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Greenland Aquifer Expedition: Radar Days on the Greenland Ice Sheet

April 16th, 2013 by Maria-Jose Viñas

By Clément Miège

Hi there! Today I will give you some background on the radar measurements we collected in southeast Greenland. The radar we deployed is sensitive to snow density changes and to wet snow. The main goal of the radar measurements was to provide information about the spatial variations of the top of the aquifer (a water layer trapped within firn, or old snow).

The radar we used is made by GSSI, a company specialized into geophysical measurements, and it has a center frequency of 400 MHz. In snow and firn, the electromagnetic waves sent by this ground-penetrating radar can image approximately the first 50 meters of a dry snowpack. The layers that we observe in radar measurements show the snowpack stratigraphy (density changes). If there is water within the snow and firn, we observe a really strong radar echo in the radar profile. Then, by dragging the radar around, we are able to see how this water layer evolves spatially.

Here is the radar system in action, with Ludo pulling the sled. It can be a pretty tiring job with the wind and the cold. The balaclava was an absolute must to protect your face from the freezing temperatures.

Here is the radar system in action, with Ludo pulling the sled. It can be a pretty tiring job with the wind and the cold. The balaclava was an absolute must to protect your face from the freezing temperatures.

Mostly to lighten our helicopter loads, but also to exercise a bit, we decided to pull the radar sled with skis. But it ended up not being an easy job at times: some of our field days were really windy and cold, so we needed to be warmly dressed and have our face well-protected. In addition, we carried a backpack with the GPS unit and a battery – they became pretty heavy after an hour of pulling the radar. Ludo and I set up the rule of not doing more than 2 hours of survey at a time, which corresponded to about 5 km total.

Once on the ice sheet, as soon as the helicopter took off, we turned on the radar. Indeed, we wanted to make sure that we had been dropped over water and then find the best location for our drilling site. By looking at the radar profile, we identified the water layer (great!) and we converted its depth from electromagnetic wave two way travel time to meters. We observed that over a 2-km transect, the top of the aquifer varied up to 10 meters. By knowing this variation, we were able to pick the site location at a depth that fitted our science needs.

An example of the radar profile observed: the bright reflector represents the top of the water layer. Other internal reflections can be seen -- they are linked to previous summer layers, which are denser.

An example of the radar profile observed: the bright reflector represents the top of the water layer. Other internal reflections can be seen — they are linked to previous summer layers, which are denser.

The advantage of doing this preliminary radar survey is that we then knew before drilling at which depth the drill would encounter water and penetrate into the aquifer. And the good thing was that the radar picked the right water depth in both drilling sites! The radar ended up being a really good tool to extend spatially the localized information obtained by the firn cores.

Doing some radar at sunset with no wind was just so great!

Doing some radar at sunset with no wind was just so great!

For the radar survey, we were doing some elevation transects, to see how the water layer changed with the local topography, and some grids and bowties to extent spatially the core site stratigraphy. We stayed within a radius of 2 km from our camp.

Overall, doing the radar surveys was a great experience. It’s incredible to think that we were skiing with liquid water right below us, while surface temperatures averaging -15C.

Finally, concerning the radar setup, we have already some improvements in mind for the next time. For example, the GPS unit and its antenna need to be in the sled, maybe mounting the GPS antenna on a corner of the radar sled, trying to keep the all setup stable. That will allow us to drag the radar longer. We will work on that for our next radar adventure!

SEAT: Satellite Era Accumulation Traverse: Camp Life

January 24th, 2012 by Maria-Jose Viñas

By Michelle Koutnik

This is one of our six camping sites. The Scott tent is the big yellow tent and the others are the sleeping tents. The bathroom is at the end of the site.

