Among the many science experiments taking place at South Pole one of the more interesting field experiments is AGO – the Automatic Geophysical Observatories Network. While Research Scientist Dr. Bob Melville and his team were stationed here at the South Pole Station, I had the opportunuty to help build various electronics, which were subsequently installed at the AGO remote field sensor sites. It was a great experience working with them this year, and I’m certainly hoping to continue my involvement during future seasons on the ice.
Continued progress in understanding the Sun’s influence on the structure and dynamics of the Earth’s upper atmosphere depends upon increasing knowledge of the electrodynamics of the polar cap region and the key role that this region plays in coupling the solar wind with the Earth’s magnetosphere, ionosphere and thermosphere. Measurements that are central to understanding include the electric field convection pattern across the polar cap and knowledge of the response of the atmosphere to the many forms of high-latitude wave and particle energy inputs during both geomagnetically quiet and disturbed situations.
The U.S. AGO network, which consists of a suite of nearly identical instruments (optical and radio wave auroral imagers, magnetometers, and narrow and wide band radio receivers) at six locations on the polar plateau, actively studies the coupling of the solar wind to ionospheric and magnetospheric processes, emphasizing polar cap dynamics, substorm phenomena, and space weather.
Here at the south pole, we get lots of visitors – and many of them are extremely interesting. This past week I had the honor of meeting NASA Astronaut Scott E. Parazynski, MD. Dr. Parazynzki is now working as the Medical Director of the United States Antarctic Program. Having dinner with both Dr. Parazynzki as well as Dr. Sean Roden, former International Space Station Lead Flight Surgeon and now South Pole Chief MD was extremely interesting. Among other things, we discussed the various missions that Dr. Parazynzki and Dr. Roden had worked together on, as well as a few of the more interesting logistics for Antarctic medicine.
Although this happened at McMurdo and I didn’t get to see it personally, it’s still cool – a high altitude weather balloon launch in Antarctica.
BLAST-Pol is a balloon-borne submillimeter-wave telescope designed to study star formation in our galaxy. It was launched on its 2012 long-duration stratospheric balloon flight by the crew of NASA’s Columbia Scientific Balloon Facility on December 26, 2012 from Willy Field near McMurdo Station, Antarctica.
Last week, amidst some interesting weather, blowing snow, and what looked like (to the untrained observer) real snow falling, I reported that we were actually getting snow at the South Pole. As it turns out, the precipitation we received here was actually “snow grains”, not real snow. To clear up a bit of the confusion, and fill my in on general weather phenomenon here, I asked our Meteorologist Phillip Marzette a few questions.
Over the last few days here at the south pole, I’ve noticed some snow-like precipitation. I hear it’s exceedingly rare to get actual snow here. Was that snow we got, or something else? How often does it actually snow here? What’s the main form of precipitation?
As far as precipitation at South Pole, they come in three forms; ice crystals, snow grains and snow. Ice crystals appear about 90% of the time and are the product of water vapor after it encounters very cold and dry air poleward. Snow is made up of six-sided dendrite branch crystals. These are rare at South Pole and occur with warmer temperatures. Snow grains (8-9% occurrence), like snow, occur in warmer temperatures but they are more opaque, graupel-like in structure. Snow grains are what you saw out there, Jeffrey and there hasn’t been any “snow” recorded so far this season.
So, if we’re in a desert here and there’s such low amounts of precipitation, why is the ground covered with snow? Why isn’t it just slick ice on the surface?
The snow on the ground has mainly to do with the continent drifting towards the polar regions over millions of years. During that time, accumulations here have topped out at 2 miles while places further into the continent are at 3 miles. The ANDRILL project here on the continent can tell you more about that than I can. Over time, the snow hasn’t had a chance to melt and refreeze into ice that we are accustomed to, so the ground is still soft to walk on at South Pole.
