Our Approach to Studying the Ross Ice Shelf

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The Ross Ice Shelf (RIS) is a floating extension of the West Antarctic Ice Sheet that occupies the southern Ross Embayment in West Antarctica, and acts as a buttress to the flowing Antarctic ice sheets. The bathymetry beneath the RIS in West Antarctica controls the circulation of sub-shelf ocean water that may warm the ice shelf from below, with consequences for shelf stability and climate warming.

Sparse depth-sounding data from the 1970’s Ross Ice Shelf Geophysical Glaciological Survey (RIGGS) provide control points, but the map produced from this survey is at 55 km resolution. ROSETTA-Ice will improve upon this, mapping the RIS using 10 km resolution.

The sub-RIS bathymetry cannot be measured directly. Whereas marine surveys might be able to map bathymetry using echo sounding or by towing a gravimeter, we cannot do that because there is a massive ice shelf in the way. The bathymetry must be determined through the use of geophysical data— gravity and magnetic data, specifically —to determine the subsurface geology, which can then be applied to interpretations of the probable bathymetry beneath the shelf. The subsurface geology can be constrained by airborne gravity and magnetic data, that reflect the size, type, and origin of geological features, such as igneous bodies or fault zones.

 

 

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Subglacial geologic map (Elkind et al., 2016) for western Marie Byrd Land and magnetic anomaly flightline data from the ROSETTA-Ice 2015 survey. Topography is vertically exaggerated.

The aim of ROSETTA-Ice (A systems approach to understanding the Ross Ocean and Ice Shelf Environment, and Tectonic setting Through Aerogeophysical surveys and modelling) is to learn more about the interactions between ice, ocean, and underlying rock.

ROSETTA-Ice uses IcePod

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Nicholas Freason securing the IcePod to the LC-130 aircraft. The IcePod connects to a lever arm attached to an LC-130 aircraft. Picture taken last season.

…a suite of instruments that includes three gravimeters, a magnetometer, LiDar, visual and infrared camera, DICE (deep ice radar), SIR (shallow ice radar), and a PNT (position, navigation, and tracking) system that includes GNSS and IMU.

 

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Our airborne survey uses not one, not two, but THREE gravimeters!

Stay tuned to see the IcePod in action!

 

The Office

Every morning, I take a ~20 minute shuttle to get to work.

We work in a RAC tent…

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…located on Williams Field (an airfield) so that we have easier access to load and unload our equipment.

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The view from the back of the tent. Two (broken) LC-130s sit on the runway.

Our RAC tent is split into two main rooms: the front room is our office space and the back room is our lab space.

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Setting up the tent itself was an entire project. My intention was to upload a stimulating time-lapse of the process, but unfortunately McMurdo’s connection is quite stubborn.

The office is where all the data archiving, QC’ing and processing occurs, to ensure that each flight of data is sound and secure. The lab space contains all the hardware that will be installed in the plane.

Obtaining a grant from the National Science Foundation (NSF) was a hard-fought process, and given the high frequency of flight cancellations due to gnarly weather and/or mechanical issues, we use our time on the ice as efficiently as possible. Each opportunity to fly is critical, the data we collect from each flight precious. After each flight – the goal is to fly twice a day – the data is carefully archived and copied to several safe locations. The data is then QC’ed. Lines, or even segments of lines for flights are closely examined so that we can be confident that our surveys are producing good, usable data.

These processes can take many hours, since our survey collects data using a variety of instruments. For details on methods and instrumentation, check the blog soon!

 

 

 

Observatory Hill

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After many hours in the RAC tent sitting and working with computers, preparing for and eager to begin surveying, we needed to stretch our legs.

I joined a few other ROSETTA-Ice members on a night hike to Observatory Hill, or Ob Hill, as it is commonly called.ob_hill

The trail is steep and partially covered in snow, but avoiding the loop and hiking just to the summit and back totals less than a mile. Ob Hill is accurately named, and rewards hikers with unobstructed, beautiful views.

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We had warmed up quite quickly from the climb and having gained some elevation the relentless sunshine felt even stronger, so we relaxed on the summit for about a half hour. There is a cross at the summit, erected in 1913, and it is a memorial for Captain Scott and his crew who died in 1912 on their trek back from the South Pole.

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We were surprised to realize it was 10:00 pm when we got to the bottom – it is easy to lose a sense of time when the sun never sets!

 

Scott Base and Pressure Ridges

The ROSETTA-Ice team had their first full day off on Sunday and everyone was eager to get out and explore McMurdo, after catching up on much needed sleep.

