going into
like the fjord system and sometimes it
has to travel
really far away before it's in the open
ocean or the bays around greenland
we started with a study that was like
really sedimentary geology
uh mapping the sedimentary infill of
one um terrestrial part you can see the
ice cap is like
indeed quite near the ocean downstream
or the fjord heads downstream fullness
is only like 10 kilometers downstream or
so from this point where we're standing
so you see the ice
and the ocean is like not quite inside
but close
um what i want to show you here is
the sediment style like so these are
braid planes they're the sedimentation
is coarse there's some aeolian activity
that like
leaves the aeolian deposits as well
often there's glacial lakes that have
formed
over time um and have been breached over
time so those are in the sort of
deposits that
have been all deposited after the um
declaration so these are only like 8 000
years or so of deposits
the finer grain sediments are
interesting
in that um they form these huge packages
and the marine sediments are actually
exposed and so we can do some
terrestrial field work
on the marine sediments because
of isostatic rebound that with
the unloading of the ice sheet melting
away after the
late glacial maximum the land started
popping back up
and so some of the marine deposits are
exposed
um and you can just walk these marine
terraces and make
um cross-section or like sections
sedimentary sections
and um we found marine shells in these
so we could like date
some of the sediments one of the
messages of this like
slide in general is like look at this
section
being about 15 meters 16 meters long
um so this would be a section that looks
like something like this but then
stacked on top on top on top of each
other um
you can see that there's like maybe
annual layering perhaps tidal but like
where you're thinking annual layering in
these
uh fine grained sediments sometimes we
see like small turbid
turbidites in them too um but in this
13 meter section we have these two c14
samples
and what it shows you is that there's
like very little time difference between
this
these two fine-grained samples
and one they're only like a few
a hundred years apart at best and so
like 13 meters of
sedimentation in maybe 300 years
so really rapid sedimentation rates
um the student this is work of a student
ilyada winter who is a phd student with
me and you storms in
delft um and he
used a glacial model that i had been
exposed to during my post-op before i
was in delft
or back in delft that is called
gc2d uh glacial code and then build in
an
um sediment entrainment model
and so what you see here is sort of a
concept model
of the model where like there's a cross
section there's a
glacier tongue that comes out here and
then there's like sediment at the base
that can be like
engrained into the um into the basal ice
um and so what he was after was trying
to figure out
like when does sediment get eroded when
does it get picked up
what is the timing of this release of
settlement into the fjord where we had
some
uh age control over the Holocene
and so uh in a planned view that looks
something like this this was like
a glacier toung that was sort of
representative of the
situation in this kangaloo swat shore
that we had data for
um and i'm just gonna show you one graph
uh or like a um time
in and time this is simulation time so
like this is like starting like at the
glaciation
and um running to the present
um and it's a distance from the
glacial front map and the ela
map so like this is a large cross
section of the
ice sheets and with ela being the
equilibrium elevation
so the area where there's ablation
versus
um accumulation on the glacier
and so this the color schema i should
have added the color scheme here
the blues are um
faster sedimentation
so deposition and then the reds are the
places where net erosion is taking place
and so over time you can see that
there's times when
deglaciation early on was at a fast rate
and the um actual like delta front like
or the glacial margin retreats fast but
at that time there has not been as much
erosion yet
and thus there's like less sediment in
stock in the glacier basal layers to
like get transported out to the system
and so some of these like depositional
um
peaks when um this segment really like
starts like being deposited at the
glacier margin
um and is able to being flushed out into
the like source to sync system as we
look at it
are relatively late in the deglaciation
cycle
so so this lagging of the system is
something that i've been interested in
and we're still working on like
getting the processes representative
better with a phd student
now at the university of colorado too
so there are some lessons that we
learned from these like holocene glacial
valley fields
that the sedimentation rates can be
extremely rapid
that the sedimentary architecture is
like really dependent on the timing of
the glaciation
and when a certain short at a certain
latitude
um starts deglaciating um
and that the glacial sediment pulse the
time that there's as
like maybe peak production of sediment
or peak availability of sediment
um in
to like ingest it into the source to
sink system
might lag the sort of melt water uh
declaration
peak and these are like hypothetical
because that's model behavior that we're
looking at and there's
some indication in the congolese work
sure that that holds up
