Posts Tagged ‘Science’

Firn Chantey

November 27, 2012

This is about the work I’ll be presenting at AGU. Written at the request of the University of Alaska Fairbanks crowd, sung to the tune of The Sailor’s Prayer (not to be confused with the somewhat more serious “Sailor’s Prayer” that’s the first Google result for that song title.) I very much want to record all these and post videos, but I haven’t really worked out a good recording setup.

If we wish to learn
About the firn
Upon the ice sheets polar
We’ll want to know
About the snow-
fall and the input solar

Chorus: Oh, snow is white
And clean, and bright
A tricky thing to model
But easy flowed
The Matlab code
‘Longside a friendly bottle

Some grains of snow
Will slowly grow
While others are a-shrinkin’
Which ones win out
Is still in doubt
And needs a bit of thinkin’


Grains change their state
They sublimate
From many different places
When they commence
To recondense
They prefer partic’lar faces


And so we find
Grains are aligned
C-axes all together
And from this state
We can relate
Ice flow to ancient weather

(chorus again, with FEELING)


The Ballad of AGU

November 27, 2012

The American Geophysical Union Fall Meeting (usually just referred to as AGU) is when something like 15,000 scientists descend on San Francisco’s Financial District for a week. There are talks and posters, of course (so many talks and posters!) but as with any convention the main point is to connect with new colleagues and re-connect with old friends. This is a poem I wrote for the Cryosphere gathering at AGU a couple of years ago. The meter and rhyme scheme are modeled after “The Egyptian Diamond” by Randall Garrett.

I will be at AGU again next week! Monday is Science Open Mic Night at Jillian’s Billiards Club, so I have to decide what to perform, which is going to be tricky.

The Ballad of AGU

Sunday, just a bit past five
And you’re feeling half alive
With your poster on your shoulder as you stumble to your flight
You’ve been staying up too late
Your data won’t cooperate
And you found a whole new error around ten PM last night.

But now you’re at AGU
There’s a million things to do
There are friends from far-off places who you haven’t seen all year
In the morning, though, I’m betting
You will find yourself regretting
That moment you decided “Sure, I’ll have another beer!”

Bright and early, you will fight
The grand excesses of last night
You will struggle bravely out of bed and stagger to Moscone
There’s a talk you must attend
By an early-rising friend
And a cutting-edge announcement you suspect might be baloney

Now you’ve coffee cup in hand,
with which to aid your mental band-
width, for a firehose of data’s aimed directly at your brain
There’s a clever new device
To gauge the temperature of ice
And a host of novel ways to watch a glacier from a plane

There’s a brand-new data set
Barely even processed yet
That details the Greenland ice sheet’s elevation, shape and speed
There’s a fellow at a booth
Who, if his pitch has any truth
Sells an instrumental system that does everything you need

There’s an algorithmic way
To take the data from a day
And extrapolate behavior of the system for a week
There’s a dozen gloomy talks
On how the planet’s on the rocks
And the global warming outlook’s gotten just a bit more bleak

Then, before you’re really read
When your spiel is still unsteady
You’re onstage—your poster’s posted and your work you must explain
Visitors interrogate you
Some to praise, some to deflate you
And your voice is going hoarse from giving out the same refrain

But look! some kind soul brought beer
And the end is getting near
And suddenly it’s over, just as quick as it begun
Battling through the teeming streets
You reach a trove of drinks and treats
And the denizens of Cryosphere are here to have some fun!

Whys and Wherefores

January 4, 2011

This one’s a bit late–sorry about that! I’ve gone for a longer post to make up for the tardiness.

Antarctica, as you may have noticed, is a long way away from almost everything. And even aside from being distant, it’s logistically tricky to get to. The Southern Ocean is stormy and mercurial at the best of times, every iota of fuel and supplies must be shipped in, and the preponderance of ice and snow presents its own special problems. So why have we made the trek back once again?

You may recall that last year we came down seeking types of ice that can’t be found anywhere else on Earth: sea ice so cold that the salts trapped within it can crystallize, and ice whose surface has sublimated away to leave behind a crust of the salt mirabilite. This year we’re once again seeking ice that exists nowhere else. In this case, we’re looking for ice that has formed from the accumulation of snow and eventually become re-exposed to the sun by sublimation without ever experiencing temperatures above freezing.

There are three main layers to the Antarctic ice sheet. At the surface is snow. Over time, as surface snow is buried by the accumulation of later years, it compacts and grows dense and hard. This deep-down, compacted snow is called firn. In the rest of the world “firn” simply means snow that has survived through the summer melt season, but in Antarctica, where there is no summer melt season except at a few places near the coast, firn is sometimes defined as snow that has reached a certain density (550 kilograms per cubic meter, which is the density at which simple rearrangement of ice particles gives way to more complicated densification processes.) The firn continues to grow denser under the weight of the snow and firn above it until the spaces between snow grains close off to become bubbles, and the firn becomes ice.