I went to Scott Base, the New Zealand station, which is about a 3.6 mile walk across the ice from McMurdo.

Scott Base.

Scott Base.

Scott Base is much smaller than McMurdo Station, home to about 100 residents as opposed to 1,000 (as of yesterday, 913). Residents from McMurdo are not allowed in Scott Base unless by invitation, though, they will let you spend money in their (arguably better) gift shop and sell you a drink; shuttles to Scott Base every Thursday night are popular for those looking for a livelier nightlife. However, Scott Base residents do have free reign in McMurdo. In my opinion, Scott Base is generally a much prettier station. It includes a breathtaking view of the Pressure Ridges, sits by the wind farm, and the buildings are all painted the same green color. I mean, whoever designed the buildings in McMurdo could have tried a little harder.

That night I took a two hour tour of the Pressure Ridges.

Pressure Ridges.

Pressure ridges form when the ice sheet and sea ice hit converge and meet land, and they fluctuate with the tides. Tours are always different as tidal forces vary, and so the structure can change quite spectacularly.

Castle Rock in the distance, with Mt. Erebus to the right.

Castle Rock (left) and Mt. Erebus (right), beyond the Pressure Ridges. 

I was utterly amazed by both the architecture of the ice and the wildlife among the ridges. By wildlife, I am really just speaking of seals and skuas…penguins do not inhabit this part of Antarctica. When penguins are seen around McMurdo they are usually lost and, sadly, probably will not make very far before dying. We saw many seals, and even witnessed a seal dive into a hole in the ice!

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Mama seal and her pup.

* No three-letter acronyms were used when writing this post *

Mactown — the first few days

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Although we have yet to begin our survey, these first few days in McMurdo have been quite busy. All scientists must go through a bunch of training/briefings that pretty much cover what not to do and how to survive while in McMurdo. During our (thankfully) indoor three-hour Field Safety & Training (FST) session held in the Science Support Center (SSC), we got acquainted with the contents of a survival bag, which, should our team get stranded on the barren ice, provides enough food, shelter, and some reading material until rescue.

The housing situation in McMurdo is dorm-style. I have a roommate (it happens to be his eighteenth season in Antarctica), and share a bathroom with two others who live next door. Each dorm has a resident assistant, a lounge, and if you are lucky, a library.

McMurdo, from Hut Point  Trail.

McMurdo Station, from Hut Point Trail.

Yesterday I went for a walk to Discovery Hut – a memorial for Antarctic explorer George Vince who fell into McMurdo Sound in 1904 and died was erected here – and along the ridge on a loose path of volcanic rock known as Hut Point Trail. I was practically racing up the hill as I forgot to bring my neck gator and the wind here is incredibly cutting.

Memorial for explorer George Vince, at Hut Point.

Memorial for explorer George Vince, at Hut Point.

Since Mactown is populated with many scientists working on a variety of projects across disciplines in atmospheric science, ecology and oceanography, to name a few, it is not surprising that there are talks held twice a week. Yesterday I attended a talk focusing on paleomagnetics given by professor Lisa Tauxe of Scripps, UC-San Diego. I learned why we study the earth’s magnetic field, why it is so tricky to do so, and the probability that our planet is headed for a total field reduction (!) or reversal.

Volcanic rock on Hut Point Trail. [My fingertip for scale].

Volcanic rock on Hut Point Trail. [My fingertip for scale].

I am currently writing this in our cozy RAC (Remote Access Cave?) tent on the airfield known as Williams Field. Since the ROSETTA-Ice team will be spending many hours here, we stocked up on supplies taken from the Berg Field Center (BFC), including coffee & tea, mugs, coolers, sleeping bags, and pee bottles, among other camping essentials.

Delays are simply a part of life on the ice; planes break down, storms are fierce and the weather is hard to predict. Though I have spent a decent amount of time at the airfield, I actually have not heard or seen any planes take off or land. Hopefully, we are able to install the IcePod on Saturday and begin flying sometime next week!

 

The Journey to 77° South

I left the States from Denver on November 3rd and arrived at McMurdo Station on the 7th, travelling through Los Angeles, Sydney, and Christchurch. We arrived in Christchurch on the 5th , and the next day we were shuttled to the United States Antarctic Program (USAP) campus where we had a series of briefings & trainings regarding life on the Ice, and were brought to the Clothing Distribution Center (CDC) to be issued our Extreme Cold Weather gear (ECW).

The CDC hosts a warehouse of parkas, fleece coats & pants, mittens, hats, goggles, boots, and pretty much everything else needed to keep you cozy while in the field – except for good ol’ long undies. Anyone headed to McMurdo Station is allowed up to 85 pounds of luggage, including all the issued ECW.

