Archive for ‘Greenland Aquifer Expedition’

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Back in Kulusuk

August 18th, 2015 by Lynn Montgomery
Our camp setup on a cloudy night.

Our camp setup on a cloudy night.

Nick, Olivia, and Lynn enjoying a beautiful afternoon with lunch outside.

Nick, Olivia, and Lynn enjoying a beautiful afternoon with lunch outside.

After 18 long days of successful science and arctic adventures on the ice sheet, we were finally done and ready to head back to civilization. On the morning of August 13th, our expected pull out date, we received bad news from the pilots – they were not even in Kulusuk due to weather delays the day before. They planned to travel that morning and the next day to arrive so pickup should be in the coming days, however to call back later for an update. We went on with our day making pancakes and playing UNO because all the work and all the packing was complete, what else are scientists to do when all the science is done? We called the pilots in the afternoon for an update and got the best news possible – one pilot had arrived and was on his way to pick us all up that afternoon!

We headed back to Kulusuk just in time for dinner and had three sling loads come in the following days (August 14 and 15).   Huge thank-you to our fantastic pilots Diddi and Johannes for the smoothest and quickest field put in/pick up so far.

The helicopter taking in a sling load full of our gear.

The helicopter taking in a sling load full of our gear.

This field season could not have been more rewarding and efficient. We completed all our our science goals and even got some extra data. In the field, we were able to visit all four sites as well as check out some other interesting spots near camp and near the crevasses (though still at a very safe distance!). These extra sites were chosen based on ground based radar data processed and provided by Clem in the field. The field team even got overlapping measurements of radar, seismics, MRS, hydrology, and ice core data from the same site sometimes simultaneously!

When science overlaps -- Taking a seismic shot while drilling for ice cores and taking hydrological measurements of the aquifer!

When science overlaps — Taking a seismic shot while drilling for ice cores and taking hydrological measurements of the aquifer!

The weather was perfect almost every day, we only had two days of clouds and a bit of snow overnight. The winds would moderate in the morning and generally die down in the afternoon, but wonderful conditions for working as it was not too cold. This heat would cause a bit of melt at the surface in the afternoon with no winds which would make it a bit slushy, but work was always manageable. We took no rest days, as the weather did not permit us with any spending all of our time working, some days lasting 11-12 hours. However, we do not complain about the long hours, we take this time to work in great conditions as a huge gift not often seen in Southeast Greenland especially after our last field season.

As for the seismic portion of the mission, we are very happy to report that we were absolutely successful on all fronts. Due to some logistical issues, we decided to use a smaller version of the streamer cables, the one we brought in weighs only 65 pounds instead of the 350 pound original one which also required a snowmobile to tow. We ended up doing about seventeen lines in total at 6 different sites combined. One line corresponds to a 115 meter cable with 5 meter spacing on the geophones. We took shots from 80 meters before the line and 80 meters after the line as well as on the line at ten meter spacing allowing us a much finer spatial resolution for the incoming P-waves to determine the first arrivals. That translates to over 1500 manual hammer shots and almost 600 data files. We had some very sore backs some days but the team really pitched in to help out, even slightly bending the steel hammer plate by the end! We cannot wait to analyze the data and begin looking at results.

The seismic software setup.

The seismic software setup.

Here’s a video from the field showing how we collected the seismic measurements:

Science in the Fast Lane

August 10th, 2015 by Lora Koenig
MODIS Rapid Response Arctic Mosaic showing the clear weather over Southeast Greenland that is enabling great field science.

MODIS Rapid Response Arctic Mosaic showing the clear weather over Southeast Greenland that is enabling great field science.

The field team continues to have good weather and is ahead of schedule. They have completed the seismic and magnetic resonance soundings. They drilled into the aquifer about 15 meters below the surface and are starting hydrology measurements. All science equipment is running well and the team is in good spirits. There has only been one glitch this season so far; there was water in the fuel that was sent into the field. This has caused the generator and snowmobile to have some issues. A mechanic has been helping the team over the phone to fix the issues and over the next few days the team will be testing the reliability of the snowmobile.  Currently they keep the snowmobile within 5 kilometers of camp for safety, just in case they need to walk back. No major break downs yet though, so fingers crossed. They do need to reach a site that is 20 kilometers away from camp to service a weather station. If the snowmobile is deemed unreliable they will likely use the helicopter to complete the few science goals that remain. The team may even be out of the field soon so stay tuned for lots of great field pics and commentary to come.

