Transport of the 2017 Canadian wildfire plume to the tropics and global stratosphere via the Asian monsoon circulation

CORINNA KLOSS; GWENAËL BERTHET; PASQUALE SELLITO; FELIX PLÖGER; SILVIA BUCCI; SERGEY KHAYKIN; FABRICE JÉGOU; GHASSAN TAHA; LARRY W. THOMASON; BRICE BARRET; ERIC LE FLOCHMOEN; MARC VON HOBE; ADRIANA BOSSOLASCO; NELSON BÈGUE; BERNARD LEGRAS

ATMOSPHERIC CHEMISTRY AND PHYSICS

COPERNICUS PUBLICATIONS

Lugar: Gottingen; Año: 2019

1680-7316

We show that a fire plume originating at high northern latitudes during the Canadian wildfire event in July/August 2017 reached the tropics, and subsequently the tropical stratosphere via the ascending branch of the Brewer-Dobson Circulation (BDC). The transport from high to low latitudes in the upper troposphere and lowermost stratosphere was mediated by the anticyclonic flow of the Asian monsoon circulation. The fire plume reached the Asian monsoon area in late August/earlySeptember, when the Asian Monsoon Anticyclone (AMA) was still in place. While there is no evidence of mixing into the center of the AMA, we show that a substantial part of the fire plume is entrained into the anticyclonic flow at the AMA edge, and is transported into the tropical Upper-Troposphere?Lower-Stratosphere (UTLS), and possibly the Southern Hemisphere particularly following the north-south flow on the eastern side. In the tropics the fire plume is lifted by ∼1.5 km per month.Inside the AMA we find evidence of the Asian Tropopause Aerosol Layer (ATAL) in August, doubling background aerosol conditions with a calculated top of the atmosphere shortwave radiative forcing (RF) of -0.05 W/m 2 . The regional climate impact of the fire signal in the wider Asian monsoon area in September exceeds the impact of the ATAL by a factor of 2-4 and compares to that of a plume coming from an advected moderate volcanic eruption. The stratospheric, trans-continentaltransport of this plume to the tropics and the related regional climate impact point at the importance of long-range dynamical interconnections of pollution sources.