Ocean, ice and atmosphere in the changing Arctic

Ocean, ice and atmosphere in the changing Arctic

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- [Announcer] This conference will now be recorded. - [Heather Tabisola] Good morning, everybody, and welcome to another, and the last of the season's, EcoFOCI seminar series. I am Heather Tabisola, and I co-lead this seminar series with Jens Nielsen. This seminar is part of NOAA's EcoFOCI bi-annual seminar series that is focused on the ecosystems of the North Pacific Ocean, Bering Sea, and U.S. Arctic, to improve understanding of ecosystem dynamics and applications of that understanding to the management of living marine resources.

Since 1986, the seminar has provided an opportunity for research scientists and practitioners to meet, present and provoke conversation on subjects pertaining to fisheries, oceanography, or regional issues in Alaska's marine ecosystems. And you can visit the EcoFOCI webpage for more information at www.ecofoci.noaa.gov. So again, I thank you for joining us this morning as we continue this all virtual seminar series. As I said, this is the last of our spring series.

The fall is yet to be announced. In just a couple of weeks, most of our spring seminars will be posted on the PMEL YouTube page, so you can catch them there if you missed any this season. Please double-check again that your microphones are muted, that you were not on video, unless you're the speaker.

And then during the talk please feel free to type your questions into the chat. Jens and I will both be monitoring that and we will address questions at the end of Craig's talk. So today I am really excited to introduce Dr. Craig Lee. He is a Senior Principal Oceanographer at the University of Washington Applied Physics Lab here in Seattle.

Today, he's gonna share with us an overview of recent science results in technological developments stemming from a sequence of Office of Naval Research supported efforts, focused on changes in atmosphere ice ocean dynamics in the Beaufort Sea. Craig is a Senior Principal Oceanographer who leads a team of scientists and technologists that pursue a wide range of oceanographic field programs, including intensive studies on Kuroshio Current, coupled physical biogeochemical studies, and studies aimed at quantifying and understanding Arctic change. An important component of this work involves identifying advances that could be achieved through novel measurements and then- [audio clipping] And then developing... [man talking indistinctly] Hi, could you mute your microphone for those that just joined please? So an important component of Craig's work involves identifying advances that could be achieved through novel measurements and then developing new instruments to meet those needs.

His team's accomplishments include the manufacturer of autonomous gliders capable of extended operation in ice covered waters, including the international collaborative effort that set a new record in the survey that they did off the Antarctic ice shelf in 2018, high performance tow vehicles, and lightweight inexpensive mooring technologies. And his primary scientific interests include upper ocean dynamics, especially mesoscale and sub-mesoscale fronts and eddies, interactions between biology, biogeochemistry, and ocean physics, and also high latitude oceanography. And with that, I'm goinna let Craig take it away. - [Craig Lee] Great. Thank you, Heather. And good morning, everybody.

Thanks for having me here today. What I'd like to do is give you a fairly broad overview of our range of science programs that have been supported by the Office of Naval Research and through the Arctic and global protection program and things that I've had the good fortune to be able to participate in. They do come together to paint a whole so hopefully you'll see a common thread through these. As always for something of this scope, it's the work of many, many people. In particular, the Marginal Ice Zone, Sea States, Stratified Ocean Dynamics or SODA team, and Arctic Mobile Observing System Teams.

And I'll show you the long list of people but bear in mind, this is really the work of dozens of people that you're about to see. So moving forward here. I probably don't need to explain this to this crowd, but the Arctic is really and truly changing, right? We're seeing enormous changes, which include atmospheric changes. The thing that's most in the news, which is the dramatic reduction in summertime sea ice extent. The loss of multi-year ice.

So it's not just the extent of the ice, but it's the quality and the thickness. Changes in the stratification and fresh water content of the water column increased ocean acidification, ice sheet melting, which have one of the largest drivers of uncertainty in predictions of sea level rise, changes in permafrost. So all these things apply dramatic changes in the balance of physical processes that we're seeing. We think there are strong feedbacks.

We're seeing increased seasonality. Secular trends, so many different things that come to bear in how we think about the Arctic. When we talk about changes in the sea ice right? Which is one of our focuses. It's changes in the nature of sea ice and coverage.

And what you see here from Ron Kwok is a plot that shows you a change in the aerial coverage in multi-year sea ice. So the dark colors are considered very fresh as a multi-year sea ice. Bright colors or either open water or first-year sea ice.

And it goes from 1999 to 2015. So I'm using the most recent measurements. But what you see is what used to be large extensive multi-year sea ice clustered in the Canadian Arctic has now become a thin band. North the Canadian Arctic archipelago and Greenland. And the rest of it is really, really fairly thin first-year ice.

