Peterson David A, Campbell James R, Hyer Edward J, Fromm Michael D, Kablick George P, Cossuth Joshua H, DeLand Matthew T
Naval Research Laboratory, 7 Grace Hopper Avenue, Monterey, CA 93943, USA.
Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA.
NPJ Clim Atmos Sci. 2018;1. doi: 10.1038/s41612-018-0039-3. Epub 2018 Aug 20.
Intense heating by wildfires can generate deep, smoke-infused thunderstorms, known as pyrocumulonimbus (pyroCb), which can release a large quantity of smoke particles above jet aircraft cruising altitudes. Injections of pyroCb smoke into the lower stratosphere have gained increasing attention over the past 15 years due to the rapid proliferation of satellite remote sensing tools. Impacts from volcanic eruptions and other troposphere-to-stratosphere exchange processes on stratospheric radiative and chemical equilibrium are well recognized and monitored. However, the role of pyroCb smoke in the climate system has yet to be acknowledged. Here, we show that the mass of smoke aerosol particles injected into the lower stratosphere from five near-simultaneous intense pyroCbs occurring in western North America on 12 August 2017 was comparable to that of a moderate volcanic eruption, and an order of magnitude larger than previous benchmarks for extreme pyroCb activity. The resulting stratospheric plume encircled the Northern Hemisphere over several months. By characterizing this event, we conclude that pyroCb activity, considered as either large singular events, or a full fire season inventory, significantly perturb the lower stratosphere in a manner comparable with infrequent volcanic intrusions.
野火产生的强烈热量能够引发深厚的、充满烟雾的雷暴，即火积雨云（pyroCb），这种雷暴能够在喷气式飞机巡航高度以上释放大量烟雾颗粒。在过去15年里，由于卫星遥感工具的迅速普及，火积雨云烟雾注入平流层下部的情况越来越受到关注。火山爆发及其他对流层到平流层的交换过程对平流层辐射和化学平衡的影响已得到充分认识并受到监测。然而，火积雨云烟雾在气候系统中的作用尚未得到认可。在此，我们表明，2017年8月12日在北美西部同时发生的5次强烈火积雨云事件注入平流层下部的烟雾气溶胶颗粒质量与一次中等规模火山爆发相当，比之前极端火积雨云活动的基准水平大一个数量级。由此产生的平流层羽状物在数月内环绕北半球。通过对这一事件的特征描述，我们得出结论，火积雨云活动，无论是作为大型单一事件还是整个火灾季节的总量，都会以与罕见火山侵入相当的方式显著扰乱平流层下部。