Blue ice stratigraphy

The ice flows under its own weight. In some places, the ice surface may flow into an area of the ice sheet where sun and wind vaporize (or sublimate, which means to turn directly from solid to vapor) the snow faster than it can accumulate. In this case, the snow on the surface will sublimate away, exposing the firn below and eventually the ice. And that firn and ice—exposed to the sun, yet never melted—is unique to Antarctica. These “blue ice zones” are of interest to meteorite hunters, because meteorites that may have been buried in the snow become exposed, and are easy to spot on the surface. My colleagues already found and collected some meteorites during their first trip out.

We’re interested for a different reason, though–we want to know how much light reflects off of these blue ice zones, because there would have been a lot of them on Snowball Earth. (Here’s a great article in the Antarctic Sun that talks about our research.) Many areas of Snowball Earth, particularly near the equator, would have been so dry that snow sublimated away faster than it could accumulate.

These areas of exposed blue ice, being much darker than snow, would have absorbed a lot of sunlight and had a significant effect on the planet’s balance of energy. So knowing exactly how much sunlight they absorb is important to people trying to model Snowball Earth.

So that’s why we’re here. Mostly, anyway–some of us, including myself, also have a keen interest in snow and want to do some side projects involving the microstructure of snow and bubbly ice. But more on that later!

Ice team splits up

December 31, 2010

As I mentioned in my last post, when Martin and I arrived on the Ice the rest of our team–Mel, Peter, Ruschle, and my advisor Steve–were still out in the field. They all finally made it back on Wednesday, and so we’ve been busily exchanging information before Steve and Peter headed back out into the Real World, leaving Martin and I to take their places.

I’m working on bios for everybody–I don’t like to post them without running them past the people they’re about–but I wanted to put up a few photos of the team:

Back row: me, Peter, Steve. Front row: Martin, Mel, Ruschle.

Testing out some equipment.

Steve and Peter actually headed out this morning, after a day’s delay due to runway issues.

One of the tricky things about Antarctica, you see, is its general lack of dry, non-ice-covered land; not only is there not much of it, what land does exist is of considerable scientific interest and therefore not usable for logistics. So the runways are built on the ice shelf (Pegasus, the ‘permanent’ runway) or the sea ice near station, which is a good 1.5 meters (around five feet) thick in the winter and spring and thus more than capable of supporting the weight of a C-17. It’s too far into summer now for the sea ice runway to be considered usable, so all the flights land at Pegasus, some ways from station.

Generally these runways work fine. But snow and ice are notably less durable than asphalt, in many ways, and so when a C-17 had trouble taking off during warm conditions earlier this week, it ended up gouging a lengthy hole in the packed-snow runway at Pegasus. As a result, they delayed flights by a day to see if they could fix it, and then ended up sending passengers home on C-130 ski-equipped aircraft when they couldn’t get it up to suitable standards in time for a C-17 flight. My friend Jessie, on the medical staff here, wrote a great post about the runway issues.

Back to the Ice

December 22, 2010

I’m leaving for the Ice again in two days.

How did this happen? I spent the last few weeks getting ready for and attending the big geophysics conference in San Francisco, and now all of a sudden it’s time to leave. I’m mostly packed; I picked up some new gear, and after all my troubles with glasses fogging up last year, I ordered some disposable contact lenses to use instead. Although I still need to find out if contacts can survive freezing solid. Anybody happen to know?

In lieu of actual science content, which may have to wait until I’m finished packing, here is a chantey I wrote about my upcoming trip. Sea chanteys are the songs that sailors used to coordinate the pulling of ropes and hoisting of anchors and whatnot, as well as just to pass the time on long ocean voyages.

This one should be sung to the tune of “Bound for South Australia” (here’s a nice rendition.) I tried to include some traditional sea chantey elements–lots of heaving and hauling, of course, of which there is a fair bit when you’re working in Antarctica, as well as complaints about the difficulty of the journey, longings for bonnie lasses, et cetera.

McMurdo Bound, or, Way South of South Australia, a minimally processed a capella version sung by yours truly.