And this means it's more mobile, it's weaker There are many, many different changes in ice quality that change the dynamics. So these changes have huge impacts. Of course there are climate changes, which have impacts, which have really global ramifications. We could go on at length about the connections between Arctic and mid-latitude climate, their impacts to local communities.

In the center picture there you see increased surface wave activity eroding the shoreline in one of the Northern communities in Alaska. You see increased opportunity for shipping, for oil and gas exploration, right? For resource extraction in general. So, lots of different possible changes that have implications in terms of what we need to know to plan those changes out, to plan activity, and what we might need to know to respond to emergencies.

If we come back to the reduction in sea ice extent, one of the interesting things to ask, and this is what one of the things that motivated the marginal ice zone experiment, which we'll talk about in a minute, was it was looking at both the observed and the projected changes in the summertime sea ice extent. Where if you look at the plot in the bottom left-hand corner you see that the mean and the median of the model of results ensemble models and the range in the gray, and then observed sea ice extent changes in the black. And what you see is that the observed changes in summertime sea ice, et cetera are barely within the one standard deviation range at the model results. A couple of years prior to this, the observations weren't even really within the range of the model predictions. So what we're seeing is that the if we just think about summertime sea ice extent, those changes are happening more rapidly than what the models are predicting.

And what that tells us is that we don't really completely understand the physics that are driving that decline. So NR's invested a fair amount of resources in trying to improve our understanding of the physics. You know, any good process study starts with a cartoon, right? And so this was the cartoon that drove the marginal ice zone experiment. And really what we tried to portray here if you go from left to right is that the conditions are under full ice cover right, the old Arctic, the increase in decrease in ice cover, right? The increase in the amount of open water as you move into the new Arctic. So in the old Arctic, the ice isolated the ocean from the atmosphere. The Arctic is of course this upside down ocean.

We have a cold, fresh halocline that isolates warmer, saltier layers below. And those warmer saltier layers could be a near surface temperature maximum form from the summertime input of the solar radiation to a warmer Pacific waters to deeper layers of Atlantic waters, right? And those, I've listed those in order of decreasing availability of heat to the ice. So it's easy to get the STM up into the ice. Harder to get the Pacific water up.

And very difficult to get the heat from the Atlantic water in contact with the ice. Traditionally, the ice isolates the upper ocean from the atmosphere, forcing both from solar radiation and from momentum input which are generating internal waves, eddies, mixing, right? But as you see increasing amounts of open water as the ice gets weaker and then you get increasing open water, the ice gets more mobile, it gets more efficient, and momentum transfer between the atmosphere and the ocean. And so you suddenly have the ability to input more momentum to generate internal waves, generate approach and mixing at rates that are perhaps more efficient than they would be an open water. And so you see mixing and therefore an ability to bring that heat up from the layers below. And then as you get lots of open water you get the ability to generate surface waves. And those surface waves, you get increasing amounts of fetch, more wind activity, have the ability to propagate into the ice pack and do a mechanical breakup of the ice.

Right? So that was one of the thoughts was that perhaps the increase in surface wave activity would be driving increased mechanical breakup of the ice. And so you can see some of these are positive feedbacks where I have more open water, more surface waves, more mechanical breakup, more open water. There's the famous ice albedo feedback, where as you get more open water, which is dark, you absorb more solar radiation which generates more melting. But there are also negative feedbacks, that is the ice melts or injects fresh water into the upper ocean, which is stratifying which therefore isolates the lower layers from mixing. So part of the game is understanding how the balance of feedbacks plays out in the new Arctic.

In order to understand these things, we think about a need for a nest observing system. I tend to use this diagram to indicate the difference between, right, if you look on the left-hand column, the difference between measurements that were used to understand climate, which are very long-term and distributed as you move down that column, the measurements we need for situational awareness, which are very, very limited shelf life, we need the measurements right away. But typically you only need them in a very limited area, right? To understand what's going on.

And everything in between, which measurements used to constrain models, right? Maybe a little broader, maybe a little more timely delivery. You can think about those in terms of policy and decision-making, right. Long-term measurements, strategy. What do I need to do next year or the following year? The ability to make those forecasts in tactics, support for day-to-day activity, ranging from is it safe to navigate your ship through the ice here? To if I'm a hunter, can I go out onto the ice today? Right, so these imply different timescales and different spatial scales for those observations ranging from pan-Arctic to focused regional observations and observations of resolve scales of just seasons or months to really observations needed at hourly timescales.

And the problem here is that the physics are non-linear, right? So the interactions between the scales are important. And in order to really make predictions at some of these timescales you need to understand the dynamics. It's shorter timescales and shorter spatial scales. So that there kind of is no shortcut.

