Great news! We made it to McMurdo yesterday afternoon (approx. 6pm Saturday, Nov. 21 CA time). We were one of the last groups to fly in on the C17 (yay!). Actually, our plane returned to Christchurch with the remaining winterovers of the last season. You could see their smiling faces as they headed toward the plane. Those great people had been on the Antarctic continent for more than a year and were very eager to be going home I'm sure.
The weather here in McMurdo is a rather pleasant 43 deg /37 F with wind chill. After arriving yesterday, I walked around town and down the cove to Discovery Hut, the original hut from explorer's in the early 1900's. Because it is so cold and dry in Antarctica, it takes a long time for decay to occur. Surrounding Discovery Hut are several mummified/petrified seal. They were covered in snow but you could make out their mouths and little flippers!
The sea ice surrounding McMurdo is still very thick so there are a limited amount of wildlife in the area. There were a few seals resting next to Discover Hut, but unfortunately no penguins. Maybe I'll see some on my way out.
We were scheduled to head to South Pole today, but as a backup flight. This means they had another flight planned, but if that couldn't go for weather, then we'd get to South Pole. That flight did take off (which is great since there were people waiting for several weeks to get to their field site) and we are now expected to leave tomorrow. Keep your fingers crossed!
I've been resting up from all the traveling in the last week.
Until next time,
I am safely in Christchurch, New Zealand. The local time here is 21 hours ahead of California time, so I'm basically living in the future. We arrived in Cheech (how the locals call Christchurch) on Friday, Nov. 20th at around midnight (12 am local time or roughly 3 am on Thursday Nov 19th west coast time).
The journey to the South Pole began for me on Tuesday, Nov. 17th at 11pm when I boarded a non-stop flight from Los Angeles to Sydney, Australia. The 14-hour flight took me across the international date line and the equator. When we crossed the date line, I basically skipped the day of November 18th. We arrived in Sydney around 10 am on November 19th. If you're confused about all that, so am I and I'm the one living it! When passing over the equator, we experienced quite a bit of turbulence, which is impressive considering we were flying on one of the largest commercial airplanes. Larger planes don't typically get as "bumpy" as smaller planes. The reason for the turbulence was due to the inter-tropical convergence zone (ITCZ). This band of thunderstorms forms north and south of the equator due to the converging air masses from the northern and southern hemispheres. In fact, if you look at a satellite image of the earth from space, you can clearly see this band of thunderstorms. Maybe I'll write a blog post about this interesting weather phenomenon at a later date (considering I'm a trained meteorologist and weather still excites me).
We had an extensive layover of about 8 hours in Sydney, so a group of the SPICE Core team left the airport and took a train to the city. I did this same journey last year, but it was still awesome to see Sydney again. We found a nice shaded area in the botanical gardens adjacent to the Sydney Opera House and took a nap/break. I didn't get much sleep on the flight. In fact, I'm running on about 10 hours of "good" sleep in the last 48 hours - yikes! We also had some delicious food at a side street cafe before making our way back to the airport for our flight to Cheech.
The flight from Sydney to Cheech was much shorter, only about 3 hours. We got to the hotel rather late at night and had an early shuttle ride to the Clothing Distribution Center (CDC) this morning. At the CDC, every person traveling to the Ice (Antarctica) is issued their extreme cold weather (ECW) gear. This gear consists of the "Big Red" parka, Carhartt bib overalls/jackets, the insulated "bunny" boats, and other cold weather gear like mittens and beanies. After getting the ECW gear, we had the rest of the day to tour the city.
I opted to take a relaxing nap in my hotel room. It was a bit overcast and windy in the early afternoon so I felt this was the best weather to catch up on some rest. When I woke up, the sky was clear and it was a gorgeous afternoon. I took a brief walk around the city and visited some of the main attractions. Christchurch was struck by a 6.3 magnitude earthquake in 2011 which caused a great deal of damage to the city, especially the older structures. The city is doing a beautiful job of recovering from this disaster and many new buildings have been erected in the last year alone and so many more are currently in construction. Cheech is becoming on of my favorite cities - not too big and a very cultural place.
