Stratospheric Injection of Massive Smoke Plume from Canadian Boreal Fires in 2017 as seen by DSCOVR-EPIC, CALIOP and OMPS-LP Observations

Unprecedented amounts of tropospheric carbonaceous aerosols generated by wildfires in British Columbia (BC) on August and September 2017 were injected into the stratosphere on at least three different occasions. This extraordinary event was observed from space by both active and passive, profiling and mapping sensors. The Earth Polychromatic Imaging Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR) at the L-1 point observed the spatial and temporal evolution of the aerosol plume for about six weeks since the onset of the wildfires in early August. EPIC's unique capability of observing the diurnal cycle during daylight hours at any point on the Earth's surface allowed following the progression of the BC smoke plume several times (as many as six) depending on the location. EPIC's characterization of the BC plume was initially done in terms of the qualitative UV Aerosol Index (UVAI), that yielded record high values (in excess of 20). The unusually high UVAI pointed to an elevated aerosol layer well above the tropopause. The event was promptly confirmed by CALIOP and OMPS-LP observations, that clearly detected the presence of the stratospheric smoke plume in a layer between 12 and 16 km. CALIOP profiles of attenuated backscatter were used to constrain the aerosol layer height as the plume travelled above tropospheric water clouds in some instances and in completely clear skies on others. The resulting stratospheric carbonaceous aerosols ascended to at least 22 km. It was quickly mobilized eastward across the Atlantic Ocean, reaching Europe and Asia in a few days. It quickly spread in the northern hemisphere reaching peak concentration values in the stratosphere (15-17 km) between October 2017 to January 2018, when the NH poleward of 30°N was blanketed with carbonaceous aerosols. The temporal extent of the BC plume stratospheric aerosol perturbation lasted about 10 months, and its effect in terms of increased aerosol extinction in the stratosphere was comparable to that of a moderate volcanic eruption.