ONR has been interested in a variety of these things and to to make this short, ONR is very interested in developing technologies to make these measurements in improved physical understanding. So process of our understanding of the other dynamics, and they're all feeding fully integrated Arctic system models, right? So that's been the thrust within the ONR Arctic and global prediction program. And more of those two sit under the same program.

The challenges of course are that we're trying to observe over multiple domains. Atmosphere, ice, and upper ocean, which are not easy to observe at the same time in the same place. Need to resolve at a variety of scales. Physics are fundamentally four dimensional. We would like to have persistence the ability to stay up there over a long period of time, so we understand those interconnected scales. Access is difficult, all right.

Making measurements under the ice is particularly difficult at those scales. Then we'd like to be able to do that in a way that lets you range from focusing on a smaller area to making more broader distributed measurements, so something that's highly scalable. We're fortunate to live in a time when robotic measurements are becoming widespread, right? Our ability to make measurements with small, relatively inexpensive robots is exploding. I'll talk about a variety of platforms. I won't go over them in detail here, but and fundamentally when you combine these robotic measurements with some more conventional measurements and the ability to collect widespread remote sensing. We can now achieve that kind of persistence sustainability that we've been after for such a long period of time or gained a point where we can scale the measurements over broader areas.

And I think we're also getting to the point where we we're able to make more adaptive measurements. One of the keys of this has been to use the ice as an observing platform, right? It's a nice stable observing platform we can put things on. That's changing as the Arctic changes.

It's getting harder and harder to use the ice that way. Harder to land on it, harder to put instruments out that will be out there for a long period of time. So right. And they talk about robotic observing has to start with floats.

They've really been the game changer in how we think about observations in the ocean interior. They're operationally fit for physical floats and becoming an operational for biogeochemical floats within the global ocean. These are still harder for the Arctic to acquire.

We can do five-year deployments of floats right now. One profile every 10 days with the network distributed over the entire ocean. But in the Arctic geolocation is still difficult. Data exfiltration is difficult because you need to have satellite service with data now. So float deployments in the Arctic are still in the infancy, but they are still, they are happening.

And NOAA's been one of the leaders in doing that. The platform that I've been most involved in in developing with my team is the lead developer for one of the three production glider platforms for sea glider. These are small inexpensive buoyancy driven vehicles. I won't belabor this because people are probably aware of them.

Being 50 kilograms, two meters in length. Pretty routine year-long operations in ice-free waters now. And we've been learning to operate them in ice-covered waters but we've been doing that for about a decade and we've achieved year-long deployments in Arctic sea ice and Antarctic sea ice and ice shelf environments. So something that we can do these days but really the existing autonomous platforms that operate under the ice floats and gliders rely on GPS Iridium comms. So satellite services. In order to get around that, we need to be able to navigate under sea ice.

And we do that by in the dumbest way possible really, which is by multilateration. Putting out beacons where you know the location of the beacon. The beacons broadcast on a normal schedule.

When a vehicle hears those broadcasts, that can can calculate a range, I mean, again, multiple ranges, you can draw marine circles and look at the intersection between those range circles to achieve a position to estimate. And what you see in the animation right now that's going are the deployments in Davis Strait, which were really our first deployments in the ice. Then you see glider marking back and forth across the strait.

The ice is coming in and white right now. The blue is open water. And what you'll be able to see is the glider navigating back and forth under the ice now. It might be difficult to see in this display but there are a number of circled moorings, green dots, which are sound sources, which is what the glider is navigating from. Fixed location. Navigation gets rougher as the glider starts to go under the ice.

And that's because we go from navigation which has meter inaccuracies to navigation that has roughly kilometer accuracy which no longer calculate average currents. So the glider gets pushed around in the currents more. But that gives you an idea of a year long deployment of operating under the ice in the strait.

And as I said, those measurements are roughly 10 years old now. Those operations with that was really the first go at doing that. So how that works. Again, the modern system uses a 900 Hertz broadband sources from the [indistinct] buoy. The sources transmit every four hours. Because of the broadband, they can transmit some information on the signal which used to transmit the location at the source of location at the transmission.

So now the sources can move. They can maneuver on the ice and they can drift and the glider or float can navigate from those. This also allows us to send a very limited command set to the gliders and floats say, commanding them to adopt a new sampling pattern or commanding floats to fish more frequently to try to collect positions or report data. One of the interesting things about the Beaufort, about the Western Arctic, is it now has a sound channel. The Pacific summer water comes in, provides a sound channel of roughly a hundred meters, which gives us a roughly 500 meter range from the sources.

Sources are transmitting in most of the Arctic have only about a hundred meter range because they're surface ducted. Meaning that the transmissions reflect off the ice bottom, which is pretty lossy and they don't go very far. A demonstration of that. If you look at the bottom left here, our transmissions in the Beaufort. You can ignore the red and green dots.