but the dating is also sparse enough
that
you could argue a little bit different
ways too
so that made me even more fascinated
with like also thinking about the modern
um sediment loads and uh
taking um observations on like
a more like day-to-day year-to-year time
scale
um what's interesting is that that
has not been systematically done um
for a long time like sort of the pioneer
of that
is um professor household at the
university of copenhagen
and he um monitored this one river
um that we did the holocene sedimentary
architecture work on um so that's how i
could
connect it to that community and what i
wanted to point out to you
here is that so greenland is a really
important component
the melt water of greenland is a really
important component to like
global sea level rise at the moment and
we model this and people or we
um as a community um scientists model
this
and you can see that there's this like
big like ramp up of
um runoff and melt of greenland and even
this week that was in the news right
that
if you would add the data point for like
2019 and 2020 there would still
like again be like high up here um but
interestingly the river observations are
like actually like really
pretty short duration and not very
systematic on on this one river system
they're like
now a record that's a little longer than
10 years but that's it
um so our group built another
gauging station on a river system a
little bit further south
and then there's another um more
long-term
um gauging station on the on the east
coast that
copenhagen maintains too
so river river observations
at first cut like we want to know just
volumes of water that's the
the relevant question for sea level rise
but i got interested also in this like
high
turbidity that these river systems have
and how much
export is there of sediments to
um did we know that before well
people had been doing back of the
envelope um
reconstructions but still john millerman
and katie fransworth
in 2011 like state that like as far as
we know
which is a big sign no global sediment
budget has taken into account the impact
of glacial
erosion in high latitude land masses and
particularly greenland so that's
sort of an endorsement that they want to
see some more research there
and so that then leads to questions like
what is the total magnitude
how is it distributed around greenland
is relevant more for ocean
and oceanic processes um and
what are the processes that control that
magnitude and distribution
so we had we've had like field campaigns
on and off since 2007 uh i'll show you
a bunch of work that i did with ben
hudson um
this was in the kangaroo fjord in the
pacquico river and then in that nyu at
quad river that i just showed the
gauging station off
um in general these were short campaigns
where we um collected
water samples um for kangaroos work
there's an automatic suction pump so
that's the most continuous record over a
season
and then for the others we build like
stage to discharge relationships to like
have an idea of what kind of discharges
and loads come out of these
um there's some like small boat
oceanography that we did
that helped us constrain plume dynamics
as well and grain size measurements
cool so when you
hear me talk about this one river system
the the watson river in kangaluswak
um from the get-go we knew that we
needed to upskill to like something like
a satellite coverage um if we wanted to
say something about the sediment flux of
greenland as a
bigger system and so ben hudson was like
a key player in that he was a phd
student with me
um at the time and he
um started mapping both water coverage
from landsat automatically and it's
these automatic
algorithms in google earth engine that
we take advantage of the fact that
they've organized the whole stacks of
landsat landsat data
and provided this idea that
if we know for each pixel in each
landsat image that is cloud-free
whether it was water or not water we can
then look in the reflectance of the
the visible bands um whether there's
sediment in the water or there's no
sediment
and so what i'm showing you here is like
we calibrated of course first
whether that could be done or not and so
in the watson river where there is the
most data we
like um constructed a retrieval
algorithm
for suspended sediment concentration
so that is what i show here um
it relates uh band 4 reflectance so this
comes out of the landsat products
and is a measure of like how turbid the
water is
and so you can see if you like tie every
single pixel
to like an actual bottle sample what
that relationship
pans out to
there's hundreds and hundreds more about
bottle samples
but you needed this like golden thing
where like the pass of the landsat
is the day of the bottle sample or
the four hours around the bottle sample
is how ben
defined the window that he thought was
acceptable
so then you're like suddenly down to
like a really small data set
um and so then what we started doing is
like we realized the data
that we had was still like relatively
sparse um
that is because the season is short that
is because the
cloud cover is pretty um abundant
or frequent and so um
ben and i decided that we would make
maps
of um average suspend
concentration in these river systems so
the way that works is like you start
stacking and mapping suspended sediment
concentration
from like every single image and that's
what i'm showing you here
