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SEAT: Satellite Era Accumulation Traverse: Chers lecteurs francophones

December 8th, 2011 by Maria-Jose Viñas

By Ludovic Brucker

Chers lecteurs francophones (que nous savons nombreux tels que familles, amis, et élèves de Goddard French Immersion Schéol), voici un petit récit résumant notre situation actuelle à Mc Murdo (77 o 51’ S, 16640’ E). Lors des prochains messages, nous essayerons d’avoir un court résumé du texte en français. N’hésitez pas à nous poser vos questions!

Tout d’abord, relatons l’objectif scientifique motivant cette campagne de terrain où nous ferons une traverse légère (déplacement en motoneiges et “nuitées” sous tentes) de 500 km durant le mois de décembre sur la partie ouest de la calotte Antarctique.

Nous cherchons à estimer l’accumulation de neige sur la calotte Antarctique, soit combien de centimètres de neige précipitent chaque année et s’accumulent avec le temps jusqu’à se métamorphoser en glace. L’Antarctique étant un immense continent d’une superficie d’environ 14 millions de km2 il est impossible d’obtenir cette information à partir de mesures locales obtenues depuis quelques stations. Par conséquent, notre objectif est d’utiliser des mesures satellites afin de retrouver cette information sur l’accumulation de neige à l’échelle continentale. Pour cela il nous faut tout d’abord obtenir des mesures in-situ pour développer des algorithmes servant à convertir la mesure satellite (celle d’un rayonnement électromagnétique, généralement dans le domaine des micro-ondes) en une grandeur physique (telle que accumulation de neige, température, densité, taille de grains de neige, ou encore présence d’eau liquide dans le manteau neigeux, etc.). Avec plus de 30 ans de mesures continuellement collectées par des radiomètres en orbite autour de la Terre, ces grandeurs servent au suivie climatique de la cryosphère en régions polaires.

Durant la traverse, cinq personnes seront présentes avec des rôles clés, définis:

- Michelle, au vue de son expérience lors de déploiements en régions polaires, est en charge du groupe. Après une prise en compte des idées/préoccupations de chacun, elle aura le dernier mot sur les choix stratégiques nous permettant d’évoluer en sécurité. Par exemple, il lui revient la décision de démonter le camp au petit matin afin de continuer la traverse, ou, au contraire, de rester une journée supplémentaire si le vent ou la visibilité ne permettent pas d’atteindre notre prochain point de ravitaillement en carburant (qui sera déposé dans quelques jours par avion). Michelle est également le contact radio avec le camp d’été à Byrd et la station McMurdo.

- Jessica et Randy s’occupent du forage de carottes de neige jusqu’à 15-20 mètres de profondeur, ainsi qu’aux premières analyses. Ils vont extraire des carottes d’environ 1 m de long et 5 cm de diamètre, puis les mesurer, peser et les mettre dans des tubes afin de les protéger. Ensuite, ces tubes seront transportés par avion jusqu’aux Etats-Unis.

- Clément travaille avec deux radars (bande C et Ku) que nous transportons sur un traineau spécial tracté par motoneige. Les jours de déplacement, Clément et Ludovic alterneront leur présence sur ce traineau et sur la motoneige. Comme vous vous en doutez, rester assis 8 à 10 heures à contrôler le bon enregistrement des mesures radars donne rapidement froid dans le dos ! Nous changerons donc de position très régulièrement. Durant les jours au camp, Clem passera l’essentiel de son temps aux révisions des instruments.

- Ludo, en plus de partager son temps avec Clem et les radars, réalisera des mesures des propriétés physiques de la neige dans des puits de 2 m de profondeur. En plus des mesures classiques de températures, densités, conductivité thermique, etc, nous prendrons également des photographies infrarouges permettant d’enregistrer  la stratigraphie du manteau neigeux, et d’estimer la variation verticale de la taille des grains de neige.

Notre équipe présente cette année en Antarctique est composée pour le moment de 6 personnes, les 5 déjà présentés plus Lora! Lora est une experte de la NASA dont la thématique principale est l’analyse de mesures par télédétection active et passive des manteaux neigeux en Antarctique et au Groenland. Elle a déjà réalisé 7 déploiements sur calottes polaires, dont 3 en Antarctique, elle a aussi passé 4 mois consécutifs à Summit durant un hivernage au Groenland. Sa maîtrise des préparations d’expédition est un atout incroyable tout comme sa connaissance de la station McMurdo. Lora va venir avec nous jusqu’à Byrd afin de s’assurer que tout soit parfaitement en place, puis elle rentrera dans le Maryland pour célébrer la Noel avec sa famille.

