Skip to content

Author: eliza

The lesser known models of SoCal

I spent the last week and a half modeling in Los Angeles. Rather than making my way through Hollywood studios, I spent days glued to my computer screen as I ran model simulations of Antarctica using the ice sheet system model (ISSM) developed by the NASA Jet Propulsion Lab (JPL).

Situated in Pasadena, CA on the northern outskirts of the LA area, this NASA campus boasts over 5,000 employees working on everything from glaciology research to the Mars 2020 mission and beyond. Among scientists, I think it’s fair to say that Pasadena beats out Hollywood for its modeling claim to fame. (If you’re curious what all of the upcoming missions are, check out this link: https://www.jpl.nasa.gov/missions/)

My research visit was arranged to work with our collaborators who built and continue to develop the ISSM model. Much of my PhD research involves running model simulations of Antarctica so this visit was an opportunity for me to advance my capabilities using ISSM, report on my current research, and discuss the next modeling steps I plan to implement.

Here's an example of a simulation I did showing surface velocity in m/yr

Why run an ice sheet model? We don’t have many tools to explore what the world will be like in the future. Models are one of the few ways we can capture the current physical state and then run experiments into the future to inform ourselves about the impacts of possible climate scenarios. In my case, I run model simulations of Antarctica to examine how climate forcing could affect the stability of the Antarctic ice sheet, especially at the bed of the ice sheet where the thermal state is very important. Models enable us to predict what regions are most vulnerable to collapse and how much sea level could rise. Many of the news reports you’ve probably seen about climate impacts are ultimately from models like ISSM that work to capture the future state we will experience. 

Leave a Comment

My summer of melt

I’m sure you’ve seen it. People have been asking me about it. This year Greenland has had record breaking heat and extreme melt, and headlines everywhere have been announcing it. This heated media attention over the last month has yet again put the Arctic and climate change in the spotlight. 

Here's one of the many surface melt streams I saw on the Greenland ice sheet

While I could echo news reports in this blog, I’m not going to. Instead let me add two additional pieces to the story about Greenland and melt. 

Part 1: A first hand account. I’ve only been to Greenland once — this summer — so I have no way of comparing the melt I observed this year to previous years. However I tried to capture what this year felt like. From my perspective on the ice sheet, this is what a record setting melt season looks like.

Part 2: What does melt mean for an ice sheet? A glaciologist could answer this question in a lot of ways because melt has many implications. At the most fundamental level, let’s explore some of the roles of meltwater.

Naturally, the lower part of a glacier melts. Even if the climate wasn’t warming, the section called the “ablation zone” is characterized as a region that looses mass via melting. To balance this, there is a region called the “accumulation zone” higher up on the glacier. In this zone there is no melt and instead the glacier gains mass via snowfall.

From the USGS

In a stable climate, the accumulation and ablation balance each other. Ice flows from higher up on the glacier where there is net gain to lower down on the glacier where there is net loss. In total, the glacier does not gain or loose mass. 

What happens when the climate is warmed? The balance is perturbed. The net ablation zone expands while the net accumulation zone shrinks. 

Image showing an expanding ablation zone in northwest Greeenland (Stef Lhermitte, TU Delft; MODIS Aqua)

Since there is more melt than snowfall, the glacier recedes until it reaches a new balance. If warmed enough, large sections of the glacier can be lost before it stabilizes again. In Greenland, I was in the ablation zone and this zone has been expanding over time.

Meltwater also plays a role in basal sliding. Glaciers can slide because of a film of water at the ice bed interface. Naturally, just from the heat due to the pressure of ice weighing down, ice right near the base of the glacier will thaw and a thin water film will develop. 

Increased surface melt due to warmer climate conditions can introduce more water to the bed and cause faster glacier flow. How does the water get from the surface to the bed? Over time melt ponds on the ice surface get big enough to cause cracks (hydrofracturing) in the ice and the water drains since it is more dense than ice. This water will eventually make it to the bed adding further lubrication for the glacier to slide.