Each of our six different camping sites consisted of one cook tent, four sleeping tents, and a bathroom area (more on that later). The cook tent was a “Scott” tent, which is an enduring style and named for the polar explorer Robert Scott. It was a tight space for five people but we were able to crawl in and then sit around together with one person managing the two-burner propane stove in the corner. The Scott style tent was much sturdier than our mountain-style sleeping tents, but it was also more time consuming to put up and heavier to transport. Since we were moving nearly every other day, we wanted to keep our camp as simple and as light as possible. The Scott tent was a necessary addition for cooking, but also as a reliable shelter in the two strong storms we experienced during the traverse.

Camp with our snow machines and the radar sled.

It took a few hours to set up camp, and a similar amount of time to break it down and repack the gear on the sleds. Randy, Jessica, and I were responsible for breaking down most of the camp and for setting up some of the camp on our own while Clement and Ludo collected radar data on traverse days. Once camp was set up at a new site, we could start melting snow for water and start cooking dinner.

On a traverse day, our camp life included the take down and setup of camp, plus collecting radar data. On an ice-coring day, our camp life included digging and sampling the snow pit, drilling the ice core, and eating a hot lunch. We ate well out there! Our standard meal plan included tortellini with pesto, spaghetti with meatballs, sausage with rice and vegetables, and burritos.  Sausages were popular and made their way into many meals. Special nights featured hamburgers with tater tots, and on Christmas we cooked scallops with rice and vegetables. Hot lunch on ice-coring days featured cheesy bagels fried with butter in our cast-iron pan. Since all the cheese and bread was always frozen, it required frying it all together before we could eat it – but it tasted great this way! Stormy-day food was simplified but did afford us the time to enjoy pancakes (two storms, two pancake breakfasts).

Frying cheese and bagels in butter for lunch.

The storms also affected our standard bathroom situation – usually a snow pit and tarp configuration. Ludo took the high winds and blowing snow as a challenge and created a snow-brick bathroom, which we tried our hardest to maintain from drifts!

Snow-brick bathroom and camp after a storm.

Maintaining camp and completing the science goals was a big job but we enjoyed being out on the ice sheet. For example, Christmas was a wonderful day to share together because a big storm started to clear, and we had lovely gifts to exchange, two small Christmas trees, and a very nice meal. Overall, the camp life was comfortable and enjoyable and with such a hard-working team, we were efficient at all the tasks necessary to make the camp run and be successful with the science.

Traversing to a new camp site.

SEAT: Satellite Era Accumulation Traverse: Radar days on the West Antarctic Ice Sheet

January 23rd, 2012 by Maria-Jose Viñas

By Clement Miege

Hi there! After more than three weeks spent in the field, our team is very happy to be finally back, with many memories of the traverse. This year has been a very intense experience and I would like to tell you a little more about this expedition. I will focus on the days we were doing radar surveys. Indeed, two different studies were set up during this field work. The first one was during the traverse days, where we did a radar survey from one camp to another with a range of 50-90 kilometers (31-56 miles) between the camps. On the other days the surveys were smaller, set up around each camp; they consisted of a 10-km bowtie and a 280- by 280-meter (918- by 918-ft) grid to get a better idea of the spatial variability of snow layer depth surrounding each core site. These grid surveys will show us how representative the ice core is compared to the surrounding area and help answer the question of whether we would have gotten a different result if we had drilled our ice core a few paces this way or a few paces that way. We were also looking more in detail at the layering in a 2-meter (6.56-ft) snow pit; to do that, we were using a metal plate at different depths of the snow pit.

The radar is sitting on a triangle-shape sled that is pulled by a snowmobile.

Here is a picture showing the two radars that operated simultaneously on the sled:

Both radars looked at the first 20 meters of the snow pack, sending electromagnetic waves into the snow. The snow radar (the big green horns in the picture) operates in a frequency range of 2-8 GHz. The other radar (the smaller brown horns) is the ku-band radar, sweeping between 12 to 18 GHz. The lower the frequency, the deeper the radars look. We have both radars for some redundancy in the system, imaging the snow/firn closest to the surface, which we core twice, and then the snow radar peers deeper than the cores to provide literally a deeper look. In addition to the 2 radars, we needed to know the elevation we were at, which is important for comparison with airborne data and also for modeling precipitation and temperatures. For that, we simultaneously collected GPS coordinates, which gave us our exact latitude, longitude and elevation every 5 seconds. The GPS antenna was on the very top of the sled, about 2.5 meters (8.2 feet) high.