Les présentations étant maintenant faites, résumons les différentes étapes excitantes de ces derniers jours! Nous avons quitté les Etats-Unis le 17 novembre en direction de Christchurch (Nouvelle-Zélande) avec un passage par Los Angeles (Californie) puis Auckland (Nouvelle-Zélande). Après avoir perdu une journée en passant la longitude de changement de date, l’arrivée en Nouvelle-Zélande s’est très bien déroulée pour toute l’équipe.

Dimanche 20  a été consacré à récupérer nos habits polaires (voir les photos associées aux autres textes en anglais). Nous avons notamment reçu “Big Red”, cette fameuse parka rouge de la National Science Fondation (NSF) et du programme antarctique américain (USAP).

Lundi 21 fut le jour du départ pour l’Antarctique. Après un vol de 5h, le C-17 de l’US Air Force a atterri sur la glace de mer au large de la station McMurdo. Un moment magique!

Aéroport sur la glace de mer au large de McMurdo.

Nos premiers pas nous ont menés vers de particuliers engins, Delta et Terra bus, dédiés au transport en commun afin de relier la piste d’atterrissage à la Station de Mc Murdo.

Station McMurdo, vue du sommet de Observation Hill.

Les engins de transport à McMurdo sont soit équipés de chenilles, ou possèdent des roues d’une largeur exceptionnelle et d’une hauteur aussi grande que Clem!

Une illustration de la taille des roues des engins présents sur la base!

Mardi 22 et Mercredi 23, Jessica, Randy et Ludo ont suivi une formation de sécurité pour les déploiements en extérieur. Cette formation, bien mieux connue sous le nom de “Campeurs Joyeux!”, inclue une nuitée ensoleillée dehors, à proximité du Mont Erebus sur la plate-forme glaciaire de Ross. Pour varier les plaisirs, Jessica a passé la nuit dans une tente standard en forme de dôme, Randy dans une tente Scott en forme pyramidale afin de résister aux vents antarctiques. Sur recommandation de Clément, Ludo a quant à lui creusé une tranchée pour y passer une excellente nuit ensoleillée avec un panorama fantastique.

Le panorama depuis McMurdo est exceptionnel, nous profitons bien de la vue des montagnes car dans quelques jours nous seront dans une zone très plates...

Durant ce temps, l’autre partie du groupe a commencé la chasse aux caisses d’équipement envoyées depuis le Kansas en septembre dernier. Malheureusement, nos radars n’ont pas été trouvés… Apres quelques heures de recherches ils ont été localisés sur un bateau à Christchurch.

Durant la journée du Jeudi 24, nous avons tous apporté notre grain de sel aux préparations. Il s’agissait de préparer les caisses de nourriture pour les prochaines semaines, soit 350 kg d’aliments.

La dernière journée de cette première semaine était dédié à finir les préparations de toutes les caisses en partance pour Byrd. Malheureusement les radars n’étaient toujours pas arrivés à McMurdo due aux conditions météorologiques empêchant les C-17 de voler. Plus précisément, les avions auraient pu atterrirent sans difficultés mais durant la phase de descente ils avaient à traverser une couche humide qui auraient généré de la glace sur la carlingue de l’avion une fois posé. L’aileron de queue étant très haut sur ces avions et l’usage des produits dégivrant limité, aucun avion en provenance de Christchurch s’est posé depuis notre arrivé.

Dans l’espoir de recevoir très prochainement les radars, nous allons poursuivre notre découverte de Mc Murdo et de la base néo-zélandaise Scott durant le week-end de Thanksgiving.

McMurdo avec en arrière plan Mont Terror et Mont Erebus (de la droite vers la gauche).

 

SEAT: Satellite Era Accumulation Traverse: Happy Camper School

December 2nd, 2011 by Maria-Jose Viñas

By Ludovic Brucker

Jessica, Randy, and I were scheduled to attend a 2-day Field Safety Training Program (a.k.a. Happy Camper survival school the nickname makes it sound much more fun than its official title!) on Tuesday and Wednesday, 23-24 November. The training includes spending a night outdoors. I heard about the program months ago and I was definitively looking forward to this enjoyable and educational experience. The invitation read: “Be sure to show up the morning of your course dressed for the field in your Extreme Cold Weather (ECW) clothing.  […] Trust us!  We want you to be comfortable and safe for the Antarctic environment.” Sweet!

Our group on our way to the Happy Camper site, near Mt Erebus (on the left, 3794 m, or 12,448 ft, high).

