(540 words, ~2-3 minute read)
Over the last few weeks, I (Peter) have been in the lab testing our new ice melting system for extracting ancient air from Antarctic ice in order to study carbon-14 of carbon monoxide (14CO). 14CO can tell us about how the atmosphere oxidizes trace gases and particles out of the atmosphere, something we know little about before modern observations.
We are primarily running these tests to quantify the CO contribution of individual parts of the sampling process. For instance, moving an air sample through transfer pumps adds on the order of 10 ppb CO, while the sample itself begins with less than 100 ppb CO. We want to quantify this “blank” so we can correct our final sample measurements.
To sample the test gases, we use a Picarro cavity-ringdown spectrometer which, briefly, uses laser-light absorption to measure gas concentrations down to parts per billion (see more information from Picarro).
While not running tests, this instrument has been measuring ambient concentrations of trace gases in our laboratory. You can see it in the pictures below, along with the shiny new stainless-steel 14CO melter system.
Over this past Labor Day weekend, I noticed something very interesting in the Picarro data: the concentration of CO in room air was steadily rising from just over 100 parts per billion (ppb, same as 0.1 parts per million on the plot) on September 1st, and nearly doubling to over 200 ppb by September 6th!
By September 7th the concentration had dropped back down to near where it was before the weekend.
What caused this!?
It took me until September 5th to realize the likely culprit: smoke from forest fires burning across the western US and Canada traveling across the continent on the jet stream.
I am originally from Washington State and had been hearing from friends and family about the many active fires and thick smoke and even ash falling in metropolitan areas!
The image below was taken on September 4th, from the NASA Visible Infrared Imaging Radiometer Suite and featured in a NASA Earth Observatory article last week. You can see a pall of smoke crossing the entire United States, reaching to New York and beyond.
Upstate New York air quality data, gathered from AirNow, show a clear rise in the air quality index—indicating moderate/poor air quality—at the same time as the lab background air rising.
Carbon monoxide is produced in fires due to incomplete combustion (not all the way to producing CO2), so where there are large forest fires or other biomass burning events one can expect elevated CO concentrations—which are dangerous for human health if concentrations reach into parts per million. For more information, NASA Earth Observatory in 2015 wrote a great in-depth article about large fires and CO in Indonesia.
Luckily, this rise in background CO didn’t affect the tests I was running—our systems are quite leak-tight by design—but this demonstrates the long-reaching effects of events occurring on the other side of North America!
We live in a very inter-connected world in many ways, and this goes to show how we can detect impacts of events like forest fires even 1,500 miles from where they occur!
*The lab air data in the plots (magenta +) is taken from approximately representative 10-20 minute periods, plotting all measurements to show variability (about one measurement is taken every 2.5 seconds).