They just have to do with whether or not the data pack was decipherable. But what you see is that in the sound channel at a hundred meters, we get ranges out to 500 kilometers outside of the sound channel, right? Deeper. We get ranges only up to 100, 150 kilometers, which would be more typical of the general Arctic. So that Pacific layer might change over time.

You fully might expect that it would change as the Arctic changes. And as it changes, we may lose the sound channel and go to a more general Arctic sound channel which has fairly limited ranges. So the other platforms we depend on in the Arctic are ice-based. The International Arctic Buoy Program has been going since 1979.

So real easy, oldest operational observance system in the Arctic and measures just position in barometric pressure and air temperature really on the surface. We also use ice mass balance buoys that tell us something about the structure and nature of the ice as it melts out in the snow on top of it and surface buoys either on the ice or in the open water formation and surface waves in the ice. Extending into the water column their instruments like the ice tethered profiler, which has had great success measuring profiles on the ice from an instrument mounted on top of the ice that drifts. Arctic ocean flux buoys, which are really aimed at measuring turbulence in the upper part of the water column. The O-buoy which measures chemical properties and then operation temperature. Zero different buoys that are mounted on the ice and make measurements down below.

So ONR has funded a range of research programs. This gives you an idea of those programs plotted out over the years. We're gonna focus on the marginal ice zone program and the stratified ocean dynamics program with a mention of sea state here.

But you can see that there've been others in between. They all focus in this area, the central Beaufort, in one form or another. So that really has been the focus of those, that sequence of research efforts. Each of those efforts is roughly five years long, typically within a year of intensive field measurements. So to give you some contrast between three of those programs, Marginal Ice Zone was focused on the spring time meltdown, spring and summertime meltdown.

It was really focused on that interface between the open water and the pack. So that area of broken ice, it's hard to make measurements in because instruments mounted on the ice get ejected at that point and die. Whereas the open water instruments that we more typically use don't have access to that region fully, but the idea was to try to understand the changes of dynamics as you walked back away from the marginal ice zone, how that impacted the melt. The Arctic Sea State program looked at freeze-up. And was really, really focused on that period in October-November, when the ice was coming back in and trying to understand the impact of sea state or increasing wave activity on that freeze-up. So two programs focused on the ice, and then the Stratified Ocean Dynamics of the Arctic program, SODA.

Really was focused on the operation dynamics. So looking at the upper water column and how that was evolving during this period of time. So as you can imagine, the Marginal Ice Zone program wanted to work in an ice-centric frame. The other two programs were a mix of [indistinct] and Lagrangian measurements.

So we'll go to Marginal Ice Zone program. Again, focusing on the marginal ice zone, because we were doing that. We wanted to focus on drifting reference frame moving with the ice. I'll start the animation here so you can see that.

We're doing the editing view here because we couldn't quite get the presenter view to work on GoToMeeting. So what you see here, we deployed a carpet of instruments using aircraft, very, very lightweight. So just a couple of Twin Otter [speaking indistinctly] deploying these out on the ice early in the season.

The idea was to have this carpet so that it would melt out and you would see this contrast between things at the marginal ice zone and going back into the pack, but that the ice was more mobile than it had been in the past. And the drift pattern was different. So we really ended up with things strung out... you see in the yellow sea gliders being deployed and moving into the ice, right? So they're actually sampling the marginal ice zone into the pack and back up into open water. And then everybody's running away, once again.

I will play that. It's going to loop again, as we talk here. But really this was motivated by the fact that the marginal ice zone plays an increasing role in the new Arctic. Used to not be much of a seasonal ice zone, and the marginal ice zone was fairly small relative to to more modern times when the seasonal ice zone is huge, occupies an enormous part of the Beaufort and the marginal ice zone is a big part of the program. A big part of what you see in environmental variability. And you see this very large list of collaborators that was required to to make this all happen.

Many different people focused on the ice, those of us focused on the approach and remote sensing, and colleagues at the Korean Polar Institute. So I think what we'll do next, I'll just show you a cartoon of how that observing system looks. So this is one of the smaller arrays, right? Where we put out an array of wave buoys, a number of profiling instruments, looking at the operation and the sea ice and then had gliders moving back and forth between the open water, back into the pack, and then through the marginal ice zone. And then wave gliders and other instruments looking at the open water on the outside, but roughly a hundred assets deployed in this carpet. Again, with the idea that you'd have open water measurements at the marginal ice zone with these instruments being kicked out as they melted out, and then maintaining an array of instruments, moving back with the pack. All bound together by remote sensing.

