Archive for the ‘Uncategorized’ Category

The Very Model of a Modern Glaciologist

December 3, 2012

A “poster preview video” for the 2012 IGS meeting in Fairbanks. This is about the same project I’ll be presenting at AGU.

Lyrics:
I am the very model of a modern glaciologist
I’m master of all manner of arcane and icy knowledges
My derivation of the flow law rivals that of Dr. Glen
My icy glare can cause a melting glacier to refreeze again
My glacier surveys show my unmatched skill with a theodolite
I outdrink all my colleagues after seminar on Thursday night
The NSIDC sends me their data sets to analyze
I leap crevasses meters wide to save an ice core from demise

I’m here to demonstrate to you this model stuffed with elegance
Developed with the use of my superlative intelligence
It seeks to show why graphs of crystal fabric from depths Stygian
Can oscillate and swivel in a manner callipygian
The foremost of our multitude of possible hypotheses
Was that the ice preserved the stamp of ancient surface processes
To substitute for nonexistent measurements empirical
We based it on pure physics from the realm where cows are spherical

I reasoned that since snowflakes sometimes grow as columns, some as plates
Why shouldn’t grains within the snowpack lend themselves to sim’lar fates?
I made ten thousand crystals and then grew them all stochastically
And let simple diffusion change their size and numbers drastically
The output is a credit to my wit and perspicacity
And several high-speed processors all running at capacity
Come marvel at my poster and admire all my knowledges
For I’m the very model of a modern glaciologist

Transcript: The Snow Wall

July 6, 2011

Hey, back to transcripts! I’m pleased that this one was next in the sequence, because it actually ties in nicely with a post I’ve been wanting to do about engineering with ice and snow.

Original audio post.

“The wind came back today. It started out calm enough, and we almost went out to make measurements. But when we called the forecasters at McMurdo, they told us that the wind was due to pick up soon, and would get to thirty knots–gusting to fifty–sometime tomorrow.

On hearing this, Mel pointed out that we were going to need to prepare the camp for the onslaught of wind and drifting snow. This meant building another snow wall.

A snow wall is both made of snow and designed to control snow. It’s simply a low structure made of snow blocks that serves to slow down the wind and make it drop its snow upwind of camp, instead of on top of us. The wind carries truly impressive amounts of drifting snow across the landscape, and it dumps it every time it gets slowed down by passing over irregularities, such as our tents. We already have two snow walls, but in the six weeks the camp has been here, the space behind them has already entirely filled with drifted snow.


A snow wall with the space behind it filled in with snow.

Most of the snow around here is extraordinarily hard-packed, and our resident snow scientists are astonished by its strength-to-weight ration. In many places, you need a chainsaw to really make much of a dent in it in any sort of efficient way. So, Mel got out the chainsaw, and cut enough blocks to make our walls.


Sorry, no chainsaw pics--this is after it gave out and Mel and Martin were cutting out the last few blocks by hand.

We had them assembled in fairly short order, so we got a little creative. Mel built an arch, I built a turret, and Martin and Ruschle spent most of the afternoon digging a snow pit and being astonished at it.


Blocks en route to their place in the wall.


Mel's arch and flowerpot (or rooster, depending who you ask.)

Martin says the snow here consists mostly of depth hoar, a sort of re-crystallized snow that’s ordinarily [that is, in more temperate regions] light and crumbly, but here is very hard—“like cement”, he says. Ordinary snow shovels would break on the first try. We use sturdy metal gardening shovels (the labels say they’re “contractor grade”) and they still have trouble. The depth hoar snow is also full of little crystalline cups and ??, quite delicate-looking for all its strength.

So, we have a new snow wall, and hopefully we’re well prepared for the coming storm. I’ll let you know how it goes. Cheers!”


Part of the complete wall.


Detail.

Oh, and speaking of timelapse…

June 25, 2011

Speaking of timelapse videos, here are a couple of others that I quite like:

Sea ice near an Adelie Penguin colony. Shows the evolution of sea ice over a period of time (perhaps late spring and summer?) Partly I just like this because the motion of the tides makes it look like the ice is breathing.

Sea stars, urchins, Nemertean worms, and other denizens of the under-ice seafloor consume a seal carcass. Narrated by Sir David Attenborough! Not for the easily grossed out or those who are unsettled by crawly things.

