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!

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.

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.

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

Aerosols have different properties depending on what they are made of. Some of those properties that are important are roughness, color, and size. These properties affect what happens to solar radiation as it reacts with the particle such as whether it will scatter or absorb. For example, a particle of black carbon (left over after burning of a fossil fuel let’s say) is going to be much more effective at absorbing solar radiation than a piece of salt that has a much lighter color as well as a shinier surface (shiner, brighter surfaces reflect radiation better). It is also important how they are distributed spatially around the globe and how long they stay in the atmosphere. To think more about the spatial distribution, at the South Pole, we have no vegetation, dirt, salt water, or large sources of combustion anywhere close to us (aside from our own station which is downwind from where we sample). We have extremely low concentrations of aerosols in the air here compared to a sand desert or near a volcanic eruption. The time that they spend in the atmosphere can depend on many things. If it is a large particle, it may settle back to the surface quicker. If it rains, the aerosol may get collected by the raindrops and land back on the surface. Depending on the hygroscopic (the ability for a surface to become wetted or have water stick to it) properties of the aerosol, water can also condense on them to make cloud droplets.

Speaking of cloud droplets, aerosols can indirectly affect solar radiation by being an ingredient for clouds to form. Water likes particular sizes and types of aerosols to condense upon. The name this particular type are Cloud Condensation Nuclei. If there are no Cloud Condensation Nuclei present, the water has nothing to condense onto and there will be no cloud. The size and type of aerosol affect the physical properties of the cloud as well. Therefore a change of aerosols in a region can change the type of cloud, thus changing its radiative properties. This dependency on Condensation Nuclei brings up yet another complicated variable that can affect the radiation budget.

So that explains a little bit why we are so interested about the “dust” in the air. Aerosols have a significant influence on climate processes. Now let’s take a look at the instruments that deal with aerosols at the South Pole.

The Condensation Nucleus Counter (CNC) does basically what its name says. It uses butyl alcohol to create a cloud by cooling the flow of the air through the instrument. Inside is a particle counter that counts how many droplets there are.

The Nephelometer measures the radiation scattering ability of the aerosols. By running air through the instrument and shining a light through the air, we can detect how much of that light is getting scattered with a photomultiplier tube (PMT). There are filters in front of the PMT in order to detect several specific wavelengths of light. If we know the output of light initially, and subtract what is detected, then we know how much light is scattered by the aerosols.

The Aethalometer is an instrument that we use to measure radiation absorbing aerosols. For this instrument, air is passed through a filter where the aerosols will deposit onto. The filter is illuminated by a lamp and there are two photocells that sense the light. One is a reference sensor on a spot of the filter with no aerosols, and the other is sensing where the aerosols where deposited. The difference between these 2 sensors is the amount of light absorbed.

Here I am using the Pollack which is an older instrument that is used to compare to the CNC. It creates a cloud by depressurizing a chamber which causes the air to cool and form a cloud. There is a PMT that detects light and I watch an ammeter to see how much the current goes down when the cloud forms.

Not pictured is the Water-Based Condensation Particle Counter which is very similar to the Condensation Nuclei Counter that is shown above. The laser inside broke during the summer and we were not able to send it to the lab, get it fixed, and get it back to the Pole before station closing.

So that is how we measure aerosol concentrations and their scattering/absorbing properties at the South Pole. The next process that we measure at the South Pole will be the Carbon Cycle and Greenhouse Gas (CCGG) group. We’ll take a look at the CO2 analyzer and the role that greenhouse gases play in the climate.

Amundsen-Scott Station at Sunset.