The CDC hosts a warehouse of parkas, fleece coats & pants, mittens, hats, goggles, boots, and pretty much everything else needed to keep you cozy while in the field – except for good ol’ long undies. Anyone headed to McMurdo Station is allowed up to 85 pounds of luggage, including all the issued ECW.

I say this now: the USAP uses a ridiculous amount of three letter acronyms.

Fortunately, these trainings ended early enough so that we had about half a day to goof around in the city; I chose to go for a run with another member of ROSETTA-Ice, exploring Hagley Park and the Botanic Gardens, as well as some of the stone churches and building that were wrecked by the recent earthquake. The following morning a shuttle picked us up from the hotel at 5:45 am and brought us back to the USAP campus to check in, obtain our boarding passes – which were simple laminated cards with a number – pass security, and board the plane. We flew on a C-17 cargo plane; there was helicopter inside.

The inside of the C-17 from the deck.

The inside of the C-17 from the deck.

Although I was certain I was going to fall asleep once on the plane, this proved to be a very silly prediction. I could hardly even read I was so excited and taken by the interior. The pilots allowed us on to the deck (I think I was the only person to go twice, it was that cool) so that we could see the ice from the sky, as the plane didn’t really have any windows for passengers.

Looking out from a passenger window.

Looking out from a tiny window.

 

Looking out from the deck.

Looking out from the deck.

I first tried looking through the window without my sunglasses, and it seriously hurt. Antarctica during these summer months is always sunny and one must learn to adjust to twenty-four hours of daylight.

When the plane landed and I at last stepped onto Antarctica, I got goosebumps. I will always remember that ineffable feeling.

A shuttle then took everyone from the airfield to McMurdo Station. I cannot wait to fly again, with ROSETTA-Ice, in our mission to map the Ross Ice Shelf…

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Here at last!

Oh Block 2, How You Leave Me Waxing

Fourth Wednesday in the Physics department means donuts, I have discovered. As we munched away on that sugary morning goodness, we tried to wrap up everything that has happened in this block. By the nature of taking a cross-listed anthropology and physics class, the content of this block has been pretty varied. Our final projects (and there were a few) ranged from notes on a book about ethnoastronomy – the socio-historical study of the relationship between culture and celestial features – to a project using Starry Night software to compute the visibility of celestial events through history. We completed a block long project measuring the angle between the Moon and the Sun, when they are both visible in the sky. In this project, we applied the theoretical knowledge gained throughout the block regarding the angle of the Moon and Sun, relative to earth, and the way this relationship dictates Moon phase. We have talked physics and culture, and the two have complimented each other immensely.

However, it is a difficult bridge to cross. Fundamentally, we have no idea whether our current understandings of the movements of stars and planets are anything akin to the understandings of those who passed before us. We do not know what they believed, and we do not know how important such beliefs were to their culture and way of life. We have indications, but no empirical facts. This is the danger of history, especially when dealing with indigenous and marginalised populations whose peoples, culture and lifestyle thrive today: how do we infer without Othering; how do we extrapolate without stereotyping?

And once we’ve mentally wrapped our heads around all this, where does the physics fit in? How do I marry Kepler’s Third Law with the potential alignment of great kivas to the cardinal directions, when we are not even sure whether the Major Lunar Standstill was observed? In today’s world, very few people know the stars or pay them much heed. The knowledge is specific, rooted in mathematic jargon, and thus at least seemingly inaccessible to a regular Joe. Looking back we ask – how was this knowledge, whatever extent of knowledge there may have been, shared? Did these people we so easily romanticise truly turn their faces upwards to their great nightly television, or are we too easily lulled by the dream of human beings as environmental stewards?

Throughout this block I have found myself gazing skyward. A few nights ago, my housemates and I lay on the roof and gazed at the moon. I told them the story of how the earth and the sky are like a great kiva – the kiva that encompasses us all, and is the home of those ancients who built the first kiva on the ground for human dwellings. Biking home at night, I slow down to gaze at the stars, weaving my way across the road and trying to not hit parked cars. I’m currently in New Mexico, spending block break camping near Santa Fe. Last night, I pointed out the Big Dipper and Orion’s Belt, and explained to my friend why we could see a waning gibbous moon rising at midnight.

If there is one thing I will take from this class, it is to look at the sky more. I have navigated by the stars before, and remember making the same assertion then. In the mania of everyday life, both at CC and elsewhere, it is too easy to forget the stars. To run from class to meeting to study to practice to work to bed without once looking up and saying hello to the moon. But this time I’ll try to stick to my mental note – while biking at night, while walking from the Mod Pod to Worner, while staring out the window in search of motivation to write – to look not down, but up.

