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

Corinna Kloss (1) , Gwenaël Berthet (1) , Pasquale Sellitto (2) , Félix Ploeger (3) , Silvia Bucci (4) , Sergey Khaykin (5) , Fabrice Jégou (1) , Ghassan Taha (6) , Larry W. Thomason (7) , Brice Barret (8) , Eric Le Flochmoën (8) , Marc von Hobe (3) , Adriana Bossolasco (1) , Nelson Bègue (9) , Bernard Legras (4)

1 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
2 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques
3 IEK-7 - Institut für Energie- und Klimaforschung - Stratosphäre
4 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
5 STRATO - LATMOS
6 USRA - Universities Space Research Association [Washington]
7 LaRC - NASA Langley Research Center [Hampton]
8 LAERO - Laboratoire d'aérologie
9 LACy - Laboratoire de l'Atmosphère et des Cyclones

We show that a fire plume injected into the lower stratosphere at high northern latitudes during the Canadian wildfire event in August 2017 partly reached the tropics. The transport to the tropics was mediated by the anticyclonic flow of the Asian monsoon circulation. The fire plume reached the Asian monsoon area in late August/early September, 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 from the extratropics to the tropics, and possibly the Southern Hemisphere particularly following the north– south flow on the eastern side of the AMA. In the tropics the fire plume is lifted by ∼ 5 km in 7 months. 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 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 com- pares to that of a plume coming from an advected moderate volcanic eruption. The stratospheric, trans-continental trans- port of this plume to the tropics and the related regional cli- mate impact point to the importance of long-range dynamical interconnections of pollution sources.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

Corinna Kloss, Gwenaël Berthet, Pasquale Sellitto, Félix Ploeger, Silvia Bucci, et al.. Transport of the 2017 Canadian wildfire plume to the tropics via the Asian monsoon circulation. Atmospheric Chemistry and Physics, 2019, 19 (21), pp.13547-13567. ⟨10.5194/acp-19-13547-2019⟩. ⟨insu-02354522⟩