Ice Stories: Dispatches From Polar Scientists Mon, 15 Nov 2010 20:40:36 +0000 en hourly 1 South Pole Ozonesonde Launch Sat, 09 Oct 2010 00:12:53 +0000 Nick Morgan SOUTH POLE, ANTARCTICA– Preparation for an ozonesonde launch takes place in the Balloon Inflation Facility (BIF) and begins about 7-10 days prior to launch day. We open up the styrofoam package which contains a pump, some circuitry, and a battery. There is some important information we need to know about the pump such as the sensor’s response time, and how much air it pumps through it. The flow rate through the pump is probably the most important piece of information because we enter that into a program that calculates the ozone. For example, if there is more air flowing through it, then it is going to measure more ozone so that needs to be taken into account. All the sondes have slightly different flow rates so they all have to be checked. There are various other checks that we run though to make sure that the sonde is up to specs as well on the day of the launch. Some tests are just repeated the day of the launch.

Then we head into the “hangar” to prep the balloon (plastic balloon, in warmer months we use rubber). The balloons are filled with helium and are clipped to a set amount of weight so we know that we will get consistent rise speeds and burst altitudes. Since the plastic balloons don’t expand, most of it left empty so when it get’s to high altitude at low pressure, the helium has space to expand into.

Then after some final preparation of the ozonsonde package which may include some heating elements to keep the pump warm and getting the battery ready, we are ready to launch!

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Sunny Days Are Here Fri, 01 Oct 2010 18:06:33 +0000 Nick Morgan SOUTH POLE, ANTARCTICA– Well to tell the truth, there hasn’t been too much to write about lately until now (hence the reason I have been absent in writing lately). But now we have the sun well above the horizon and it’s great to see again. Not only has it made my walk to ARO (Atmospheric Research Observatory) easier, being outside in the sun sparks a bit of energy and helps motivate to get some work done as we get ready to turn over to next year’s crew.

Notice the bit of sunlight on the side of my face!

The main station and sunrise. This photo was actually taken a day before “official” sunrise. In actuality, the sun takes a several days to rise.

On station, we have begun the large list of tasks posted by our station manager which mostly involve shoveling out buildings that have been dormant for the winter, and performing deep cleans of bathrooms, hallways, and work areas. I’ve decided that I have spent enough time inside so I volunteered for a few shoveling tasks namely the cargo office, cargo DNF (the building that houses cargo waiting to be sent out or received that can’t be frozen), and a summer camp Jamesway tent. The FEMC (Facilities Engineering Maintenance and Construction) crew is probably the busiest group with the station opening work as they have to get fuel to all the buildings and start heating them up so they are ready when the summer folks arrive. Our heavy equipment operators are busy as well removing snow and beginning to smooth out the skiway for the first flights. They have had a little bit of trouble due to the cold temperatures because they cannot operate the bulldozers under certain temps.

The BIF (Balloon Inflation Facility) is just below the Sun. To half cylinder shaped buildings to the left are the Jamesways that are being dug out and warmed up for the summer crew.

At ARO, I’m just finishing up inventory to figure out what needs to be shipped down during the summer. It is mostly unchanged from last year because we haven’t had many problems with the instruments this year so there will probably just be a few items to alert people back at ESRL in Boulder, Colorado about. We are also at our intensive ozonesonde launching period where we are launching every 2-3 days as opposed to our normal one per week. It’s been rather unexciting in the depletion department this year. It seems that the polar vortex may not be all that well defined as some years with very low ozone levels. A description of the process of the annual ozone layer destruction over Antarctica can be read in my previous post, “The Ozone Hole: It’s Still There!” Once the sun is a little higher in the sky, we will be able to resume daily measurements with the Dobson Spectrophotometer (measures total column ozone through the atmosphere).

The solar instruments have also been placed back on the roof and are collecting data again. Initially they were having trouble with the -90F temperatures, but we have seemed to iron out the problems and they are now tracking the sun well. For an overview of the solar instruments, see the previous post, “As Sunset Approaches, Let’s Talk Solar Radiation”.

The roof of ARO and various solar instruments.

The next thing that is on tap for myself is organizing all of the flask samples that have been taken over the winter and getting them ready to ship out in the summer. Mostly that just involves writing up the paperwork so it’s ready to go for my replacement (yay paperwork!). Oh, and packing. The thing I look forward to least is also on the agenda. I will need to find boxes to ship home all the things that have kept me entertained here such as my Playstation 3 and movies. As well as excess clothing that I don’t want to travel with.