So this gives you an example of the kinds of things that we were doing with remote sensing where you try to use it for navigational access but then also create sea ice mass and flow size distribution charts that we could use during the analysis phase of the program. And it also gives you an idea of how deceptive the remote sensing can actually be. Where if you looked at the RADARSAT images say from mid-September, you would think there wasn't really any open water, but in reality there was enough open water for the gliders to surface, most of the time.

So sea ice refraction was lower than you might've expected. So quick overview of some results on the half-hour now. This is looking at surface waves. One of the things that we have hypothesized going into this was that we would see increase in surface wave activity and that would penetrate into the marginal ice zone and really be effecting the mechanical breakup of the ice. Sub soundwave in the break up.

But instead of what you see if you look at surface wave activity in terms of as a function of frequency. So this is wave spectrum, as a function of ice fraction and where the oranges are open water, and as you go to increasing blues, those are increasing amounts of ice. What you see is that the ice essentially dampens high-frequency surface wave activity, and there really wasn't that much low-frequency surface wave energy. So the ice was in a sense protecting itself. The marginal ice zone, the lower ice fractions were absorbing the high-frequency surface wave activity and preventing it from properly leaving to the ice. You see that turbulent dissipation rate in the upper meter so the other water column where you see in open water, a fair amount of turbulence and you don't really see that in even small fractions of ice cover.

So the message here was that no, the ice is dampening the high-frequency surface waves. It's not propagating into affect breakup of ice inside the marginal ice zone. We don't yet see it long period. Low-frequency swallowed propagate deep into the pack sort of like what you see in the Antarctic, right? Where the long period swell can propagate deep into the pack, obviously affect breakup. So at least at this time we don't see surface waves having a large impact. What we do see is the thermodynamically forced MIZ.

These are results from Shawn Gallaher. And what he sees here is a function of year day. You're looking at the temperature of the sea ice. The temperature relative to to the freezing point of the upper ocean and the salinity of the upper ocean, and buoyancy frequency. So you see three phases. One here which is the springtime mixed layer.

We don't really see very much happening. You see the start ablation at the top. Where it's just surface melting. The period two, when you see the mixed layer warming and freshening. So ice is melting both from the top and basal melting is starting from the bottom. And you see this freshening of the surface layer.

Here in period three, you've got enough open water that you have solar radiation penetrating so you see the formation of this near surface temperature maximum. And the development of a halocline, which is isolating that from the surface. Again, more surface melting. And then period four when you have a true marginal ice zone ocean boundary layer. You've got a very nice halocline developed and you've got this trapped summertime heat in the surface layer. But again, the message here is that no, we're not seeing the waves propagating and forming it.

Like you would see in the Greenland Sea and the Antarctic, but instead you really see this thermodynamic marginal ice zone. So surface melting primarily, and some basal melting. Here are the results from the ice-tethered profilers. These are from clusters C2 and C4.

So again, I just have the profilers profiling from the surface into the interior. This is Sylvia Cole's work. And what she's seen if you look at the difference between periods when there's a great deal of ice, right? The blues and the blacks, versus the periods when there's not much ice, you see increasing clockwise internal wave activity. So you see increasing downward as you propagation and the internal wave bands.

So we're seeing what you would expect which is more surface generated internal wave activity, probably getting in the interior and presumably generating more mixing. And the last bit of result from the marginal ice zone program is signs of stirring and mixing of the Pacific summer water. Here, you see a mean and standard deviation of temperature on ice before the ice had to retreat and during last edge advance. And the thing I like to point out here is that these are from glider sessions and moving back and forth into the pack, from open water into the pack. And it's referenced relative to the ice edge where the ice edge is defined as 0.15 ice concentration. So not much ice at all really for that ice edge.

But you see an increase in the standard deviation of temperature at this area that it's associated with the essentially at the top of the Pacific summer water. And you see that very strongly during the ice edge retreat, plus strongly during the advance. So here you're essentially moving ice backwards.

Ice is retreating. You're seeing an area that hasn't really been written on by the atmosphere, or at least here as it advances. This has all been impacted by atmospheric forcing some mixing, if you map it. But that southward tail ice is a clue that we're starting to see sea ice that we would usually associate with the stirring along the isopycnal, right, that enhanced variability along the isopycnal. So I'm not really going to talk about the sea state program. They've currently generated a beautiful volume in JGR.

I would encourage you to go look at that. But fundamentally they were driven by this idea that if you look at the trend in freeze up, we're seeing a lengthening of the ice-free period, and that's been driven at both ends, but in particular it's been driven by an increasingly late freeze up in the Beaufort Sea. At the same time that you see increase in surface wave height, increasing wave period in the Beaufort at that time of year.

