Fig. 4: Time evolution of the daily total mass of CO, CH3CN, H2O and aerosols above the 380 K potential temperature, between 20 °S and 82 °S. | Communications Earth & Environment

Fig. 4: Time evolution of the daily total mass of CO, CH3CN, H2O and aerosols above the 380 K potential temperature, between 20 °S and 82 °S.

From: The 2019/20 Australian wildfires generated a persistent smoke-charged vortex rising up to 35 km altitude

Fig. 4

The dotted and solid lines correspond to daily data and 1-week smoothed data, respectively. Envelopes represent two standard deviations over the 1-week window (see “Methods”). As shown in this figure, the levels of CO, CH3CN, H2O, and aerosols started to increase simultaneously and kept increasing during ~2–3 weeks, a duration corresponding probably to the time taken by products injected in the lowermost stratosphere to ascend above 380 K. The stratospheric masses of carbon monoxide (CO) and acetonitrile (CH3CN) bounded within the southern extratropics increase abruptly by 1.5 ± 0.9 Tg and 3.7 ± 2.0 Gg, respectively during the first week of 2020. This gives a CO/CH3CN mass ratio of 0.0025, consistently with previous estimates for temperate Australian wildfires42. The injected mass of water was estimated at 27 ± 10 Tg that is about 3% of the total mass of stratospheric overworld water vapour in the southern extratropics. The shading shows that the amplitude of fluctuations increases sharply during the sharp rise of species masses, reflecting the fact that sampling of the bubble by MLS is more random than on a more homogeneous field. The lagging increase of the aerosol mass is due to the fact that the OMPS-LP extinction retrieval saturates at extinction values above 0.01 km−1. Profiles are, therefore, truncated below any altitude exceeding this value, which can lead to an underestimation of the early aerosol plume when it is at its thickest. This artifact, which explains the slower increase of aerosol mass than gases, persists until mid-February when the plume is sufficiently dispersed so that OMPS-LP extinction measurements no longer saturate.

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