As I mentioned in “The Ozone Hole: It’s Still There!”, I will be posting an ozonesonde launch with the plastic balloons that we use. Don’t worry, I haven’t forgot! I have it videotaped and will get it posted soon!

Here are some more nice pictures during the last month or so:

The Moon and Venus. The were the last two visible objects in the sky as the sun was closer to coming above the horizon.

ARO from halfway between the station and ARO

The Moon over the Clean Air Sector, directly opposite of the rising Sun.

Nice reflection off the corner of ARO

The Moon about to set out over SPT (South Pole Telescope)
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The Ozone Hole…It’s Still There! Tue, 17 Aug 2010 22:30:39 +0000 Nick Morgan SOUTH POLE, ANTARCTICA– With the arrival of mid-August, comes our first glimpse of dawn on the horizon. Not only is this a welcome sight to us “Polies”, but it brings upon us initiation of the destruction of ozone in the stratosphere (location of the “ozone layer”). When I was in grade school I seem to remember that the ozone hole was all the rage as one of the primary environmental concerns. These days, it is far overshadowed by the rise of greenhouse gases and the study of climate change. The ozone hole has taken somewhat of a back seat in the public eye. And maybe that is a sign of success. In 1989, the Montreal Protocol was put into effect beginning the phase out of chlorofluorocarbons (CFCs). CFCs were used in things such as refrigerants, solvents, and aerosol sprays. We are now beginning to see a leveling off and even a decrease in some CFCs in the atmosphere. So is that an environmental problem that we chalk up as successfully solved? Well, maybe.

The atmosphere has four main layers which are the troposphere (the lowest layer in which most weather occurs), the stratosphere, mesosphere, and thermosphere. There is some ozone in the troposphere, but it is a very small amount and is produced by the reaction of pollution and ultraviolet (UV) light. Most of the ozone in the atmosphere is located in the stratosphere, hence the name the “ozone layer”. The ozone layer is important because it filters out some harmful UV radiation. CFCs eventually make it into the stratosphere and mix in with the ozone molecules. The CFCs don’t do their damage until they react with UV radiation which breaks the bond of the chlorine or bromine atom apart from the rest of the CFC molecule. Chlorine and bromine are highly reactive with ozone (a molecule consisting of 3 oxygen atoms) which then breaks the ozone apart becoming a ClO and O2 (regular breathable oxygen). The creation of ozone in the stratosphere is from the interaction of UV radiation with an O2 molecule. It splits the O2 creating two single oxygen atoms which then react with O2 creating O3 (ozone).

Example of the CFC/Ozone destruction cycle from NOAA’s ESRL website

These appear to be processes that could take place all over the world so why is the ozone hole unique to the Antarctic region? There are two main factors that enable a hole in the ozone layer to form over Antarctica: the polar stratospheric vortex and polar stratospheric clouds. Antarctica’s extreme cold temperatures allow for these polar stratospheric clouds to form. The clouds enhance CFC/ozone reaction causing the destruction of ozone to become very effective. The polar stratospheric vortex forms every winter over the Antarctic continent and keeps the air from interacting outside of the vortex. So basically ozone from outside the vortex is unable to flow in and replenish during this time. That is when we see the lowest ozone values. As temperatures warm through the summer, the polar stratospheric vortex begins to break up, polar stratospheric clouds disappear, and the air mixes back into the Antarctic stratosphere replenishing the ozone layer. The filling in of the ozone hole causes a decrease in ozone worldwide which how it becomes a worldwide issue. The ozone hole hasn’t proved to be decreasing yet but the fact that the harmful CFCs look to be working their way out of the atmosphere is encouraging and we look for the hole to begin decreasing in decades to come.

So right now we are at the point where the sun is getting just high enough (still well below the horizon) that its rays are beginning to hit the stratosphere breaking down the CFCs that are up there. At the Atmospheric Research Observatory (ARO) we measure ozone in three different ways. One is with a surface analyzer that gives us a baseline level of tropospheric ozone, and the other two include the Dobson Spectrophotometer and launching ozonesondes which both give us an idea of stratospheric ozone.