So the thought is you see an increase in impact of the surface wave generation in driving the the freeze up until later period of the fall. And that's by extracting heat from the new surface temperature maximum and perhaps on the Pacific water layer. And also by this mechanical activity that changes the nature of the ice that's forming. You're seeing an increase in the amount of pancake ice versus other ice types, say frozen formation then information to other ice types through the winter.

So just in the interest of time I'm not going to focus on that, but it really is worth looking at. The sea state program has really really been producing a lot of fantastic results. So lastly, I'd like to move on to the Stratified Ocean Dynamics program.

And the analysis on this data is still in progress, but here the goal was to focus on annual cycle, right, to look at the entire year. So we try to look at seasonality over the course of the year. Get really focused on the upper ocean rather than on the ice. And so we did this in a more [indistinct] framework so that we could see contrast as we look towards areas. If you look here, the stars are moorings.

The southernmost mooring is an area that sees dramatic changes in ice cover over the course of the year. The Northernmost are is an area that is really under the pack, either the entire year or least most of the year. And that middle one is in the area that sees a lot of marginal ice zone. So quite a lot of contrast through the year. There was also acknowledgment that the incoming Pacific water was a huge player here in setting what you see.

And so we'll focus on looking at the Pacific water inflow . A split between process cruise on the Sikuliaq during the summertime, looking at Pacific water inflow and a variety of assets on the ice. And mooring to look at the annual cycle.

And again, an enormous team of very talented people looking at a broad range of activity there. Or broad ranges of science. And one of the hallmarks I'll talk about was there was an attempt driven by the awesome science and technology policy at the present to make this a broad inter-agency program and to see how far we can get by expanding the activity out.

So cruises, a lot of ship-based work. Sikuliaq went out for the process studies and Healy went out twice to deploy moorings ice-based assets and to recover them. Sikuliaq divided the work up into modules.

Looking at the shelf break and slope, looking at an area where you see these plumes of Pacific water separating off and moving off shore then looking at the mid base at the ice edge. Whereas Healy really focused on the deep basin, looking at primarily deployed assets but doing some process work within underway CTD, particularly during freeze up. Sikuliaq is particularly interesting.

It was led by Jen MacKinnon and she really put together this cruise that the process stays the modern way, right? Where you have a variety of intensive process-based measurements from the ship, a very fast CTD, intensive meteorological measurements, [speaking indistinctly] stereo cameras looking at the ice, and a bow chain looking at undisturbed approach and water column, right from the bow of the ship but then expanding that footprint out, right? So this is the way we do these measurements these days, is you take the measurements from the ship but then you deploy an array of autonomous instrumentation around the ship to expand the footprint to do things in places where the ship is not. And just in general, to take measurements that are very difficult to collect from the ship. So they had wave gliders making measurements around the ship. They had a variety of Jim's surface drifters making surface wave measurements around the ship, and then a wire walker drifting around profiling the upper part of the water column and making micro structural measurements.

So beyond that there was this push to make an inter-agency SODA and that was NASA, Coast Guard, BOEM and NOAA, NSF, National Ice Center. So, a large number of collaborators. And I'll focus on just a few of those at this point. As I said before, right, remote sensing is key to a lot of what we do upon the ice. In this case, we had dedicated analysts from the National Ice Center sailing with us. Sofia Montalvo sailed with us.

John Woods coordinated a lot of this. What I meant was that we got a continuous feed of very high quality imagery from the NIC. Ship to shore guiding both Sikuliaq and Healy. And that imagery was archived for use in the science analysis afterwards. But that tactical analysis allowed us to target what we did at sea. Right, we could find these large multi-year flows, which you see circled here, and drive to them to put instruments out onto the ice.

We can navigate efficiently through the pack. So very, very critical both for science analysis and for operations. In addition to that, we had a collaboration with NOAA Arctic Heat and SIZRS - Seasonal Ice Zone Reconnaissance program to make a variety of flights. You can see lots and lots of aircraft activity dropping both Expendables and ALAMO profiling floats into the Pacific inflow and in the leads around the ice.

So these are all great because they allow us to track specific inflow properties as the floats get carried along the inflow. We also allow this broad look at what the scope of the Pacific water was during the course of the major field parameter during the southern campaign. I threw this in here because it was interesting.

We had a group from JPL NASA aboard who were testing a new salinity sensor, right? So the driver here was that they're learning how to do salinity here from space, and we're getting very nice results from that in the global ocean. But as you go into colder waters, the dynamic range of that sensor gets very narrow. And so they need to learn how to use that sensor in an Arctic environment. In order to do that, they manage a radiometer from Healy as we drove around, collected measurements at a variety of different frequencies and looked for different frequency bands where they saw a particular response, right. Where they could see signatures, that they could relate to changes that we saw in the intake temperatures. That was successful in the first iteration.

