Science Plan

December 23, 2013
McMurdo Station, Antarctica

Here's a quick recap of what's been going on so far down here, and then I'll share with you our plans for the season.  It has now been three weeks since we left Santa Cruz.  We have gotten all camping gear and food and some of our equipment palletized and ready to be loaded onto an LC-130, which will fly us out to our field site.  We were originally scheduled to fly on Friday, December 20.  There is not currently a plane on base that can take us.  Three flights were scheduled to fly from Christ Church to McMurdo today.  Two of them are cancelled already and the weather is not looking great.  If we don't get out tomorrow we'll be here through the Christmas holiday.  The next date we may be able to fly would be Friday.  The days we are delayed are not added on to the end of our season, so we hope to get out soon and get the science done. 

This well-known ice velocity figure generated by Eric Rignot
shows what we mean by ice streams.  They are the high velocity
(blue to purple) regions that extend inland.

So, what are we doing this season?  The focus this season is studying how ice flows over the bed.  Ice streams are regions of faster flowing ice within a much larger volume of ice which in our case is the West Antarctic Ice Sheet (right).  The ice stream we will be studying, the Whillans Ice Stream, is relatively slow-moving because it is moving down a shallow slope.  Its flow is so interesting to us because it is in sync with the tides.  The ice here is grounded on weak sediment but it still gets stuck in places and then slips forward once per day as the tides change. Our colleague Martin Pratt has identified two locations where these slip events initiate, marked on the map below as Sites 1 and 2.  When the ice slips it generates seismic waves which we can detect with seismometers placed on the ice.  This season we will be installing seismometers both on the surface and down boreholes so that we can better localize the slip events and learn more about how the characteristics of this signal.  We also use GPS grids to understand the spatial distribution of flow and infer the frictional properties of the bed.  We measure the ice stream's motion on short timescales with continuous GPS, of which we have a few instruments, and long-term changes with sticks, of which we have hundreds, whose location we'll measure in a year. 

The ice-bed interactions are complicated by the presence of subglacial lakes and rivers, whose water levels and flow paths may change with time.  Last season, WISSARD drilled into subglacial lake Whillans (labeled 'SLW Camp' below) and, using clean access techniques, found native microbes (chemoautotrophs).  A group from the Center for the Remote Sensing of Ice Sheets (CReSIS) will be occupying the SLW camp this year and conducting ground-based and aerial radar surveys.

Next year, we hope to drill to the grounding zone in order to investigate ice-ocean interactions, the biological communities at this interface, and the stability of ice streams as is believed to be offered by sedimentary wedges located at the grounding zone.  In order to aid these investigations, we plan to lay out GPS grids at the future grounding zone camp (labeled 'GZ Camp' below) this year, continuing and extending our record of ice flow.  There is a legacy of fieldwork on the Whillans Ice Stream which has guided us in designing our field plan and will be immensely valuable to us as we interpret our data.

Satellite data from the Canadian RADARSAT-1 Antarctic Mapping Mission (AMM-1)