Ozone surface analyzers

The Dobson Spectrophotometer. During the winter, observations are only available when the moon is up. Bad weather and poor visibility can hamper opportunities thus making balloon launches extremely important (especially so this winter it seems!).

For most of the year we launch one balloon a week but as the ozone hole forms we start launching two to three times a week. The idea is that we increase the resolution of the data so that we can see the peak of the ozone depletion. The balloons are great because they give us a complete profile of the ozone all the way up to 30-35 kilometers high.

In the winter we launch plastic balloons. The rubber balloons don’t get high enough due to the cold air. (ideally we like to get up to 28-30km).

When there is enough light outside for video, I will take you through an entire launch sequence explaining how we prep the sonde, prep the balloon, launch the balloon and show the software that gives us the profile of the data. We can even compare what a normal “healthy” layer looks like prior to the hole forming to the hole itself.

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Measuring Atmospheric Carbon Dioxide at the South Pole Mon, 26 Jul 2010 18:45:39 +0000 Nick Morgan SOUTH POLE, ANTARCTICA– Carbon Dioxide is now one of the most studied environmental phenomenons. It has had such a boom in attention due to its properties and effects on the earth’s climate. By now everyone has heard of the “greenhouse effect” and how it works. Basically the shortwave radiation from the sun (ultraviolet) passes through the atmosphere and hits the earth’s surface and some is absorbed, while some is reflected. When solar radiation is absorbed it causes the surface of the earth to warm up which the surface is then emitting infrared radiation (heat). Carbon dioxide in the atmosphere (among other gases such as methane), just happens to absorb certain wavelengths of infrared radiation which causes some of that energy that came in from the sun to be trapped within the atmosphere.

Part of the Radiation Budget, pulled from the IPCC Fourth Assessment Report. Source: Kiehl and Trenberth (1997).

Carbon dioxide has a carbon cycle much like water has the water cycle. CO2 is emitted and absorbed in numerous ways. Whether it’s a chemical reaction in the atmosphere that changes molecules of CO2 into something else, the combustion of a fossil fuel producing CO2, or the oceans taking in CO2 from the air and depositing it deep under the surface, they all play roles as sources and sinks of atmospheric carbon dioxide.

Figure from ESRL Carbon Cycle Greenhouse Gases Group. The data comes from the Carbon Cycle Network that includes NOAA Baseline Observatories (like the South Pole Observatory) as well as cooperative programs around the world.

The figure above graphically depicts the carbon cycle on an annual basis. The red strip indicates the data that has been gathered over the last 10 years from the South Pole. The waves in the graph are from the seasonal uptake of carbon dioxide by plant life. For example, in the summertime when trees have their leaves, and plant life is not dormant, you see a large dip in CO2 values especially in the northern hemisphere because plants take in CO2 for photosynthesis. Also notice the difference in variation (waviness) of CO2 between the Northern Hemisphere and Southern Hemisphere. This is due to the very large forests in the N. Hemisphere compared to the S. Hemisphere, and the fact that the N. Hemisphere is more populated. Aside from the annual variation, notice the steady rise of CO2.

In previous posts, we’ve looked at some of the instruments at the Atmospheric Research Observatory (ARO) that measure things like solar radiation. At the South Pole, carbon dioxide has been measured for just over 50 years now and there are a few different methods of obtaining a CO2 value.

One of them is using our Portable Sampling Unit (PSU) that looks like a suitcase containing a pump inside. Using the PSU, we walk out into the Clean Air Sector (CAS), turn on the unit, and pump air into glass flasks which are then shipped back to the Earth Systems Research Laboratory in Boulder, CO for analyzing. (I shot a video of the process which can be seen here.)

The second is hooking the same type of glass flask that we use in the PSU to the Through Analyzer. What this does is bottle up a sample using the same sample lines as our third method uses a Non-Dispersive Infrared Detector (NIDR).

The Portable Sampling Unit (PSU). Flask samples with this unit are done once a week. On the first and fifteenth of the month, they are done in conjunction with sampling from the Through Analyzer.

Upper right: The Li-COR Non-Dispersive Infrared Analyzer. Lower Left: A display graphing the voltages recorded over the past four hours. The spikes are the calibration gases measured once every hour.