ANDRILL (ANtarctic geological DRILLing) is a multinational collaboration comprised of more than 200 scientists, students, and educators from seven nations (Brazil, Germany, Italy, New Zealand, Republic of Korea, the United Kingdom, and the United States) to recover stratigraphic records from the Antarctic margin using Cape Roberts Project (CRP) technology. The chief objective is to drill back in time to recover a history of paleoenvironmental changes that will guide our understanding of how fast, how large, and how frequent were glacial and interglacial changes in the Antarctica region. Future scenarios of global warming require guidance and constraint from past history that will reveal potential timing frequency and site of future changes.
In addition to the light precipitation we’ve had lately, there’s also been a thick cloud cover, and it’s also been very warm – maybe around -10F. Do these have anything to do with each other?
As far as clouds bringing us warmer weather, that’s a two part answer. The first part being that clouds in general do a good job in trapping in longwave radiation, thereby keeping our temperatures up. The second part is a tad more complicated, but I’ll try to explain. At South Pole, the coldest air settles at the surface and the air is warmer above us. This condition is called an inversion. When cold air meets warmer air, conditions become calmer, while when warm air meets cold air, that’s when we get clouds. When we have low pressure air moves upward from the surface, while when we have high pressure air moves downward to the surface. During low pressure at Pole, the colder air at the surface meets the “warmer” air aloft and conditions are pretty good. During high pressure events, the warmer air goes down to the cold air and we get our clouds, precipitation and otherwise bad weather.
So far during my time here on the ice (Since November 13th), I’ve seen ice crystals drifting in the air, sundogs, thick haze, weird wave-like clouds, and driving winds. What other special weather phenomenon are you looking forward to seeing during the summer season? Anything really special we haven’t seen yet?
As far as anything else that pops up, we do have some Kelvin-Helmholtz clouds (the clouds that look like ocean waves, due to different layers of stability in the atmosphere) that show up from time to time. Other than that, it just learning more and more about what weather events occur normally at South Pole that I would not see anywhere else around the world.
This image was obtained just south of Laramie, Wyoming (Home to the University of Wyoming) by Patrick Shea on the morning of August 6, 2007 between 8am and 9am. Courtesy of the eFluids image gallery. http://www.efluids.com/efluids/gallery/gallery_pages/cloud_instability_2.jsp
The South Pole Cryogenics Laboratory, usually known as Cryo Barn, was originally established to service various telescopes and science experiments with cryogenic cooling liquids such as Liquid Helium and Liquid Nitrogen. However, in recent years, most new experiments which operate at cold temperatures have been of the “closed loop” variety – that is, they don’t vent or leak any of their coolant. Therefore, most of the new experiments don’t need the regular coolant refils that Cryo Barn was built to provide. Last week, I got to watch as the last Liquid Helium dewar was filled from the main tank, and then shipped off to the Bicep2 CMB Telescope. A few pics:
Cryogenics Technician Flint Hamblin prepares the main Liquid Helium holding tank for transfer to the smaller transport dewar.
Fill volume of the dewar is measured by weight, and here Flint is seen checking the dewar weight as it’s suspended from the ceiling.
Liquid Helium is at about 4 Kelvin, or -452.2 degrees Fahrenheit. During the fill, the valves and piping that handle the liquid helium get extremely cold. In fact, they get cold enough to condense out the gasses from the air, turning the air into liquid. In this picture, the wet drips seen coming off the exhaust nozzle are drips of liquid nitrogen and oxygen condensed out of the surrounding air. Basically liquid air. The small grey plume coming out of the tip of the nozzle is actually a small amount of liquid helium, instantly vaporizing. The small white crust seen at the tip of the nozzle is solid air.
The dewar is transported from Cryo to MAPO on a sled pulled by a snowmobile. Here’s Flint and Physicist Jon Kaufman on the snowmobile, as I ride on the sled with the dewar.
The final step of the process, hoisting the dewar up into MAPO, where it’s used to fill the Bicep2 CMB telescope.
Since moving to the south pole, I’ve learned an incredible amount of new terms to describe the area around where I’m living. One such term is “Pole of Inaccessibility”.