In '19, they weren't able to get things together. They'll have to come out again in the subsequent cruise. We're hoping they'll come out again in this coming year in '21, when we go out to continue testing that sensor. That would be a huge advance if you do salinity from space in the Arctic in the open water regions.

So to wrap up I just wanted to show you some early results. Some things that we're seeing from the SODA data that people are pursuing in the analysis. These are results from a couple of the ice-based instruments that were drifting around in the central part of the Arctic.

So these were deployed pretty far North as part of SODA and drifted south. But interestingly, what they see over the course of the wintertime are these injections of Pacific water, right? So they're seeing these what look to be mixing up events, where they see warm water being brought to the surface during times we think that there's pretty extensive ice cover, right? There might be.... We're trying to figure out if there were leads if the ice was more mobile during these times, open water periods, but we see these events in data from multiple instruments. So it's not just a single instrument.

They're fairly commonplace. So trying to understand that wintertime injection of Pacific summer water under the water column and to what role they may play in weakening the ice cover in maintaining and forming leads or enhancing early ice melt. These are results from Jen McKennon and company from Sikuliaq.

And the thing that they're seeing, if you look at that top row of plots, those come from one of Mary Louise's papers. Mary Louise has really done a lot of creative work on looking at Pacific summer water, and its spread and its influence in the central Beaufort. And that work is generally done from a variety of platforms with available data is heterogeneous, it's from ITPs and from SIZRS measurements on pretty much anything you can get. And when you look at the spread of Pacific water from that lens, it looks like this widespread, right, this generalized spread of warm water over the central Beaufort.

But if you look at an individual snapshot, you look at something like what Jen and her crew did using Sikuliaq, you see, instead, these filaments in Pacific water that come out, you know... Pacific water comes, flows in the Bering at the surface, flows along the coast, and then turns out in this case, kind around Barrow Canyon, right? Which is one of the areas that [indistinct] and others have been modeling and looking at as a major inflow site and subducts, right? At this point, it slides under the cold of a much much fresher, fresher part if it's out in the central basin. And to some extent disappears from view. So Jen sees a large event prior to large filament coming out and subducting and starting to ask questions about what controls the rate of these kinds of processes, right? Where did these filaments peel off the coast and enter the open basin? How often do they do that? Right? How efficient are they at moving into the open basin? With an understanding that the actual mechanism that gets you to this upper row of plots is really probably an amalgamation of lots of small scale processes that look like this, right? Filament already formation and ejection from the coast. So we're trying to understand those dynamics. And then the last piece from SODA that I like to leave you with is the work of Sam Brenner, who's a graduate student here at UW.

This is been recently published. And Sam was looking at as a first cut at the mooring data, data from the moor instruments looking at observations ice ocean drag, and trying to understand the division of labor between skin drag, so the drag just on the surface of the ice, keel drag, so the drag associated with major keels and ice formation roughness on the bottom, and flow edge drag right on the edge, and to understand how well the current models do in predicting that. And so he looked at three different areas, all right the three different moorings, lots of open water, lots of marginal ice zone, lots of pack. And tried to understand the difference in his ability to predict if he took the geometry that was measured from insurance we have in the mooring. So we have measurements that can estimate that geometry. And so now you're not trying to parameterize geometry.

You're just, parameterizing the drag. Versus what happens when you don't really know the geometry and you're trying to parameterize the whole thing right? So you say parameterizing the geometry based on open water fraction. And then parameterizing the drag from there. And the answer they gets is that if we know the geometry, the parameterizations for drag work really well, and most of the drags in the keel track, but if you don't know the geometry, the parameterizations for geometry, they're based on say flow size distribution or open water fraction, don't do particularly well. And therefore the parameterized association drag doesn't do particularly well.

So that's where we stand in terms of being able to do these things for the models at the current time. So I'll conclude with the next step which is Arctic Mobile Observing System program, which is where we're at right now. Now, we're currently in the second year of that program. It really, this is a primarily a techonolgy focused program trying to develop the technologies that will allow you to do event driven sampling around the central node. So the idea that you'd have a large central node that was well-provisioned might support a fast propeller driven AUV that could dock with the node and be sent out occasionally for very short range missions. You might have other platforms, ice based platforms distributed around the node.

The combination of these platforms would provide acoustic navigation for long range gliders that will give you the ability to sample both closely around the node and arrange tens or hundreds of kilometers away from the node to sample the area around it. Perhaps storing profiling floats on the ice, right, for time distribution or time release into the area. So you could drop them either driven by events or times into this area. And then they would profile as profiling floats do at intervals, so it would eventually drift away from the node, but probably give you an intensive profiling capability for a while.