On this sled, beside the radars sitting in the red box, we had packed: a blue bag, two black duffel bags and an orange bag. The blue bag was a survival bag, with all the gear needed in case we would have been caught in a storm; it included a tent, a stove, a shovel, and some food. The two black bags contained Ludo’s and my sleep kits, and the orange bag had some extra food, in case we were stuck for couple days. For the snow mobile, we had a repair kit under the seat to troubleshoot a possible failure. We were carrying two extra cans of gas as well. With this set-up, we were able to get a pretty light sled that was still comfortable and had all the gear we’d need in case of a storm or other circumstance separated us from the rest of the team, who were carrying all the camp gear. Fortunately, this never happened!

But now, let’s go back to the survey. The travelling days were the ones where the team was the most vulnerable: while we were traveling we had no shelters or camp set up to get back to if anything went wrong because we had to break down the entire camp in the morning, pack all gear on the sleds and ride with the snowmobiles pulling the sleds to the next camp. After driving between 50-90 km (31-56 mi), we would build our new camp, usually that same day in the afternoon. We had a total of seven travel days, covering a distance of about 500 km (310 mi).

Our sleds at camp. Strapping all your gear on the sled takes time and requires inventive skills; we called this the art of “Strapology”!

During travel days, the radar team left camp first, mostly because we had to drive at low speed to ensure the radar’s safety. Indeed, on the days we ran into large sastrugi (small ridges of hard snow), we drove at less than 10 km/h (6.2 mph). These sastrugi made our travel a little bit more difficult. Toward the end of the day, the team responsible for breaking down camp would leave the radar team and go 20 km (12 mi) ahead, to start setting up the new camp.

The days we were at camp, we did some small radar surveys: a bowtie and a grid around the core site. To help us drive the snowmobile straight for the grids, we set up flags to visualize the corners and sides. In the deep field, everything is white and flat, so it is hard to maintain a nice bearing just by following the GPS for such a small grid.

Clem and Michelle, getting ready for a short walk to set up the grid flags.

The last side survey with the radar was done in the snow pit. After analyzing the snow pit and picking up snow samples for further laboratory analysis, we used the pit to calibrate the radars and look at a detailed snow layering for the top 2 meters.

Ludo in the snow pit, sliding a metal plate in the snow at different depths. The plate creates a very bright horizon that is easily detectable on the radar return signal.

After a day of travel or after doing a grid, it is important to back up the radar data. The sleeping tents are a warm and cozy shelter to set up a “recharging station”. In addition to backing up the radar data, we recharged the satellite phone, GPS, and computer batteries.

We had to check the integrity of the radar sled at each camp site. Here is Ludo, checking the screws on one of the three legs connecting the snowboard to the sled.

To conclude, I want to say that this traverse was definitely an amazing experience and I was happy to share such a good time with the team. I am already excited to start looking at the radar data in detail to see what we can learn of the past few decades of snow accumulation in this part of the West Antarctic Ice Sheet.

SEAT: Satellite Era Accumulation Traverse: The Traverse Begins

December 22nd, 2011 by Maria-Jose Viñas

By Lora Koenig

Byrd Station (Antarctica), 11 December — We all got up at 5 AM this morning. I had gone to bed at 2 am because I had been backing up all of the radar data, which took much longer than anticipated. The traverse team went to bed early to be rested for the day.

It was a beautiful morning: warm, no wind, with thin, low, overcast clouds. The sleds were loaded and ready to go, already hooked on to the snowmobiles. Ludo was the first to the sleds and he started the generator, which powers heating pads that are used to warm the radars after being cold soaked all night. After about 15 minutes of warming, the radars can be started. During this time, the GPS is also turned on so it can obtain lock with the satellites and provide accurate positions.