Soon we will begin covering up all the windows on station and other buildings. At the South Pole, there is a Dark Sector where there is extremely light sensitive equipment and can be affected by any stray light coming though windows from the station. Not to mention it is a distraction from the beautiful night skies (or so I hear from winter-over veterans). We also have the flaglines that mark the path out to any of the outlying science buildings set up. They will come in handy when visibility is poor in the dark of winter. It is still in the dusk stage right now so we aren’t seeing any stars or auroras yet. Apparently by the second week in April is when it gets dark enough. I can’t wait to take some pictures! Camera batteries last only 5-10 minutes when it gets really cold and windy here so I’m going to have to make some kind of insulated housing for it pretty soon.

Sunset plus two days from the Atmospheric Research Observatory.

We’ve now fired up the TV series Battlestar Galactica (on Blu-Ray HD!). I had heard good things about it so I bought it last summer (northern hemisphere) thinking I could use a good TV series to get into for the winter. So far it’s keeping us entertained. I do a Thursday showing of three episodes every week to try to make it last through the winter. It’s tough to stop at three! Most of the weeks lately have involved me lifting weights before dinner, and then either playing volleyball, video games, watching Battlestar, or some other TV show/movie. Things are quite routine around here.

We’ve had a lot of windy conditions lately resulting in large drifts right smack in front of the stairs up to the Atmospheric Research Observatory (ARO). I’m sure we’ll be fighting these all winter as they get worse. ARO was built so that it could be raised as the snow drifts build up. It is in major need of being either raised or dug out completely. Hopefully this gets done next summer. It looks like it will be somewhat of a project because all of our instrument and inlet lines heading out in different directions and will have to be dealt with. Hopefully it’s with minimal downtime for the instruments. The wind has also carved out a lot of sastrugi that are wave like features on the surface of the snow. We use to have a nice waking path from the station to ARO but now it’s bumpy. Once it gets pitch dark, I’m sure I’ll be tripping and falling all the time on my walks to and from ARO. I already did just the other day!

Just the other day, we had the cold weather phenomenon of yukimarimos form on the surface. They would all collect in the pits of drifts and sastrugi creating a cluster of little cotton like balls of ice. They are very strange. They almost remind me of the seeds that come from cottonwood trees that drift around.

Yukimarimos piling up on a snow drift.

A close-up of the Yukimarimos.

The Final Flight: February 14th, at 2:30am New Zealand time.

We have just barely over two weeks until the sun sets and temperatures are already starting to drop quickly. The day of station closing, temperatures were around -40F. Today it is the coldest since I’ve been here at -63F, and tomorrow it’s suppose to bottom out at almost -70F. It’s amazing how quickly it drops when that sun gets low. The cold temperatures also make everyday things difficult to deal with. We had an emergency response drill today that took place outside and I volunteer on the fire team. You have to be really conscious about your gear because the SCBA (Self Contained Breathing Apparatus) hoses start to freeze and can crack easily. A fire fighter isn’t much good without a working SCBA. Frostbite is a big concern as well. The fire gear gloves and boots are not insulated for cold and do a very poor job of keeping your fingers and toes warm.

South Pole Station from ARO.

As for the science here at ARO (Atmospheric Research Observatory), not too much has changed. I’m still coming out here every day to check to make sure everything us running as it should be and taking air samples in flasks every week. One thing that is starting to change is our ability to do Dobson observations. The Dobson Spectrophotometer is an instrument that uses sunlight to measure total column ozone in the atmosphere. When the sun is this low on the horizon, there is a lot of stray refracted light that affects the measurements and can give us bad results. You may ask, “How do you take measurements in the winter?” Well this is done by using the reflected sunlight off of the moon. So we are able to take sporadic observations to coincide with our balloon flights through the winter. The solar radiation instruments on the roof will be coming down soon after sunset as well, which will be a small project for us. Here is a brief description of the solar radiation measurements we have at ARO and why we are measuring it.

Incoming solar radiation is the backbone of what drives our climate. Changes in the amount of radiation reaching the earth from the sun can be the difference between being in an ice age or not. It is important for us to know how much radiation is a) reaching the surface, b) what type of radiation it is (wavelength), and c) how much is bouncing back off the surface. This is what’s called the “Radiation Budget” in its most basic form. The “Radiation Budget” involves many other processes but the pictures and descriptions below show how we break down the “Radiation Budget” into its basic components at ARO.

