The Mother of all PyroCbs: How did the Pacific Northwest PyroCb Event in 2017 Stand Out?
Abstract
On 12 August 2017 a cluster of pyrocumulonimbus (pyroCb) storms erupted in Washington state (USA) and British Columbia (Canada). It has already been established that the resultant stratospheric smoke plume was unprecedented in the satellite era (since 1979). However, to date, this Pacific Northwest pyroCb event (PNPE) has not been thoroughly quantified in a manner that establishes its source term in relation to other big pyroCb events. We use an assortment of space- and ground-based remote sensing to characterize the number of pyroCbs, eruption timeline, initial stratospheric perturbation, plume height and transport in the first five days after the eruption event. We also compare the metrics we establish for the PNPE with other notable pyroCb events, such as Norman Wells (Northwest Territories Canada, August 1998), Chisholm (Alberta Canada, May 2001), Canberra (Australian Capital Territory, January 2003), Great Divide (Victoria Australia, December 2006), Black Saturday (Victoria Australia, February 2009), and Great Slave Lake (Northwest Territories, Canada, August 2014). We find that with respect to UV absorbing aerosol index--a trustworthy signal of optically dense and high-altitude smoke and ash plumes--the PNPE stood out strongly from all other pyroCb events, even though plume height and optical depth were not unusual. We also report that, like the other pyroCb cases listed, the pyroconvective pathway fully explains the source term for the noteworthy and unprecedented plume observed around the Northern Hemisphere stratosphere for several months.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC11F1151F
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0230 Impacts of climate change: human health;
- GEOHEALTH;
- 4313 Extreme events;
- NATURAL HAZARDS