and this would be like suspended
sediment concentration in the cells
where there's water
what is the turbidity for each of them
and then what if you like
contrast two different images and you
look at what the segment concentrations
are and so like this systematically got
done
by stacking all the imagery that's cloud
free and available
to be used over the landsat 7 record so
it's about 10 years of data or
um and then what i wanted to point out
with this example is these
this is like one big river system it's
west greenland
um one would expect that the
glacier lobe in the north versus the
glacial lobe in the south have
probably exactly the same climatology
with like small differences maybe in
snow and wind patterns
but these are not like high relief
areas so much when you're like at the
level of the ice cap
they're like pretty gentle um sloping
ice caps or outlets of the ice sheet
so if you think that the the climatology
is very similar you
think like melt water pulses may be
similar too or maybe this is even the
bigger system and you would like expect
that there's
like also bigger loads coming out of
this northern arm and that's not the
case
so something else there is still up
so like you could not predict suspended
concentration by just saying like oh the
like warm areas of greenland are doing
this the cold areas of greenland are
doing that
so um if you systematically go through
the whole
um landsat archive you can
um map about 160
land terminating glaciers that have a
river stretch
over which you can apply this technique
and you generate something like this map
over here
where um the color of the
dots is an indication of like how turbos
that river system as an average over 10
years
in the melt season is and so you see
that variability that i was just showing
you for one system like somewhere over
here
um is compare compared to like
some of the regional patterns still hold
up the warmer areas
definitely have like higher sediment
concentrations than the real cold areas
um the other thing that i wanted to
point out too that was really
interesting to us is that there's these
hot spots
in um turbidity and so
if you plot this as a frequency diagram
then you can see that
about like maybe 10 of the rivers
only have rivers have like
concentrations that are systematically
overseas and like
really really high and then there's a
lot of rivers that are like
much more quiescent in parts of the
season
um so we started tinkering with
explanatory regression models and
sort of the simple process model that
i casted for this is an erosion
potential model this is used quite a bit
in that glacial geomorphology
um where you just pose that the erosion
of a glacier
is dependent on the driving shear stress
the gravitational driving shear stress
and the sliding rates
of the ice so the sliding rate of the
glacier
it turns that you can say something
about the sliding rate at the base
um by a relationship to like
what's the sliding rate at the surface
or the velocity that people track
from glaciers um if you also know the
um the mass of the ice moving through so
like the density of ice the
gravitational constant the thickness and
the slope and so
this is a very first order uh kind of
model but
it's been shown that at first order that
it can work
so the good thing about this is that
we're doing this in a time that
satellite data sets and the work that's
been done on the glacier
on the green ice sheet like provides
every single one of these elements
so i collaborated or we collaborated
with materia mourigam
and then with etoile moon and ian yorkin
to like use
both the velocity so that surface
velocity that i pointed out in that
previous little equation
um as well as ice thickness from the bad
map that had been like matched from
airborne radar
and so what you then can do and then did
this
um is for each sort of glacial
hydrological catchment
calculate the mean erosion project mean
erosion proxy
um we did this only over the melt
affected area so we don't like
extend the catchments like way up to the
ice divide um because we assume that
like such a large part of these
catchments are um inactive and
um are not sliding so like we wanted to
make our sliding proxy or our erosion
proxy relevant for the part that's
really active
so that is what i plot here so this is
the erosion
potential for each of these catchments
compared to their long-term
turbidity or like plotters versus the
long-term turbidity
so any single data point on this has
like
the uh glacier ice glaciological
catchment behind it and then
mapped this erosion potential for that
specific catchment and that's what this
relationship is showing you
and so it's a scattered plot
but it is a positive and significant
correlation between those two factors
so what we concluded is that the
turbidity of these river systems is
maybe more controlled by like the ice
processes and the sort of the sliding
rates etc
um as opposed to just the water
um the water
melt water discharge
um if you do the same plot for a melt
water discharge from mottled melt water
per
catchment you'll still find the positive
correlation too but it's quite a bit
less than this
correlation with ice processes
um most people ask me is there also a
lithology effect so i like threw this
slide in
um to say like we tried uh we thought we
would
back it out and i think the obvious
understanding of like how this works in
geomorphology is like there should be an