Sending Seismic Waves Through the Ice

August 4th, 2015 by Lynn Montgomery and Nick Schmerr
Fog rolled in over the airport with the helicopter we'll be using in the background.

Fog rolled in over the airport with the helicopter we’ll be using in the background.

Anatoly, Nick, and I arrived in Kulusuk on July 24 after a very long journey from Maryland and France. We spent the day organizing and weighing gear from the container and are in serious need of a warm meal and good night’s sleep. This field season the seismic measurements are the top priority since they were delayed from the spring season.

The seismic portion of experiments will aid us in understanding the subsurface hydrological structure and composition of the ice sheet. These experiments are crucial for understanding how deeply the aquifer layer extends into the firn and capturing the variation in its thickness across the ice sheet. The main focus of our experiment is to use seismometers to measure the velocities of layers within the ice sheet. Based upon the various phases of water (ice, snow, and liquid water) present, we expect to see different wave speeds for each material. By examining how these wave speeds change with depth, we can deduce the relative amounts of how much water, ice, or snow is at depth.

To obtain these measurements, we will be using an active source seismic array that is being provided to us by the Incorporated Research Institutions for Seismology Portable Array Seismic Studies of the Continental Lithosphere Instrument Center. The array consists of multiple geophones attached to a towable streamer cable that will capture seismic waves propagating both along the surface and down through the ice sheet. We can move the array by towing it behind a snowmobile. To generate the seismic waves, we strike an aluminum plate with a sledgehammer to propagate a wave into the ice sheet. A single hammer strikes is typically called a “shot.” A multichannel seismic data collector connected to the seismometers then collects the ground motion recorded at each geophone, and sends the data to a computer where we can look at how long it took for the seismometers to receive data at different distances from the shot origin.

As the seismic waves travel through the ice, the time it takes for the seismometer to receive the vibration from the shot will be shorter or longer depending on the different velocities of material the wave travelled through. By looking at a number of different locations, we can then map out geographical variations in the thickness and character of the subsurface ice sheet structure. This effort is vital for understanding how water is flowing through the layers of our ice sheets in order to see how the melt is affecting sea level rise globally.

We plan on leaving for the ice sheet very soon and hope we got all of our bad luck with delays out of the way last season.

Nick and Olivia having lunch in Kulusuk.

Nick and Olivia having lunch in Kulusuk.

Lynn, Nick, and Anatoly testing out the seismic gear at the airport.

Lynn, Nick, and Anatoly testing out the seismic gear at the airport.

A Dash to the Field

July 28th, 2015 by Lora Koenig

Our team’s season has gotten off to a great start! So good that the field team was whisked into the field site early; so fast they couldn’t even get off a blog post. So I will fill you in from a nice comfy office in Colorado.

If you have followed our blogs in the past, or any Greenland research blog for that matter, they usually start out something like this, “Due to another weather delay we are still waiting for our flight into the field.” This usually goes on for a few weeks before the “WOW we actually made it to the field” blog is posted. In truth, we generally double the amount of time needed for the measurements to accommodate weather delays. Well this season is different!

Half the team arrived Kulusuk, Greenland, on July 22 and the rest on July 24They quickly organized the gear, arranged helo loads and were setting up camp at the field July 26. They started taking science measurements on July 27. This is certainly a record for us and after a very tough weather season in the spring we are hoping the sunny summer weather around 0 C (32 F) will help us.

Olivia did manage to get out a few photos from Kulusuk which is much more thawed out than it was a few months ago. Check out this old post with picture from Kulusuk just three months ago to see the change that occurs during the Arctic summer.

View from flight into Kulusuk with broken up sea ice (flat round ice) and ice bergs that have calved from the nearby glaciers (taller more jagged ice).

