To keep an eye on our changing climate, the National Oceanic and Atmospheric Administration’s Global Monitoring Division (GMD) operates six atmospheric baseline observatories around the world. They stretch from high in the Arctic Circle to the South Pole. Each facility collects similar data, and uses near-identical instruments and operating procedures to do so. By standardizing research at each site, GMD is able to paint an accurate picture of the chemical constituents that impact Earth’s climate. All of GMD’s data is available for free online, so if you are interested in seeing how the abundance and distribution of Aerosol Particles have changed over the past 10 years take a look at our website.
At the South Pole’s Atmospheric Research Observatory (ARO), we operate and maintain instruments that are used for studying solar radiation, aerosols, ozone, ozone-depleting substances and carbon dioxide (CO2). Most of the instruments run continuously, processing steady streams of air that are pumped in from atop our 30 meter meteorological tower or from a 6 meter mast attached to the top of our building. This continuous, on-location data collection is known as “in situ” or onsite sampling. It allows us to collect an abundance of data, often by-the-minute averages that are useful for studying high resolution, day-to-day trends.
Of course, there is a limit to what our in situ instruments can measure, and the accuracy and precision with which they do so. The carbon dioxide analyzer we use cannot measure the presence of CO2 isotopes, which are important in understanding whether the CO2 we see is coming from burning fossil fuels or from forest fires. Similarly, our gas chromatograph can measures tens of different compounds with part-per-trillion accuracy, but a slight leak in any of its hundreds of delicate parts can destroy our data’s robustness and be nearly impossible to detect.
We address the shortcomings of our in situ measurements by collecting physical in vitro or glass flask samples of the same South Pole air our instruments analyze. Every week, air is collected in a variety of flasks and each summer, they are sent back to various laboratories around the world for detailed studies of the air they contain. In the proper setting, the in vitro samples allow for more precise and accurate measurements than our in situ systems, and can often reveal chemical compounds such as CO2 isotopes that would otherwise pass through our instruments undetected.
Furthermore, in vitro sampling allows us to identify and troubleshoot problems that may arise with our in situ experiments. For example, if a series of flask samples taken from the Gas Chromatograph air lines show a higher or lower detection rate of a Halon (an ozone-depleting substance found in old fire suppression systems), then we know there may be an issue with the instrument, and in turn, the data it’s collecting.
Over the course of a year, I’ll collect more than 300 flask samples for five distinct research projects. Flask sampling days are perhaps my longest, with some individual flasks taking more than an hour to flush, fill and package.
The samples can only be collected when the winds are blowing at high speed through our clean air sector; in other words, not over the power plant. This means flask sampling days often coincide with some of the South Pole’s worst weather—whiteouts, blowing snow and wind chills below minus 73 Celsius (minus 100F).
The most challenging flasks to fill are those that require me to collect air from deep within the clean air sector, using heavy portable sampling units that must be hand-carried through the night, across snow drifts and ankle-breaking sastrugi, to designated sampling locations.
Walking into the wind, my goggles removed to better see and avoid the more hazardous topography, my eyelashes will collect snow and ice, and mini drifts will form against my eyelids. When this happens, I’m careful not to blink too slowly, because if I do, my eyes will freeze shut and I’ll have to work in an even greater darkness.