The NIDR uses an infrared source which is a heated filament that emits infrared radiation around the same wavelength that carbon dioxide likes to absorb (usually around 4.26 µm). This energy travels through two absorption cells, one of which is containing a sample of air from outside, and another that is containing a reference gas from a compressed gas cylinder. A mechanical chopper wheel then alternates between the sample and reference gas measuring the difference in the amount of absorption between the two. Using the difference of the two cells helps negate the problem of changes in temperature and pressure. Changes in pressure and temperature change the density of the sample which would skew the amount of carbon dioxide molecules in the measurement. This is a very useful machine that requires very little maintenance and gives us measurements continuously 24 hours a day, 7 days a week (there is about 15 min of each hour that it measures accurate known amounts of carbon dioxide in other gas cylinders for calibration).

On the right are the three calibration gases and the reference gas.

Here is a comparison of when the winds are in the Clean Air Sector (CAS), and when they are blowing station air towards the Atmospheric Research Observatory (ARO). The this graph is when the winds were from the direction of the station and the graph that follows is when the winds are in the CAS.

As you can see we easily pick up local carbon dioxide when the winds are blowing from the station. Winds at ARO are within the CAS probably greater than 90 or 95 percent of the time which is why it is such a good place to get long term continuous measurements of CO2.
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A Midwinter Toast Thu, 08 Jul 2010 18:46:49 +0000 Nick Morgan SOUTH POLE, ANTARCTICA– Station Manager Mel MacMahon leads the toast before midwinter meal at the Amundsen-Scott South Pole station. The occasion is in celebration of reaching the half way point of the long six months without seeing the sun.

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The South Pole galley staff puts together great meals for celebrations of various milestones throughout the winter such as sundown, midwinter, and sunrise. Their hard work all winter long is much appreciated by the South Pole winter over crew. The menu was designed by Matthew Lee.
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So, You’re Eight Months In And… Wed, 16 Jun 2010 17:24:35 +0000 Nick Morgan SOUTH POLE, ANTARCTICA– This was a question that I was just asked the other day. It was a friend of mine down here that has wintered-over previous years and was wondering what my opinion was having being my first winter here. I didn’t really have a whole lot to say about it but this. “Eh” (shoulders shrug). But really, the day-to-day down here is very boring. Every day is pretty much the same aside from the events here and there such as the mid-winter celebration and other festivities. After a few moments of thinking about it, I told him, “Well on the day-to-day time scale it’s pretty boring here and you just let the days pass.” Which they do very quickly when every day seems to be pretty much the same. But then I thought about it and said, “But when you think about it as a whole, it’s really an amazing experience.”

See, scattered throughout the year, there are really cool things that happen. Such as the first time getting off the plane and seeing Antarctica (definitely had some butterflies in the stomach), standing at the South Pole marker the first time, seeing the last plane leave, seeing the sun go down knowing you wouldn’t see it for 6 months, the beautiful polar night skies, and this Friday the mid-winter mark.

Shoveling out a path to ARO (Atmospheric Research Observatory) just after station closing

And there are still some to come like the sun rising, the first plane landing and taking a flight out of here. So there are all these milestones that are exciting which add up. Yeah, the day-to-day is pretty boring here, but the sum of all the milestones make the entire time down here an amazing experience. That’s what helps me anytime I’m feeling a bit homesick or anxious to move on. And that is what I’m going to remember when I leave in 5 months. (Wait, why am I talking like I’m almost done? Hehe.)

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South Pole Nights Wed, 19 May 2010 18:04:34 +0000 Nick Morgan SOUTH POLE, ANTARCTICA– Here are some photos of the night skies at the South Pole.

South Pole Telescope (SPT) with a half moon

Early auroras over the Atmospheric Research Observatory (ARO)

Full moon rising over the Clean Air Sector

Dusk at ARO

The drift creeping up to the station

Managing my way around the snow drifts at ARO’s entrance

Starry skies with the LIDAR in view at ARO (similar to a radar but it’s a laser)

A view of the station from ARO

ARO and the meteorological tower with vivid aurora
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South Pole Update Mon, 10 May 2010 17:03:59 +0000 Nick Morgan SOUTH POLE, ANTARCTICA– We are nearly 2 months into the Antarctic winter now and it’s hard to believe that we only have just a little over a month until we are at mid-winter. April was somewhat uneventful here as everyone seems to have on the winter cruise control. There were some interesting things that happened however.