Illustration by Jack Cook, Woods Hole Oceanographic Institution

All this to say meltwater plays many important roles in an ice sheet. Some meltwater is normal for a stable glacier but too much can cause irreversible change. Now behind the news stories and pictures you see, I hope you think about some of the mechanisms of meltwater and what implications this has for a glacier profile.

1 Comment

The scoop on ice camping?… it’s cold

To be perfectly honest, I didn’t anticipate quite how challenging it would be to simply live on ice for 3 weeks. Putting all research related challenges aside, the daily living routine demanded a lot of stamina and discipline.

For starters, I’ve never camped in such an alien environment for so long before. Wherever you’re sitting right now, let me try to bring you to this world. If you’re indoors, remove the building you’re in. In fact, remove every single building, every plant, every animal, and any other objects for as far as you can see in all directions. Flatten the ground to be a bumpy but relatively level surface and make it stretch out in all directions to the horizon. Now make the ground hard white ice. Turn the temperature down to about 32 degrees and put on a big parka, snow pants, heavy mountaineering boots, a hat, gloves and sunglasses. Look around. There’s now a white icy surface stretching as far as you can see in all directions. The only contrast against this white surface is a cluster of small colorful fabric tents flapping in the wind. You’re living here for 3 weeks. This is Earth but it almost feels like you’re on another planet. You pull out your phone to snap a couple pictures and in the process you’re reminded again that you have no service. Not that you thought you would have service, but just seeing those ‘no service’ words everyday makes you feel as if you’ve arrived in an alternate universe.

Yes, our camp is actually in this photo. It's a dot in the center.

Challenge 1: Wet and cold

With the temperature climbing just above freezing during the day and dropping below freezing at night, everything was perpetually cold and damp. Even inside the tent, there was no avoiding the icy floor. My hands and feet were frequently numb. I lived in my parka, only taking it off for a quick second to slip into my sleeping bag. Since there was no indoors and no heating, it was critical to constantly monitor body temperature. I don’t think I’ve ever had so many hot drinks and soup in my life.

Challenge 2: Where’s the bathroom?

There was merely a bin with a toilet seat sitting out on the ice about 100 meters downwind of camp. A tarp strung up by some bamboo poles served as a make shift curtain. The wind and cold did not provide any comfort when using the toilet. I found myself frequently in the “how long can I wait to go pee debate”. Even worse, was the rotating job to change the toilet bag when it got full. Further, the waste was burnt in an incinerator since we couldn’t take it out with us. What about a shower? There was none. That’s right, 3 weeks and no shower.

The toilet
Watch out for frostbite

Challenge 3: The tent moving ritual

Every 6 or 7 days you had to move your tent. But seriously, you really did. Over time, the ground around the tent melted away. The tent footprint served as a striking marker of surface melt. Over the course of a few days, the insulation provided by the tent sheltered the ice directly underneath. While the surrounding ice slowly and inconspicuously melted away, the ice directly under the tent remained and soon the middle of the tent would be elevated on a pedestal of ice a couple of feet thick. This really shrunk the space inside the tent making it an acrobatic act to simply get in and out. The ice below the tent became a slippery, lumpy surface. Rather than a restful sleep, I’d feel more like I’d just spent the night holding some sort of yoga pose – my head and feet awkwardly sloping down with a big rounded lump underneath my back.  

I just moved my tent off this huge lump of snow that formed under it.
Drilling in my tent so it won't blow away

Challenge 4: Cooking a meal 

Meals took place in a bigger dome tent. Inside, eight chairs made a ring along the tent wall. While the food was mostly, dried, canned, or otherwise preserved to last for a long time, everyone surpassed my expectations with their creativity and ability to pull together a decent meal. Dinners often turned into long multi hour group conversations since there was little else to do in the evenings. After dinner it was time to take the dishes out and wash them in a melt stream and then also brush your teeth next to a melt stream.