The Solar Tracking NIP (Normal Incidence Pyroheliometer)

The NIP tracks the sun in all 360 degrees. It measures direct incoming solar radiation of specific wavelengths.

Diffuse Pyranometer

The diffuse pyranometer blocks out the incoming direct solar radiation and measures any radiation that is getting reflected and refracted from substances in the atmosphere (or any radiation taking an indirect path to the surface).

Pyranometers

These pyranometers detect all incoming solar radiation both direct and indirect. The two outer ones have filters on them to divide it up into shortwave (UV) and longwave (infrared) radiation.

Albedo Instruments

The “Albedo Rack” is basically exactly the same as the pyranometers except that they are turned upside down. They then measure the amount of solar radiation that is reflected off of the earth’s surface. Roughness and color play a role in Albedo meaning that a smooth surface is going to reflect more than a rough surface, and a white surface is going to reflect more than a black surface.. Therefore, it is important not to disturb the snow under these instruments because we want the natural state of the surface. In addition to reflected radiation, it monitors infrared radiation emitted by the earth.

A more complex version of the “Radiation Budget” or “Energy Balance” pulled from the IPCC Fourth Assessment Report.

As you can see, in the above figure, there is a lot that really goes into the “Radiation Budget” and it is a very complex system. When the solar energy comes into the atmosphere, it can take a variety of paths. It can get interrupted by clouds, gases, aerosols and other substances. Two of these processes in the system we observe at ARO as well such as Aerosols, and Greenhouse Gases which I will talk about in a later post.

Hopefully this explains a little bit what’s behind the solar radiation observations that we take at ARO. The South Pole and Mauna Loa have the longest continuous running solar radiation observations of this kind. It’s extremely important that we understand what happens to solar radiation as it passes through the atmosphere and hits the earth’s surface if we want to gain a good understanding of how earth’s climate works. It is even more important as we try to predict future climates.

The entrance to the ARO (Atmospheric Research Observatory).

Those daily tasks that I mentioned mostly just involve going through all the equipment in the station and making sure that it is running correctly. Some instruments need daily adjusting to keep them acquiring good data. Others operate on their own pretty well (look for future posts to go more in depth on what exactly these instruments are and what they measure). Throw in setting up some new instruments, launching two ozonesondes (ozone measuring weather balloons) a week and flask sampling (capturing air to sample in flasks), it keeps one pretty busy especially when not really experienced with much of it.

Help has now arrived as Mark VanderRiet arrived last week and Lana Cohen has arrived today. With a couple of weeks under my belt, I am starting to feel much more comfortable on the day-to-day operations and things seem to be running smoothly for the most part. We’ve shipped most of the sampled air flasks that have accumulated over the winter back to their project locations (due to the fact that there are no flights to ship them during the winter season), and are getting ready to receive the shipment of new flasks and other supplies for the up coming year.

As for life on station, it is pretty incredible how we are living down here if you consider what a remote location this is. The room I was assigned is plenty big for my needs and is pretty comparable to the size of room that I had when I was on the NOAA Ship Fairweather. The recreation schedule here is full. Every night of the week there is something going on in the gym (volleyball seems to be the most popular), and there is a great selection of movies and TV shows in the store. The observatory is a great place to hang out in the evenings too if you want to relax and watch a movie. It also gives you a chance to shoot some evening Dobsons too (the Dobson is an ozone measuring instrument)! And by the way, winning bingo twice in one night is not a good way to make friends around here.

Once things settle down, I’m excited to show you all what kind of equipment we have at the Atmospheric Research Observatory, and what it measures. Hopefully I can get into some of the other projects that are going on down here at the Pole as well. I would think I’ll have time, I’m here for the long haul!