April weather was somewhat significant being the coldest April on record averaging -80.7F which was lower by 0.2F than the previous record set in 1998 (records began in 1957). On top of that, we set the second earliest mark in reaching -100F ever recorded dipping to -100.7F on April 13th. It’s only typical that as soon as April ended, we are on a streak of warm and unsettled weather. For instance, temperatures today are supposed to rise into the -30s Fahrenheit. It’s amazing to me that you can have a range of about -65 degrees without any daily help from the sun. If things keep up, which they look like they will for the near future, we are on pace for the warmest May ever! I wonder what is in store for the rest of the winter?

Taking in the sky from the Atmospheric Research Observatory

The station atmosphere was much quieter however. We only really had only one major event which was a glycol leak in the power plant. The power plant uses a 60/40 glycol to water ratio to cool the diesel generators. The waste heat from the generators transferred to the glycol mix is then run throughout the station to heat the building. My knowledge of how the whole system works is very limited but as I understand it, a thermostat broke open and created a geyser of glycol. It then landed on some of the exhaust manifolds causing it to vaporize and create a huge cloud in the power plant. This triggered the fire alarm. Luckily it wasn’t one of the loops that carry the bulk of the glycol or it could have been a much worse mess. Over the summer, we had so many false alarms that you kind of become desensitized to it always thinking it’s a false alarm. But when you hear the automated alarm system say that smoke was detected in the power plant, and that it’s not a drill, it really gets the adrenaline pumping. As you can imagine, the power plant is one of the locations on station where you could have things really go wrong.

Everyone on station is assigned to an emergency response team and mine is the fire team. Because we are on are own down here, it is our responsibility to deal with these situations. The fire team had some firefighting training back in Denver before we came down Antarctica and we also try to do some training on our own once a week to keep methods fresh. But we are by no means professionals. Needless to say, I was very relieved to find that the power plant was not engulfed in flames and nobody was injured in the incident. The heart rate definitely jumped initially with the thought that I might actually have to go in and drag someone out of a flaming building. We don’t have fire hoses so all we have are fire extinguishers to use on station (there are fixed water and CO2 suppression systems at various locations however). With all the luxuries that the station has, it’s easy to slip into a false sense of security. These types of incidents are reminders that we are still in a dangerous environment.

There are not any traces of the sun on the horizon any more. When the moon is out, it is like a floodlight on the South Pole. It’s amazing how bright it is. It sure makes walking to the observatory every day much easier. Now the moon has gone below the horizon and it’s extremely dark but the stars are incredible. Yesterday walking back from the Atmospheric Research Observatory (ARO), I was lucky enough to see an iridium flare coupled with a really nice aurora. An iridium flare is when the solar panels of a satellite are at just the right angle that it reflects the sun’s light at you. It does it for just a few seconds as it passes overhead. Unfortunately I did not have my camera ready for a photo.

Well that about does it for the update. Seven months down, six to go!

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Foxes on the Edge Wed, 28 Apr 2010 17:26:21 +0000 John Whiteman DEADHORSE, ALASKA– Once they kill a seal, polar bears will often eat only the fat and move on. This behavior may have evolved to help maximize their return on investment, allowing them to use a minimal amount of time for eating, but consuming the most energy-rich portion of the seal. I previously described how bears kill seals, during the capture season last spring here. This spring we have seen some kill sites of bearded seals (Erignathus barbatus), which we did not see much of last spring – the bearded seal is much larger than the ringed seal (Phoca hispida) and presumably is more formidable as prey. Once a polar bear leaves the carcass it is available for other scavengers. They aren’t many other animals out on the sea ice, but we have seen birds and frequently, Arctic fox (Alopex lagopus).

Arctic fox seem to make their living by following bears around and scavenging. We have seen foxes trailing behind bears as they travel, and their tracks often wind around bear prints. (My apologies that the pictures below are graphic. However, the carcass below illustrates a critical aspect of the life of predators).

These bones – the vertebral column and attached ribs – are all that remained of a large seal that was most likely killed by a polar bear. The area was covered with fox tracks, and the carcass had been thoroughly scavenged.

Even a flipper had been used for food – the bones of this flipper were intact, showing the similarity to the shape of my hand.

