August 4th, 2015 by Kathryn Hansen
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.
Lynn, Nick, and Anatoly testing out the seismic gear at the airport.
July 28th, 2015 by Kathryn Hansen
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 24. They 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 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.
Open Fjord in Kulusuk with icebergs.
July 27th, 2015 by Kathryn Hansen
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.
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.
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)
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,
May 5th, 2015 by Kathryn Hansen
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.
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.
Monitoring station ready to transmit data (temperature and pressure) for a year or more.
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.
The quiet village of Kulusuk in the evening light with resting huskies.
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.
April 28th, 2015 by Kathryn Hansen
The slope of the ice sheet was crazy! Or we just took a very crooked picture. From left to right: Clem, Lynn, Olivia, and Anatoly.
April 25, 2015 — The team had come back exhausted and cold but very happy to have a warm meal and bed on Thursday (April 23). Anatoly and I were very excited to have everyone safe after the very long and stormy two weeks they had had in the field. On Friday (April 24), the next day, we had to go back to dig out and load the 2,400 kilos of remaining gear. As a team, we discussed the possibility of trying to do the magnetic resonance (MR) measurements between the first and last flights to get the remaining gear out. It would only take about a few hours to set up and take the measurements so we were hopeful that we would have enough time to do it, as three flights would take most of the day to complete. Olivia, Clem, Anatoly, and I would head out to the camp on the ice sheet in the morning to load the rest of the remaining gear and attempt to complete the MR science at site one. Lora, Josh, and Kip would stay to help unload the incoming helicopters.
A frozen tight-water (outflow) glacier we saw on the way to the field site.
Sestrugies along the expanse of the ice sheet.
After a month of delays in Kulusuk, I had become a logistics expert. I knew how the flights worked and the pilots by name, how to organize all of the helicopter loads, and how to correspond with the team and project managers. But this would be my first experience doing science on the ice sheet. I woke up beyond excited Friday morning to finally be going to the field! As Anatoly said, “Working in Greenland is comparable to fishing: patience and good luck. And one has to have the necessary time for waiting for this chance and then to catch it.”
We headed off to the airport around 8:30 a.m., taking just personal bags packed with food and back-up gear as we did not plan to spend the night in the field. The weather couldn’t have been better; it was sunny with almost no wind and not a cloud in the sky. The Bell 212 helicopter landed at 9 a.m. and we loaded it with the MR gear and our bags. We said a quick goodbye and took off to the field. The flight was about 45 minutes from Kulusuk airport to the field camp, easily recognizable by the bright orange Arctic oven tents. We hopped out of the helicopter and immediately began unloading our gear and reloading with the gear set up by the team in the cargo lines the day before.
Fueling up the Bell 212 and giving Lora giving last minute advice.
The team had filled us in on the conditions on the ice sheet including many stories about how they had to wade through the waist deep soft snow and the terrible 40-knot winds most days. I expected the worst and had dressed in my warmest layers ready to combat the harsh conditions. When we landed, there were similar conditions to Kulusuk; no wind, very sunny, and not a cloud in the sky. It was a great white expanse and we could see for miles. This was the perfect day to work and fly on the ice sheet. I took my first step off the helicopter and my foot sank down so the snow was up to my knees. The first ten minutes were like learning to walk again, as I fell with every other step trying to catch my footing while carrying boxes to load the helicopter. The pilots took off with the first load, which we had stuffed as full as possible with gear. We were alone on the ice sheet.
Loading up the first helicopter flight.
Anatoly, Olivia, Clem, and I decided it would be best to split into two groups. Anatoly and I would begin set up the MR and Clem and Olivia would move gear and begin to take down tents for the next flight load. We unpacked the MR gear quickly and I began placing cables to create an 80 meter by 80 meter loop then attaching connectors at each corresponding point of the cables. It was exhausting having to trudge through the snow but I knew it had to be done as fast as possible in order to get measurements before the last helicopter. Anatoly began the setup of all the computer gear in one of the remaining tents and within an hour we were beginning the measurements! Magnetic resonance imaging has never been used in this part of Greenland and in the framework of the project was seen as a challenging technique that may help to constrain hydrogeological modeling.
Anatoly taking magnetic resonance measurements.
All the while, Clem and Olivia set up the next two cargo lines, took down one of the sleep tents, and shoveled out gear. While the MR measurements were running, Anatoly and I helped with shoveling and taking down the tents. The helicopter arrived for the second flight load and I even got to assist them with landing, standing in a meter or two front of the landing spot as a point of reference, then kneeling down when they got close to protect myself from the massive wind storm they bring with the rotors. We loaded the second flight just as the first and they were off again. Only one more flight to go!
Clem and Olivia digging out the tents.
Clem beginning to shovel out the gear lines.
Lynn and Clem with the second helicopter load.
We ate a quick late lunch in the remaining tent with the MR gear in it and saw the initial results. The radar, hydrology, and drilling were confirmed; there was indeed an aquifer filled with water around 20 meters below where we were standing. How cool is that?! We called Lora to check on the last helicopter flight and they had already landed and were on their way back. Anatoly needed a bit more time to finish his measurements. We devised a plan to get everything taken down in time. Olivia and I would be ready to coil all the cables and get all the connectors collected as soon as the MR was done collecting data, and Clem would take down the rest of the final tent. Anatoly gave us the “go” signal and we all sprang into action. With a little luck and a very quick pace, we put the last coil into the MR box as we heard the helicopter in the distance. Within 8 hours of exceptionally hard work, we had done what was planned to take 3-4 days.
We loaded the last few boxes with the pilots help and jumped in the helicopter ourselves. The pilots even told us they had seen polar bear prints around 10 kilometers from our camp! We scoured the ice sheet on the way back but never saw any prints. Around 50 minutes later, we were back home in Kulusuk just in time for dinner.