From Wikipedia: The old Soviet Pole of Inaccessibility Station, revisited by Team N2i on 19 January 2007
The southern pole of inaccessibility is the point on the Antarctic continent most distant from the Southern Ocean. A variety of coordinate locations have been given for this pole. The discrepancies are due to the question of whether the “coast” is measured to the grounding line or to the edges of ice shelves, the difficulty of determining the location of the “solid” coastline, the movement of ice sheets and improvements in the accuracy of survey data over the years, as well as possible typographical errors. The pole of inaccessibility commonly refers to the site of the Soviet Union research station mentioned below, which lies at 82°06?S 54°58?E[4] (though some sources give 83°06?S 54°58?E[5]). This lies 878 km (545 statute miles) from the South Pole, at an elevation of 3,718 m (12,198 ft). Using different criteria, the Scott Polar Research Institute locates the pole at 85°50?S 65°47?E.[6]
So, it seems like I’m not living at THE most inaccessibly place in Antarctica, but it’s darn close.
From Wikipedia: Map of distance to the nearest coastline[1] (including oceanic islands, but not lakes) with red spots marking the poles of inaccessibility of main landmasses, Great Britain, and the Iberian Peninsula. Thin isolines are 250 km apart; thick lines 1000 km. Mollweide projection.
This week, I was fortunate to be given unprecedented access to the Keck Array Microwave Telescope in the MAPO Observatory at the Amundsen-Scott South Pole Station by the Keck Array Science Team, in order to witness the disassembly of two of the five cryostats that form the telscope array. Photos.
The Keck array is a microwave telescope, just like Bicep2 and the South Pole Telescope (SPT). However, Keck (or SPUD, as some call it, depending on which side of the funding table the person you’re asking is sitting) is special. Keck, in an effort to up sensitivity and resolution, has taken the best of all worlds, and combined them into one super-telescope. They’ve taken the extremely successful and proven focal plane design from Bicep2, as well as the extremely efficient and self contained pulse-tube cooled cryostat from SPT, and made it into their own super telescope. And then multiplied it by five.
The Keck has not one, but five identical cryostats, each housing its own focal plane. Having five instead of one gives the team an incredible amount of sensing options and flexibility. One distinct advantage that I was able to see up close and personal is that individual parts can be serviced and worked on without bringing the entire telescope to a halt.
This past week, the Keck Array science team removed two of the five cryostats, and left three in place and operational.
Here are a few photos of the disassembly of the cryostats, stripping away all of their shielding and refrigeration to get to the heart – the focal plane.
Keck Array is housed in the MAPO Observatory, a 15 minute walk from the Amundsen-Scott South Pole Station. Although it’s only a short ways away, in -40 degree F temperatures, full sunlight, driving wind, and an active ice runway to cross, full gear and extreme caution must be used on the walk across the ice. It feels a bit like walking to class – although much colder. And at one of the most remote spots on the planet. That big plywood cone in the background in the groundshield of the telescope.
Looking straight up inside the telescope, as Scientist Colin Bischoff explains the inner workings.
Before disassembly, the cryostats are inspected for defects or light leaks.
Disassembly begins – very slowly and carefully – each cryostat is custom built and unique, the result of thousands of hours of R&D.
The team mid-project. I even got to help out a bit!
The inner core is revealed. This is the core refrigerator that’s responsible for cooling the focal plane down to an incredible 250 millikelvin. That’s just barely above absolute zero. The refrigerator uses both commonplace Helium-4, as well as exotic Helium-3, which is contained within the smaller titanium pressure vessel in the close-up shot.
Transition edge sensor (TES) bolometers sense small temperature changes that occur when photons are absorbed and converted to heat. The use of TESs enables arrays with a much larger number of pixels than is practical with spider-web bolometers. Sustaining its leading role in superconducting TES array technology, MDL developed and continues to improve a process to create arrays of thousands of TESs with high yield (>90 percent). These arrays are being employed on three major astro physics projects, all with the same goal: generating detailed maps of the polarization of the cosmic microwave background (CMB).
That’s it. Thanks very much to the entire Keck Array Science Team for generously inviting me into their lab.
