Posts Tagged ‘ice’

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Greenland Aquifer Expedition: 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.

Greenland Aquifer Expedition: 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.

Greenland Aquifer Expedition: 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.

Greenland Aquifer Expedition: 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

Greenland Aquifer Expedition: Away From the Ice Sheet Until the Fall

May 5th, 2015 by Clément Miège

Hi there!

I am writing this post from Iceland, a few days after the last team members left Kulusuk, Greenland. Back from the field, we spent five days packing up our equipment and organizing the container for the end-of-summer field campaign. Overall the firn aquifer field campaign was a success. However, since we experienced difficult weather conditions, we did not fully complete our initial goals because we were not able to bring the seismic equipment into the field (the snow surface conditions prevented us from using snowmobiles which were required for the seismic surveys). The weather is difficult in this region, which makes measurements more challenging to make. Therefore, we needed to make adjustments to maximize the science that could be done.

Olivia uses everything available  to dry our tents.

Olivia uses everything available to dry our tents.

Anatoly and Lora ready to go home via Reykjavik, Iceland.

Anatoly and Lora ready to go home via Reykjavik, Iceland.

We spent 14 days camping on the ice sheet at a location about 130 kilometers northwest of Kulusuk, at a latitude close to the Arctic Circle. We spent three days extracting a 56-meter firn/ice core using a combination of an electromechanical drill and an electrothermal 4-inch drill provided by IDDO. We equipped the freshly drilled borehole with temperature sensors and a pressure transducer to monitor the seasonal changes of the firn aquifer temperatures and to monitor the changes in height of the water table. In the meantime, our team deployed a piezometer above, within, and below the aquifer to measure hydraulic permeability with a vertical resolution of 1 foot. In addition, aquifer water samples were collected to date the water by using different techniques. I invite you read Olivia’s blog post for further details on the water sampling. We measured ice surface velocity using a high-precision GPS from UNAVCO. Finally, we successfully used the magnetic resonance to estimate the volume of water in the in a non-destructive way as described by Lynn in our previous blog post.

In terms of weather, we experienced a five-day snowstorm with two storms back to back which dropped about 1 meter of snow. After the snowfall, katabatic winds started, blowing this freshly fallen snow at 40 knots and our tents needed hourly maintenance for about 36 hours to avoid being buried. The small mountain tent was too much work to maintain and we decided to only stay in the bigger Arctic Oven tents. At the end of the storm, important efforts were necessary to dig out camp and the cargo lines, which exhausted the team. In addition, the relatively warm temperatures during the storm (maximum at about -5˚C) got us wet and it was difficult to dry out. After 72 hours of continuous shoveling and tremendous efforts to avoid being buried and maintain camp, our PIs voted for team extraction as safety was compromised. Two days later we were picked up by the B-212 Air Greenland helicopter and after 50 minutes of travel we arrived safely in Kulusuk.

Olivia and camp after the five-day storm.

Olivia and camp after the five-day storm.

Monitoring station ready to transmit data (temperature and pressure) for a year or more.

Monitoring station ready to transmit data (temperature and pressure) for a year or more.

Last evening in the field.

Last evening in the field.

Overall, this field season was instructive and extremely helpful to plan our next field campaign which will happen in September this year. We confirmed that southeast Greenland was a challenging place to work, but we successfully collected a great hydrology data set, as well as confirmed the potential of the magnetic resonance to estimate liquid water content over a 80 by 80 meter wired loop. We postponed the radar and seismic studies for the fall campaign since we would be more likely able to bring a snowmobile to the field, crucial of the deployment of such experiments.

Lynn and Olivia enjoying the Kulusuk sunset on their last day.

Lynn and Olivia enjoying the Kulusuk sunset on their last day.

The quiet village of Kulusuk in the evening light with resting huskies.

The quiet village of Kulusuk in the evening light with resting huskies.

Northern lights from the Kulusuk Hotel.

Northern lights from the Kulusuk Hotel.

The spring 2015 campaign is now over. I hope you enjoyed reading the blog posts, and we now wish for a great and warm summer! Please stay tuned as we will be back in August/September for additional measurements on this part of the Greenland ice sheet, and will update the blog then.

Notes from the Field