More Digging? Seriously? We Have To Dig To Do Research?
Anyway, I digress. One of the science projects we did while in the field was looking at snow accumulation at our campsite at Windless Bight. Why?
So, to find out about snow accumulation, we dug 2m snow pits. That’s right, 2m deep. I mentioned we were at digging boot camp didn’t I? Once we’d got down 1m we took measurements every 100mm of snow density, hardness, and temperature. Then we dug another 1m down, and did measurements for the second half of the pit. Exciting huh?
If you’re wondering how these things are measured, I have to admit, it’s not very high-tech. For density we simply filled a cylinder with snow, and then weighed the snow. Since we knew the volume of the cylinder, we could work out the density (which equals mass/volume for those of you who did high school physics a while ago).
Hardness is measured using the extremely non-technical method of seeing what you could stick into the snow. If you can push your fist in, then the hardness is 1 (i.e. not hard at all). If that doesn’t work, then you try to push in four fingers, then one finger, then a pencil, and finally a knife (hardness = 5). If you can’t even get a knife in, then it is automatically a hardness of 6. The upside of this method is that you don’t need a degree to operate the equipment. The downsides are that: a) you don’t get to play with cool equipment, and b) your hand gets cold since you keep sticking it in the snow.
Once we’d done all that digging and measuring, you’d think we could take a well-deserved break. But no. Instead, the hardiest souls in the group banded together, and continued digging one of the pits down to a very respectable 3.8m. Apparently the record for PCAS is 6m; all I can say is that a lot of people must have loved digging the year that happened!
Anyway, having done all of these measurements, what did we find out? After analysing the data at home, I discovered that Windless Bight gets approximately 1m of snow accumulation a year. I worked this out based on the layers that we observed in the pit – an ice layer corresponded to summer (melted snow froze to become ice), as did a dust layer (exposed soil due to melted snow gets blown around). That’s a fairly healthy level of snow accumulation, and indeed, research has shown that Windless Bight is an area of high accumulation. What is less well-known is the rate of ablation (loss of mass). Losses from the ice shelf can happen through iceberg calving, melting, or sublimation – which nicely brings us back to one of my previous blog posts. The radar we set up is measuring the thickness of the ice shelf at Windless Bight over a year, gathering data as to what is happening underneath the shelf. Pretty cool huh?
For the present though, it looks as though the Ross Ice Shelf is here to stay, which is pretty good news.