On Monday evening (Nov. 22), I had carefully prepared my ECW++ pack (the ++ stands for water and food). My ECW gear consisted of: socks, bottom and top thermal base- and mid-layers, a fleece jacket, a thick bib, Big Red, boots, and all the basics (such as hat, gloves and glove liners, mittens, face protection, etc). Additionally, we took the sleep kits and tents that we will be using during our traverse. These last two are very similar to the ones you most probably use when camping, but the sleeping bag is much thicker and we also use pads, a fleece liner, warm fleece pants, and a pee-bottle. Our bag also contained other basic and mandatory items, such as sunglasses, goggles, sunscreen, lipstick, and water bottles, among other things.

The first morning of the training was dedicated to listening to lectures about the harsh Antarctic environment and its rapidly changing weather conditions, with focused courses on topics such as how to deal with hypothermia, etc. We then headed out to the field a few miles away from McMurdo station, in the vicinity of Mt. Erebus. It was gorgeous! We were a total of 20 people, all freshly arrived from New Zealand the day before.

Jessica in her ECW gear.

The outdoor session was much cooler (pardon the easy pun) than the lectures and it provided us with information on setting up camps, such as mounting a mountain tent and a Scott pyramid tent. The latter is particularly well suited to Antarctic conditions and it’s inspired in the tent Robert Scott designed for his 1910-13 South Pole expedition. It resists high wind speeds very well; we will have one in our traverse. Obviously, the tent resistance to wind is all about the quality of its snow anchors.

Folks setting up Scott tents.

Our BYU team members (Jessica and Randy) installing anchors in the snow to strongly fix the Scott tent structure.

Instead of spending the night in a tent, I opted for the alternative, which was digging up a trench and sleeping in it. “Why not,” I thought. “I’d rather experience my first night in an Antarctic trench when the weather is pleasant and I have resources close by than when I have no alternative to using a trench.”

A general view of our Happy Camper site with yellow Scott tents (right), classic mountaineering tents behind a wall made of snow bricks that protects the tents from the wind, and trenches (front).

Our dining area, with boiling water for tea and dehydrated meals.

My trench had a narrow opening and got wider a few feet deeper. The ceiling was made of snow bricks covered by lighter snow to close joints and holes. I used my bag as an horizontal ceiling door, right above my head. An easier option would have been using a sled for the ceiling, as others did.

A view of my trench. It is narrow at the top and wider at the bottom. Being 6 feet 3 inches tall meant I had to dig a long trench.

Me finishing up a few details to ensure an enjoyable stay in my trench.

The interior of my trench.

My night was perfect: cozy and unbelievably quiet! I didn’t even notice that the wind had started to blow strongly during the night. I woke up around 4 AM feeling a bit chilly; I ate a chocolate bar, drank some water, and went back to sleep. It was interesting to wake up in the middle of the night and be able to see like if it was day time. At this time of the year in Antarctica, all nights are bright, with only one star in the sky. It felt weird to be sleeping in a snow trench only three weeks after having slept in a hammock hung between palm trees in Big Island, Hawaii. Thanks Lora and Thorsten for these two experiences!

Happy Camper also taught us how to use a High Frequency radio. It is significantly different to use from the common very high frequency radio. After deploying the two 10-meter antennas, we made calls to South Pole station (1360 km, or 850 miles, south of us.)

In summary, these first two days outdoors were successful. However, we expect tougher conditions once we’re out in the field, in the West Antarctic Ice Sheet.

SEAT: Satellite Era Accumulation Traverse: IceBridge Retraces 2010 SEAT traverse route

November 10th, 2011 by Maria-Jose Viñas

By Lora Koenig

Yesterday was an exciting day in the office. While I was downloading satellite data, answering e-mails and tying up loose ends before leaving for Antarctica, I was also closely following the NASA Airborne Sciences Flight Tracker and the flight path of the NASA DC-8 aircraft. The DC-8 is currently flying over Antarctica as part of the Operation IceBridge mission and yesterday it overflew the 2010 SEAT traverse line and ice core drilling sites. (For more detailed info on Operation IceBridge, check out the mission’s website).

I spent part of the day yesterday watching my screen as the flight tracker showed a little green aircraft moving over our 2010 route. Here is the aircraft approaching our line at about 1:40 PM Eastern time.  (The tracker was not updating the plane image at this time, but the aircraft was at the end of the red line.)

Here it is halfway through. (Note that the plane does a 270-degree turn to line up on our traverse line to make sure it is leveled as it crosses our 2010 ice core sites. This ensures the best quality of radar data.)

 

And here is the plane at about 2:35 PM EST, finishing the portion of its flight that retraced our traverse and four ice core locations:

I watched on my screen as the IceBridge plane covered in just less than an hour the same ground that took us 12 days to cover last year.

