Two physics students have worked out some of the final kinks in a complicated computer code, making it possible for a Bowdoin physics professor to finalize the data analysis from his six-year atmospheric study in a New England forest.
In 2006, Associate Professor of Physics and Astronomy Mark Battle began collecting data from a climate-monitoring device, affectionately named by a former student “the Armadillo,” at an environmental research station in the Harvard Forest, a 3,000-acre tract in north-central Massachusetts. Battle’s equipment measures the flows of carbon and oxygen that enter and leave the atmosphere above the forest canopy and midway to the ground.
“[Nearly] every second for the past four years, the equipment has been capturing data,” Sam Seekins ’14 explained. Seekins and Karina Graeter ’14 spent eight weeks this summer detecting and eliminating possible anomalies in Battle’s enormous amount of data.
“We’re working out the bugs to process the data so we can understand it and see what the oxygen and carbon dioxide are doing,” Graeter said. “So we can compare the high- and the low-intake [from above and below the forest canopy], to see how they’re affected by seasonal changes, day and night changes, and biological activity.”
Biological activity in this case refers to plants absorbing carbon dioxide and releasing oxygen as they build leaves and roots, and microbes in the soil doing the reverse, that is eating up roots and leaves and releasing carbon dioxide and consuming oxygen. “In ecosystems with diverse biological activity one cannot assume a constant consumption/production ratio if considering a plant’s need for water and nutrients. It is our opinion that current models can be improved and we would like to contribute to that improvement,” Seekins said. The research should help refine estimates of the amount of carbon the forest can absorb.
Perhaps most importantly, establishing a precise understanding of carbon fluxes in this situation will also help future researchers better predict the buildup of greenhouse gases, and estimate the extent of current and future warming, Graeter explained.
The carbon dioxide and oxygen concentration on the air samples taken from the top of the tree canopy and from the midway point must be refined and exclude periods that could produce potentially poor data, Seekins said. “Much of the behind-the-scenes work involved writing the code that would process the data and prepare it for analysis, graphing, etc.,” he said.
Graeter and Seekins spent their days this summer in front of computers in a computer lab, each focused on defusing different data landmines. Seekins first studied how the climate-monitoring instrument reported pressure, and then prepared code to calculate the actual pressure values and find any pressure imbalances within the instrument that will throw off measurements of oxygen levels.
Graeter corrected for other instrumental biases, calibrations and related errors. She also designed and ran an experiment testing the effect of airflow imbalances in an oxygen analyzer. Neither had experience working with coding before; they learned everything on the job. Seekins and Graeter both worked with MATLAB, a programming environment for algorithm development, data analysis, visualization and numerical computation.
“Although it was hard at times to dive blindly head first into a heap of broken code, I am thankful that I had the experience of figuring out the solutions for myself,” Graeter said. “I now feel much more confident about my coding ability, and it is a skill which I can apply to many academic or other pursuits.”
Graeter and Seekins are two of 10 students who have assisted Battle’s project over the years. Graeter, who has a yearlong Maine Space Grant/Women in the Physical Sciences Research Fellowship, will continue working with Battle this fall, helping to interpret the data.
Besides physics, Seekins is majoring environmental studies and Graeter is majoring in earth and oceanographic science. Both said they hope to continue working in the field of climate science after graduating.