It got pretty crowded in here

Challenge 5: Attempting a workout

Being someone who usually spends multiple hours each day working out, I was a bit distraught by the lack of exercise opportunities. The ice surface was so rough that it made it impossible to walk fast without slipping. Even when I accumulated a lot of walking over the course of a day, it was at such a slow pace that I didn’t feel like I’d exercised at the end of the day. Additionally, because it was so cold and there was no way to shower, I didn’t ever really want to break a sweat. On a whim, I did bring a jump rope with me and I have to say, jump roping on ice worked surprisingly well to warm up and get my heart rate going!

I wouldn't be too surprised if I'm the only person crazy enough to use a jumprope on the Greenland ice sheet
Leave a Comment

Radar: a window into the ice

I haul a large box antenna, a laptop, and a software refined radio (the receiver) over the bumpy ice surface, trudging off to a radar transmitter stationed about a kilometer south of camp. I jump over melt streams and weave my way through the maze of crevasses. Eventually I spot a small black flag on a bamboo pole waving in the distance and I gradually make my way in that direction. Interestingly, black is actually the easiest color to spot against the stark white surroundings.

Carrying the antenna to the start of the survey
The transmitter is in the blue box on the left.

When I arrive, I open up the box containing the ApRES radar – a phase sensitive, low power, light and compact instrument. From the outside, it’s just a yellow waterproof box that resembles an oversize briefcase. Inside, there’s a circuit board and a few cables to connect antennas, a laptop, and a power supply.

Looking inside the ApRES radar box

Working with my teammate from Stanford, I set up our transect. We turn on the radar transmitter, sending electromagnetic waves into the ice. As we walk away carrying the antenna and receiver, we hope that it will be able to detect the signal after the wave has bounced off the bed of the ice sheet.

In the middle of a radar survey. Inside the black box is the receiver. The blue box has the antenna.

These invisible electromagnetic waves are very powerful. While we can’t see or hear anything, these waves are propagating down through the ice. When they reach the transition between ice and bed rock, they reflect and travel back up through the ice to the surface. By recording how much time has elapsed while the electromagnetic wave travels down to the bed and back up to the receiver, we can calculate the exact thickness of the ice in the particular location. In this case, the ice-bed interface is over 1 km (0.6 miles) below us. 

Radar survey diagram - we walked away from the transmitter carrying the receiver and antenna in the blue box

We can also use this electromagnetic signal to recover properties of the ice column, like what the temperature of the ice is and how it varies spatially. This is important information for understanding the evolution and stability of outlet glaciers and how they may contribute to sea level rise.

Leave a Comment

What’s a night like? Bright and windy

I wake up to the sound of wind beating against my tent, the fabric walls flapping up against my sleeping bag and battering my head. Gusts of wind find there way underneath the corners of my tent and threaten to lift up the bottom. The flapping is so loud that I feel like I’m trying to sleep directly under a huge flag. Even before I open my eyes I can tell it’s bright out… But when I check my watch, it’s 2 AM.

The Arctic Circle marks the southernmost point at which the center of the midnight sun is just visible on the June solstice. I was camped just north of Ilulissat, well above the Arctic Circle.

North of the Arctic Circle the sun never sets in the summer. A bit disoriented, I pull my eye mask back on and try to curl deeper into the folds of my -30F sleeping bag as the wind continues to howl. I feel very small as I drift in and out of sleep.

At night, the sun gets low on the horizon but never quite sets

These winds I experienced almost every night are called Katabatic winds -​ a wind carrying high-density air from a higher elevation down slope under the force of gravity.

In this case, the katabatic wind originates from the air cooling at night on top of the cold interior of the Greenland ice sheet. Since colder air is denser, the air will flow downwards and outwards towards the warmer coast.