impact of lithology
i think the part where we get the effect
not uh being apparent is that there's
not that much
like really friable rock in greenland
there's only small patches
and so um our data does not
resolve differences in mythology well
enough if we
map it back to like schmidt hammer
erodability etc
another maybe complicating factor is we
don't know precisely what's happening
under the ice
right there's sort of a general like
this is the province we know these are
nice again granitic but we don't maybe
know like how
fractured those beds are or not
fractured the beds are
um so um i
wanted to hone in a little bit into
these like hot spots into the sediment
transfer and i know paul is interested
in this
fjord cermelik fjord this is like one of
the biggest producers
um it's just south of the capital um
in west greenland and i think it's a
really good case
uh for like looking at these processes
better and looking at the whole source
to sink system
um what i show you here
is the bad map in a color scheme
and um
in the uh sub-glacial topography there's
these huge troughs
like sort of they're basically fjords
that extend way under the ice too
and so some of these troughs are
associated with the big sediment
producers too
you can see that over here you can see
that over here and you can see that over
here
and so just um
the inherited topography over many
glacial cycles
probably controls some of these like hot
spots in
sediment production at the like really
modern time scale as well
um this is hypothetical um it comes out
of our
erosion relationship too because you
like that's a nice discharge that you're
calculating
and thus you would get high ice
discharges if there's really big troughs
but it is not something that we know
what's going on
under these like big troughs under the
ice sheet
so the burning question then was like
how does this
how do these like suspended sediment
concentrations like tell us something
about like the whole total load well
as you guys probably are relatively
familiar with
it's like you can just do a fairly
simple multiplication by
assuming that you have a turbidity um we
pulled the melt water discharges
in collaboration with utrecht university
from the rakmo model this is a
mass balance ice sheet model and so that
gave us per
glacial catchment um what was the annual
total discharge for these systems
so total melt water discharge so that's
like it's a
regional climate mo original weather
model that drives it but then there's a
mass balance model that's
highly or reasonably phys physics based
um that sets this term of discharge
so this is like our long-term
turbidities and that's
like modeled not whatever
so if you then do the math on that and
organize greenhouse by the different
bays in which the rivers
um drain to you can kind of see like how
that's distributed it's like the
southernmost bays are the ones that get
most of the sediments
um drained into into their fjords
um and then into the arctic ocean and
like really northern parts of
uh east greenland it's very modest but
what i wanted to like pull your
attention to is this like total
suspended load
and put that in the context of like um
global sediment loads as reconstructed
by like
jaia syvitski and albert kettner and
we sort of felt that we were on to like
an element that hadn't been mapped so
there's
a new sediment flux that hadn't been
quantified before that's
at with a large error bar
but at the scale of like about seven
percent
seven to nine percent of the global
total sediment loads as
river drain into the ocean so quite
significant
and greenland i think is only like one
percent of the land mass
so just to give you an idea of how
inflated that contribution of this
mini continent is
um lessons learned um
is is this something that's of global
relevance
um yes it is a significant contributor
to global sediment flux
we learned quite a bit on like
non-uniform distribution of these
sediment fluxes
that it can depend on glacial processes
at least at like at a proxy level
um and possibly on like better
topography over multiple
glaciations and so there's quite a bit
of process
suggestions that are worth chasing
further and
um ethan pierce is interested in doing
some of that
another uh sort of spin-off of this is
how much
bioavailable iron comes with all this
sediment flux and so
one indicator and sort of suggestion
that there
may be something to that hypothesis that
was casted initially by uh
my uh my uh about here
is that summer blooms in western
greenland and i'm showing you that here
have actually increased over having
increased net productivity and so um
that really big hot spot is like right
in this area
too like so there's a lot of sediment
that goes in there fairly directly
without a huge
buffer over a short so that's
interesting too
the mechanism and nutrient
concentrations still are in a march
debate and that's more of a like
i would need to collaborate with people
who
do the oceanography side of that to get
anywhere
um i wanted to switch it a bit to local
implications and tell you about delta
propagation
so meta bendix and um
for her phd out of copenhagen um
was one of the students who got involved
in using a rare air photo archive
and applied that to
100 i think
oh 121 deltas
um to show progradation of
delta x system so she has like old
aerial photos she has
the earliest satellite imagery and then
a more dense sediment
