Canadian Pyrocumulonimbus Storms in 2014 Within a Global Context

Wild fire activity in western Canada in 2014 was noteworthy for fire size and total area consumed. It was also notable for the frequency and intensity of pyroconvective events, perhaps a signal of particularly aggressive fire behavior. As the northern hemisphere fire season of 2014 unfolded, biomass burning and pyroconvection were monitored continuously by an informal, international collaborative group intent on documenting occurrence of pyrocumulonimbus (“pyroCb” for short) storms, the tip of the pyroconvection intensity spectrum. Prior pyroCb case studies have shown these storms to coincide with extreme rates of spread, destruction of property and life in the wildland-urban interface, and injection of smoke to the upper atmosphere. PyroCb activity in western Canada in 2014 was unusually abundant. We analyze satellite data to determine that there were 24 pyroCbs in Canada in 2014 (8 in a single day, 14 July). However, it represented only a fraction of the pyroCb activity across the northern hemisphere. The global pyroCb activity led to several instances of stratospheric smoke pollution, which has still not been quantitatively assessed in terms of its role in weather and climate impact. Our study will detail the pyroCb occurrences in Canada, with a focus on major pyroCbs in Northwest Territories in July and August. The Canadian pyroCb activity and its impact on stratospheric smoke will then be placed in the context of other pyroCb activity in the United States and Siberian Russia.