The barren surface of the ice sheet provides no protection against the wind. To secure my tent, I had to drill a ring of holes into the ice around it and then insert bamboo poles into the holes and lash my tent to that. I never quite blew away, but listening to the sheer power of the wind each night was a very humbling experience.

4 Comments

Entering the Icebox

I just made it out of the ice research camp after bad weather and helicopter scheduling problems delayed our departure by a whole week. Luckily we had 10 day emergency rations to pull us through. I’m very happy to be back on ice-free land and sleeping in a warm bed after a hot shower! But as promised, here’s a glimpse into my experience camping on the Greenland ice sheet for 3 weeks while doing glaciological research. I’ve broken it up into a series of blogs. (Many more will follow!) To start with the adventures, let’s rewind the clock to day one.

First view of camp from the helicopter
Leaving Ilulissat in the helicopter

I descend into a world of white. As the thrum of the departing helicopter rings through the arctic air I take my first steps on the hard, lumpy, cold surface of the Greenland ice sheet extending out of view in all directions. Through my heavy down jacket, I can feel the bite of cold but other than that the weather is fair with bright blue skies bouncing off the sparkling white ice and a gentle breeze circling through the air.

The icescape

Glancing around, the landscape almost resembles the middle of an ocean if all the waves were suddenly frozen in place. However, this isn’t a frozen ocean. 1 km (0.6 miles) below my feet, this ice is sliding over land – Greenland – at a speedy rate of 700 m/yr (2300 ft/yr). In fact, here in West Greenland, I’m standing on one of the fastest flowing outlet glaciers in the world, serving as a major conveyor belt of ice from the interior Greenland ice sheet to the ocean. About 30 km (19 miles) away from me is the glacier terminus where Store glacier will reach the ocean and discharge 14–18 km3 of ice annually.

I turn back to the long wave-like ridges noticing that they are punctuated by rushing melt streams. This time of year, the surface temperature of the ice sheet climbs above freezing during the day and as a result, melt ponds and rivers form on the surface and flow downhill. About 200 m away, the surface reaches a low point where many melt streams merge into a churning river which suddenly vanishes into a void in the ice sheet, plunging hundreds of meters down through the icy abyss until eventually reaching the ground below. The glaciological term for this hole is a moulin.

Don't fall in!
Not a pot of gold at the end of this rainbow... it's a moulin!
Another view of the big surface melt stream

I turn away from the moulin. Apart from the rushing streams of melt water, my surroundings are deafeningly quiet. My boots crunch on the hard, weather-beaten surface of the ice as I follow my field teammates to camp. When I arrive, I’m greeted by a scattering of small 2-person mountaineering tents across the ice, next to one larger dome tent where I’m told meals take place. I’ve arrived at my home for the next 3 weeks.

"Glacierville"
Communal dome tent
Home
The cozy interior of my tent. After 3 weeks it started feeling more cramped then cozy.
1 Comment

In the world of ice, water, and whales

The colossal white fairyland is quiet, still, motionless. Suddenly cracking, ripping, and crashing envelops my ears breaking the intense silence with an awesome power. I squint through the glare of the arctic summer sun trying to catch a glimpse of the ice that has just broken off, somewhere jumbled in the chaotic transition from ice sheet to water (the glacier terminus). In fact, this glacier (Sermeq Kujalleq) in Ilulissat icefjord is one of the most productive and fastest flowing glaciers in the world. The glacier has doubled it’s speed in the last 10 years and now flows at a rate of 40 m/day (130 ft/day) and produces about 10% of all the icebergs in Greenland. The glacier calves (breaks off) around 46 cubic kilometers of ice per year. To put that to scale, 46 cubic kilometers is roughly the annual consumption of water in the entirety of the USA. While it’s hard to appreciate scale in a picture, here are some attempts at capturing it.

 

If I’ve learned one thing today, it’s that sound travels far in the arctic. That’s also what clued me into the whales feeding in the bay. Believe it or not, I could hear the whales breathing from miles away. Even when they were only a speck out in the water, their heavy breathing sounded as if they were right next to me. Despite the fact that the whales were active all day, I struggled to get a good picture. I think they outsmarted me.