This afternoon we also got verification that we are scheduled to leave for McMurdo, Antarctica tomorrow morning at 9 am. We will be flying an Air Force C-17 cargo plane. I'll update from McMurdo tomorrow!
Until next time,
We leave to start the second field season of the South Pole Ice (SPICE) Core Driling Project next week. In honor of that momentous occasion, here is a throwback picture of me in front of the ceremonial South Pole marker last November (2014).
Besides the extreme cold, the biggest hurdle when arriving at the South Pole is acclimating to the high elevation. The station itself is at an elevation of 9,301 feet, but because the air at the poles is thinner (due to earth's circulation), the human body feels an elevation that is closer to 10-11,000 feet. We will all take it pretty easy the first few days at the Pole.
Please send your questions and comments my way!
Until next time,
A few days ago we analyzed our first sample of the SPICE core! It has come full circle. It is pretty amazing to think about the journey this little piece of ice has endured.
First, let’s just talk about its age. This piece of ice came from about 192 meters deep in the Antarctic ice sheet below the South Pole. That gives this ice an age of roughly 2,500 years! WOAH! I’m holding ice that is over two thousand years old! The air inside the bubbles is quite a bit younger at about 1,500 years old. The reason for the large age difference is because it snows so little every year at the South Pole because it is very cold there (average annual temperature of -50 deg Celsius/-58 deg F) and far removed from moisture sources (aka, the ocean).
Now, let’s talk about the journey this little guy had. First, about a year ago, he was just hanging out doing his little ice guy things in the ice sheet and minding his own business. Then, a big drill came in and plucked him away from his home. He was brought back to the surface and packaged gently into a container. He then flew on a C-130 from the South Pole to McMurdo Station. He found his way into a refrigerated shipping container where he hung out comfortably at -30 degrees Celsius/-22 degrees F for several months. He then got to travel back to the West Coast of the U.S. on an awesome ship. (Hopefully he didn’t get too sea sick making his way through the Southern Ocean). Once he made it to dry land, he got driven all the way from Port Hueneme, CA to Denver, CO. I bet he really enjoyed the mountain views. Once in Denver, he hung out for a few months at the National Ice Core Lab. Then, I came along (with the help of many others) and cut this guy into a smaller piece, packaged him back up into a shipping container and then shipped him back to the West Coast to Irvine, CA. In total, that is about an 11,000 mile journey that took almost a full year!
Many thanks goes out to the ice core drillers, scientists, contractors, and everyone involved in making sure the ice cores made it safely from the South Pole to the National Ice Core Lab and back to our lab at UC Irvine. None of the science we do would be possible without the hard work and dedication of dozens (quite possibly hundreds) of people and countless organizations.
Until next time,
A few weeks ago, I posted this picture to my personal Facebook account and received some great questions about how scientists date the ice core and the air bubbles inside the ice core. This is actually one of the most important parts of ice core science, besides recovering a pristine ice core and successfully transporting it back to the lab in one piece of course!
Now, I'll openly admit that ice core dating is not my area of expertise, but I do have a general knowledge of what takes place.
First, you have to understand the way ice forms at the polar regions (Antarctica and Greenland, for example) is much different than what you've understood your whole life. Most of us think of the ice cubes in our freezer when someone says “ice”, especially if you grew up in Texas like I did. The ice in your freezer forms when you put water in its liquid form into the freezer. The air temperature in the freezer is below water’s freezing temperature and, boom, in a few hours you have ice cubes. The freezing temperature for the many liquids on Earth varies. For example, gasoline is a liquid. Many people don’t think about it freezing, but it can freeze. The reason we don’t is because gasoline’s freezing point is at temperatures most people never experience: around -40 to -50 degrees Celsius (-40 to -58 degrees F). Gasoline freezing is why airplanes cannot land at the South Pole in the winter when the temperatures plummet to -100 degrees F.
