I sat down to write a simple little science piece tonight. Turns out that the fact i am not a natural writer is never more self evident than when i have something simple to explain. And a saw thumb. Two of them actually. The right thumb injury from a (still unexplainable) sticky tape dispenser incident at work. This is fine because i never use it to type. Ever. The left one however it turns out of DO use. A lot. And it hurts. This injury occurred today as i was preparing food platters for the Christmas party. I was trying to remove one of this plastic lids from a dip. I think it was Hommus. Not that the type of dip is important. Just know that it is taking me ages to type....and i make a hash of spelling at the best of times.
Now to the science bit. Actually, sorry, a bit of background first.
One of the most fascinating aspects of my research has been the breadth of knowledge needed to understand polynyas. This is highlighted in a paper published in Annals of Glaciology (33) called “Effects of Regional Fast-Ice and Iceberg Distributions on the Behaviour of the Mertz Glacier Polynya, East Antarctica” [massom et al]. This paper highlighted some of the many factors that come into play which determine a polynya and its associated measurable parameters (size, width, shape, duration, open mechanism, closing mechanisms etc).
One of the mechanisms is the strong katabatic drainage (sweeping off the ice sheet). These strong winds drive ice away from the coastline (or fast ice, an ice bridge etc). The polynya forms by initially sea ice being driven away from the coast, which leaves an area of open water within which new ice is formed [This new ice is then herded down wind (by ocean, winds etc)].
If you want precise information then try the International Antarctic Weather Forecasting Handbook at:
http://www.antarctica.ac.uk/met/momu/International_Antarctic_Weather_Forecasting_Handbook/index.php
Or read the excellent paper (Chapter 2 details the wind stuff [i know. I amaze even me with how little i sound like a scientist too]):
Or read the excellent paper (Chapter 2 details the wind stuff [i know. I amaze even me with how little i sound like a scientist too]):
Bromwich, D. H., 1989, Satellite analysis of Antarctic katabatic wind behaviour. Bulletin of the American Meteorological Society, 70, 738–749.
The thing about these strong winds (Commonwealth Bay is known as one of the windiest places on earth) is that they dissipate not far from land. Given this information what i want to highlight is the difference between having meteorological data from a location n the polynya and from a land based station near the polynya. They do differ and that is why every bit of information helps.
These two images represent meteorological data presented in “wind rose” form. That is the wind speed and direction from a fixed point (the centre of the rose). The first is data collected at the D’umont Durville station (over a 6 week period in winter). This compares to a fixed station further seaward. You can see where the strong winds come from the same direction (in general) however weaker wind systems can be recorded from any direction. This is less likely at the station where there is generally speaking strong katabatic flow. The roses were recorded at the same time.
As the fixed stations have more reliable and longer term data they are what is used most often for other research activities. The difference between the images highlights the natural variability for measuring a phenomenon even (relatively) closely. Say between at station and a ship (in polynya). Also, why drones over a polynya are necessary. And cool:
Another interesting little thing i have been re-reading about (which has nothing to do with my PhD at all) is sastrugi. More pointedly the remote sensing analysis of them (i did this AGES ago so this is all from memory). Now sastrugi (which is the plural form) are sharp irregular grooves or ridges formed on a snow surface by wind erosion and deposition, and found in polar and temperate snow regions. They differ from sand dunes in that the ridges are parallel to the prevailing winds. That means that if you have remotely sensed data you can determine the prevailing wind directions. Cool yeah? Now you just know it is all more complicated than that. It always is.
Anyway my injured digits need to go have a rest. So do i. Also big Bang theory is on the telly.
I might not get a chance to blog before Xmas (unless the weather is really bad and i have to stay inside all week) so let me wish you a happy and safe holiday. XX
[BTW the xmas party was alright. I got to sit on the floor as there weren’t enough chairs. Some might think this not so good but it did mean i didn’t have to talk to people sitting next to me (even though i like them). I am just a bit socially impaired and suck at parties unless everyone else is drunk in which case i don’t feel less shy. I also scored an excellent secret santa gift (this year).]
it took two reads of every paragraph to engage my dormant science brain, but very good and readable...despite the thumbjury! get ye thumbs better soon, babe. xox
ReplyDeleteoh! Bear. i wasn't even trying to be science like. no wonder people (civilians) never want to talk shop with me *grin*. i promise to never send you a copy of my thesis (should i ever finish it).
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