The Ceremonial South Pole

NOAA’s Atmospheric Research Observatory

NOAA’s Atmospheric Research Observatory (ARO) at the South Pole is part of a network of stations around the world that monitor properties of the earth’s atmosphere. This station is part of NOAA’s Earth Systems Research Laboratory (ESRL), Global Monitoring Division (GMD) located in Boulder, CO. Some of the items that GMD monitors are aerosols, radiation, carbon cycle gases (CO₂), ozone and water vapor, as well as halocarbons and other trace gases. NOAA has been maintaining some of these measurements, including tracking the increasing concentration of carbon dioxide in the atmopshere, dating back to the International Geophysical year of 1957 giving more than 50 years of continuous data.

The Amundsen-Scott South Pole Station

Long term data is extremely useful when studying the earth’s climate. Due to climate’s high variability, it is necessary to have a long set of continuous data to pick out trends and to help predict the state of the atmosphere in the future. Because it is in such a remote location, far from any source of emissions or human activities, the ARO gives scientists a baseline level of the global average measurements. Air at the South Pole is the “cleanest on earth,” free of local influences from humans such as factories and cars, as well as natural effects from things like volcanoes.

Flight path for our second science flight to Terra Nova Bay. The Pegasus ice runway, where the Aerosondes take-off and land, is at the bottom of the image. Terra Nova Bay is at the top of the image and is approximately 350 km north of Pegasus.

Close-up of the flight path over Terra Nova Bay. The yellow pushpin symbols mark locations where we had the Aerosonde spirals up and down between 150 and 1500 m altitude to measure the vertical structure of the atmosphere.

The purpose of this mission was to observe the low level winds and temperatures in the atmosphere, with the goal of relating these to the processes happening at the surface of the sea ice and ocean. To help us relate the atmospheric processes to the surface processes we took aerial photographs as we flew over Terra Nova Bay. Seeing the surface state will be very useful as we try to understand the meteorological data we’ve collected.

The flight arrived at Terra Nova Bay around sunset, so we didn’t have much time to take aerial photos before it became dark, but the photos we did get are stunning and raise some interesting questions that we’ll be trying to answer as we analyze the data we’ve collected. One of the big questions is how there was almost no open water despite winds blowing offshore at over 50 mph.

The edge of the continent – the Nansen Ice Shelf (left) and Terra Nova Bay with a thin coat of sea ice and maybe just a little bit of open water (right).

All of the aerial photographs shown here were taken from an altitude of 150 m and each image covers a horizontal distance of approximately 150 meters.

All of the photographs were taken on the first leg of the flight (the leftmost blue line) in the flight path shown above.

The violent mixing caused by the strong winds creates some stunning patterns in the sea ice. In this photo thin slivers of sea ice are rafted onto adjacent sea ice in a process known as “finger rafting”.

One of the common features we observed in the aerial photographs was bands of thicker ice (the brighter white ice in the image) oriented in the direction of the wind. In this photo the wind is coming from the top left corner of the image and is blowing at 50 mph. You can also see some areas of thin ice or open water (the darkest areas) where waves are present.

Another surprising feature seen in the photographs was the presence of ocean waves traveling under the sea ice surface as seen in this photograph. Given the very small amount of open water that we observed it is surprising that any waves were generated at all, since waves are created when winds blow across the surface of the water.

Patterns in the sea ice.

You can see areas of open water (or very thin ice) (darkest spots), areas of thin ice (dark grey) and areas of thicker ice (brightest areas) in this image.

We are planning to switch to daytime flights this week, since the days are getting long enough to allow us to launch at first light and fly until dusk and still have 14 or 15 hour missions. Of course the time between sunrise and sunset is just at 12 hours right now, as it is everywhere on Earth on 21 September. What will allow us to fly 14 or 15 hour flights and still take-off and land in daylight is the fact that the length of twilight before sunrise and after sunset is very long here. We’re hoping to get lots more images of the polynya during these daytime flights.