近日，美国哈佛大学Frank N. Keutsch团队报道由野火驱动的雷暴产生的大气溶胶颗粒增强辐射冷却。2025年12月12日出版的《科学进展》杂志发表了这项研究成果。
大型野火能催生火积云，将巨量烟尘气溶胶喷射至上对流层/下平流层区域，这些气溶胶可存留数月并影响气候。然而，由于直接观测数据有限，人们对火积云气溶胶的辐射效应认知仍很匮乏。
研究组通过飞机原位观测获取了生成5日后的火积云烟尘数据，弥补了从新排放到数周乃至数月龄期气溶胶演化过程的关键观测空白。采样烟尘主要包含通过云内过程及上对流层/下平流层高效聚并作用形成的超大尺寸气溶胶颗粒（直径达500-600纳米）。与典型非火积云烟尘中较小颗粒相比，这些大颗粒使向外辐射增加30%-36%，显著增强大气辐射冷却效应。气候模型若沿用较小气溶胶尺寸假设，可能严重低估火积云烟尘的冷却效应。随着火积云事件日益频繁，精确表征其气溶胶特性对改进气候预测至关重要。
附：英文原文
Title: Enhanced radiative cooling by large aerosol particles from wildfire-driven thunderstorms
Author: Yaowei Li, John A. Dykema, David A. Peterson, Xu Feng, Xiaoli Shen, Nicole A. June, Michael D. Fromm, Theodore M. McHardy, Justin L. Jacquot, Jasna V. Pittman, Bruce C. Daube, Steven C. Wofsy, Jonathan Dean-Day, Anita D. Rapp, Kenneth P. Bowman, Daniel J. Cziczo, Loretta J. Mickley, Jeffrey R. Pierce, Frank N. Keutsch
Issue&Volume: 2025-12-12
Abstract: Large wildfires can generate pyrocumulonimbus (pyroCb) clouds, injecting massive quantities of smoke aerosols into the upper troposphere and lower stratosphere (UT/LS), where they persist for months and affect climate. The radiative effects of pyroCb aerosols, however, remain poorly understood because of limited direct measurements. Here, we present in situ aircraft measurements of 5-day-old pyroCb smoke, addressing a critical observational gap in aerosol evolution from freshly emitted to weeks-to-months-aged states. The sampled smoke primarily contained unusually large aerosol particles (500 to 600 nanometers in diameter), formed through cloud processing and efficient coagulation in the UT/LS. Compared to smaller particles in typical non-pyroCb smoke, these large particles increase outgoing radiation by 30 to 36%, substantially enhancing atmospheric radiative cooling. Climate models may greatly underestimate this cooling effect by assuming smaller aerosol sizes for pyroCb smoke. As pyroCb events become more frequent, accurately representing their aerosol properties is essential for improving climate projections.
DOI: adw6526
Source: https://www.science.org/doi/10.1126/sciadv.adw6526