And then you wrap all this up into a system where you've got some ability to bring the data back in real time, understand what's happening and respond or control the system. And you can see a little cartoon here of what we're trying to do, where the central node is actually a substantial Spar buoy that has been moored into the ice. So that is the current effort. And I'll leave you with a summary slide there of where we're going. But then again, this is a sequence of stage on our research programs focused on the basic research, mainly on the physical part of the science, but you can see where the impacts might be for the biology and the biogeochemistry and a mix of understanding process level dynamics and developing the technologies we need to maintain that persistent presence and access to space and time scales that are really of central interest in our ability to advance our understanding of both the physics and to monitor the Arctic over a much longer period of time in a much more distributed fashion.

Thank you. That's what I have. - [Heather] Awesome. Thank you so much, Craig. Just gonna turn on video really quick.

Thank you. That was, there is a lot to do in that program. It's been going on a lot longer than I realized, especially starting with the MIZ program. So I'm just gonna go through a couple of the questions.

I know we only have a couple of minutes and you have to leave right at 11. So I'll start with Libby's second question, actually. Which was, "Why was the Beaufort sea the focal area for the studies?" - [Craig] A couple of reasons, you know, if you think from a an Arctic impact standpoint, that the Beaufort has really been the focus of a lot of our thinking, right? It's a fresh water reservoir that we think breathes in response to atmospheric forcing. So it's potentially the source of a major freshwater release, which may actually be underway right now. It's part of the work we're doing at Davis Strait.

It's an area of interest to the Navy and it's area of interest to the U.S. from both a national security and from a human activity standpoint, right? It has an impact on our Alaskan communities. And it's also a very convenient laboratory.

It's a place that we can get to fairly easily and has has the right range of dynamics and ice types that we would like to focus on. - [Heather] Thanks for that, Craig. Chidong also had a question. "A major challenge of observing the MIZ is to have co-located data of the upper ocean surface with or without ice and the atmospheric boundary layer. What technologies are out there that may make such co-located observations possible?" - [Craig] So that is indeed the problem with the MIZ. One of the elements of the AMOS program is a large, and I really do mean large, Spar buoy.

I didn't throw a picture of it in the diagram, but it's large enough that we can only carry a couple of them on the ship at a time for deployment. And it's meant to survive freeze up and melt out pretty routinely. One of the things we're using it for right now is a test bed for boundary layer measurements. My thinking about that is a test bed for developing the kinds of technologies we need to make these measurements unattended from high space platforms over long periods of time. But because the platform is a bit of a brute, right, it gives you that ability to hang out in an area almost no matter what's going on and collect those meteorological measurements. So the combination of that and the ability to have mobile platforms, gliders, AUVS, floats in the water column gives you atmosphere and ocean.

And for the ice, it's harder, right? I think you just have to rely on things that they're going to die over the course of making their measurements, and make them cheap enough and that they can be put out in great quantity. - [Heather] That's a hard thing to come to grip with, of losing something you've made. - [Craig] Yeah. We're good at that though. At losing things. [Heather laughing] Trying to understand how to make them so that we can lose them.

- [Heather] Right, yeah. It doesn't always make it any easier, but yeah. Libby had another question which I think we have time for, it seems, and this goes back to your early slide on like the timescales and sort of the applications where that has, she says, "It seems that intermediate scale of strategy might be the most challenging to achieve. Any thoughts on that?" - [Craig] You know, the strategy and the climate scale are not terribly different from each other, I think, in that they nest pretty well. You could think of the strategy scale is doing more of what you're already doing at the climate scale in areas of focus, say, you know, if you knew you wanted to make predictions of ice or out of ice cover on an annual, inter-annual timescale, you might concentrate measurements in the areas where you think shipping activity was going to happen more than you did just distributed across the pan-Arctic area.

And you still might not need the data back at any much more rapid at the timescale as when you needed it for the climate scale observations. The one that worries me more are the more focused measurements where the data is required and over a small area in real time, right. Which can be very, very difficult to achieve. But, I think if you thought about it from a modeling perspective, you're probably right. That strategy zone is very very difficult to achieve from a predictive standpoint. I'm thinking purely from the observational standpoint.

[No audio, Heather muted] I'm not sure whether that completely answered your question or not, but that was a... - [Heather] Libby says, "Interesting, thanks." [laughs] I'll let her follow up if she needs to. [laughs again]

It is 11 Craig, and I want to be respectful. I know that you need to go, but thank you so much for joining us and closing out our seminar series. It's really a privilege to have you join us over here. And I really always like listening to what you're up to. So thank you again for joining us.

Thank you to everybody for joining us. And we'll be back again sometime in the fall. So hopefully feel good things happen.

So thank you so much. - [Craig] Thank you for having me.

2021-05-03 21:43

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