Studying the Impact of Lightning on Atmospheric Chemistry: focus on the Tropics (SPARkC)

Until now, all the reactions taking place in Earth’s atmosphere were assumed to result, directly or indirectly, from sunlight.

These reactions determine the ability of the atmosphere to maintain a stable composition (“oxidizing” or “self-cleansing” capacity) and are thus essential for climate and for the sustainability of life and most ecosystems. Lightning can also trigger numerous reactions in the atmosphere but many of them have never been studied.

Project SPARkC proposes to study these unexplored contributions of lightning to atmospheric chemistry, focusing first on the regions the most impacted by lightning: the tropics.

Experiments will be performed at the High Voltage Laboratory of Uppsala University, where the different components of lightning, represented by different types of high-energy electrical discharges, will be produced in different gas mixtures relevant to tropical air masses.

The formation of radicals, stable tracer compounds, and aerosol particles from electrical discharges in humid air and in the presence of isoprene, terpenes and related compounds, will be investigated using expertise and instruments from KTH. Models will be developed to quantify the impact of lightning in tropical regions and in the global atmosphere.

SPARkC will thus provide the first extensive information on the contribution of these long-overlooked processes to tropospheric chemistry.