or satellite record for like the later
parts of like the
90s into the 2000s up to now
this archive is really stunning um
it was one of the first places where
like really aerial photography got used
to like systematically map
um coastlines and glacial outlets etc
um this was started in the 1930s they
flew this with an open plane you can
kind of see the pilot like sitting
there and then there's like two people
who manage the camera that's like in the
bottom here
and like takes photos down and so um
the other part of this um
oh yeah and it must have been like
really cold even if they're flying this
in the summer so like they were wearing
like
polar bear pants um
the other part that was interesting
about these archives is
they got archived in these bunkers in
denmark and
basically disappeared out of like
scientist attention for a long time and
they were
rediscovered by like the museum of
copenhagen in the 2000s instead of
a bunch of these comparison studies and
meta was
one of the students who worked on that
so what she did is she classified delta
x systems in
two types one were like the ones that
were in
constrained in the fjord head the other
ones were the ones that were more open
and wave
potentially wave dominated or wave
impacted
and then systematically mapped through
time in three time
slots like how these deltaex systems
prograded or
how the coastline prograded on these
um delta area is on the
y-axis here and time is on the um
x-axis and then this is like the
statistical shape of
the wave or wave uh dominated
deltas on the left there and then more
restricted deltas
on the right there so like the ones that
are constrained really at the short head
of the narrow
place and so what
she is showing or what we were showing
together is that
if you step systematically from the
1940s to the 1980s to the 2000s
late 2000s um you
can see that there's like progradation
in these systems like they
systematically gain in
delta exposed authentic area and it's a
little bit more pronounced in the
restricted deltas than it's in the open
deltas but both
show this pattern
to put that in map view um there was
already progradation from the 1940s to
the 1980s these are like the glaciating
systems they always get sediment
um and are active and so they were doing
this
early on but then there's quite a jump
um in progradation rates when you like
look at this later period
um over time and in a way i thought this
was really interesting because it's sort
of an independent validation of these
models that do the physics of the mass
balance of the glacier
systems that melt water correlates
delta progradation rates um
is that counterintuitive with these
suspended sediment concentration stories
that were
that i was just telling you where the
melt water was not the dominant control
i don't think so i think they are
consistent in the sense that the
delta progradation is much more bedload
driven which is
directly related to like melt water
discharge
cool um mette
um came to this idea of like wow um
if there's that much sediment being
produced maybe that's a sustainable
source of
um sand for greenland
um to be an exporter of
of sand and so she dug um quite a bit
deeper into this in her postdoc that she
did that
in our group or has been working on this
um and even in a more
like much bigger global context now um
and is showing that while greenland is
one of the places where they're not
shorter in sand and where
um at least the government can think
about like
mining sand as a um construction
material
which is not true in most large delta
systems
i'll show you a tiny little bit um
i was like not having time when i'm in
presenter mode
um i'll show you a tiny little bit on
like what's up in our group
uh for like sort of next questions or
questions that are still lingering
because we haven't resolved them
um we're still working on glacial
sediment this is a project with
phd student ethan pierce um
brandi carlson wrote a nsf postdoc
fellowship project and got awarded that
and she will be working on delta front
dynamics and i'll show you a
tiny little bit about that and then the
last thing that's been really
interesting collaboration
and we have a paper in grl that's about
to come out that i'm advertising here
is collaborative work with sasha
lightman and us
um who look at sediment that actually is
generated on the ice sheet and like how
much
is that and does that have an effect
on albedo of the ice sheet it's a small
component in the source to sync system
but
it's a really interesting uh complex
component
so ethan and i look at um
how much sediment is transported as ice
rafter debris
and so this was a sort of a gap in the
budget that we
casted or that i showed you about
because
anything that i was talking about was
derived from glacial melt water and
transported with glacial melt water
and none of the sediment that is being
entrained in the glacier and then calves
off
into the fjords was captured in that
budget there so that's really a
component of the budget that's still
an open estimate as well and you can do
like some back of the envelope
calculations based on like old
um concentrations that have been
measured in these like very
um or sediment rich basal
layers and um compare that with like
thicknesses of the total packages of ice
and since um satellite data of ice
calving are also really well constrained
now this comes out of ellen enderlin's