Two Roads Diverged… But Both Led to the Stars

One class, two professors; this week diverged in two educative directions. Dick’s material is the numbers and figures I, in all honesty, have a much harder time translating into words. My head is swimming with the ratios of the surface area and volume of Earth and Mars – tonight’s homework. For my visual mind, far more practically applicable was the experiment we conducted during Friday class. We used something called a gnomon to determine the cardinal points – North, South, East and West. This process was extremely simple – we recorded the shadow of a piece of string (the gnomon) held vertical at hourly intervals, in relation to a circle drawn such that its radius was the same length as the gnomon. At the two points of intersection between shadow and circle, we drew a straight line – this was West-East. By drawing a second line, perpendicular to the first, we now knew North-South. The applicability of this experiment? Let me show you an excerpt from my group lab write up (the introduction):

 

Imagine you are lost in the woods. You do not know up from down, left from right, North from South. You know you need to walk South-East to reach the highway, from where you can hitch yourself a ride home, but you have no idea which way that is. You have the whole day ahead of you, until nightfall, to work your way out of the forest and back to the city lights. You come across a clearing in the trees, where a patch of light falls upon the forest floor. In your pocket, you find chalk and a piece of string. You realise: I can use these things to determine the points of a compass! And once I know which direction is which, I can walk on out of here. This is where the question “what can a gnomon tell you” comes into play. A gnomon is a simple, basically tools free method of determining the directions West and East, from which North and South can be calculated. It takes time – the shadow of the gnomon needs to be monitored every hour for a good part of the day, if true cardinal points are to be determined. But if you have time and a piece of string and a tool to write with, it could just be your ticket out of the woods.

 

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(This was what our gnomon experiment looked like – the straight lines show West-East and North-South, just like a compass!)

 

Scott is the Anthropologist in the room, and my Sociologically trained brain grooves much more quickly to the rhythm of what he says (though I must admit, tonight’s ratio equations did give me a strange but definitive sense of satisfaction). We have been delving deeper into the people that inhabited the South West/North West region, and gazed at the stars. We have been asking: What did they see? What did they make of it? Why, even, did they turn their eyes skyward? This week, we read about the symbolism of the hooghan – the house – for various Native American peoples. The belief system emphasises an interrelated and interdependent natural universe, of which humans are a part. The Gods built the first hooghan or sacred building, as a personification of our natural world. This, there is the physical hooghan of the earth, but there is also a wider, metaphorical hooghan, in which the floor is our Earth and the roof is the stars. The physical house is a site of ritual and healing, through sand painting and chanting, situated within the wider metaphorical house of our universe. Just as the physical hooghan will decay and collapse with age, so too will we humans. Spirits, however, remain – they may continue to dwell in the physical hooghan, just as they linger in the universe.

 

Something about this story of interconnectedness and interdependence spoke to me. In my opinion, our lives are carried out independently, yet exist as part of a wider network of living entities. As I have mentioned, the act of chanting was also highly important. To chant was to make something real. To put desire into the universe, at full power. I guess I think similarly. I tend to consider my thoughts as formless until I say them out loud or write them down. Before this, they exist only as a jumbled, coherent cloud. Words, formed through speech or writing, give the cloud form. It may take a few tries until I reach true coherence, or grapple what I truly think into words, but that action simply cannot be done within my own head. I don’t think in words, so my thoughts aren’t ‘real’ until I put them into the physical world. My class reflection has wandered a little down the path of personal retrospection, but why else do we educate?

Baca Adventures: Chimney Rock and Major Lunar Standstill

Coming to Baca makes perfect sense for a block on Cultural Astronomy. It’s not just the wide, largely un-light-polluted sky, but something about the sense of quiet tranquillity that engulfs Crestone, a site of important spiritual convergence. There’s something befitting of this mindful environment, as we turn our eyes to the night sky. Considering celestial bodies, I think, demands respect of the wider forces that govern our universe – how can I fully appreciate the gargantuan gravitational orbits of planets in our solar system, amid the frantic hustle of campus life at Colorado College.