Feeding life, feeding back

June 16, 2011
A scanning electron microscope image of cells of Chaetoceros dichaeta, from Cefarelli et al. 2011.

A scanning electron microscope image of cells of Chaetoceros dichaeta, a type of diatom, from Cefarelli et al. 2011.

One of the most interesting aspects of climate dynamics is the role of feedbacks. There are two kinds of feedbacks, positive and negative. This earlier post about Snowball Earth describes a positive feedback, in which Effect One (the freezing of seawater) leads to Effect Two (the reflection of light back into space, which cools the planet) which in turn intensifies Effect One (more seawater freezes.) You can see a positive feedback effect at work in a more familiar environment when there’s a run on a bank: Effect One (the bank looks like it might fail) leads to Effect Two (depositors rush to get their money out of the bank) which strengthens Effect One (the bank, bleeding cash, now looks like it’s in even more trouble.) Positive feedbacks tend to make a system unstable. So they’re not really all that positive in the conversational sense of the word; in most systems, you want to avoid them.

This post, on the other hand, describes the carbonate weathering cycle–a negative feedback effect. In negative feedback, Effect One (warming of the planet from CO2) leads to Effect Two (weathering speeds up, removing CO2 from the air more quickly) which damps down Effect One (with less CO2, the planet cools down again.) Negative feedbacks make systems more stable.

Climate is an incredibly complicated system, with many feedbacks both positive and negative. This article at Science News, Melting icebergs fertilize ocean, describes the discovery of yet another one.

Living things in the ocean are limited by available nutrients, including iron. Some people think we should deliberately dump iron in the ocean to spur the growth of plankton that will suck CO2 from the atmosphere as they grow and then seal it away on the ocean floor when they die and sink to the bottom. Of course, many other people think that this is likely to have a lot of unintended consequences if we do enough of it to make a dent in atmospheric CO2.

But it turns out that icebergs in the Weddell Sea are already doing this, on a smaller scale. Glacier ice has a lot of iron in it compared to seawater, probably due to a combination of dust collected from the atmosphere and sediment from underneath the glacier. When icebergs break off the glacier and melt in the ocean, that iron is released, and thriving communities of algae and plankton spring up around the bergs. The more the planet warms, the faster glaciers flow and the more icebergs end up in the sea; the more icebergs there are, the more carbon gets soaked up by sea life, slowing down warming a little bit.

This effect is probably small compared to other feedbacks that are part of climate change, and it’s not very helpful from a human perspective, since each melting iceberg contributes to rising sea levels. But it’s always interesting to discover a new cog in the great machine of the Earth.

References:

Cefarelli, A.O., Vernet, M. & Ferrario, M.E., 2011. Phytoplankton composition and abundance in relation to free-floating Antarctic icebergs. Deep Sea Research Part II: Topical Studies in Oceanography, 58(11-12), pp.1436-1450.
Lin, H. et al., 2011. Free-drifting icebergs as sources of iron to the Weddell Sea. Deep Sea Research Part II: Topical Studies in Oceanography, 58(11-12), pp.1392-1406.
Raiswell, R., 2011. Iceberg-hosted nanoparticulate Fe in the Southern Ocean: Mineralogy, origin, dissolution kinetics and source of bioavailable Fe.Deep Sea Research Part II: Topical Studies in Oceanography, 58(11-12), pp.1364-1375.
Shaw, T.J. et al., 2011. Input, composition, and potential impact of terrigenous material from free-drifting icebergs in the Weddell Sea. Deep Sea Research Part II: Topical Studies in Oceanography, 58(11-12), pp.1376-1383.
Smith Jr., K.L. et al., 2011. Carbon export associated with free-drifting icebergs in the Southern Ocean. Deep Sea Research Part II: Topical Studies in Oceanography, 58(11-12), pp.1485-1496.

The Voyage of the Endurance

June 11, 2011

Hey guys! I wrote you a song! It’s about the epic tale of survival that resulted from Shackleton’s attempted Trans-Antarctic Expedition; I used this website as a reference for some of the events, or you could read Shackleton’s own book on the experience, South. Be sure to check out the pictures, which are widely and deservedly regarded as the best part of the book.

Sung to the tune of (The Bonnie Ship) The Diamond.