Back to water. Most places in Greenland and Antarctica stay below water’s freezing temperature of 0 degrees C (32 degrees F) for most of the year. Although, many coastal areas do go above freezing. South Pole is ALWAYS colder than 0 degrees C. Therefore, any precipitation that falls is in the form of snow. Because it never gets above freezing, this snow does not melt. When it snows again, this snow falls on top of the older snow and piles up. If you’ve held snow, you know it’s very fluffy and light. This is because the crystalline structure of snow (aka a snowflake) allows for a lot of air or void space to be present between two snowflakes. If you squeeze that fluffy snow together in your hand, you reduce the air or void area between the snowflakes. The same idea goes with the snow at the polar areas. Year after year, snow falls, it does not melt (this is not the case at all places, but a general statement) and it piles on top of the last year’s snow. Eventually, the weight of the snow above causes the void space between the snow crystals to reduce until there is no longer any void space and the snow is now ice. This process occurs over many years.
Scientists call the snow that is above the ice at the polar areas, firn. Porosity is also another term scientists use to describe the amount of open/void spaces in a material. More porous materials have more air pockets or open spaces. So, firn is the porous snow (see the diagram). As we move deeper into the ice sheet, the firn becomes less porous and eventual turns into the ice at a zone called the “lock-in” zone. At this lock-in zone, the air bubbles are locked into the ice. Before, because the firn is porous, the air can move freely around. Therefore, in the upper most part of the ice sheet, the air in the firn is still exchanging with the atmosphere. Once locked into the ice, the air bubbles no longer exchange with the atmosphere. That is how ice core scientists can determine the concentration of gases in the ancient atmosphere.
The time it takes for firn(snow) to turn to ice depends on the amount of snowfall or accumulation. Ice forms at a certain density (mass per volume). In order to reach that density, snow must be compacted year after year. Places that have more snowfall/accumulation per year will have a shallower firn column – or will reach the ice zone sooner (in terms of depth). For reference, a location that has high snowfall is the West Antarctic Ice Sheet Divide. This location receives about 22 cm per year of snow that will become ice. We call that ice equivalent accumulation because that is how much depth of snow we will see in the ice core. The West Antarctic Ice Sheet Divide has a lock in depth of about 75 meters. That means that until will drill down past 75 meters into the ice sheet at this location, we are still in firn(snow)! At South Pole, the yearly ice equivalent accumulation is much less at around 8 cm per year. The lock in depth at South Pole is much deeper at nearly 120 meters!
So now for a little math. If South Pole receives 8 cm per year ice equivalent of snowfall each year, how old is the snow/ice at the lock in depth of 120 meters?
Well, first we need to cover to the same units. Eight centimeters = 0.08 meters. Then we can do some basic math:
120 meters / 0.08 meters per year = 1500 years.
Wow, did you catch that?!
At the depth where the snow turns to ice at the South Pole, the snow/ice is roughly 1500 years old!
At the West Antarctic Ice Sheet Divide the math becomes:
75 meters / 0.22 meters per year = 340 years.
Okay, so know we know that the snow/ice is rather old at the depth in which it fully becomes ice. If you remember, in the firn layer, the air bubbles between the snow crystals are still able to move around and exchange with the atmosphere. That means the air in the firn is not aging at the same rate the snow is aging. There are some details that I’ll skip over here (if you want those you can email me), but basically right above the lock in depth the air bubbles in the firn have an age of zero. An age of zero means the air bubble is informing us about today’s atmosphere. All the concentrations of the gases such as carbon dioxide and methane would be roughly today’s concentrations (not exactly true, but I’ve skipped some physics just for simplicity).
