Posts Tagged ‘radar’

Newer Entries »

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.

SEAT: Satellite Era Accumulation Traverse: Another Bumpy Ride for the Radars

December 16th, 2011 by Maria-Jose Viñas

By Lora Koenig

Byrd Station (Antarctica), 8 December — Today was our first day in the deep field at Byrd Camp. Byrd Camp sits in the middle of the West Antarctic Ice Sheet at an elevation of about 5,700 ft (1,737 m). We are standing on over 2,000 m of ice, with the oldest ice being about 50,000 years old. (The ice nearby at WAIS divide camp is a bit older and deeper. To find out more about the deep ice underneath us check out this information on the WAIS Divide ice core, which is being drilled deep into the ice nearby.) When you look out from camp you see nothing but the flat white snow and an old drill tower sticking out of the ground.

The tents of Byrd camp. The longest one is the galley.

We are, specifically speaking, at Byrd Surface Camp. The original Byrd Camp, established in the 1956-1957 season, is underneath us, except for a drill tower that still sticks out above the snow. Over the years, snow accumulation (which averages around 12 cm per year at Byrd) buried the original camp and created Byrd Surface Camp, which everyone just calls Byrd. It is exactly this snow accumulation that we are here to measure with ice cores and radars.  Here is an article about the history of Byrd.

Michelle, jumping of joy after a good night’s sleep in her tent at Byrd Camp.

Tent City is where we are staying while at Byrd Camp.

The team was prepared to work hard today because we know the more time we make up from the weather delays, the quicker the traverse team can get home. The day started with all of us breaking down the pallets of gear. Once all the gear was off of the pallets, we divided and conquered the tasks for the day. Michelle started loading and organizing the sleds. Randy fueled all the snowmobiles and Jerry cans. We brought nine 55-gallon drums of premix gas for the snowmobiles for the entire traverse. Jessica prepared all of the drilling gear for the first core, which we’ll drill tomorrow. Clem, Ludo and I built the radar sled, attached the antennas and hooked up all of the radars for testing. Clem also set up a GPS base station that we will use to correct our roving GPS on the radar so we know precisely where the radar data is located throughout the traverse.

An Antarctica gas station. We have mogas and premix. The snowmobiles take premix the generators mogas. We can’t mix them up, so they are labeled well.

 

The radar sled is assembled and ready to go.

We discovered a few problems today. First, Jessica realized that the power converter for the drill battery did not make it to the field. The drill is made in Switzerland and has a different power plug. While this was an unfortunate oversight, it will not affect the science: We can charge the drill battery with the solar panels. The sun is up 24 hours a day here, so that will provide more than enough charge for the battery. Also, we carry an electronics tool kit, so in case of need we can cut the wires and make a new plug.— we call it “MacGyvering” (i.e., improvising fixes to our materials in the field).

The second problem of the day is a bit more worrisome. The Ku-band radar data has a systematic noise level that we cannot troubleshoot. We know that it has something to do with the computer that runs the radars, but we cannot determine whether or not the problem is coming from radio frequency emission from the computer itself getting into the antennas or if it is a data writing problem with the computer software. It has been a long day, so the trouble-shooting will have to be left for tomorrow. We hope that nothing was broken on the computer during the combat off-loading.  We will know more tomorrow.

The sleds are ready to drill our first core tomorrow!

Our sleds lined up and ready to go for our first day of drilling tomorrow.

 

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: Waiting Again

December 8th, 2011 by Maria-Jose Viñas

By Lora Koenig

It’s Thursday, December 1, and I am, yet again, sitting in our office, waiting.  As the saying goes, “hurry up and wait”: This rings true in Antarctica. Last week, we were waiting for our radars to arrive on a plane from Christchurch. Usually there are about three flights a week from Christchurch to McMurdo, but an entire week of flights was canceled due to bad weather here. And finally, a plane arrived on Monday, November 28, bringing fresh fruit, new people and, most importantly, our radars.

Ludo and Clem quickly set up the two radars, ran a few tests to make sure they were working and repacked them for shipping to Byrd Camp. Normally we would take a few days to do this but, since we were delayed, we all worked hard and completed the tasks in a few hours. We repacked the equipment very carefully to prevent damage, and put it into the cargo system. (See Michelle’s blog post to learn more about the cargo system). Our intracontinential cargo needed to be in the system 48 hours in advance, and we were hoping to fly to Byrd on December 1 (that is, today).

Clem and Ludo testing the radars. The coil of wire, in the center of the picture, is a delay line that sends the radar signal through a wire that attenuates the wave. Delay lines are a good way to test the radar when the antennas are not yet hooked up.Clem and Ludo watching the radar echogram to make sure the radars were not damaged in shipping. Clem is holding a set of notes: We always have good documentation of our procedures to make sure we take consistent measurements. The notes also help us in case we forget anything.

Just as a reminder here is the location we are trying to get to.

So our estimated departure date has come and gone, and here we are still in McMurdo. This is not a big surprise; delays are common in such a harsh environment. We are now scheduled to go to Byrd on Monday December 5. All of our work in McMurdo is done, so we will use the delay to rest a bit before the hard work of the traverse begins.

Michelle and I took advantage of the nice weather to go skiing on the McMurdo Ice Shelf, which is connected to sea ice. In a few weeks, people will not be able to ski here anymore because the warm summer temperatures from both the air above and the water underneath the shelf will thin the ice.

Why are we delayed? First, as I mentioned, McMurdo had a week of bad weather and no planes could land or take off.  And once the weather in McMurdo cleared, it was Byrd’s turn to have bad weather, so planes could not land there. On top of that, there is a lot of science going on at Byrd this season, including another traverse lead by a NASA colleague, Bob Bindschadler, headed to Pine Island Glacier. (Check out this video on the Pine Island project, or visit their website.) Because there are so many teams flying to Byrd, we have to wait for five flights to get in before we are assigned a plane load for our science gear, fuel, snowmobiles and ice core boxes. Our team has a full LC-130 plane load of gear that needs to make it to Byrd.

Yesterday, they were finally able to get some flights into Byrd. Our flight number is T012; flight T010 will take off for Byrd this evening, then T011 has to fly and then it’s us. We are watching the monitors in McMurdo that show the flight status, just like at the airports, hoping that flights get in. We cheer when a flight returns and groan when a flight is canceled due to weather.

There is one more issue that is causing delays.  This week they are moving the runways at McMurdo. In the early season, when it is still cold, the planes land very close to McMurdo on the sea ice at a place called Icey Runway. As temperatures warm, sea ice thins and the runway is moved farther inland to Williams Field, where the ice is thicker. This weekend is when they move airports, so there are no flights scheduled for Friday or Saturday (normally, there would be flights Monday through Saturday). So we will have another weekend in McMurdo, and when it’s time to fly to Byrd we’ll do it from William’s Field, about a 45-minute drive from McMurdo.

While we were waiting, I finally took some pictures of Percy the Penguin. Percy was given to me by a friend; it came from a geocache site in Seattle, WA and has now made it to Antarctica. Percy is actually the only penguin we have seen here. So far, the only wildlife we have encountered are skuas, large seagull-like birds, and Weddell seals that lounge on the sea ice just outside of McMurdo and Scott base.  Through there are no seals in the picture of Michelle skiing, she is on an ice shelf below which the seals could be swimming. When the seals find a hole in the ice they come up onto the sea ice or ice shelf and lounge in the sun.

Percy the penguin overlooking McMurdo Station.

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.

Notes from the Field