OK, so I guess you are asking yourself: Why do we go out in the field, in sub-freezing weather, to drive around on snowmobiles for 12 days to do what a plane can do in an hour? Because you can not drill an ice core from an airplane. The airplane carries radars, which provide great spatial coverage of radar data, but we need to calibrate the radar data with the annual cycles we get from ice cores. (See last week’s blog post on how we determine annual cycles in the lab).  So, yesterday, IceBridge collected great radar data that will compare to the data from our ice core sites, as well as to data from the WAIS divide ice core and the ice cores collected by a group led by Dr. Ian Joughin at University of Washington.

The IceBridge DC-8 aircraft flies with radars that are nearly identical to the ones we use on the ground. They are named Snow Radar and Ku-band Radar and are built by the Center for Remote Sensing of Ice Sheets, CReSIS. We will use the airborne radar data gathered yesterday to investigate any differences between what the radars are measuring from the air and on the ground.

In a week, we board our flights to Antarctica. After watching the IceBridge plane flying in West Antarctica yesterday, I am even more excited to get my boots on the ice.

SEAT: Satellite Era Accumulation Traverse: Ice cores: From Antarctica to the lab

November 4th, 2011 by Maria-Jose Viñas

By Lora Koenig

Two weeks ago, I traveled to Utah to help the team finalize planning for this season and to visit the ice core lab and our 2010 ice cores at BYU. The entire was there, except for Ludo, who was in Hawaii competing in a triathlon. (Ludo is not only a top scientist but a top triathlete. I hope he is not getting too use to the warm weather because in less than a month he will be facing temperatures around 0°F.)

There were a few tasks to complete in Utah. The first was to look at many different types of satellite data on the region where we will be traveling to make sure there aren’t any crevasses or other dangers along the route. A crevasse is a crack in the ice. As the ice flows (yes, ice flows just like a mound of putty), it can crack when it goes over a bump or accelerates. Here is a recent picture of crevasses in Western Antarctica, from a NASA Operation IceBridge flight.

Photo Credit: Michael Studinger/NASA

As you can imagine, we would not want to drive a snowmobile in an area like this. So we spent hours looking over maps of the rock bed under the ice sheet to look for bumps, visible and radar satellite images of the surface of the ice sheet, and satellite data showing the velocity of ice flow to make sure that we are traveling on the safest possible route. We ended up moving one ice core drilling location slightly to avoid a dark spot that we could not clearly identify in one of the radar images, just to be extra cautious. Once the route was established, we generated waypoints (coordinates) every kilometer to load into the GPS units that we will use for navigation. The place we are going to is big, white and flat: It is very easy to lose your sense of direction, so we rely heavily on GPS units for navigation.

For some great images and videos on how ice flows in Antarctica please check out this video, made by our NASA colleague Eric Rignot who (thanks again, Eric!) also checked the data that sits behind these videos to help ensure our safe route.

If you would like an in-depth look, this file, which opens on Google Earth, shows our final route with points every 1 km.

Our second task in Utah was to visit last year’s ice cores and have our first meeting to discuss the initial data coming from them. First, here is a picture of a core in the field, taken in December 2010.

In this photo, Michelle (right) is labeling the core and I (left) am getting the core tube ready for storage. The arrow on the ice core bag shows which direction is up.  It is very important that all the cores are labeled in order, or we would lose our time series. The metallic tube in the center left of the picture protects the core during shipping. The core in the tube gets placed in the white core box sitting open on the left side of the picture. (Also, notice that Michelle is standing on a bright green pad to help insulate her feet from the cold snow. It’s a veteran trick for keeping your toes warm.)

Here is that same core in the lab today.

Summer is holding what was about 8 feet of the core and the rest of the about 50 feet of core is stacked in the boxes behind her, waiting for analysis.

Here is a very basic explanation of what happens to the cores once they arrive at Summer’s lab at BYU. (Normally, Summer would be the one writing this, but she is currently studying glaciers in Bhutan.)

When the core arrives, we put it in the freezer.  Here is Landon peering out of the freezer door:

In the freezer, we weigh the core to determine its density and measure its electrical conductivity, which tells us about its chemical composition. A volcanic event would be detected in the cores by the electrical conductivity and can be used to set a point in time. We take all these measurements twice, or even three times, to make sure they are accurate.

Here is a picture of a core that Landon is preparing, sitting on the freezer’s core handling tray:

This freezer is set to -4°F, so when not posing for a picture, Landon would normally be in a parka with gloves on.  As you can see, the core is still in its protective bag, which will be removed when actually processing the core. From here, the core is cut up into sections less than an inch (2 cm) long, and melted for the next stage of analysis.