I took the snowmobile covers off and helped Michelle load the final sleep kits on the sleds. The sleep kits are the last things to be loaded and contain a sleeping bag, sleeping bag liner, insolite pad, thermorest, pillow (if you want one, though most of us prefer to just use big red as a pillow), and a pee bottle so you don’t have to leave the tent in the middle of a cold night or storm. All of this is stuffed into a duffle bag and goes with you everywhere inAntarctica.

Clem bringing his final fear over to the sleds.

Jessica and Randy ready to head out on the traverse.

Once the generator was started, the team headed into the galley for a quick breakfast. Most of the camp was still asleep because Sunday is their day off; however, Kaija and Tony, the camp manager and assistant manager, came up to see the team off. After breakfast, the radars were turned on and the snowmobiles started. We took some final pictures and I tried to shoot some video but the small video camera we brought along is not operating well in the cold. The feeling of both excitement and nervousness was in the air. Excitement for finally getting to the traverse portion of the science and nervousness because the team is headed out into the remoteness ofAntarcticaalone. They will no longer have the security of an established camp and will have to rely on each other for everything. The team is strong and I know they will do well. During the traverse they will most certainly cover ground that no human has ever walked on before.

Ludo (left) and Clem(right) the radar team ready for the traverse.

The team loading the final items into their snowmobiles including their lunches for the day.

A final picture of the traverse team just before they took off. From left to right: Clem, Ludo, Randy, Jessica and Michelle.

At 6:41 AM, Michelle led the team out of Byrd Camp. She pulled a Siglin sled and a Nansen sled with food, the Scott tent, an HF radio for emergency communication, the radar spare parts, the sleep kits and personal gear. Michelle rides one of the two snowmobiles with mirrors so she can easily watch the team. Jessica followed pulling 2 Siglin sleds with food, the ice core drill and two ice core boxes. Randy was third in line with two Siglin sleds with even more food, the mountain tents, emergency bag, and all of the fuel. Ludo pulled the final snowmobile out and into line pulling the radar sled with Clem on the sled operating the radar. We all screamed and waved as they pulled away.

Michelle leads the team out of camp with a final wave goodbye.

Jessica follows Michelle out of camp.

A final wave from Ludo pulling the radar sled that is measuring the accumulation layers. Clem is sitting on the sled operating the radar.

I continued to watch as they moved further towards the horizon. They became smaller and smaller dots on the horizon above tent city as they moved away from camp. At 7:12 AM their dots blurred into the horizon. The traverse had begun.

The four sleds seen above the tents as they get farther from camp.

The sleds appears as tiny dots on the left of the horizon, as the team disappears into the West Antarctic Ice Sheet.

They will travel 95 km (59 mi) today, their longest stretch of the entire traverse, to the first camp site. They are moving toward higher snow accumulation and towards WAIS Divide field camp. When they reach the site tonight, they will be95 km(59 mi) from Byrd and85 km(52.8 mi) from WAIS Divide, so if they have any problems they will head to WAIS Divide, not Byrd.

I am feeling very lonely sitting in Byrd camp without the team, but there is still important work to do. Remember, the team still does not have their fuel caches. The pilots are in camp, but today’s overcast weather, while great for traversing, is not adequate for flying: The clouds make it difficult to see the snow surface. The pilots call this surface definition. In order to do open field landings (landings not on a ski way), the pilots cannot have overcast clouds at any level. Now I am just waiting for the weather to clear so that the plane can cache the team’s fuel and ice core boxes. I am also waiting for an LC-130 to come into Byrd so I can get a ride back to McMurdo and then back to the U.S.

Today I will also check the base station GPS and give a science lecture about our traverse to the Byrd Camp residents.

Everyone at Byrd Camp has helped us so we can complete our science goals and it is much appreciated. Thank you, Byrd Camp! We especially enjoyed the wonderful food made by Chef Rob. The team’s send-off dinner was duck with a port sauce, chicken with polenta, pureed carrots, broccoli with hollandaise sauce, and Boston Cream and Lemon Meringue pie for dessert. Yummmmm!

