Smoke with Induced Rotation and Lofting (SWIRL) in the Stratosphere
Smoke with Induced Rotation and Lofting (SWIRL) in the Stratosphere
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DOI：
10.1175/jas-d-20-0131.1
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发表时间：
2020-12-01
影响因子：
3.1
通讯作者：
Nedoluha, Gerald E.
中科院分区：
文献类型：
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作者：
Allen, Douglas R.;Fromm, Michael D.;Nedoluha, Gerald E.
2019/20 年的澳大利亚丛林大火产生了异常大量的火积雨云 (pyroCb)，将大量烟雾注入平流层下部。 2019年12月29日至2020年1月4日期间的pyroCbs特别强烈，产生了覆盖整个半球的气溶胶，持续数月。这一所谓的澳大利亚新年 (ANY) 事件产生的羽流演变成平流层气溶胶团，直径约 1000 公里，厚度约数公里。该羽流最初于 1 月份向东移向南美洲，然后在 2 月份逆转航线向西移动，经过澳大利亚南部，最终于 3 月初到达南非。这种奇特的运动与1月份接近8 K day(-1)和2月份接近6 K day(-1)的羽流位温稳定上升有关，这是由于烟雾吸收太阳辐射造成的局部加热所致。这种加热导致了垂直温度偶极子异常、正位涡（PV）异常和反气旋环流。我们将烟羽的这种动力成分称为“诱导旋转和飘逸的烟雾”(SWIRL)。本研究使用海军全球环境模型 (NAVGEM) 分析来详细描述 2 个月内的 SWIRL 结构。主要诊断工具是基于标量 Q 诊断的反气旋边缘计算。这提供了计算各种 SWIRL 属性随时间演变的框架：PV 异常、流函数、水平尺寸、垂直厚度、流速和倾斜。此外，我们还研究了温度异常偶极子、旋涡与大规模风切变的相互作用，以及与空气从平流层下部到中部的飘移相关的臭氧异常。
The Australian bushfires of 2019/20 produced an unusually large number of pyrocumulonimbus (pyroCb) that injected huge amounts of smoke into the lower stratosphere. The pyroCbs from 29 December 2019 to 4 January 2020 were particularly intense, producing hemispheric-wide aerosol that persisted for months. One plume from this so-called Australian New Year (ANY) event evolved into a stratospheric aerosol mass similar to 1000 km across and several kilometers thick. This plume initially moved eastward toward South America in January, then reversed course and moved westward passing south of Australia in February and eventually reached South Africa in early March. The peculiar motion was related to the steady rise in plume potential temperature of similar to 8 K day(-1) in January and similar to 6 K day(-1) in February, due to local heating by smoke absorption of solar radiation. This heating resulted in a vertical temperature anomaly dipole, a positive potential vorticity (PV) anomaly, and anticyclonic circulation. We call this dynamical component of the smoke plume "smoke with induced rotation and lofting" (SWIRL). This study uses Navy Global Environmental Model (NAVGEM) analyses to detail the SWIRL structure over 2 months. The main diagnostic tool is an anticyclone edge calculation based on the scalar Q diagnostic. This provides the framework for calculating the time evolution of various SWIRL properties: PV anomaly, streamfunction, horizontal size, vertical thickness, flow speed, and tilt. In addition, we examine the temperature anomaly dipole, the SWIRL interaction with the large-scale wind shear, and the ozone anomaly associated with lofting of air from the lower to the middle stratosphere.