The Voyage of the Endurance

‘Twas early in the century
The world prepared for war
But Shackleton intended the Antarctic to explore.
Some men sail for profit
Some sail for renown
But this one sailed for Science and the glory of the Crown.

Through the icebergs that clash, through the great waves that roll,
The mighty ship Endurance went a-sailing for the Pole.

The whalermen had warned them
That the ice would be severe
They were still above the Circle when the first floes did appear
Still bravely they sailed southward
But soon they were beset
Imprisoned in the heaving ice, but not defeated yet

Through the icebergs…

They whiled away the winter
Drifting ‘cross the Weddell Sea
When finally the sun arose, they thought they’d soon be free
But the mounting pressure of the ice
Was more than she could bear
In just days the stout Endurance was crushed beyond repair

Through the icebergs…

They loaded up the lifeboats
With provisions piled high
They watched her sink beneath the ice as, helpless, they stood by
The men camped on an icefloe
Let it take them where it would
It brought them near an island before breaking up for good.

Through the icebergs…

The isle was cold and barren
Inhospitable to man
So Shackleton devised another daring rescue plan.
He’d sail eight hundred miles
‘Cross the world’s most stormy sea
To the whalers on South Georgia he would make his earnest plea.

Through the icebergs…

A thousand times the pounding waves
Near sank the tiny boat
They lost most of their gear and food, yet somehow stayed afloat
When the party reached South Georgia
Thirst-tormented and sore
They realized the whaler-camp was on the further shore.

Through the icebergs…

They scaled the craggy mountains
And crossed crevasses deep
They stumbled into whaler-camp half-crazed from lack of sleep
The whalers were astonished
When these strange men came in view
Soon Shackleton secured a ship to rescue all his crew

Through the icebergs…

Let Shackleton’s Antarctic fame
For centuries survive
For with all their trials and troubles, every man came back alive!

Ice Sectional Preview

May 2, 2011

Not much time–heading to the airport soon to wing my way home to Seattle–but here are some nice pictures of ice sections, the things I spent long long hours in the cold lab working on. I’ll talk more about the process, and their scientific importance, soon.

Vertical section, from around 10 cm below the surface.


Same section between crossed polarizers to show some of the crystal structure.



Larger, more clearly defined crystals in a horizontal cross section of the core.

Also, because everyone likes charismatic megafauna, here is a Svalbardian reindeer! (“Reindeer” in English means a domesticated caribou, but the Svalbard ones are wild.)

This reindeer is foraging just a short ways from our lodgings.

A Compendium of Measurements

May 1, 2011

So what does a typical day of fieldwork look like, for this trip?

The first order of business is to actually get to the field site, Tempelfjorden. It’s around fifty or sixty kilometers (thirty to thirty-five miles) away from Longyearbyen by snowmobile, which is the conveyance of choice. Snowmobiles have numerous benefits: they’re fast, they can pull good-sized sleds full of equipment, they can deal with a wide range of snow and ice conditions, and they’re loud enough to repel polar bears.

The trip out takes one-and-a-half to two hours, depending on the light and snow conditions; for instance, it’s more difficult to drive fast on days with cloudy, diffuse light because snow features become very hard to see. It’s quite the scenic commute, although snowmobiling is more physically draining than you might expect if you’re not used to it. We arrive around 11 AM, if we’ve planned things right.



Time for a photo break.


Once we get to Tempelfjorden, Bonnie and SvalSteve select a good site for taking measurements–mainly they want something that’s not too close to well-traveled snowmobile routes, since Tempelfjorden is actually a reasonably popular tourist destination. (I discovered yesterday that there are actually daily snowmobile tours out there; it’s kind of cheering to find out that your field site is someplace people pay to go to. And the tourists only spend about eight hours on the roundtrip, but we get to be out doing science for THIRTEEN hours!) Once it’s selected, we get to work putting together the equipment.

Not scientific equipment, but nevertheless important, given that it's difficult to take sea ice measurements from inside a polar bear.

This has been an ambitious trip in terms of the number of measurements we’re trying to take on each day out. We measure snow and ice albedos, using a piece of equipment somewhat similar to the one I’ve used in Antarctica, only smaller and more portable (currently set up so it can be mounted in the Backpack of Science, of which I have a picture around here somewhere.)

