Thursday, January 30, 2014

Loneliest gas station

Refueling at what Neil likes to call
"The loneliest gas station in the world"

Saturday, January 25, 2014

continuous GPS unit and Matt

It was a windy day servicing seismic instruments. Here's Grace and I
hunkering behind a skidoo, snow blowing around us.

Four boreholes drilled successfully

26 January 2014
Site 2b, Whillans Ice Stream

When we first arrived to the grounding zone, the light on the mountains was gorgeous.
Site 2A location, Bush Mts in the background
Slawek with the seispod at the bottom of the cable.
Back row: Grace, Slawek
Middle row: Susan, Dan, Neil, Matt
Front: Me

This afternoon we finished deploying instruments in our fourth and last borehole. These last two boreholes were located near the grounding line of the Whillans Ice Stream.

We have been doing maintenance on a GPS array
near here that has been collecting data for the past couple years. We were excited to find that several of them have been running throughout the entire year, being powered by solar energy in the summer and wind energy in the winter. Today we will put in a few more GPS units. Tomorrow is a packing day and then we head back to the now-almost-abandoned CReSIS camp for our flight out of the field. We are really happy with what we have been able to accomplish this season!

Sunday, January 19, 2014

2 holes drilled

19 January 2014
Site 1B, Whillans Ice Stream, Antarctica

The traverse is off!

We did have flat light for our journey out to the first borehole location but the journey went fairly smoothly with a few adjustments to our sled loads.

A mid-journey break
The scientists on skidoos and the drillers on the traverse pulled up to the location which would be the site of our first borehole. It was marked by a seismic station, on the surface a box and solar panel, which looked miniscule by comparison with the large tractors and the wide ruts they made in the soft snow. The drillers got right to work and by lunchtime the next day the hole was finished. We found out the approximate thickness of the ice from the CReSIS team based on the raw data from this year's survey so that we could avoid entering the subglacial environment, not being equipped with clean access technology as we were last year.

Drill Site 1
Water hose rigged for drilling

The depth of this hole was 690 meters and took about 12 hours to drill. The drill uses hot water to melt the ice. At its maximum speed, it melts the hole at 1 meters per minute and exits the hole at a rate of 2 meters per minute, also pumping hot water to keep it open. The hole ends up 0.8 meters across.

Tiltmeter above seispod about to go down the hole.
My job for part of the deployment was to
ziptie the cables together as we put them
down the hole.
Then us scientists set up reels of cables to send our equipment down the hole. This equipment includes small seismic sensors, and distributed tilt meters. These all went down the hole simultaneously, taping the cables together as we went. All of our equipment was in by dinner and so far everything is running as it should. We are all happy with this success.

Bulldozer pushing snow into the hot water tank.
We repeated the process at the second hole, which is located a little more than a kilometer from the first hole. At this distance, we think that both sensors will be able to detect some of the same seismic events. Both of these boreholes lie within the zone of high seismic noise we detected over the course of last year, indicating sticky motion of the ice over its bed. This time, we sent down distributed temperature sensors in addition to the instruments used at the last hole. When we had deployed about 300 meters of cable some bit of the cable got caught on the wall of the hole. We tried raising and lowering the cable a few meters to get past but we soon found that the cable was frozen at that point, for it took a lot of force to turn the reel. We would have liked to get closer to the bed, but we still expect to get a better seismic signal of the stick-slip motion at half the ice thickness than at the surface.

Me with the GPS receiver.

Today Slawek and I took static GPS measurements in a line perpendicular to
the flow of the Whillans Ice Stream with subglacial Lake 7 at one end and stretching across the seismic array within which we have been drilling. We set flags in the locations of our measurements so we can return next year and see how far the ice has moved. We expect we might see the sticky spot slowing down ice flow.

Tomorrow we travel forty kilometers to the grounding zone, where we will drill two more holes. I'm excited to go to a new location for the last 11 days of the project.

Monday, January 13, 2014

Field update: 6-man operation

14 January 2013
CReSIS camp, Antarctica

A belated happy new year to you all! On New Year's Day we set out from CReSIS camp toward the Transantarctic Mountains. It was slow going with all of our camp gear and some of our science gear, and we arrived late in the evening to our chosen patch of ice.

 From the cleanest, whitest slate we began constructing our town, equipped with a kitchen tent (yellow above), science tent (red and blue above), bathroom (read: hole with a tent overhead, orange above), mountain tents for sleeping, and a few pee flags. Most of our time at camp is spent in the kitchen tent, where we spend a lot of time melting drinking water from snow, eating and talking. The floor in the middle of the tent is compacting and melting at a greater rate than the rest, and chairs and
tables are starting to list toward the middle.

Just enough room for my sleeping bag
and luggage.
A bit of drifting around my mountain tent
 The snow beneath my tent that is not insulated by my sleeping pads has also melted significantly - those mountain tents get hot enough to make a fleece bag liner sufficient at night. The weather has been quite nice, most days between -4 and -2 degrees C and sunny. The wind comes in pretty steadily from the Ross Sea and one day picked up enough to make huge drifts around camp. I find the undulating topography behind our line of snowmobiles rather fun; the spacing is perfect to leap from one drift to the next.

We have now been out in the field two weeks. We have visited the seismometers we left on the ice last year and collected the data. The data does show the slip events that we hope to study further and has some interesting patterns associated with different stages of these slip events. Grace is using this data to design a distribution of seismometers that will allow us to constrain the geometry of the sticky spot at the ice-bed interface. We are installing seismometers in these new locations. The sensor itself is buried several feet below the surface to get better coupling to the snow and to increase the odds that it will remain level through the year. After placing the sensor we test the reception on three
channels corresponding to three axes oriented vertically, north-south and east-west by jumping up and down. Neil, Grace and Doug are also using active seismics, creating a wave by hitting the ice with a mallet, targeting the regions with a lot of seismic noise. The reflection from the bed should give us information about the characteristics of the bed surface. This season the CReSIS team collected airborne radar data on the Whillans Ice Stream that will show internal ice layers and the ice-bed interface when it is processed.

We took a trip out to Subglacial Lake Mercer, another one of the lakes in this regional hydrologic system that has been active in the past decade. GPS stations have been collecting data there for the past two years. Matt, Slawek and I travelled there to service the stations, installing new turbines on one of them and removing another (see photo). The one we moved will help us calibrate the GPS measurements we will be taking at locations in a grid once this season and once next season to measure a year of movement over the sticky spots and at the grounding zone.

The traverse has arrived at CReSIS camp with our equipment, and they will be heading straight to the site of the first borehole we will drill this season. We traveled to CReSIS camp to meet the traverse and welcome Susan Schwartz and Dan Sampson from UC Santa Cruz and the drillers, who arrived
by plane. We are very excited to start this new phase of the project. We said good-bye to Doug Bloomquist, who has been a huge help in getting the seismometers installed and running. While we are here, Slawek collected distributed temperature measurements down the hole from the surface to
Subglacial Lake Whillans. The sensor string was lowered into the hole last season and is now completely frozen into the ice. Today we leave by skidoos with Susan and Dan for our camp, which will pack up and move closer to the drill site. This morning I awoke to a fog that wipes out
the horizon completely. I hope we get better visibility soon so that our newcomers can enjoy a view of the mountains on our journey. Here's to smooth travels! Off to loading sleds -