Antarctica is where I’m bound
Heave away, haul away
I’m headed for McMurdo Sound
Yes, bound for old McMurdo

Haul away, my icy friends
Heave away, haul away
Haul until the season ends
We’re bound for old McMurdo

I’ll board a plane in old Christchurch
And head down south to do research
Haul away…

The Southern Ocean’s very wide
Eight hours’ flight to the other side
Haul away…

The storms blow up at a frightful pace
Can’t see your hand before your face
Haul away…

From blinding sun there’s no respite
For Mactown has no summer night
Haul away…

If you’d like a girl upon your knee
There’s a bonnie lass behind ev’ry tree
Haul away…

Keep gear at hand, ’cause if it’s not
You might end up like poor old Scott
Haul away…

The Altered Nature of Things

September 4, 2009

One of the weirdest things about the extreme cold is the way familiar substances begin to betray your expectations. Plastics stiffen and become brittle after just a few seconds’ exposure to the outside air. Metal burns to the touch. Moving parts freeze together or shrink apart. Batteries dwindle to a fraction of their former capacity and LCDs update sluggishly. The various vital fluids of vehicles freeze and coagulate. I can’t even imagine how much more bizarre and difficult it is at the South Pole, where ambient temperatures regularly dip below -100F.

We had a lot of this out in the field today. My issues with spectacles persist (frosting over completely, attempting to freeze to my face, what have you) and the goggles do nothing don’t help very much. (The little fan died their first day out, as I sort of expected it to do.) Our ice corer nearly got stuck in the ice. And our electronic thermometer, which we use to take the temperature of ice cores, refuses to function properly when it gets too cold. This meant I spent quite a while with it stuck down the front of my pants, nestled against my belly, trying to get it warm enough to give a reading–like an emperor penguin incubating an egg, as my advisor put it.

Speaking of penguins, I saw my first sign of the local wildlife today. Small clouds of steam, puffing up from a crack in the sea ice once a second or so: a Weddell seal at a breathing hole. We didn’t see the actual seal, of course. Weddell seals are fascinating creatures. They live under the sea ice, so they have to breathe through any cracks or holes in the ice they can find. They keep them open by chewing away at the ice as the holes freeze over. Any hole in the ice is likely to attract a Weddell seal; Antarctic divers often find themselves suddenly sharing their diving hole with a half-ton of blubbery, snorting Weddell, and our Kiwi friends say that their little hut on the sea ice has been visited (and splattered with seal snot) more than once.

A Weddell seal breathing hole in a sea ice crack.

It seems like a precarious lifestyle, being dependent upon the ever-shifting sea ice just to be able to breathe. Antarctic animals are a resilient and determined lot.

Salt, Sea Ice and Science

August 27, 2009

Science-wise, our team has been busy getting settled in to the lab and taking all the trainings required for us to be allowed to do things. We won’t be able to get out on the ice until after our Sea Ice Training on Friday, so I thought I’d take this opportunity to talk a little about the actual science we’ll be doing.

You may recall from earlier posts how increased albedo can lead to a Snowball and CO2 can end one. As the planet cooled off and the climate system change, new types of ice could form that are rarely, if ever, found on our modern Earth. That’s why we’re down here in Antarctica in the winter–to find modern analogs of this very, very cold ice.

During our first couple of weeks here we’ll be looking for cold sea ice. “Sea ice” in science terms means ice that forms when seawater freezes–ice that formed from fresh water just happens to be floating on the sea, like icebergs, doesn’t count. When sea water begins to freeze, it forms a large number of small crystals of ice, called frazil. This stage is also called “grease ice” because it looks a bit like an oil slick on the water. Eventually the crystals begin freezing together into a solid sheet. As they freeze they trap small pockets of salt water, and these are what we’re really interested in.

As you may know, salt lowers the melting point of ice so that it becomes liquid at lower temperatures, a property that is useful when melting ice off of driveways or making ice cream by hand. Sea water averages about 3.5% salt (that’s six or seven teaspoons in a quart of salt for you American types, or 35g in a liter for the rest.) This particular salinity level means it freezes at 28F or -2C. As it freezes, the ice pushes out the salt, and the water in the pockets of salt water–the brine pores–gets saltier. If the ice gets colder, this saltier water will also start to freeze, pushing out more salt and making the brine pockets smaller and saltier still.

At -9F/-23C, some of the salt in the water starts to form crystals, called hydrohalite. Like the many small crystals in snow or table salt, these crystals of hydrohalite are good at scattering light. By sending light back out the way it came, the crystals in the brine pockets can increase the amount of light reflected from the sea ice. Our colleague Bonnie Light demonstrated this effect in the lab, and we are hoping to find it out in the field. These albedo measurements will help improve models of Snowball Earth. Because so much area in the sunlit tropics is covered in sea ice on Snowball Earth, small changes in albedo can have large effects, so it’s helpful to have measurements that are as accurate as possible.

Not all of our equipment is here or unpacked yet, but I’ll post photos when it is.