Bonnie and Naomi take albedos of the bare ice.

We measure the transmission of light through the ice using several instruments mounted on two different arms, Bonnie’s and SvalSteve’s.

Bonnie's arm. When it's underwater, the foam makes the lower part float upwards so that the instruments are right under the ice, some distance from the hole.

SvalSteve and colleague Mats carrying their arm. It has two different instruments, one for general transmitted light and one for transmitted UV radiation.

We drill a hole through the ice to make a detailed profile of the light at each level within it.

Naomi calibrating the profiler.

We make ice cores to be melted and filtered a few different ways and additional cores to slice thin and put under the microscope.

SvalSteve drills a core the fast way, with a motor.

We dig snow pits (to measure profiles of snow characteristics such as density) and take snow samples so we can melt and filter those too.

SvalSteve and Naomi work on a snow pit.

Phew. By the time we’re done with all of that and have packed away all the equipment, it’s late in the day, and we generally get back to Longyearbyen just in time to rush to a local restaurant before they stop serving food at 11 P.M.

Next: more about how all that equipment actually works, and what we get up to in the lab!

The many qualities of light

April 28, 2011

Yesterday’s fieldwork was bright and hot; it got up to 37 degrees Fahrenheit at one point. Here Bonnie and Naomi prepare to put the under-ice arm (which carries sensors below the sea ice to measure the transmission of light) through a hole we’ve drilled in the ice.

Svalbusiness

April 26, 2011

I really must remember that there are times and places for short sweet blog posts, and that one of those times is during very busy fieldwork days. It’s a bit of a catch-22, actually; there’s so much going on that the number of things I want to write about increases in inverse proportion to the time available to write about them. Our lodgings don’t have Internet, so my usual tactic of forgoing a little sleep to write blogs at the end of the day doesn’t work as well.

So far we’ve been out to the field twice and spent the rest of our time mostly in the lab. Our field site is a fjord about forty or fifty kilometers from town, called Tempelfjorden; we commute there on snowmobiles (“scooters” in the local parlance) which makes for a lengthy but scenic trip. Out on the ice, we make a plethora of measurements and take numerous samples–mostly of ice, but also of the snow on top of the ice. It’s been remarkably warm, near freezing most of the time; I get much colder working in the cold lab to process the samples than I ever do out on the ice making them.

We’re headed out again tomorrow; in the meantime, here are some pictures from our fieldwork.

Svalblog!

April 21, 2011

Hello! I’m writing from Longyearbyen, in Svalbard. I actually got here yesterday afternoon, but was a bit too jet-lagged and befuddled by my ~24 hours of travel (Seattle to Newark to Oslo to Tromso to Longyearbyen) to do much.

I am surprised at how much this place reminds me of Antarctica, with its stark black-and-white scenery. One notable difference is the open water that comes right up to the land. We’ll be visiting some landfast (frozen to the shore) sea ice when we go to the field, but near the town the water is unfrozen. Our host/guide, Steve (not to be confused with my advisor Steve; maybe I will start calling him SvalSteve to avoid confusion), says this is due to warm Atlantic currents. Longyearbyen is slightly further North than McMurdo station is South, but due to its weather patterns and currents it’s notably warmer. Of course, it’s also warm because it’s Spring; the last sunset of the season was the day before we arrived, and a lot of residents will soon be leaving for the Easter holiday.

From Journey to Svalbard

Some Svalbard scenery.

There’s a surprising amount of tourism in this small city. People come to ski and hike and snowmobile and see polar bears; there are several sporting-goods stores near the short pedestrian corridor that serves as a sort of downtown. Snowmobiling appears to be a popular form of transport, with snowmobiles outnumbering cars two or three to one. Rifles are commonplace, since anytime you leave the city you’re apt to run into polar bears. (It’s rare that anyone actually shoots a bear, mind you; it’s very illegal to do it for any reason except desperate self-defense, and even self-defense cases are rigorously investigated.)



Snowmobile + rifle = typical Svalbard.

I’m here helping my colleague Bonnie do a project with the Norwegian Polar Institute–more on that later, as it sounds like tomorrow will be a long fieldwork day (we spent all of today sorting and prepping gear for it.) In the meantime, check out the blog of the other student accompanying us, Naomi to the North.


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