Such an existence seems precarious; polar bears range over great distances, and their successful hunts are few and far between. What if the fox doesn’t find a carcass? It turns out that foxes themselves can be successful predators of young seals. In the early 1970s, a researcher named Thomas Smith trained his Labrador dog to sniff out seal lairs (lairs are in hollow spaces on top of sea ice but below a blanket of snow; seals use these protected spaces to rest and give birth). He spent several winters digging up hundreds of lairs and found evidence that Arctic foxes were able to enter the lairs and predate on young seals. He wrote:

“A keenly developed olfactory sense allows the arctic fox to locate the subnivean seal lair, sometimes through snow depths of over 150 cm…Lairs that had been entered by foxes showed one or more entry holes. Usually the holes penetrated the lair at a slight angle and were never more than 20 cm in diameter…In the case of an apparently successful kill, blood was always present on the floor of the birth lair once the lair had been dug open…When the lair was well developed into a tunneled structure there was usually more blood and the site of the actual kill usually appeared to be in one of the small tunnels”

In fact, Smith concluded that in certain parts of the Arctic, foxes may be more important predators of young seals than bears. However, foxes were never found to kill adult seals, which must be simply too large for a fox to attack. Foxes were also more thorough than bears. They seemed to remain at the site for several days and consume the entire carcass.

So perhaps foxes don’t live as close to the edge as I originally thought, although no animal in the Arctic seems to have it easy. In a very different way, our field season is currently on the edge – due to good weather early on, we flew for more hours than were budgeted, leaving one of our two helicopters in a crunch for funding. We have scrambled to line up addition funding, to support the helicopter for more time; otherwise, we could be forced to end the season in just a couple days. We have had some tremendous luck in locating and re-sampling bears from previous field seasons, giving us great data on how bears fare over time – I really hope we are able to continue flying.

On what has become a rare, sunny day, this is my view through the bubble windshield of the helicopter, wrapping below my feet, as we fly north over the sea ice.

Thomas Smith’s article:
Thomas G Smith. 1976. Predation of ringed seal pups (Phoca hispida) by the arctic fox (Alopex lagopus). Canadian Journal of Zoology, Volume 54, pages 1610-1616.

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Some Time to Think Thu, 22 Apr 2010 21:02:19 +0000 John Whiteman DEADHORSE, ALASKA– After a very busy start to the field season, the schedule has slowed due to weather in recent days. Temperatures have warmed up into the 20s (Fahrenheit) and the ice has started to break up in some places, exposing open water to the air – I think these influences increase the water vapor in the air and generate more fog. We have had several days with delayed starts because of poor visibility and fog in the mornings. Another sign that spring may be on its way – as I write this, a snow bunting bird flew past the window over my desk, then returned and perched on the sill.

This is the view to the north from the desk in my room at the bunkhouse. The houses and power lines of Kaktovik are visible, and the fog doesn’t seem that bad, especially given the blue sky. However, this is a “sucker hole” that can trick you into thinking that visibility is good, when in fact, you happen to just be in a hole of clarity in an otherwise thick fog bank.

This picture is from the same perspective, an hour later. The fog has mostly lifted – now, beyond the houses, a hangar (about ¾ of a mile away) and the northern horizon of sea ice are visible.

The reductions in flight time have given me time to catch up on coursework and get some reading and thinking done. Even when the schedule is very busy, sometimes the helicopter can be a surprisingly good place to think. The pilot is obviously busy during flight, and as passengers we are always scanning the ground for bear sign – tracks, kill sites, carcasses. However, once you get into the rhythm of scanning and tracking, your mind can return to the larger concepts of the project, turn over the data you have collected so far, or move onto other questions. I suppose it is similar to any situation where you put several people into close quarters for several hours of travel – interesting conversation can come up, or people can mostly travel along in their own minds.

We have been talking recently about how to interpret some of our data in regards to polar bear diet. We have months of analysis before we can begin drawing conclusions, but the summary of our data up until now can provide suggestions. One of the reasons the polar bear diet is interesting is that it is fairly simple in comparison to the closely-related brown bear (grizzly bear). Polar bears mainly eat seals, and this is reflected in their dentition, whereas many brown bears consume a wide variety of food items, including lots of vegetation.

The canine and incisor teeth of an adult polar bear. Polar bears have evolved larger canines because these stabbing teeth are useful in hunting, and polar bears hunt more than most brown bears. Polar bears also have reduced molars because they eat less vegetation than most brown bears, and therefore have a reduced need for grinding teeth.
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