View from flight into Kulusuk with broken up sea ice (flat round ice) and icebergs that have calved from the nearby glaciers (taller, more jagged ice).

Camp gear at Kulusuk Airport being organized for helo flight into the field.

Camp gear at Kulusuk Airport being organized for helo flight into the field.

Open Fjord in Kulusuk with ice bergs.

Open Fjord in Kulusuk with icebergs.

Summer flowers.

Summer flowers.

Back to Southeast Greenland This Summer

July 27th, 2015 by Clément Miège

Hi there,

Our team is heading back to Southeast Greenland after about two months spent away from the ice sheet. These two months were busy; they consisted of fixing and maintaining some of our equipment (tents, thermal drill, piezometer heads…), starting to analyze samples, process the data collected in the spring, and preparing the logistic for the summer fieldwork. This fieldwork initially was planned for September, but to accommodate everyone’s schedule within the team, and the start of classes, we pushed the field experiment forward, from the end of July to August 20.

For this summer, we’ll have five team members from the spring field team. Nick and Lynn, based at the University of Maryland will be leading the seismic survey. Anatoly, from LTHE Grenoble (FR), will be in charge of the magnetic resonance soundings, while Olivia and I, based at University of Utah, will be doing hydrology measurements, firn coring, radar surveys and maintaining the iWS from IMAU Utrecht. This intelligent Weather Station (iWS) developed at IMAU in the Netherlands, was initially set up in the spring of 2014 with Ludo. We will be missing Lora, Kip and Josh who were part of the spring field campaign.

At our ice camp, the snow surface conditions will be quite different compared to our work this last spring. Not sure if you remember, but we were facing some extreme snowfalls last April, this snow was cold with relatively fine grains in general. During the summer, the story will be different: we are expecting wet snow due to melting at the surface. In fact, since June 20, 2015 the air temperatures have been rising above 0˚C, leading to surface melt. Hopefully this wet snow does not turn into slush which would make the camping a bit more challenging.

Plot of a time series of the air temperature (C) at our site since we left the field at the end of April 2015. We note positive temperatures starting around mid-June, an onward.

Plot of a time series of the air temperature (C) at our site since we left the field at the end of April 2015. We note positive temperatures starting around mid-June, an onward.

The goals for this summer are the following:

  • Seismic: armed with a sledge hammer, we will be hitting a metal plate, initiating sound waves which will propagate in the subsurface. The velocity changes of theses waves can be related to density changes and the presence of water in the subsurface
  • Magnetic resonance soundings: another noninvasive geophysical method using the signal generated by the magnetic resonance of water molecules to detect the aquifer vertical boundaries and water content.
  • Hydrology: measure water level, hydraulic conductivity and collect water samples to understand how fast water moves through the aquifer.
  • Radar measurements to image the water table spatial variations (400 MHz) and a lower-frequency system (~10-40 MHz) to also get the water-saturated firn to ice transition at greater depth.
Nick is practicing a few sledge hammer swings during the training at the PASSCAL facilities, Socorro, NM.

Nick is practicing a few sledge hammer swings during the training at the PASSCAL facilities, Socorro, NM.

Olivia retrieving the piezometer at our training site on a frozen lake near Kulusuk in the spring.

Olivia retrieving the piezometer at our training site on a frozen lake near Kulusuk in the spring.

400MHz ground-penetrating radar survey on the ice sheet.  (Credit: R. Forster)

400MHz ground-penetrating radar survey on the ice sheet. (Credit: R. Forster)

As a reminder, here is a photo of Kulusuk in the spring; we will take another photo from this summer to illustrate the landscape differences.

As a reminder, here is a photo of Kulusuk in the spring; we will take another photo from this summer to illustrate the landscape differences.

We are expecting iceberg floating in the ocean and fishermen using boats to get around instead of dog sledding on the sea ice. Stay tuned and we will be sending another update once our team is reunited in Southeast Greenland, getting our gear ready for this upcoming work on the ice sheet.

All the best,

Clément Miège

Notes from the Field