Around 7 PM tonight I expect to get a satellite phone call from Michelle. From this point on, the blog will have less pictures for a while because we will only have voice communication with the team. It should take between 24 and 30 days to complete the traverse, including (bad) weather days. The team will communicate back to me at each camp site and I will update you on their progress. When they return, we will post more posts from them with pictures of the traverse.

The team is truly out in the wilderness. The only communication they have is through the sat phone, which will only be on for a few hours in the evening. They can call their families and their families can send 160 character text messages to the sat phone. The deep field ofAntarcticais a remote place.

Go team, go!!!!!! (The extra exclamation points are for Clem, who loves to use them.)

SEAT: Satellite Era Accumulation Traverse: Packing Again

December 21st, 2011 by Maria-Jose Viñas
By Lora Koenig

Byrd Station (Antarctica), 10 December —
The traverse team is preparing to leave and quite honestly, I am starting to get sad that I will not be going with them. We have all spent a lot of time together and we work well as a team, but I do have to get home. This will be my first time not collecting myself the field data that I need for my science, but the more I work with the team, the more certain I become that they will collect all the data necessary, if not more. Clem, Ludo, Jessica, Randy and Michelle are all excited to head out into the great white open.

Today, Clem and Ludo did a little science. They dragged the radar in a grid pattern around the ice core site from yesterday. This is important data because it tells us how representative the point where the ice core was drilled is of the larger area around it. When we compare ice core data to satellite data, we want to know if the larger area is homogeneous (similar) or not.

Randy made sure all the snowmobiles were ready and fueled to leave early in the morning. One of the choke leavers on a snowmobile broke off so he was working with the mechanic to get it fixed. Jessica looked at the electrical conductivity measurements from yesterday and took pictures of all of the log book pages to create a back up of the data. Michelle spent the day making sure all the gear was loaded well on the sled and that nothing was missing.

Michelle and Ludo loading the sleds.

The box of snacks.

If you were a snow flake, this is what you would see as the radar passed over the top of you

The loaded Nansen sled.

 I spent most of the day watching the weather and talking with pilots. We cannot carry all of our gear on the sleds. A DC-3 Bassler aircraft is supposed to drop our fuel and ice core boxes and each camp site before the traverse. Due to the bad weather, the fuel cache has not yet been cached. So I have been talking with the pilots and rearranging the caches so the team can start out and not incur more delays. For now, the team will leave in the morning carrying two ice core boxes and one 55-gallon drum of fuel. This will allow them to get to the first camp site and drill. It will also give them enough fuel to get back to an established field camp if for some reason they don’t get any more fuel. They will not go to Camp 2 until they know the cache of fuel is there. Hopefully the cache will occur tomorrow or the next day so the traverse team will not be delayed. 

The DC-3 Bassler aircraft that will be used to cache our fuel and ice core boxes.

Everyone will go to sleep early tonight. Because all of Antarctica operates on McMurdo time, the time of the day at Byrd does not match the daily temperature changes. The coldest part of the day, which would generally fall from 1 to 4 AM, is usually between 6 and 10 PM our time. The warmest time falls in the morning between 6 and 10 AM. Tomorrow the team will get up at 5 AM and leave around 6 AM to take advantage of the warmest part of the day. By 6 PM they hope to be cooking dinner and in their warm tents.

I can tell the team is ready to go because this morning they were complaining about how warm their tents were, a quick adjustment from the first cold night in the tents. Everyone also took advantage of the last day in camp to take a few pictures.

The inside of the Byrd galley where all the food is cooked and served.

 

Randy taking a picture of the two penguin toys his children gave him to carry to Antarctica.

 

The penguin toys at the Byrd Bath where you can shower and wash cloths. Inside you can use a bucket of water to shower with and there is a basin with a hand crank drier that serves as a washing machine.