So, the ice is several hundred to thousands of years old at the lock in depth, but the air bubbles are basically zero years old. This difference is referred to as the “delta age”. Delta in math typically stands for “difference” so we are comparing the difference in the age of the ice and the air bubbles. After the lock in depth, the air bubbles no long exchange with the atmosphere so they age at the same rate as the ice.
Okay, so basically we now know the air bubbles trapped in the ice cores are younger than the ice surrounding it. The “delta age” depends on the yearly snowfall accumulation at the site the ice core was drilled.
But now, how is the ice dated?
Well, we count the layers, literally. Just like the Grand Canyon, the different layers of snowfall can be observed in the ice cores when they are illuminated properly with lights (see picture). This picture was taken by John Fegyveresi at the SPICE Core core processing line at the National Ice Core Lab. You can see the small pieces of paper that he laid out to depict the different layers. You can even see the faint lines that separate the different years’ snowfall. Scientists like John visually count the layers in the ice core. Eventually, the amount of pressure of the meters upon meters of ice will start to thin the layers out (just like if you push your fist through some Play-Doh).
In addition to the annual layer counting, other measurements can tell us at what depth in the ice core a volcanic event occurred (see my earlier post about this). Many volcanoes have occurred during human history and are relatively well documented in terms of a date/time.
Combining the layer counting and volcanic peaks, scientists can come up with a robust depth-age scale (for a given depth in the ice core what is the age). Measurements of gases in the ice core air bubbles also helps tie time scales from other ice core sites together, just like fossils do in geology time scale constructions.
For our air bubbles, we basically subtract the “delta age” from the age of the ice to determine the age of the air that we analyze. For example, if I’m analyzing an ice core sample from 160 meters depth, the approximate age of the ice is:
160 m / 0.08 meters per year = 2000 years old.
We know from above that for simplicity, the air at the lock in depth is 0 years old (in reality is close to 200 years old).
The lock in depth at South Pole is 120 meters, corresponding to 1500 years old.
Our ice core sample has a gas age then of:
2000-1500 years = 500 years (with the all the physics it is more like 300 years old).
That is the quick and probably very hard to follow explanation of how scientists date ice cores and the air bubbles inside. I’m always eager to answer questions, so feel free to shoot me an email anytime.
Until next time,
Annual layers counting the SPICE Core. Each piece of paper is depicting on year's worth of snowfall. This one meter long piece (roughly 3 feet) is composed of 6 years of snowfall. Scientists illuminate the ice core with lights to bring out the details that cannot be observed with the naked eye. Photo by John Fegyveresi.
Well, I am officially headed back to the "ice" this field season. I'll be headed to the South Pole in November to assist with the second field season of the SPICE Core drilling. We have hundreds of meters of ice cores sitting down at the South Pole that we have to process and ship back to the National Ice Core Laboratory. This trip to the ice will be significantly shorter than last year's - only one month.
Although I'm just not announcing my deployment, I have been preparing for the ice for several months. In order to go to Antarctica (through NSF or contractor work), all participants must pass a vigorous medical and dental screening. Antarctica is a remote place and medical emergencies are a serious concern. Doctors are on site at all times, but the medical infrastructure and equipment is just not available in these remote places. To reduce the chance of someone having a serious health emergency, all participants go through this medical screening. The screening includes a full blood panel to check to make sure we're all healthy, a physical exam by a doctor and a dental examination. Once a doctor has examined all the testing and dental x-rays, a participant passes the "PQ" process - Physical Qualification.
Now that I've passed my PQ screening, I'm ready to start packing and getting ready for my journey to the South Pole! I've already shipped a large box of snacks to myself. It takes several weeks to a few months to get packages in the mail to Antarctica, especially in the beginning of the summer season when the priority of flights is for transportation of people on and off the ice and for shipments of scientific cargo and essential supplies (food, etc.).
Until next time,
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Mindy Nicewonger is a PhD candidate in the Department of Earth System Science at the University of California, Irvine.
Banner photo: Mindy standing in front of the C-130 Hercules in McMurdo, Antarctica (Nov. 2014).