team etc
um we can have some idea of like what
kind of
amount of sediment comes out of these
systems
um if i do that math um
the basal ice kelvin flux is actually
even bigger than the river melt water
flux
and so this is really not well
constrained at all
but it is like intriguing and i think
this is worth
um pursuing more and that's what ethan
and i are doing right now
and so one strategy of that is that
we're sampling
um from icebergs at different locations
around
around greenland we did like a campaign
in west greenland
last year bent household who's a
previous collaborator
has been sampling on east greenland and
so we're starting to get like better
uh very variable um little data sets to
constrain even like the back of the
envelope
estimates better for greenland itself
so this is kind of what that looks like
um tom marquito who's here at colorado
is involved in this too and so he will
be
helping with iron concentrations in this
too so that not just can we say
something about
um total amounts of sediment and grain
sizes which comes out of these like
samples but we can also
run them in like mass back way and
get some bio available iron
brandy um works on the following prior
problem um this
is that kangaroo swap delta that i
started the presentation with uh
where there's quite a bit of monitoring
so there's it's a good site
and it was a time lapse camera that was
running on the delta front
we initially thought we would get like
really good plume imagery and
say something about sediment
concentrations that turned out not to be
true
but there is this striking collapse of
the delta front that happens
somewhere now
ish maybe a little bit later bam
there i was so i'll
show you that collapse um
so um here there's this huge scallop
that like
fills along the delta front and
it's a very significant part of the mass
and so what brandy is asking is like how
significant are these
and how when do these happen how
often do they happen um is there carbon
like sequestration that happens with
this and so she will be working on that
in the
next one and half years or two years
from spring onwards
that's it for today i know i'm a little
over time
um i wanted to thank this this has been
a large team effort and
many people came into the field and have
been working on like developing this
algorithms and the data sets etc and
also quite a bit of like logistics
supports that comes out of
different groups in greenland as well as
through the
national science foundation so most of
this work is science foundation work
um the uh greenland icebergs work is
actually an innovative seed grant from
the university of colorado so i'm
grateful that we get to do that work in
a in a bit different way too
so thank you
thank you Irina for such a wonderful
talk
and for all the audience if you have
any question if you want to ask directly
you can click the participants that
button at the bottom of your zoom
and then raise your hand then you can
unmute yourself good directly
so we here we have a couple questions
uh in the chat chat room
so Irina could you also read the chat
yeah um bin bin the first one
so uh
piedmont yeah you're asking about the
atmosphere correction model for landsat
7 to get the reflection
um
um i mean i would have to look up the
procedure to see it's like one of the
mod 09
products i mean we did um
like um do
some raw data processing too because the
turbidity and cloud cover are like
difficult when you have a
really high turbidity then sometimes
that gets picked up as cloud cover
so not all the correction models uh um
and cloud cover models are really good
so you can't like pull off the shelf
um like the sort of like half finished
products
um but like
i would have to refer you to the paper
to show like the real procedure of like
which ones we were
going through um the next question
from best from jim jim asks whether
like did we use ssc for different river
systems
there are like different different
samples in there so they
they and they fell in the same scatter
um so we felt
i mean maybe confidence is a big word
but we felt
okay with the data not falling off a
chart
very for the three different river
systems that we looked at and they were
um they're all in either nice or
granitic nice terrain but like
definitely in nuke the lithology is a
little bit different from like the
northern more
northern systems we don't have good
ssc samples from some of the basaltic
lithologies
and so there we're extrapolating um in
the different ones as well so
um
and so jim also asks are these
minimum estimates since we hire ssc near
their bed and that's a definite yes
um we use the um yeah
basically we need we definitely need
more research
so i have a question before i you know i
asked you the question from the
yak so because the most of the melting
water from the glacial is kind of
episodic
so it's any sense
based on your observation is possible
over there somehow
hypercynal flow in the fjord from that
turbine water yes um
yeah there are there's definitely a
hypepycnal new events that happen
like that hot spots um fjord
there we know there's the hyperpigment
events there
on the kangaluswap fjord that analysis
was or like we did a little bit more of
a careful analysis because we've
recognized that we would be totally
underestimating
um the total suspended sediment
concentration if you like ignore
everything that dives deep right
um and um
at the concentrations that kangaroo
