Posts Tagged ‘glaciers’

McCarthy Glaciology Summer School 2010: In Limerick Form

November 29, 2012

These are some limericks I wrote while attending the 2010 Glaciology Summer School in McCarthy, Alaska. I tried to write one about each subject that was covered in lecture, although I think there are a few missing. N.B.: the tidewater-glacier-as-leveraged-bank analogy is from the actual lecture.

Ice dynamics
Though its speed is exceedingly low,
Ice is fluid, as glacier shapes show.
Non-Newtonian viscosity
Determines velocity
According to Glen’s law of flow.

Ice fabric and anisotropy
At the microscale, ice grain migrations
Derive from crystalline dislocations
Anisotropies cause
New constitutive laws
To account for in our simulations.

Subglacial hydrology
Water flows through the glacier like blood
Makes it slide over bedrock and mud
When a tunnel melts through
Or ice dam breaks in two
Out comes pouring a Biblical flood

Tidewater glaciers
When these tidewater glaciers retreat
The destruction’s both fast and complete
It advances again
On a borrowed moraine
Like a leveraged bank on Wall Street

Mass balance
Adding up rain, wind, heat, cloud and sun
To get melt isn’t very much fun
You could try degree-day
It’s an easier way
But a somewhat less accurate one

Glacial thermodynamics
Now the species of glaciers are three
Cold are fully below zero C
Temperate’s always at freezing
Polythermal’s a pleasing
Combination of types A and B

Remote sensing with ICESat
When inspecting the tracks of ICESat
Look for spots that are curiously flat
Or locations that flex
From concave to convex
It’s a subglacial lake doing that!

Gravitational remote sensing
For the weighing of glaciers, a scale
Is inevitably much too frail
But science saves face
By celestial GRACE
Which delivers the mass-balance Grail

Laser Altimetry
To determine an ice-surface height
Send out regular pulses of light
Measure time to bounce back
Then, repeating your track
Demonstrates warming glaciers’ dire plight

Inverse methods
To extrapolate former conditions
Using presently measured positions
Although methods inverse
May inspire you to curse
They’ll reveal past climatic transitions

Debris-covered glaciers
Grand white Kennicott looms above town
But its foot is all filthy and brown
If we clean off the sand
It’ll look mighty grand
Till, uncovered, it melts, and we drown.

The consequences of setting forty glaciologists loose on a small town’s alcohol supply
There’s a flow law for ice strain and shear
What we need is a flow law for beer
Given glacier grads, N,
And a drink rate X, when
Will all booze on the shelves disappear?

Other people talk about ice!

June 25, 2011

I’ve been trying to do more with this blog than just write text and post it—WordPress offers a wide variety of features, and blogging is at its best when it’s part of a larger ecosystem rather than just one person talking in isolation. So I’ve been adding links to the blogroll. Allow me to present a few here:

From a Glacier’s Perspective offers detailed descriptions of glacier retreat around the world, with each post focusing on a different glacier. This post describes how a glacial feature called ogives can be used to help measure glacier velocity. (Ogives are “ripples” in the glacier that form due to the influence of icefalls: the area of ice that happens to be going over the icefall during the summer melt season melts faster than the ice around it, leaving a trough that then moves down the glacier.)

The IceBridge Blog recounts news from NASA’s IceBridge Campaign. The aerial surveys of IceBridge use a variety of instruments–lasers, radar, even a gravimeter–to survey the Earth’s ice. The information gathered from IceBridge will “bridge” the gap between IceSAT-1, which stopped taking data in 2009, and IceSAT-2, which is scheduled for launch in 2016. The blog includes both pretty pictures of icy landscapes and discussions of the science behind the work, such as this post on how airborne gravimetry can tell us about the shape of the land below water and ice.

For those of you wanting to see more of Antarctica (one of my favorite continents!) there’s the “Landsat Image Mosaic of Antarctica (LIMA)” which allows you to pan and zoom all over the continent. Anthony Powell’s photography shows the place on a slightly more intimate scale, mostly around McMurdo and including some justly famed timelapse films. Or Maria Coryell-Martin’s Expeditionary Art captures both the Antarctic and the Arctic, capturing the feel of the icy realms in a way photographs sometimes can’t.

I’ll be adding more as time goes along! In particular, I want to find some good resources on ice elsewhere in the solar system, which is a fascinating subject I haven’t even gone into yet.