We arrived to Baca on Wednesday of the first week of the block, and on Thursday travelled over three hours down to Chimney Rock, a site of cultural astronomical importance for the ancestral Pueblo people of the Southwest. From Chimney Rock, it is thought that people converged to observe the moon as it rose between two tall chimney-looking rock stacks, an occurrence called the Major Lunar Standstill. The orbit of the moon around the Earth oscillates, as it is offset by about 5 degrees from our meridian. As such, the moon rises and sets at different points on the horizon through the year – one can observe this on a weekly basis. Every 18.6 years, however, the moon completes this oscillation, and its point of rising and setting appears to freeze for a period of time – the moon rises at the same location on multiple nights. This is a Major Lunar Standstill, and Chimney Rock is thought to be the only place in the world with a geological formation that naturally serves as a viewing platform. The people who lived at Chimney Rock were here for this purpose – to study the moon and the stars and the sun and their relationship to each other. Dwellings and Kivas – ceremonial buildings – were built at the site to house such populations. At the time of the Major Lunar Standstill, it is thought that people from across the Chaco region flooded to Chimney Rock, which exists as a natural amphitheatre, to observe the celestial phenomenon.

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Much of our first week in class has been focused on the moon and its phases. We all know that the silver orb of in the night sky is not a light shining from the moon itself, but a reflection of the sun’s luminosity. But if the moon acts as a mirror for the sun’s rays, then how does the angle of the moon and the sun, relative to Earth, impact the reflection we may see in Colorado? In other words, how are the phases of the moon dictated by the position of the sun and the moon, again relative to Earth? For the moon to be full, the sun’s luminosity must shine directly upon the side of the moon that is visible to us on Earth. Thus, the Earth and Moon’s orbits must be such that the Earth is between the Sun and the Moon. We see a new moon, on the other hand, when the Moon lies between the Sun and the Earth. This is because most of the Sun’s luminosity is reflected back out to space towards the Sun, where we cannot see it, while only a slither of light – a crescent moon – is reflected back to us here on Earth.

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In our second class of the block, Professor Dick Hilt asked how many of us had seen the moon the night before. I’m not sure that anyone raised their hand, and to clarity, it was not a cloudy night. Going forward in the block, I will make an effort to pay more attention to the sky around me at night, and observe the celestial bodies as communities through history have done.

 

Real Analysis: Week 2 (and doing things with real numbers)

Since learning about some of the basic properties of the real numbers, about how they form a line that is completely continuous, we’ve begun to talk about what those properties allow us to do with the real numbers. When we think about and talk about math, we tend to think and talk about manipulating numbers, not simply admiring their existence. The idea that “proving calculus” is important rests on the fact that our society requires (and our minds enjoy) this kind of numerical manipulation, and that we want the results of these endeavors to have some real meaning.

The first type of active manipulation of numbers that we talked about was the act of arranging real numbers into a sequence. A sequence of numbers is a subset of real numbers which are arranged in a particular order. Further, each element of the sequence can be constructed from some formula; that is, if you want to find the fifth term in the sequence, you can plug “5” into a given formula and acquire that term. For example, we can create a sequence of all numbers of the form {1/n} where each “n” that we plug in is a natural number (the kind of number that you can count on your hands). In the sequence, the first element is 1, the second element is 1/2, the third element is 1/3, and so on.

This sequence, like all sequences, contains an infinity number of terms. This is because there are an infinite number of natural numbers, and therefore an infinite number of “n”s to plug into the given formula. An infinitely long list of numbers all sharing a common formula is a pretty astounding, but it turns out that many sequences have an even more incredible property. This property is called convergence, and it means that after a certain term in the sequence, there are an infinite number of terms which are all practically equal to each other.

The sequence {1/n} is a sequence with this property. Eventually, as the natural numbers which we plug into the formula get very large, the term as a whole gets very small. And when n gets extremely large, when we start dividing 1 by numbers like 1,000,000,000, the elements of our sequence get very close to each other and to zero. Because of this, we say that the sequence {1/n} converges to zero. Interestingly, the terms are never actually equal to zero, and never actually equal to each other. 1/1,000,000,000 is a different number than 1/1,000,000,001, although they are very, very close together in value.

There are actually a lot of sequences that converge, and which converge to a variety of real numbers. This property of convergence is deeply tied to the structure of the real numbers- that line which we learned about at the very beginning of class. Since that line contains every possible number, it is possible for it to contain an infinite number of numbers which are as close together as we could want, without those numbers ever actually being equal. This allows for convergence: if the real line were missing values, there would be gaps in the line which inhibited the closeness of terms in a given sequence.

Sequences, while fascinating, might seem on the surface to not actually “do” much in terms of manipulating numbers. They hold a lot of power, however. They allow us to not only order information, but a potentially infinite amount of it. We can add terms of these sequences together to get new sequences, or to get sums of numbers that approximate complicated functions. These are all things we’re going to talk about in the next few days of class, as we keep looking at what the line of real numbers allows us to do.

 

~Anna