I’ll have to sign off now because I need to pack up and prepare my gear for boarding the helicopter to the field camp tomorrow morning… but get excited for lots of blogs to come when I get back off the ice! Here’s a very cute sled dog puppy and one more picture of Ilulissat to leave you with!

Leave a Comment

Ice Sheet Incoming

Today I arrived on the biggest island in the world: Greenland. After just a few hours here, I am thoroughly convinced that Greenland is one of the most beautiful places in the world. This hardly does it justice, but here’s some shots I took today while walking around Ilulissat.

 

I have one more day in Ilulissat and then I will take a helicopter away from the coast to the field site on Store Glacier. Here’s a preview of what it will look like when I get to the camp. Some of my collaborators have already gotten there and took the following picture.

I’ve heard there are lots of whales in the area so I’m going to head back out to try and spot some! The great thing about the arctic summer is it never gets dark!

Leave a Comment

Farewell America, I’m off to Greenland!

Aerial view of Store Glacier - Lawrence Hislop

Preparing for a field season takes a lot of hard work and this trip to Greenland is no exception. The last few weeks have gone by in a whirlwind of packing equipment, purchasing gear, developing our experiment designs and goals, and wrapping up projects here before leaving. With that said, I still couldn’t be much more excited to finally set foot on my first ice sheet! After spending this morning packing up the last items on my list, I’m happy to say I’ve somehow managed to fit everything in two duffel bags and a backpack.

Bet you wouldn’t have guessed that there is are multiple radar receivers in there as well as a bunch of other field equipment… TSA will be in for a surprise. (I will say it took me about 10 tries before I managed to fit everything so hopefully security doesn’t unpack too much!)


Here’s my travel plans and what you can expect:

Today (July 4th): I leave the US bound for Copenhagen

July 7th: I meet up with a field collaborator and fly from Copenhagen to Illulissat, Greenland.

July 9th: I take a helicopter to the field site on Store Glacier.

……Field work and no internet access… so sadly no blogs during this period 🙁  .…..

July 28th: Return from Greenland and re-enter the modern world of internet!

Why you should keep following despite no internet at the field site: 

a. Expect more blogs up until I take the helicopter to the field site (on July 9th).

b. I will keep notes and take lots of pictures while I am in the field, so upon returning I will have lots of posts!… so please check back in after July 28th.

Ok, I’m off to the airport. I’m hoping to catch a few fireworks from the plane which would greatly improve the fact that I have a red eye flight on the 4th of July.

Leave a Comment

When you think ‘ice sheet’, think ‘sticky water’

Let’s pick up our discussion from last time and talk about viscosity. When you think viscosity, think stickiness. Viscosity is a measure of a fluid’s resistance to flow. Here’s what google has to say:

The special thing about ice is that it’s viscosity is high enough that it doesn’t instantly flow off the land into the water, yet low enough that it does eventually flow down slope. Honey, is a good analogy: If you pour honey onto a surface, it starts as a mound and slowly spreads out.

However, if you tip over a glass of water it quickly spreads all over the table.

Why? Because the molecules in honey (and in ice) experience more internal friction, which opposes flow. In glaciology, we measure viscosity as the shearing stress that causes flow divided by the rate of shear strain (or deformation), that results. I think here’s the main things to take away. 1) ice is flowing and 2) the flow speed is dependent on the viscosity of ice. Viscosity of ice isn’t one fixed number, it actually varies some with the temperature of ice. Here’s a plot. 

Colgan et al 2015

However, if you think back to that velocity map I showed in my last blog, you’ll remember that the flow of ice is like streams in some places and it’s not uniform. That’s because there are many important factors governing the flow of ice sheets and viscosity is just one sticky piece of the bigger picture!

Leave a Comment
css.php