I will add a quick note here that on last year’s traverse Landon was our lead driller. Both Landon and Jessica are masters students at BYU. They are not only integral players of the field teams, but are also the lead students for the lab analysis of these cores.

Once we have melted the core and put it in a bottle, we send it over to Jessica.

Here is Jessica operating the mass spectrometer (black box to the left in the picture with the blue screen) that will measure the stable water isotopes used to date the core. The isotopes in the snow have an annual cycle and it is this cycle that determines age of the core.  An isotope is an atom, in our case an oxygen atom, that has different variations with different number of neutrons and atomic numbers.  Oxygen has three stable isotopes: 16O, 17O, and 18O.  The peaks and valleys in the ratios of 18O/16O reflect the warmer (summer) and cooler (winter) temperatures, respectively.   Once the mass spectrometer determines the number of isotopes, we can establish the age of the core, in a way similar to counting tree rings. During this process, the core is in the little blue vials just to the right of Jessica.

After spending some time in the lab, we looked at the data from the first core that has been analyzed.  At this point the density and isotopes have been measured and Summer is carefully working to put together the depth-age scale, which is the age of the core at each depth where the core use to sit in the ice sheet.  I will use the density data from the core to determine an age-depth scale from the layers in the radar data and if all goes well the radar and ice core will line up giving us confidence in our analysis.

Last Monday, when I returned to Goddard, I had received my travel itinerary.  We will be leaving the U.S. on Nov 17th to make our journey down to Antarctica.  With all of this preparation, I am eagerly awaiting getting my feet on the Ice.

SEAT: Satellite Era Accumulation Traverse: When Canada Stands In for Antarctica

October 21st, 2011 by Patrick Lynch

By Summer Ruper

Hello SEAT blog followers. I am Summer Ruper, and I would like to share with you a little bit of the ice coring adventure that begins well before the field team heads to Antarctica. Before we start drilling ice cores in the harsh cold and wind of Antarctica, we have to train our field team on the drill and sampling procedures. To do this, we took a trip to a slightly warmer region with ice: Athabasca Glacier in the Columbia Ice Field. Athabasca Glacier is near the Canadian town of Banff, and is one of the most visited glaciers in the world. It’s a beautiful area, and plenty of ice to play with.

To begin, we must first answer the question: What is an ice core? Simply put, it is a core sample collected from a glacier or ice sheet. But the ice core is not entirely made up of ice; with the snow fall and wind also come dust, salts, and even ash from volcanic eruptions. All of this is contained in the ice cores and provides information about how snowfall, temperature, and winds have changed over time. A lot of important information is buried in the ice and snow on glaciers and ice sheets, but you have to get the ice out in order to get at that information.

Piece of ice with bubbles inside. These bubbles provide information on the composition of the atmosphere at the time they were trapped in the ice.

Piece of ice with bubbles inside. These bubbles provide information on the composition of the atmosphere at the time they were trapped in the ice.

In order to collect the ice cores, we use a specially designed ice core drill. The one we use is called the FELICS, and is designed and manufactured by Felix and Dieter Stampfli in Switzerland. Basically, the drill has a sharp ring on the end that cuts the ice and feeds the core into a one-meter long barrel. We pull the one-meter section up, empty it out of the barrel, and then drill another one-meter ice core from the bottom of the hole. We do this over and over again until we have drilled to a depth of about 20 meters, and have about 20 one-meter long ice cores.

Randy Skinner, Jessica Williams, and BYU students drilling an ice core on Athabasca Glacier.

Randy Skinner, Jessica Williams, and BYU students drilling an ice core on Athabasca Glacier.

On Athabasca Glacier, our field crew learned how to operate the drill, handle the ice cores, and generally deal with problems that might arise. We were also able to show the tourists visiting that glacier how the drill worked, let them see (and taste) the ice, and share a little of our knowledge and excitement about glaciers and the environmental records contained in the ice. We had a lot of fun, and Jessica and Randy are excited to transfer this experience to our work on the Antarctic ice sheet soon.

Summer Rupper showing an ice core to group of tourists on Athabasca Glacier.

Randy Skinner “sharing” an ice core with a budding glaciologist.

In another post, we will show you what we do with the ice cores once they return to the lab and share some of our preliminary results from last year’s ice cores.

Jessica Williams, Randy Skinner, and Summer Rupper look for the “perfect” spot to drill a core.

Jessica Williams, Randy Skinner, and Summer Rupper look for the “perfect” spot to drill a core.

Notes from the Field