Emission Impossible or a Match Made in Heaven

Created on Tuesday, 20 September 2011 Written by pre0fmp

STRATUS NEWS ARTICLE

Linking Meteorological and Chemical Observations

Local fire causes changes in trace gas measurements at Lochranza, Arran. Ground breaking results from a recently performed study show how changes in wind direction cause changes in the trace gasses in the atmosphere.

We all know that the smoke from a fire doesn't always linger but gets moved around by the wind. This is an example of the interaction between chemistry and meteorology. Being able to understand how the weather (meteorology) can affect what we breathe in (atmospheric chemical composition) is important for health and air quality. So what do we mean by the weather? We experience the weather every day: sunshine, rain, wind, snow, high temperatures. Trying to understand their effects on atmospheric chemistry is much more complicated due to numerous interactions within the system.

Five enthusiastic PhD students from across the world, from different universities, and disciplines were brought together on the not so sunny shores of the Isle of Arran by a common interest in studying these interactions. Trace gas compositions and several meteorological parameters were measured at the Lochranza field centre for a period of two weeks in the middle of September. Analysis of the data revealed some interesting areas where the meteorology appeared to influence the chemical composition.

Further investigation into the meteorological conditions and local influences at the times of interest was performed. During one particular day a small fire to the south of the site was reported. Comparisons with the wind direction suggested that the peak in the measurements could be emissions from the fire that had been transported up the island. Bus arrival times at a stop in close proximity to the field centre were cross examined with the measurements to see if there were any influences from the local buses: none were found. Remnants from a hurricane (strong winds) that passed through Arran a few days before the experiment resulted in a misaligned inlet. Representative samples of air may therefore not have been measured.

Conclusions made by the students highlighted the importance of considering a multitude of factors when interpreting data. Several correlations were found within the data but to confirm causality more variables should be collected. These include ones previously unconsidered which could potentially influence the measurements, such as times when deliveries are made to the on-site kitchen. Other aspects of atmospheric chemistry also need to be considered such as aerosol particles as these can help to determine source types and areas. Most importantly all chemical measurements taken in the atmosphere need to be examined alongside meteorological data. This union of disciplines may not always be perfect but is necessary to fully understand such complex interactions.