river has
um the component of hyperpycnal flows
is
in the order of like maybe or like that
is at the threshold of
like going hyperpigmental um is maybe
order of like nine
eight to nine percent and so
yeah that's another way how we're
underestimating
by just looking at ssc in the river uh
from the satellite um
but it wasn't as big of a component as
we
uh expected earlier on the other thing
is we know these are happening because
they're
um visible in some of the multi-beam or
the seismics you can see like
small like um like turbidites levees
channels going down the delta
delta fronts and other slopes so where
um
brandy is interested in these and
collecting observations on these two
sure we need a product proposal
yeah so uh
do you have time to like look at the
apps question real quick
question yup's questions so
one question do you expect any feedback
between segment export and ice melt
perhaps through the effect of sediment
deposition on fluid
circulation um
i think in the river systems
maybe not as much but there is
quite a bit of uh research and um
talk in the glaciological community
right now on the tidewater glacier so
the ones that have like a calving front
and the stability of the kelvin front is
really dependent on the local bathymetry
and i think there's a huge sediment
story there where like if you have all
these upwelling plumes like right there
at the
delta front is there enough sediment to
like anchor that
kelvin front in place or not and so
people like
ginny catania and john jager are
interested in this problem
um doug um
i'm blanking on his last name
brinkerhoff
and so there is a feedback there that is
being recognized and
is sort of an unknown in the tidewater
glacier dynamics
and responses so that's a good question
very good so uh we have Uri schatnar
from university of
haifa uh he had two questions so irina
can read the question
the difference in discharge seem to be
affected by civil eyes morphology
do you have a super eyes model for the
morphology
and the second custom placement and the
high resolution seismic
in the food will be very definitely i
agree
so we try to import that proposal if
anybody interesting we definitely need
to form a team
i want to bring my chip over there i
think
paul wants to bring his chirp yeah
that's the only tool i have
so uri thank you for that question um
the
sub ice morphology comes out of uh
the radar that has been flown over
greenland really systematically and
they've been
doing this because the thickness of the
ice is of course like really important
for a mass balance
so um so the sub ice
model for morphology or like the the bad
uh resolution is um
at least like at a proxy level
sufficient and we use the actual like
bad morphology to like set the
thicknesses of the eye so it is
incorporated in those graphs and in
these results
um the people who process the radar will
also tell you that that some of the
outlets it becomes hard to do the
processing quite right and they use
um like a continuity equation between
the masses that are moving through
to like resolve and invert some of the
the topography there so there's short
shortcuts or like maybe a long cut that
is made there too
um so maybe not perfect but it is
incorporated
and the dongfeng Li guess don from from
singapore right
so he asked said do you have
any idea how much how the sediment
fluxes
from greenland involved since the lgm
so is any continued change you mean in
the near future
um yeah there's there's and there's even
like a
couple of like really good papers that
came out that's
that take that to like an even much
larger time scale uh that came out of i
remember like mats houston was on this
um and they came out of copenhagen to
paul
like a uk um danish
um combination where they looked even at
over
several the glacial cycles like what
were like the big patterns in the
seismics and like what were the big
volume reconstructions of the seismics
uh for this area so there is some
control on like
how this evolves over like glacial
de-glacial dictation of the glacial
cycles
that came out of greenland like fairly
recently from like seismic data
um will they continue to change in the
near future with global warming i think
just from our results if there's speed
ups of these glaciers we would
get see more sediment coming out too
because it's like a
there's a sliding an increase in sliding
then
thanks gil it's nice to see people here
even if i don't really see them
that's great thank you Irina so if you
knew
any other question once again as
i mentioned in the beginning next week
starting from next week
we will have two webinars per week
so wednesday uh for wednesday
uh you have Jaap Nienhuis from the university talk about global
view of the
delta morphology and next friday uh
Uri from you know haifa talk about
the Nile river drum sediment
and very interesting talk please
do come back and
if no any other question i think
maybe we can
we can stop here
so thank you for organizing paul welcome
thank you very much for
wonderful talk so we will put every
together i'm sorry today
um that i don't know is the zoom com
problem or youtuber problem you know we
cannot be under the link
from the zoom to the youtube we cannot
live stream but
we recorded your presentation we were
uploaded to the youtube
and so we will figure out so
and so thank you very much i see you see
you
see you guys next week okay
bye bye
